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All dredged up and no place to go : the disposal of contaminated dredged material from greater Vancouver,… Gorham, Richard Arthur 1985

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A L L D R E D G E D UP A N D NO P L A C E T O GO: T H E DISPOSAL O F C O N T A M I N A T E D D R E D G E D M A T E R I A L F R O M G R E A T E R V A N C O U V E R , BRITISH C O L U M B I A , INTO T H E NEIGHBOURING STRAIT O F GEORGIA  By RICHARD ARTHUR GORHAM L L . B . , The University of Western Australia, 1974 B.Sc, The University of British Columbia, 1979  A THESIS S U B M I T T E D IN P A R T I A L F U L F I L L M E N T THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE  in  T H E F A C U L T Y O F G R A D U A T E STUDIES (Resource Management Science) .  We accept this thesis as conforming to the required standard  T H E U N I V E R S I T Y O F BRITISH C O L U M B I A September 1985 © R i c h a r d Arthur Gorham, 1985  OF  In  presenting  degree  this  at the  thesis  in  partial  fulfilment  of  University of  British  Columbia,  I agree  freely available for reference and study. copying  of  department  this or  thesis by  publication of this  his  for scholarly or  her  I further agree  purposes  may  representatives.  It  be is  requirements  for  an  Department of The University of British Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3  advanced  that the Library shall make it that permission  for extensive  granted  head  by the  understood  that  thesis for financial gain shall not be allowed without  permission.  DE-6(3/81)  the  of  my  copying  or  my written  i i  ABSTRACT  The  thesis  provides  information  an  from  integrated  which  review  management  and  analysis  procedures  of  for  strategic the  scientific  environmentally  acceptable disposal of dredged materials from Greater Vancouver into the Strait of Georgia are determined.  An  analysis of reported and suspected contamination of Vancouver's  waterways  identifies trace metals and hydrophobic organic chemicals that warrant concern by authorities responsible for the management of dredged material disposal. processes,  transformations  and  pathways  of  these  contaminants  in  environment subsequent to dredged material disposal are reviewed. that  areally  concern, occur,  confined  but  that  could  degradation  of  suitable  release of contaminants  have  unpredictable and  disposal  sites  is  from the disposal  perhaps  substantial  the  The  marine  It is argued of  negligible  area, were  environmental  it  to  conse-  quences.  The  major  during  or subsequent  particulate port  potential  pathway  to disposal  material.  through  the  of  Biological  food  chain  is via  is  a  organic  contaminants.  metabolites  is  potentially  chlorinated  and  lower  release  from  the resuspension  dredged  and  potentially  significant  Biological  transformation  significant  molecular  Desorptive release of contaminants  weight  for  mercury  organic  and their  release  and  material  transport of  accumulation of contaminants  hydrophobic  also  contaminant  more  some  of  compounds  trans-  pathway  to  of  fine  for  soluble the  less  concern.  from the disposed sediments into solution is  usually negligible, with the possible exceptions of cadmium and mercury.  i i i  A  review  and  of  the physical  dispersion  oceanographic  during  or  factors  subsequent  characteristics  of  and  are  disposal  promote contaminated sediment to  dredged  material  where such release will  only four areas within the Strait Two  that  of Georgia  disposal  be minimal.  at  the  other  unsuitable  as  two  one  sites,  ocean near  identifies There are  that exhibit these characteristics.  these areas are adjacent to valuable and sensitive biological consequently  erosion  dumping Smelt  sites.  Bay,  resources  Dredged  Cortes  material  Island, and  other off McNaughton Point, Sechelt Peninsula, should result in minimal  the  adverse  environmental impact.  Available that  methodologies  to  identify  preclude their environmentally  sites are discussed.  dredged  materials  acceptable disposal  with contaminant at  these  levels  recommended  i v  TABLE OF  CONTENTS Page No.  T i t l e Page  Acknowledgements  ix  1.0  INTRODUCTION  I  1.1  Study Purpose  8  2.0  A SCIENTIFIC P E R S P E C T I V E  2.1  Containment or Dispersion  2.2 2.3 2.4  Release The Chemistry of Contaminant Behaviour Chemicals of Environmental Concern  3.0  DREDGING AND MAINLAND  II II  D R E D G E D M A T E R I A L S IN T H E  Dredging in the Vancouver Region Sediment Contaminants in the Vancouver Region T r a c e Metals Organic Contaminants Conclusion  4.0  T R A C E METAL PATHWAYS MARINE ENVIRONMENT  4.2.1 4.2.2 4.2.3 4.3 4.3.1 4.3.2 4.3.3 4.4 4.4.1 4.4.2  LOWER 22  3.1 3.2 3.2.1 3.2.2 3.3  4.1 4.1.1 4.2  14 15 19  AND  P R O C E S S E S IN  Introduction T r a c e Metal Speciation T r a c e Metal Release During Water Column Passage Salinity Alteration Alteration of Redox and pH Conditions F i e l d Monitoring T r a c e Metal Release from Settled Sediments C h e m i c a l Release Processes Biological Release Processes Conclusion Environmental E f f e c t s of Released T r a c e Metals Cadmium Mercury  22 25 36 42 56 THE 59 59 62  1  66 67 70 75 77 77 81 92 96 96 99  V  Page 5.0  ORGANIC POLLUTANT PATHWAYS THE MARINE ENVIRONMENT  5.1 5.2 5.3 5.4 5.4.1 5.4.2 5.5 5.5.1 5.5.2 5.5.3 5.5.4 5.5.5 5.5.6 5.5.7 5.6 6.0  6.1 6.2 6.3 6.3.1  •  AND  PROCESSES  No.  IN 104  Introduction Release of Organic Contaminants to the Water Column Biological Uptake of Organic Contaminants Biological Transformation Microbial Degradation Metabolism by Higher Organisms Properties, Bioaccumulation and Metabolism of Organic Contaminants of Concern Polychlorinated Biphenyls (PCBs) Hexachlorobutadiene ( H C B D ) Polychlorinated Dibenzofurans ( P C D F ) Pentachlorophenol (PCP) Chlorinated Benzenes Polyaromatic Hydrocarbons (PAHs) Phthalate Esters (PAEs) Conclusion  104  136 138 140 141 144 150 152  PROCESSES EFFECTING T H E PHYSICAL O F DISPOSED D R E D G E D M A T E R I A L  157  106 117 127 128 129 131  DISTRIBUTION  Introduction During Water Column Passage Subsequent to Settling Physical Factors E f f e c t i n g Sediment Resuspension Biological Factors E f f e c t i n g Sediment Resuspension Conclusion  165 167  D I S P O S A L SITE O P P O R T U N I T I E S WITHIN G E O R G I A STRAIT  170  7.1 7.2  Recommended Disposal Site Characteristics Identification of Potential Disposal Sites  170 173  8.0  RESOURCES  182  8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 8.9 8.10  Introduction Groundfish Bent hie Crustaceans Molluscs Pelagic F i s h Marine Mammals Marine Birds Human Recreation Parks and Reserves Cone lusion  6.3.2 6.4 7.0  157 158 161 161  IN C O N F L I C T  >  182 185 189 191 196 202 204 209 21 I 213  Page No. 9.0  CONCLUSIONS  221  9.1 9.2 9.3  Introduction Dredged Sediment C r i t e r i a The Need for F i e l d Assessment  221 225 230  10.0  LITERATURE  233  CITED  VI 1  LIST O F F I G U R E S Figure  Page No.  1.  Location map - Strait of Georgia  4  2.  Location map - Greater Vancouver  5  3.  Schematic representation of contaminant transport and fate  16  k.  Freundlich adsorption isotherm  5.  Bioaccumulation of six chlorinated benzenes in guppies Relationship between current, speed, particle diameter, and sediment erosion, transport and deposition.  6.  7.  8.  9.  10.  11.  108  121  163  Georgia Strait - Location of proposed dumpsites  175  Location of proposed North Stuart Channel dumpsite (Area I)  176  Location of proposed McNaughton Point dumpsite (Area 2)  177  Location of proposed Comox and Denman Island dumpsites (Area 3)  178  Location of proposed Smelt Bay (Area k)  179  dumpsite  vii i  LIST O F T A B L E S Table I.  II.  Page No. Comparative towing costs for Point Grey and ocean disposal sites.  6  Quantity of dredged materials disposed at dumpsites adjacent to the lower mainland, 1976-79.  24  Contaminant concentrations in False Creek and Burrard Inlet sediments.  26  Potential anthropogenic sources of trace metal contamination of Vancouver's waterways.  29  Canadian Environmental Contaminants A c t list of priority chemicals.  31  E P A priority pollutant list showing classification by extraction group.  33  Priority ratings for industrial chemicals in British Columbia and the Yukon.  34  Contaminants of concern identified or suspected within Vancouver sediments.  37  T r a c e metals in sediments of the Fraser River.  38  Levels of metals in sediments from the Fraser River and the Columbia River, B.C.  40  Summary of incidents of human poisoning by toxic metals in the aguatic environment of Japan.  61  XII.  Mechanisms  64  XIII.  Potential dredged material disposal in Georgia Strait.  III.  IV.  V.  VI.  VII.  VIII.  IX.  X.  XI.  XIV.  XV.  XVI.  for trace mineral bonding. areas  174  Species names of organisms cited in Section 8.0.  184  Quantification of resource conflicts at the proposed ocean dumping sites.  214  Comparative towing costs for recommended disposal sites.  218  ix  ACKNOWLEDGEMENTS  The successful  completion of this  thesis  is  in no small  part  due  to my  wife,  Catherine, who has given me encouragement and support (as well as a charming daughter) during its preparation. for  her uncomplaining  script.  and  I also owe extreme gratitude  extremely  efficient word  processing  to Maria of  the  Mees manu-  1  INTRODUCTION  The environmental management of dredged materials is faced with the residue of past neglect.  Urban, agricultural and industrial  activities  adjacent to many areas of our coast have resulted in accumulations of contaminants and  within the sediments. The sediments  estuarine  areas  are  especially  prone to  of  protected bays  interrment of  contami-  nants.  Sediments  that  have  been contaminated  by  chemicals  from  surface  runoff and groundwater inflow, or from industrial and domestic  waste  discharges, present a difficult problem when dredging is required. removal  and  essential  to  relocation of establish  facilities.  However  deleterious  materials  this  release  organisms,  tends then  and  coastal maintain  it can into  also  short-  promote  the  and  uptake of or  harbour  navigational  the pelagic  to favour  either  and  sediments  is  waterways  and  release of  benthic  often port  potentially  environment.  the contaminants  long-term  The  by  If  marine  deleterious e f f e c t s  may  occur.  Dredging  and  dredged  material  disposal  involves  agitation of the sediments, their exposure to  the  the water  mechanical column  and  their  relocation into a physical, chemical and biological environment  that  may  differ  substantially  from  the  dredged  release may result from each of these processes.  site.  Contaminant  2  Water quality perturbations at the dredge site generally subside rapidly upon  cessation  Wullschleger, (e.g.  of  dredging  1975; Wakeman,  techniques, timing  reduce  activities  potential  and  impacts  (Lee,  1976; Hoos, rate of  upon  1976;  1976).  dredging)  particularly  Fulk,  Gruber  Mitigative may  be  sensitive  and  measures  necessary  biota,  but  to our  dependence upon navigable waterways will otherwise generally override our concern for  the short-term  environmental effects at  the dredge  site.  For  the  environmental  manager  taminated dredged material limited:  the  primary  issue  is related to disposal.  concerning  con-  The options  are  on land, into the coastal sea, or into the deep ocean. The  most economical of these is the coastal sea but this option requires careful valuable  and critical resources  examination so that we may be assured that the of  this  region  are  preserved  and  protected  for  future generations.  Vancouver, British Columbia, is the largest urban-industrial centre and the major port in western Canada.  Dredging  activities are crucial to  the maintenance of the port facilities (Willams, 1976).  Between three  million and six million tonnes of sediments are annually dredged from the  region (H. Nelson, EPS,  pers. comm.,  these materials can be disposed at  1985).  Although some  foreshore sites, .lack of  available  sites, concerns for the environmental effects of upland disposal, the high engineering costs of this disposal  methodology,  of  and  require that  substantial quantities of dredged material are marine disposed.  3  Vancouver Georgia, variety  is  located  which of  the  comprises  valuable  vities (Figures  on  a  dynamic  fisheries  I and 2).  south-eastern  and  edge  estuarine  commercial  Due to its  of  the  system and  Strait  of  supporting  recreational  limited municipal and  a  acti-  industrial  development, classical pollution impacts have rarely been observed and the region has generally been perceived as nearly pristine 1983) . Strait  The of  disposal  Georgia  of  has  dredged recently  materials induced  (Waldichuk,  from Vancouver  considerable  and  into  the  increasing  controversy.  The nearest marine alternative to disposing of dredged material in the Strait  of  Vancouver by  the  Georgia  is  in  Island.  The use of this alternative was  Environmental  contaminated  sediments  1984) . Although  the  offshore  Protection from  the use of  False  deep  Service Creek  ocean  for  to  west  of  recently required the  (Brothers  the deep ocean may  the  disposal and  of  Sullivan,  lessen the potential  environmental costs of dredged material disposal, it adds substantially to the engineering costs of a dredging program (Table I) and may  not  always be preferred.  Dredged  sediments  from  the  Greater  uncontaminated natural sediments levels of toxic pollutants. the  appropriately  Georgia  Strait  possible  substrate  result,  but  is  these  to deposits  area , vary  that contain  disposal  negligible alteration are  of  (Levings, and  natural 1982).  burial  transient  of and  sandy Short  benthic rarely  sediments term  with in  turbidity,  organisms  cause  from  substantial  The environmental hazard associated  managed  effects  Vancouver  may  measurable  4  125°  124*  123°  '  0  Compiled from Canadian E n e r g y , M i n e s and R e s o u r c e s Map N M - 9 / 1 0  FIGURE 1. L o c a t i o n  Map  6 TABLE I.  Comparative Towing Costs f o r P o i n t Grey and Ocean Disposal  Sites.3  Disposal  Component  Sites  P o i n t Grey  Ocean  Tug r e q u i r e m e n t s  500 HP  2400 HP + 1200 HP  Tug h i r e  $170/hr  $8000/day + $6000/day  Barge r e q u i r e m e n t s  1000 m 3  Barge h i r e  $300/day  $1500/day b  Trip duration  12 hrs  4 days  Trip cost  $2340  $62,000  Cost per m 3  $2.34  $8.86C  7000 m 3 i n t o t a l 6  a.  S o u r c e : P e r s o n a l communication w i t h Mr K. Longbottom, Seaspan I n t . , 1984. Costs f o r ocean d i s p o s a l are based on the use o f a dumpsite r e c e n t l y used by B . C . P l a c e C o r p . to d i s p o s e o f c o n t a m i n a t e d F a l s e Creek s e d i m e n t . I t i s 50 n a u t i c a l m i l e s west o f B a r k l e y Sound.  b.  The two 2000m and one 3000m barges used by B . C . P l a c e C o r p . were l e a s e d from San D i e g o , none b e i n g a v a i l a b l e i n t h i s s i z e range i n B r i t i s h C o l u m b i a . H i r e r a t e s used here are quoted w i t h t h e assumption t h a t , i f ocean d i s p o s a l became the common p r a c t i c e , l o c a l o p e r a t o r s would p r o v i d e t h i s s i z e barge under c o m p e t i t i v e c i r c u m s t a n c e s .  c.  This estimate r e f l e c t s costs for a r o u t i n e o p e r a t i o n . B . C . P l a c e ' s r e c e n t d i s p o s a l o f 325,000 m 3 o f contaminated s u r f a c e sediments from F a l s e Creek i n t o deep ocean water c o s t $ 3 . 2 m i l l i o n (.pers. comm., R. W a t e r s , B . C . P l a c e C o r p . , 1984). T h i s equates to a towing c o s t of $9.82/m3.  7  long  term  degradation  of  the  environmental  disposal sites (Peddicord, 1980). and  recolonization of  usually  the  restore the disposal  fact  that  clean  at  appropriate  Upward migration of buried infauna  disposal  mound  from  site to its original  tivity within the short term (Levings,  The  quality  sedimentary  adjacent  areas  will  or equivalent produc-  1982).  material  can  be  disposed  cheaply  within Georgia Strait without significant ecological impact justifies the continued use of thus  the Strait  becomes one of grossly  for this purpose.  appropriate management  natural  and  polluted sediments  degrees  of  disposal  sites and methodologies  contamination.  Georgia Strait  Up  exist  without significant  inappropriate disposal  sites,  logies, or the disposal contamination,  may  to  The guestion  at  and degree.  Between  there exists some  level  of  that will allow  impact.  the use of  However  unsuitable  continuum  of  contamination, disposal  within  the selection of  disposal  methodo-  of material that exceeds a particular level of  result  in  sufficient  environmental  within the Strait  that alternatives should be sought.  for  of  management  a  issue  dredged  material  disposal  into  degradation  The objectives the  Strait  are  therefore to identify disposal sites and methodologies that will ensure minimal ecological  impact, and  to determine the  limits  to  sediment  guality that may be appropriately disposed under such conditions.  8  I.I  Study  Purpose  This study the  analyses  disposal  of  neighbouring knowledge  and integrates strategic  dredged  Strait to  of  develop  material  information pertaining to  from  Greater  Vancouver  The  purpose  is  Georgia. ecologically  appropriate  to  into  use  procedures  the  existing for  the  coastal marine disposal of Vancouver's dredged materials. Consideration of available strategies for disposal is confined to the use of the Strait of  Georgia, which is the least expensive and most commonly  the land/ocean/coastal sea disposal options. and  coastal  zone can be accomplished with minimal adverse environmental  impact.  study  making tion  dredged  aims  material  to  provide  in the management  of  an  appropriate  disposal  a  into  issue is whether, how resource rich  The  where  At  used of  rational  this  scientific  of dredged material.  management  strategy  basis  to  decision  The ultimate s e l e c depends  not  only  on  rational scientific factors, but also upon multifarious  socio-economic  factors,  to  including  maintaining bountiful not,  the  state.  presume  the  tangible  resources of Although  authority  and  intangible  the Strait  of  environmental to  adjudicate  values  Georgia  science upon  in  their  cannot,  the  society  of  present  and  should  intangible  socio-  economic values of alternate resource uses, it has the task to reduce the myths and misunderstandings their  reckoning.  between practical  To  interpreting  which are too often an influence on  accomplish and  language, whilst  this  articulating  reguires  the  a  scientific  recognizing and avoiding  hidden subjective judgements.  I  therefore attempt  delicate  balance  knowledge  in  the imposition to  remain  a of  cog-  9  nizant  of,  and  to describe, the socio-economic  factors  that  impinge  upon this review, but I do not deliberate upon them at length.  Their  determination is properly left to the political system.  Accordingly, the objectives of this study are:  o  To define the scientific criteria hazard  associated  with  for assessing  disposal  these, to identify the critical  of  dredged  the environmental  materials  and  from  environmental objectives for which  strategies for dredged material disposal should aim.  o  To  determine  the  nature  and  distribution  of  contamination  of  Vancouver's sediments and to identify the contaminants of concern to  the  management  accomplished  by  of  dredged  compiling  and  material  disposal.  interpreting  This  relevant  will  be  existing  information, and reviewing the occupation of Vancouver's shoreline areas to identify the potential sources of contaminant release.  o  To review the current state of knowledge describing the pathways, transformations environment,  and  taking  effects  of  contaminants  and  potentially will  discuss  adverse  illuminate  the  into account the quality of sediments  or estimated to exist in the Vancouver region. identify  in  the  environmental  impacts  the  from  dredged  uncertainties  assessment of these impacts.  that  marine shown  This review will  processes material  that  induce  disposal,  constrain  arid  definitive  10  o  To  identify  environmental  characteristics  potential for adverse impacts to delineate areas  of  that  minimize  the  from dredged material disposal,  the Strait  of Georgia  and  which correspond  to  these characteristics.  o  To  describe  delineated conflict,  areas and  unperturbed identify  and  to  compare with  the  which  evaluate  sites  in  the  dredged  the  environmental  resource  dependence  of  Georgia  T o determine the limits to disposal the recommended sites. may  be  too  waters.  How  highly  do we distinguish  accommodated  at  the  ficant  adverse  ecological  impact  mental  risks  associated  with  these  disposal  these  might  areas  this  where  dredged  upon  analysis,  degradation.  in the Vancouver  for  disposal  disposal  and  those  coastal  sites  that  zone  coastal will  without  where  at  region  within  between materials  recommended  to  material  of contaminated sediments  Some sediments  contaminated  of  to  From  disposal will result in minimal environmental  o  near  material  conditions.  Strait  uses  be  signi-  the  environ-  disposal  remain  unacceptable?  Although  this  materials  from Vancouver  framework elsewhere.  study  and many  pertains  directly  to  into the Strait  the of  disposal  Georgia,  of  dredged  the  analytical  of the principles applied are equally  applicable  11  2.0  A SCIENTIFIC P E R S P E C T I V E  2.1  Containment or Dispersion  An  initial  and  thesis  is that  have  minimal  fundamental for disposal  This  is  that  is  developed within  of dredged materials  environmental  maximize containment of site.  argument  impact,  the  the materials  in contrast  to  disposal  within  the strategy  in coastal  the  this  waters  strategy selected  to  must  disposal  presently adopted at  off-  shore deep ocean dredged material disposal sites, where the dispersion of  the disposed  given  the  materials  homogeneity  is usually  and  low  preferred.  biological  In  this  latter  productivity of  case,  the  deep  ocean ecosystem, dilution offers itself as the answer to pollution.  However, if contaminated sediments  are  to be disposed  into  coastal  waters, then dispersion of the contaminants imposes unpredictable and perhaps substantial environmental risk. well  flushed,  fragile  or  ameliorate current  contaminants  highly  valued  that  disperse  environments  the environmental  regimes will  Even where coastal waters are  hazard.  may  be  before  environmental e f f e c t s of a dispersed contaminant  may  dilution  The complexity  frequently preclude adeguate  induced dilution of the contaminant  transported  of  processes nearshore  monitoring of loqding.  spread  it  monitoring program.  beyond  the  the  Dispersion  loading from a disposal operation  not reduce the associated environmental hazard, although  probably  into  detection  limits  of  a  it will  practicable  12  A  management  preference  materials to the dump-site areally  confined  degradation  a  more  counter  to the common  factors  in  assessing  criteria  possible,  discharges  to  confinement of so  in  environmental  the  extensive  the  U.S.  of  the  This  allowance  disposed  EPA,  may  than  diluted  seem  to  for mixing  risks  marine  rather  associated  system  1976).  (e.g.  But  of  becomes  alternatives,  with  important.  Other  most  water  quality  most  marine  for  rapid  run  and dilution  the pollution to the discharge  absence  effect  area.  environmental  enforcement, see  discharges  degradation  regulatory  the  confinement  implies a preference for more intense but  environmental  over  anthropogenic  towards  area  dilution  factors  availability) being equal, the bioaccumulation and toxicity of  is  not  of  (e.g.  the bio-  pollutants  are essentially dose dependent.  If ocean dumped dredged materials can be e f f e c t i v e l y contained within the disposal site, a more relevant analogy to the ecological objectives of  ocean  dumping  waste  disposal  these  instances  persion  of  the  at  management terrestrial  are  generally  pollution  is  with  sites.  The  towards  through  the  management  strategies  management  containment, atmospheric,  objectives  minimizing  aquatic  or  for in dis-  biotic  pathways.  Periodic disposal of contaminated dredged materials onto the seafloor will likely result in severe depauperation of the biological at  the  disposal  site.  However,  environmental  degradation  areally constrained site is of little concern if the following are met:  community at  an  conditions  13  1.  The  disposal  site  is  neither  highly  productive  nor  ecologically  unique. 2.  Dredged sediment disposal at the site does not conflict with other beneficial resource uses of the environment.  3.  The  detrimental  alteration  of  the  environment  will  not  extend  beyond specified site boundries. k.  Upon cessation of disposal  activities, the site can be returned, or  will naturally return over time, to an "acceptable" environmental condition.'  Fulfillment of these conditions has justified the use of many areas of our terrestrial sphere for the disposal of anthropogenic wastes. Indeed, it  is  on  materials Our  this has  basis  upland  disposal  often been recommended2  reluctance to  marine  that  sphere  redistribution of  similarly  stems waste  recommend  primarily  from  components  of  (e.g.  contaminated U.S.  disposal  concern  subsequent  dredged  EPA/COE,  of for  wastes the  to their  1977).  into  the  uncontrolled disposal  into  this fluid medium.  However,  this concern applies primarily to contaminant  breach one or all  of  the four  conditions  nominated  loadings that  above.  If  the  marine disposal of dredged sediments can be managed to comply with the above conditions, then there is no obvious  reason  why  it  should  not be preferred over upland disposal. The reluctance to use the ocean in this instance may be said to place greater weight on preserving the 1.  Because a disposal site may be recolonized by a substantially different biological community than was present before disposal, the "acceptability" of the rehabilitated condition includes both objective (e.g. biomass, productivity, species diversity) and "subjective (e.g. equivalence of the replacement community) judgements.  2.  This is despite the high likelihood of trace metal leaching and dispersion that accompanies this method (see Lee et al., 1975).  14  marine  environment  avoiding  health  than  risks  on  due  preserving  to  the  groundwater  terrestrial  environment,  contamination  and  other  social goals.  Release  Given  an  acceptance  located disposal  of  areally  constrained  site, the c r i t i c a l  hazard  of  contaminated  dredged  which  the  contaminants  may  disposed  sediments  taminant  release  inshore  pollution.  to the  impact  if  the  disposal  remobilized  is  or  is  released  contaminant  whether  dredged  materials  are  release  harm,  disposed  occurs,  adding  into  the  they are mixed with the oxygenated seawater the bottom.  Dissolution  may  suitably  degree  to  from  the  Without  we  con-  relocate the  act  unpredictable  perhaps substantial environmental cost to the dredging  When  a  the  environments.  merely  potential  at  in determining the potential  material  adjacent  guestion  But  relocation accentuates  be  factor  detriment  our of and  program.  marine  environment,  during their descent to  occur, and a fraction of  will remain suspended within the water column.  the  particles  Pore water will also  be partially released to the water column.  The disposed sediments which settle to the bottom will be subject to physical and biological resuspension processes at the disposal  site.  In  addition, the chemical environment in which they have settled may be substantially  different  from  where  they  were  dredged.  Chemical  15  transformations water,  and  may occur that permit long term release to the pore  chemical  flux  from  the  sediment  system  to  the  water  system may thereby be promoted.  The  questions  at  issue  are  the  extent  to  which  these  physical,  chemical and biological processes at the disposal site cause release of contaminants and the degree to which the contaminants  released due  to the disposal operation e f f e c t the biological system.  The Chemistry of Contaminant Behaviour  By  definition, contaminants  strong  association  insoluble  in  ecosystem sorbed have  the  has  water  the  concern in dredged sediments sediment  phase,  so  phase.  their  They  introduction  are to  or  absorbed)  deposited  on  to  the  suspended  bottom  particulate  when  the  have  a  relatively  the  resulted in an eguilibrium condition where  (adsorbed been  with  of  aguatic  they  have  matter  suspended  and  matter  settled.  Although  the  sediments  act  as  a  "sink"  for  these  contaminants  in  aquatic ecosystems, the water and biological systems can also become enriched.  Figure  transport  and  environment. and  the  water  directional Physical  fate  3  describes of  change  as  taking  (sedimentation  schematic  contaminants  The contaminants system  a  occur  dissolved place  and  representation  introduced  to  of  the  marine  in both the sediment or  across  resuspension)  sorbed the  species,  solid-water  and  chemical  the  system  with  two  interface. exchange  16  FIGURE 3.  Schematic R e p r e s e n t a t i o n o f Contaminant T r a n s p o r t and Fate i n the Marine Environment.  INTERNAL  DISTRIBUTION  EXTERNAL LOSS  WATER  D i r e c t Uptake  DISSOLVED Sorption  AOVECTIVE Partitioning  TRANSPORT I n d i r e c t Uptake  SUSPENDED PARTICLES  BIOTA »  PELAG C/EPIBENTHIC.  <«  Depuration,  , Foodcha i n processes  Excretion  CONSUMPTION  BENTHIC  SEDIMENTS  IRREVERSIBLE BURIAL  PARTICULATE  Sorption  I n d i r e c t Uptake  P a r t i t i o n i ng  INTERSTITIAL WATER  D i r e c t Uptake  17  occurs  between  Biological  the  sediments  and  the  overlying  organisms take up the contaminants  water  column.  from either the  water  column or from the sediments.  When contaminants are released into the ecosystem, a new equilibrium between  the  respective  concentrations  in  column and the biota has to be established. tend  to  favour  taminants the  greater  by biological  mechanisms  contaminants  which  dissolution,  or  organisms. control  An  the  the  sediments,  sorption  understanding and  The  partitioning  may  be  in  is  the  con-  required of  and the  of  the  responses  to environmental alteration.  behaviour  described  of  distributions  between environmental compartments  of these mechanisms  water  This new equilibrium may  more  forms  the  of  terms  pollutants  of  their  sediment, water and biotic phases.  in the  marine  environment  relative chemodynamics  Spontaneous  in the  transfer of chemical  and thermal energies occurs across the interfaces between these three phases until an equilibrium condition is reached. the net chemical  transfer  the environmental  phases,  at  equilibrium,  the  If  is the sum of reversible transfers thermodynamic  chemical  "escaping  considerations tendencies"  molecules in each phase will be egual (Thibodeaux, of  the  "escaping  equilibrium  position  tendencies" of  we assume  results  from  changes  the pollutant, which  is  1979). in  between  require of  that  that  pollutant Alteration  the  dependent  relative upon  chemical reactivity of the pollutant molecule with each phase.  the  18  An  important  distinction exists  in this regard between the chemistry  of trace metals and hydrophobic organic compounds.  T r a c e metals are  simple  forms  cations  environment,  that exist and  are  repeatedly  through  chemistry  of  in a number of chemical  essentially  indestructable.  the different chemical forms  their  environment.  Metals  within  They  may  the  cycle  dependent upon the  react  as  electron-pair  acceptors (Lewis acids) with electron-pair donors (Lewis bases) to form various  chemical  coordination organic  groups  compound  complexes  sediment,  water  or  are  and  such  as  an  ion  pair,  a donor-acceptor  formed,  biotic  and  phases  is  contrast,  toxic  management  are  variation  their  in  organic large  compounds  non-polar  speciation.  metal  complex.  their  influenced by  of  a  and  between  the  the diverse  and  associations.  concern  molecules Chemical  complex,  Inorganic  distribution  dynamic chemical interactions of these many  In  a  to  which  ocean  dumping  exhibit  minimal  reactions  involving  these  compounds in the natural environment are generally very slow and are uni-directional. a  series  of  They result in the formation of new compounds within  reactions  leading  ultimately  to  either  destruction of the compound (metabolized to CO2 incorporation  of  fragments  into  other  organic  the  complete  and H2O)  or to the  polymers  (e.g.  humic  acids).  This difference in the environmental organic  contaminants  discussing  necessitates  their availability  of trace metals  chemistry  their  separate  to the biological  of  trace  metals  consideration  system.  and when  The reactivity  in the environment requires analysis of the  processes  19  which  alter  the equilibrium condition of  hence e f f e c t bioavailability. mono-specific:  trace metal  Toxic organic  their availability  speciation,  compounds  to the biological  are  system  and  essentially is simply  a  guestion of their exposure to, and their tendency to incorporate with, the biological  system.  Chemicals of Environmental  Concern  T r a c e metals  in nature.  are ubiquitous  of soils and sediments organisms. normally  They are natural  and most are required nutrients for  low  levels  in natural systems (parts per  million or less).  A t higher concentrations, many  the  metals"  amounts that  biological  As implied by their nomenclature however, these elements  occur only at very  term  components  "trace  usually  includes  all  are toxic.  metals  Although  found  in  in the marine environment, my concern is with trace  are  highly  cadmium,  toxic  lead,  to  chromium,  marine  biota.  copper,  zinc,  These arsenic,  include nickel,  trace metals  mercury, silver  and  selenium.  While considerable quantities of organic natural  components  concern  to  ocean  of  matter of biogenic origin are  all  ecosystems,  the  organic  compounds  dumping  management  are  principally  of  of  anthro-  pogenic origin, either due to limited natural production or because the compounds  are  DDT,  other  and  biphenyls (e.g.  totally  (PCBs),  HCB),  man-made.  organohalogen  compounds  terphenyls (PCTs),  phenols  (e.g.  PCP)  Chlorinated  and  such  dibenzofurans butadienes  pesticides as  as  polychlorinated  (PCDFs),  (CBDs),  such  do  benzenes not  exist  20  naturally  and  worldwide are  have  significance.  ubiquitous  resulted  become  in  nearshore  in  Although  nature,  substantially marine  notorious  environmental  petroleum and  industrial  elevated  sediments.  and  core  samples  from  phenanthrene, cantly  Buzzard's  flouranthrene  in sediment  and  to  in  LaFlame  hydrocarbon (PAH)  started  have  compounds  Hites,  Massachusetts,  pyrene  hydrocarbons  activities  these  of  and  levels  found  increase  in  that  signifi-  indicative of the period 1850 to  1900. The  persistence and high toxicity (and carcinogenicity) of many  petroleum  hydrocarbon concern  layers  Bay,  and  of  example,  Farrington (1977) measured polyaromatic  related  domestic  loadings  For  contaminants  derivatives  about  their  such  as  these  distribution,  cause  for  and  effects  in  concern  to  fate  give  appreciable the  marine  environment.  The  organic  pollutants  of  primary  management  are the relatively  and persist  within the sediments.  the  marine  concern,  but  environment because  are  they  insoluble  compounds  that  material  accumulate  More soluble organic pollutants  not  are  dredged  necessarily  more  prone  of to  less  in  environmental  advective  transport,  hydrolysis and/or biodegradation, they are not of such direct concern to the management soluble  of dredged material disposal.  contaminants  recent spill  or  within  discharge.  dredged This  outside the scope of this thesis.  sediments  warrants  High levels of more is  indicative  concern, but  is  of  a  essentially  21  Highly halogenated organic compounds, as well as the higher molecular weight  non-polar petroleum hydrocarbons, are generally not soluble in  surface waters (ug/L).  at concentrations  direct  product  environmental  of  hydrophobic  interactions,  so  concerns  for  sediment-bound  is  an  inverse  1979).  organic  pollutants  pertain to their persistence in the environment, their toxicity carcinogenicity, animal  tissues.  sistence  and  pollutants relationship  and As  their will  tendency  is  largely so  to accumulate  be outlined  bioaccumulation  are  potential  related  significant  in Section  to that  of  their Lu,  Water  solubility  less than 0.5 mg/L,  to  5.0  high  water  and/or  levels  below,  the  water-insoluble  and  in  per-  organic  solubility.  Metcalfe  suggested a classification of organic compounds  1.  with  Their tendency to associate with the solid phase  function of their solubility (Chiou, Peters and Freed,  The  per billion  organisms or suspended sediments (Poirrier, Bordelon  and Laseter, 1972). a  than a few parts  Most water column concentrations are found associated  either biological  is  higher  This  Cole  (1978)  as:  likely to be environmentally  hazardous. 2.  Water  solubility  mentally 3.  greater  than  50  mg/L,  likely  to  be  environ-  nonhazardous.  Water solubility from 0.5 to 50 mg/L  to be used, with caution.  22  DREDGING AND  Dredging  D R E D G E D M A T E R I A L S IN T H E L O W E R  in the Vancouver Region  The vast majority of dredging  activities  Mainland  River.  removes  occur  in the Fraser  approximately  the Fraser  River  1985).  addition,  In  dredged  two  navigation  million  in British  Columbia's  Public Works Canada  tonnes  channels  substantial  varies from less than annually  MAINLAND  of  freshet  (H. Nelson,  quantities  of  Lower annually  sediment  EPS,  from  pers. comm.,  sediment  (the  amount  I million to approximately 3 million tonnes) are  from the river by private commercial  interests  for  industrial and urban developments.  Dredging  activities  elsewhere  sporadic.  Occasional  dredging  Burrard Isolated  Inlet  in  the  adjacent  is required to maintain  dredging  activities  have  or  also  Lower to  Mainland  harbour  improve taken  wharf  berthing  place  for  are  more  areas  in  facilities. foreshore  developments, although these are often cut and fill operations that do not  involve ocean dumping.  The most recent requirement for major  dredging outside of the Fraser River has been for the B.C.  Place  Expo  the entire  '86  developments  in False  Creek.  Excavations  for  and  False Creek rehabilitation have involved the dredging of approximately 2.26 million m3 (B.C. Place et al., 1983).  23  Much of the clean sediment dredged from Vancouver's waterways  are  in-river  For  dumped  example, during 2.35  million  estimated niques,  or  at  designated  foreshore  sites.  1985 the Department of Public Works plans to dredge  m3  of  850,000  of  disposed  sediments  m3  which  will  180,000  from  be  the  dredged  m3  will  lower  using  be  Fraser  River.  suction-pipeline  disposed  in-river  remainder on the foreshore in the Duck-Woodward-Barber and at Steveston  Island (see Figure 2).  An tech-  and  the  Island area  A further 1.5 million m3 will  be dredged by suction-hopper.  Of this, some 700,000 m3 are planned  for  dumpsite  disposal  at  the Sandheads  Channel: the other 800,000  m3  at  the  mouth  will be disposed  of  the  Main  in-river (H. Nelson,  pers. comm., 1985).  A n average of approximately been annually  disposed at  1.5 million m3 of dredged materials have  nominated Dredge  adjacent to the Lower Mainland (Table II). materials and  Material  debris.  The  Sites  This comprises a range of  including sand, mud and silt, woodwastes,  construction  Disposal  Sandheads  and  and rock, gravel  Fraser  South  Arm  dumpsites primarily receive clean riverine sediments with particle size distribution or organic content which deem them unsuitable for use as aggregate or landfill. Arm,  Burrard  Inlet  Dredged material from the Fraser River and  False  creek,  as  well  struction debris and contaminated sediments Vancouver's waterways, dumpsite.  The Point  as  woodwastes,  dredged from  dumpsite  Point Grey in 240 m of water.  is four  nautical  con-  throughout  are predominantly disposed at the Point Grey  North  miles  Grey  west  of  TABLE I I .  Q u a n t i t y o f Dredged M a t e r i a l s Disposed at Dumpsites A d j a c e n t t o the Lower M a i n l a n d , 1976-1979. (Compiled from Ward and S u l l i v a n , 1980).  Dumpsite  P o i n t Grey  Volume Dumped (thousands o f m ) 1976 1977 1978 1979 Average 192  737  181  58  292  Predominant M a t e r i a l s Dumped  Silt,  s a n d , mud, r o c k , g r a v e l , c o n s t r u c t i o n  d e b r i s and woodwastes. Sandheads  1,408  1,083  14  986  873  Sand and s i l t  from maintenance d r e d g i n g o f  the F r a s e r R i v e r Main Arm. Burrard  Inlet  24  154  0  0  44  Mud,  silt,  sand and c o n s t r u c t i o n d e b r i s  ( i n a c t i v e dumpsite s i n c e Fraser  River-  169  503  256  50  244  1,793  2,477  451  1,094  1,454  South Arm Total  Sand, s i l t ,  mud and c l a y .  1977).  25  This  review  is  mainly  concerned  with  dredged  materials  currently  disposed at Point Grey, particularly the woodwastes and fine materials  that  accumulate adjacent to Vancouver's sawmills,  organic and the  organic "oozes" from quiscent areas of the Fraser River, Burrard Inlet and  False  materials,  Creek. and  It  not  is  the  normally  coarse  the  grained,  fine that  grained  and  warrant  organic  environmental  concern related to disposal (Boyd et al., 1972).  These fine sediments frequently  include natural and anthropogenic deposits,  contain  high  contaminants.  Table  various  and  metals  concentrations  III  summarizes  toxic  PCB  of  organic  and  and  inorganic  the elevated concentrations  compounds  that  have  been  found  surface sediments of False Creek and adjacent to Vancouver  of in  Wharves  Ltd.'s terminal in Burrard Inlet.  Sediment Contaminants in the Vancouver Region  Data  describing the degree of  sediments  in the Vancouver  are  limited.  very  A  by Stancil through  (1980).  the  chlorobenzene  lower  Garret  and  recently  published an  presents  additional  pounds  of  in the Vancouver  the  date from the  available  data  marine  1970's  and  describing  the  of  chlorinated  reviewed the pesticides,  chlorinated phenols.  on  riverine and  in the Fraser River estuary was compiled  overview  data  mostly  (1980) similarly  Fraser  (HCB)  region  review  distribution of trace metals  contamination of  of  the  region.  PCB's  aquatic  PCB's,  Garrett  in British distribution  Intensive sampling  distribution  (1983)  Columbia, of  these  data  hexamore which com-  describing  26  TABLE I I I .  Contaminant C o n c e n t r a t i o n s i n F a l s e Creek and B u r r a r d Inlet  Sediments.  C o n c e n t r a t i o n i n S u r f a c e Sediments (mg.kg Element  Background! Sediments  Copper  F a l s e Creek  ,  dry wt)  Vancouver Wharves Terminal,Burrard Inlet  25  237.0  6  562.0  141 d  Cadmium  0.2  3.5  18.7C  Mercury  0.05  0.96  2.47c  Zinc  80  808.0  l,635d  Nickel  20  25  61d  Lead  Arsenic Chromi urn  6  11.3  95.3C  32  60.2  38.8C  0.37e  14.4f  0.2  PCBs  17 , 9 0 3 u  a.  For uncontaminated Puget Sound s e d i m e n t s , r e p o r t e d by Mai i n s e t a l . , 1980.  b.  From Nix and Chapman, 1984.  c.  From Chapman and B a r l o w , 1984.  d.  From Chapman, Munday and V i g e r s , 1982.  V a l u e s shown a r e average f o r 11  stations.  Values shown are from a c o m p o s i t e o f 2 s a m p l e s . Values shown are average  for  13 s t a t i o n s . e.  From B r o t h e r s and S u l l i v a n , 1984.  Value shown i s average f o r 13 s t a t i o n s  i n F a l s e Creek East B a s i n . f.  From G a r r e t t ,  1983.  Value shown i s f o r s i n g l e sample i n A u g u s t ,  P r e v i o u s sample i n J u l y ,  1976 showed 0.18 m g . k g ^ . -  -  1980.  27  the distributions of polychlorinated phenols, PCB's and trace metals in False Creek sediments are summarized in Brothers and Sullivan (1984). Garrett,  MacLeod  contamination  and Sneddon's  in  the  British  (1980) summary Columbian  and  of data on mercury Yukon  environments  provide additional limited data with respect to Burrard Inlet.  Sediment quality data on the common parameters used in evaluating ocean dumping permits in Canada were, for a few years, compiled on computer file in the System 2000 Ocean Dumping Environmental  Protection Service (EPS)  Data  Base by the  of Environment Canada.  The  parameters listed for storage in the data base comprised a wide range of chemical and physical characteristics of dredged material. The data file  thus  provided  a  potential  vehicle  for  the  accumulation  of  extensive information on coastal sediment quality in Canada. However infrequent monitoring of these parameters within the ocean permitting Hg,  Cd,  process  PCB's,  routinely  has  COD,  monitored  in  substantially TOC,  degraded  moisture  ocean  dumping  and  permit 1981).  base  1983  not  been  maintained  since  opportunity.  particle  P a c i f i c coast (McGreer and Konasewich, has  this  dumping  size  have  applications  Only been  on  the  The System 2000 data (H.  Nelson,  EPS,  pers.  comm., I 985).  Substantial organic  gaps, particularly with respect to a wide  contaminants  document sediments. to  data  trace  of  concern, thus  frustrate our  ability  the nature and distribution of contaminants  chlorinated  organopesticides,  and  to  of  fully  in Vancouver's  Most previous studies have been limited in their metals,  range  analyses  PCB's,  with  28  occasional  monitoring of chlorinated phenols and benzenes.  these substances the  local  distribution  chlorinated  of  butadienes,  hydrocarbons. organic  is sporadic,  The  compounds:  and virtually  other  persistent  polybrominated  U.S.  EPA  there are  no data organic  exists  data  such  as  and  polyaromatic  list  includes  Pollutant  inadequate  on  describing  chemicals  biphenyls  Priority  Data  describing  the  I 16  distri-  bution of most of these compounds within the Vancouver region.  A prohibitively expensive sedimentological survey would be required to fully document the nature and extent of contamination of sediments.  However  information  describing  an past  integration and  of  present  the  available  activities  data  along  local concern.  receives  wastes  For example, the from  approximately  contaminants  lower Fraser River five  metal  with  Vancouver's  waterfront can assist compilation of a list of "suspected" of  Vancouver's  and  finishing  estuary  and  fabri-  cating plants; thirteen pulp and paper and lumber mills, twenty preserving plants; six sewage treatment plants; landfills sites;  and  one  numerous  hundred  and  smaller  wood  waste  eighty  storm  sewers;  five active  and a  municipal  industrial coal  wood  disposal  bulk  loading  terminal; and unknown numbers of chemical plants, cement producers, and numerous other facilities (Garrett, broad spectrum  of  nated trace metals Table  IV  with  sources  activities  to the environment.  the  indicates a significant river sediments.  and  1982).  range  of  activities  that A  Table IV examples may  contribute n o m i -  comparison of the  discharging  the  into  the  list  in  river  potential for trace metal contamination of the  29 TABLE IV.  Potential  Anthropogenic  Vancouver's  Waterways (compiled from G a r r e t t ,  Hall,  S t a n c i l , 1980;  1976;  Metal Mercury  Manufacture  of e l e c t r i c a l  Metallurgy  apparatus,  ores.  fungicides,  finishing,  fertilizers,  z i n c , copper and l e a d o r e s .  foundries,  p a i n t s and the d i s p o s a l o f  P r i n c i p a l l y e l e c t r o p l a t i n g and metal  Metal  batteries.  f i n i s h i n g . A l s o from  p r o c e s s i n g , the c o n c r e t e i n d u s t r y and wood  E l e c t r o p l a t i n g and metal  preservatives  plumbing,  preservatives.  z i n c and copper o r e s ,  preservatives,  preservatives.  f i n i s h i n g , c o r r o s i o n o f household  c o n c r e t e p r o d u c t i o n , wood Lead,  paints,  f i n i s h i n g , a n t i - f o u l i n g p a i n t s , a l g i c i d e s , p e s t i c i d e s , base  metal o r e s , c o r r o s i o n o f household p l u m b i n g , wood  Arsenic  fungicides,  ( a l l o y s , s o l d e r s ) , e l e c t r o p l a t i n g and metal  photographic  Zinc  paint,  P r i n c i p a l l y from motor v e h i c l e s . A l s o from base metal ores and metal  Copper  1980)  c h l o r i n e , caustic soda,  A l s o from l e a d and z i n c  rubber t i r e s , motor o i l s ,  1980;  Sources  p a i n t and v a r n i s h , b a t t e r y m a n u f a c t u r e ,  Chromium  Swaine,  p h a r m a c e u t i c a l s , c h e m i c a l s , pulp and p a p e r ,  amalgams and cement.  Lead  1982;  of  and G a r r e t t , MacLeod and Sneddon,  Potential  drywalls,  Cadmium  Sources o f Trace Metal Contamination  i n s e c t i c i d e s , h e r b i c i d e s , wood  ceramic and g l a s s m a n u f a c t u r e ,  manufacture  of  semiconductors. Nickel  Electroplating  Silver  Photographic  and metal  f i n i s h i n g , base metal  materials, electroplating, electrical  dental a l l o y s , p a i n t s , glass Selenium  Copper,  ores.  manufacture.  l e a d and z i n c o r e s , p h o s p h a t e s , manufacture  c e r a m i c s , s e m i c o n d u c t o r s , metal photocel1s.  equipment  finishing, paints,  o f g l a s s and photocopying,  30  Although  the  existence  of  particular  urban  or  industrial  activities  adjacent to a waterway does not automatically indict those activities for contaminating the sediments, it does provide, through reference to documented  cases  of  pollution  elsewhere,  presumptive  suggesting the existence of nominated contaminants. very  limited  presume  the  evidence  is  account  for  data  base,  presence provided. the  ocean of  dumping  suspected  This  identified  In the face of a  management  contaminants  presumption  implies  contaminants  evidence  until  a  within  must  often  contrary  requirement the  to  management  scheme.  Many of the compounds that are presumed to enter our aquatic system do  not  constitute  management  as  an  they  environmental are  relatively  concern  to  non-toxic,  ocean  are  dumping  not  likely  to  associate with the sediments in amounts great enough to cause harm, or  are  metals  rapidly and  many  environment  in  degraded  by  man-made significant  natural organic  mechanisms. compounds  amounts  However  that  associate  may  trace  enter  predominantly  the with  sediments, are extremely stable and exhibit a high toxicity to various organisms.  Numerous mental  documents  exist  which  contaminants  that  warrant  authorities.  purport  to  priority  nominate concern  the environby  regulatory  The Departments of Environment and National H e a l t h and  Welfare (1979) have identified an assorted list of priority contaminants requiring (Table V).  further  study  The U.S.  under  EPA  the  Environmental  Contaminants  (1977) List of Priority Pollutants  Act  includes  31 TABLE V.  Canadian Environmental  Category  I:  *  Contaminants  Act L i s t o f P r i o r i t y C h e m i c a l s .  Those s u b s t a n c e s which the government  i s s a t i s f i e d pose a  s i g n i f i c a n t danger to human h e a l t h o r the environment  and  f o r which r e g u l a t i o n s a r e b e i n g d e v e l o p e d . Polychlorinated Biphenyls  (PCBs)  Chlorofluoromethanes Category  II:  Those s u b s t a n c e s which a r e b e i n g i n v e s t i g a t e d to the n a t u r e and the e x t e n t the environment  determine  o f the danger to human h e a l t h o r  and the a p p r o p r i a t e means to a l l e v i a t e  that  danger. Cadmium Chlorophenols Mercury Category  III:  Those s u b s t a n c e s which may pose a s i g n i f i c a n t danger human h e a l t h or the environment and about which detailed information  (for  to  further  example t o x i c o l o g y and amounts  used) i s r e q u i r e d . Chlorobenzenes Hexachlorobutadiene Hexachlorocyclopentadiene  and i t s  Adducts  Organoti ns Triaryl  Compounds  phosphates and r e l a t e d substances  f o r which r e g u l a t i o n s a r e a l r e a d y i n f o r c e under the Polychlorinated Biphenyls Mi rex Polybrominated Polychlorinated  Canada G a z e t t e , 1979  (la)  Biphenyls Terphenyls  (PCBs)  Act.  32  129 substances  (Table VI).  On a more regional scale, Garrett (1982)  priorized industrial chemicals that warrant concern in British Columbia and the Yukon (Table  However,  the  substances  in these  biota  man.  and  VII).  environmental  concerns  supporting  lists are multifarious, Environmental  including  management  essentially concerned with substances  the  of  inclusion  air, water, ocean  of  land,  dumping  is  from these lists which meet the  following c r i t e r i a :  o  they are known to be toxic and/or mutagenic to bioaccumulate  to marine biota, or  in marine biota to an extent that  health concern to subsequent consumers (including o  they  tend  to  associate  with  the  sediments  they pose a  humans).  where  they  are  not  readily degraded under normal environmental conditions o  they have documented or potential distribution in the sediments of the Lower  For  the  includes  Mainland.  purposes all  of  this  substances  study,  which  the  can  definition of  cause  death,  "toxic  disease,  substance" behavioural  abnormalities, cancer, genetic mutations, physiological or reproductive malfunctions, or physical deformities in any organism or its offspring, or  which  can  become  poisonous  chain or in combination  with  after  other  its  concentration  substances.  This  in the  definition  food was  jointly derived by the Governments of Canada and the United States for the 1978 Great Lakes Water Quality Agreement (IJC,  1978).  33 T A B  L E VI-  U.S.  E.P.A.  Extraction  P r i o r i t y P o l l u t a n t L i s t Showing C l a s s i f i c a t i o n by Group.  PESTICIDE  PURGEABLE GROUP Benzene Bromodichloromethane Bromoform Bromomethane Carbon T e t r a c h l o r i d e Chlorobenzene Chloroethane 2-Chloroethylvinyl ether Chloroform Chloromethane bis-Chloromethyl ether Di b r o m o c h l o r o m e t h a n e D i c h l o r o d i f l uoromethane 1,1 , - D i c h l o r o e t h a n e 1,2,-Dichloroethane 1 . 1 , - D i c h l o r o e t h y l ene t r a n s - 1 , 2 , - D i c h l o r o e t h y l ene 1.2 ,-Dichloropropane 1,2 ,-Dichloropropylene E t h y l benzene Methylene C h l o r i d e 1,1,2,2,-Tetrachloroethane 1,1,2,2,-Tetrachloroethene Toluene 1,1,1 ,-Trichloroethane 1,1,2,-Trichloroethane T r i c h l o r o e t h y l ene T r i c h l o r o f l uoromethane Vinyl Chloride  GROUP  Aldrin alpha-BHC beta-BHC gamma-BHC ( L i n d a n e ) delta-BHC Chlordane 4,41-ODD 4,4*-DDT alpha-Endosulfan beta-Endosulfan Endosulfan sulphate Endri n Endrin Aldehyde Heptachlor Heptachlor Epoxide PCB-1016 PCB-1221 PCB-1232 PCB-1242 PCB-1248 PCB-1254 PCB-1260 Toxaphene  C h l o r i n a t e d Benzenes 1.2- 0ichlorobenzene 1.3- Dichlorobenzene 1.4- Dichlorobenzene 1,2,4-Trichlorobenzene Hexachlorobenzene Nitrosamines N - n i t r o s o d i m e t h y l amine N - n i t r o s o d i p h e n y l amine N - n i t r o s o d i - n - p r o p y l a m i ne  p-Chloro-m-cresol 2-Chlorophenol 2,4,-Dichlorophenol 2 , 4 , - D i m e t h y l phenol 4 ,6 , - D i n i t r o - o - C r e s o l 2 ,4 , - D i n i t r o p h e n o l 2-Nitrophenol 4-Nitrophenol Pentachlorophenol Phenol 2,3,6,-Trichlorophenol  MISCELLANEOUS  BASE NEUTRAL GROUP P o l y n u c l e a r Aromatic Hydrocarbons Acenaphthene Acenaphthylene Anthracene Benzo ( a ) a n t h r a c e n e Benzo (b) f l u o r a n t h e n e Benzo ( k ) f l u o r a n t h e n e Benzo ( g h i ) p e r y l e n e Benzo ( a ) p y r e n e Chrysene Oibenzo (ah) anthracene Fluoranthene Fl uorene Indeno ( 1 , 1 2 , - c d ) p y r e n e Naphthalene Phenanthrene Pyrene  ACID GROUP  GROUP  Phthalate Esters Butyl Benzylphthalate Di-n-butylphthalate Diethylphthalate Dimethylphthalate Di-n-octylphthalate bis-(2-ethylhexyl) phthalate  Acrolein Acrylonitrile 2,3,7,8,-tetrachlorodi benzo-p-dioxi n Asbestos Cyanide Total Phenols  Haloethers 4-Bromophenyl phenyl e t h e r b i s ( 2 - C h l o r o e t h o x y ) methane bis (2-Chloroethyl) ether 4 - C h l o r o p h e n y l phenyl e t h e r  Antimony Arsenic B e r y l 1ium Cadmi urn Chromium Copper Lead Mercury Nickel Selenium Silver Thallium Zinc  O t h e r compounds Benzidine 2-Chloronaphthalene 3,3'-Dichlorobenzidine 2,4,-Dinitrotoluene 2,6,-Dinitrotoluene 1 , 2 , - D i p h e n y l h y d r a z i ne Hexachlorobutadiene Hexachlorocyclopentadiene Hexachloroethane Isophorone Nitrobenzene  34 TABLE V I I .  P r i o r i t y Ratings  for Industrial  Columbia and the Yukon.  Chemicals i n B r i t i s h  (From G a r r e t t ,  1982).  Toxicity, Q u a n t i t y Used Persistence and P o t e n t i a l & Bioaccumulation for Release  Chemical  Relative Regional Concern  4  4  16  Other Wood P r e s e r v a t i v e s ( c r e o s o t e , a r s e n i c compounds)  3  4  12  Heavy M e t a l s  3  4  12  C h i o r i ne  4  3  12  3-4  3  9-12  Chlorinated  Phenols  Cyanide  4  PCBs Plastics Additives ( t r i a r y l phosphates, o r g a n o t i n s , phthalate e s t e r s , chlorinated paraffins) Chlorinated (solvents)  Hydrocarbons  Chlorinated  Benzenes  PAHs Chlorinated Dibenzodioxins Dibenzofurans Flourides  and  2-2.5  8-10 6-9  2-3  2-3  6-9  3  2  6  3  2  6  4  ?  2  f  a.  low = 1 ;  moderate = 2 ; high = 3 ; v e r y high = 4  b.  low = 1 to 4 ; moderate = 5 to 8 ; high = 9 to 12;  v e r y h i g h = 13 t o  16  35  Uncertainty definition nants  and controversy  to quantify  are  surrounded  concentrations  considered  measuring,  have  toxic.  at  The  which  problem  listed  in Tables  responses at some at  which  continue  sedimentary  is  much less predicting, the e f f e c t s of  marine environment is still in its infancy. elements  the application of  they  and VII  the  contaminants  known  to  be  considered  to  certain definition.  be  are considered to be toxic  approach refrains risk  of  in the  induce  environmentally  For the purposes  toxic  sea  if they are  sediments,  as  "safe"  of this  study  listed within the Tables are  considered to be toxic at current levels of detection.  in deep  science  E a c h of the compounds and are  therefore, all of the organic contaminants  trations  contami-  level (hence their inclusion in the lists), but levels  may  to defy  V, VI  that  this  in excess of  Trace  average  reported by Bryan  from the controversial evaluation  of  metals concen-  (1976).  This  environmental  i.e. whether "no e f f e c t " levels exist or whether carcinogenic risk  can be extrapolated to all levels of exposure (Maugh, 1978).  Although thus  fall  all of the priority pollutants within  the  criterion  of  listed in Tables V, VI  toxicity,  many  fall  and  outside  VII the  criterion of persistent association  within the sediments.  For example  chloroflouromethanes  purgeable  hydrocarbons  and  other  chlorinated  introduced to agueous systems will mostly volatilize to the atmosphere (Callahan  and  substances  in the aquatic system (e.g. nitrosamines, cyanide, fluorine)  is  dispersion  Slimak,  in  solution  1979).  rather  The  than  major  fate  adsorption  process  to  the  of  other  sediments.  36  Hexachlorocyclopentadiene, triaryl phosphates, chlorinated paraffins and chlorine  tend  to  associate  with  sediment  material,  but  are  not  environmentally persistent (Callahan and Slimak, 1979).  Contaminants  that  do meet  concern in the management  the  first  two  c r i t e r i a justifying  priority  of dredged materials from the Vancouver  region are listed in Table VIII.  Summary  information supporting their  inclusion in the list and describing our knowledge of their distribution in the sediments of the Lower Mainland  3.2.1  follows.  T r a c e Metals  Trace  metal  discharges  to  the  Fraser  River  lower reaches below the Pattullo Bridge.  occur  throughout  Ferguson and Hall  the  (1979),  Swaine (1980) and Stancil (1980) describe the sources and distribution of  metal  loadings  to the river, particularly for  lead, copper, nickel  and zinc.  The distribution of trace metals location and hydrodynamic the  lead and  nickel  loading  in sediments  relocation.  is determined by input  Approximately  to the Fraser River  60 percent of  comes  from  storm-  water discharges, and is dispersed over a wide area from  more  180 outfalls  Treatment  Plant  (Hall,  discharge  1976).  clearly  In  effects  contrast, trace  Sturgeon Bank (Table IX, c f . Roberts  the  metal Bank).  lona Sewage levels  in  than  sediments  of  37  TABLE V I I I .  Contaminants o f Concern I d e n t i f i e d o r Suspected w i t h i n Sediments o f G r e a t e r  Vancouver.  Trace Metals Mercury  Zinc  Cadmium  Arsenic  Lead  Nickel  Chromium  Si 1ver  Copper  S e l e n i urn  Halogenated  Organics  Organochlorine P e s t i c i d e s Polychlorinated Biphenyls C h l o r i n a t e d Butadienes Polychlorinated  Dibenzofurans  Polychlorinated  Benzenes  P o l y c h l o r i n a t e d Phenols Halogenated P o l y a r o m a t i c  Non-halogenated Polyaromatic Phthalate Organoti ns  Organics  Hydrocarbons  Esters  Hydrocarbons  38  TABLE IX.  Trace M e t a l s i n Sediments o f the F r a s e r R i v e r ( C o n c e n t r a t i o n s , i n mg/kg, dry  Area North Arm Sturgeon Bank Roberts Bank  Copper  (From H a l l ,  wt.)  Zinc  Lead  34  72  16  183  170  157  28  61  4  Main Arm  17-36  25-60  4-11  Ladner Slough  43-57  95-115  14-23  1976).  39  Hydrodynamic considerations result in a tendancy for trace metals to especially accumulate in backwater areas, which are sinks for the fine sediments to which metals preferentially sorb (Boyd et al., 1972).  For  example, sediment metal loadings are higher in Ladner Slough than at adjacent sites in the main channel (Table  Table  X  examples  data  metal  concentrations  in  compiled  by  Fraser  River  IX).  Stancil  (1980)  sediments,  describing with  trace  comparative  figures from a relatively unpolluted area of the Columbia River,  B.C.  For each of the trace metals except mercury, sediment concentrations in one or more levels.  Of  the data. tions  reaches of  particular  the river  interest  is  are substantially  above  natural  the very wide variability shown in  For example, although mean copper and nickel c o n c e n t r a -  did not  vary  substantially  among  most stations,  the  sediments  from the Ladner Side Channel showed high variability in each of these metals:  some sediment samples contained up to four times the river's  average  concentration.  Select  samples  from  New  similarly showed extremely elevated concentrations of cadmium. sediment  This variability demonstrates characterizations.  concentrations  requires  The  site  appropriate  Westminster lead, zinc and  the difficulty of specificity  site  of  specificity  broad-scale trace  in  characterization analyses during ocean dumping  assessment.  Trace  False  metal  Vancouver documented  levels  Wharves in  in  surface  terminal  Table  III.  sediments  in  Burrard  Both  areas  of Inlet  have  showed  concentrations of copper, lead, cadmium and zinc.  sediment  Creek been  extremely  metal  and  at  previously elevated  Concentrations of  TABLE X.  L e v e l s o f Metals i n Sediments from the F r a s e r R i v e r and the Columbia R i v e r , (from S t a n c i l , 1980).  B.C.  Metal C o n c e n t r a t i o n s i n mg/kg (dry Hg Mean Range  Cd Mean Range  Barnston I s l a n d  0.07 0.05-0.11  1.4 <1.0-3.0  New Westminster  0.10 0.05-0.36  <2.2 <1.0-19.0  0.08 0.06-0.10  <1.5 <1.0-3.0  Pb Mean Range  wt).  Cu Mean Range  Zn Mean Range  Ni Mean Range  26.4 24.0-28.0  54.6 48.0-62.0  41.8 35.0-50.0  30.6 21.0-42.0  211.0 55.0-470  30.9 23.0-39.0  11.5 9.0-20.0  28.8 23.0-32.0  68.8 58.0-95.0  45.0 39.0-60.0  25.7  63.0  ND - 0 . 6  16.0-51.0  41.0-118  0.09 0.06-0.12 0.06  1.7 1.0-3.0 <1.6  39.0 32.0-45.0 44.1  29.0 25.0-33.0 32.8  117.0 100-136 114.0  40.0 31.0-50.0 32.8  0.04-0.09  <1.0-<2.0  27.0-76.0  27.0-43.0  80.0-170  26.0-46.0  19.0  29.0  44.3  FRASER RIVER 1.  MAINSTEM 12.2 6.0-20.0 142.0 18.0-370  2 . MAIN ARM D/S Annacis I s l a n d Ladner Side Channel  -  <0.3  115.0 83.0-200  79.3 63.0-170  3. NORTH ARM Mitchell Oak S t .  Island Bridge  COLUMBIA RIVER U/S from T r a i l Smelter  0.38  <0.5  41  arsenic, chromium and mercury were also substantially levels  in  False  Creek,  as  were  arsenic,  nickel  above natural  and  mercury  in  determined prior  to  sediments adjacent to Vancouver Wharve's Bulk Terminal.  The False Creek data described in Table III  was  the major dredging program recently conducted for the B.C. Place and Expo  '86  projects.  Up  to  325,000  m3  of  contaminated  surface  sediments dredged for B.C. Place Corporation have now been removed from  False  Creek  Vancouver Island.  and  disposed  in  oceanic  water  to  the  west  of  However, approximately 25,000 m3 of contaminated  surface sediments dredged from the south-eastern area of False C r e e k for Expo '86 were disposed within the central area of the False Creek East Basin (Nix  and  Chapman,  1984).  Also,  not  all  areas  of  False  Creek have been dredged. The dredging program has certainly reduced the contaminant described  loading of the waterway  in Table  III,  but  from  localized areas  will  the very still  high  exist  levels  with  high  trace metals.  There  is  a  paucity  of  data  describing  dredgable areas of Burrard Inlet.  trace  metal  levels  The extreme pollution of  adjacent to Vancouver Wharves Bulk Terminal (Table III) from  spillage  and  washdown  during  ore  (copper,  lead,  loading operations (Chapman, Munday and Vigers, 1982). Barlow  (1984)  reported  similarly  elevated  levels  of  in  the  sediments  has resulted nickel,  zinc)  Chapman and cadmium  (LI  mg/kg dry wt), chromium (29.8 mg/kg), copper (199 mg/kg), nickel 238 mg/kg),  lead  (59  mg/kg),  and  zinc  Neptune Terminals in Burrard Inlet.  (145  mg/kg)  in  sediments  of  It is considered likely that each  42  of the bulk major high  loading terminals surrounding Burrard Inlet, and also the  shipyards  (Burrard  contaminant  Yarrows,  loadings  were  Vancouver the  Shipyards),  sediments  would  analysed.  show Areas  adjacent to boat marinas and to sewage and stormwater outfalls also warrant monitoring.  In conclusion, existing data waterways  has documented areas within  Vancouver's  with substantially elevated sediment concentrations of  C d , Pb, C u , Zn, As and N i .  Hg,  The failure to document pollution by C r ,  A g and Se is more likely due to the paucity of data rather than their absence from the sediments. occurrence  in  our  Given their high toxicity and their likely  sediments,  it  is  recommended  that  trace  metal  analyses of contaminated sediments should also routinely include these metals.  Concern  for  their  presence in  the  sediments  can  only  be  confirmed or denied by routine measurement.  3.2.2  Organic  Contaminants  Existing  data relating to organic contaminant  of  Vancouver's  pesticides  and  waterways PCB's,  with  are  confined  occasional  levels in the sediments  primarily data  for  to  organochlorine  chlorinated phenols,  chlorinated benzenes, polyaromatic hydrocarbons and phthalate esters. Other persistent and toxic organic contaminants that are identified in Table  VIII  organotins.  are  the  chlorinated  butadienes  and  dibenzofurans,  and  43  Orqanochlorine Pesticides  The  common  but  this  either  representative of  pesticide  was  in forestry  or  the organochlorine  never  used  agriculture  extensively  (Waldichuk,  pesticides  in  is  British  1983).  Hall  DDT,  Columbia and Weins  (1976) analysed 37 sediment samples from the agricultural Salmon and Sumas River basins, but only one contained detectable D D T . samples  from  the  lower  Fraser  Inland Waters D i r e c t o r a t e (IWD) organochlorine dieldrum,  pesticides  endrin,  lindane,  were  (Garrett,  1980).  Only  two  not  of  Brunette  and  Chan  River  basin  Of  the  sediment  measureable  guantities  gamma-chlordanes Creek.  Total  collected  by  metabolites,  epoxide,  amounts  pesticide  methoxychlor, These  in any  sample  contamination  sediments  presence of  of  the  analysed,  organochlorine  of  and  DDT  levels  at  did  its  four  not  12  of  exceed 0.19  in, a  Hall,  pesticides.  them  metabolites.  stations  of  urban/industrial  the same as was tested in the IWD  found  the  aldrin,  were found in the literature.  chlordane levels were below 0.09 mg/kg. low  its  its  samples  were  DDT  the  was  30  and  in measureable  tested  for  The range of analyses  and  organochlorine  (1976)  were  and alpha- and gamma-chlordane.  sediments in the Lower Mainland Yesaki  DDT  heptachlor  present  reports  that  in 1977 were analysed for a range of  including  alpha- and beta-endosulphan compunds  River  Sediment  study.  contained Alpha-  reach  mg/kg,  of  while  and Still total  It was speculated that these  levels were the result of recent illegal usage rather than historic  residuals (Hall and Weins,  1976).  No other pesticides were detected.  44  Garrett  (1980)  reported  Control  Branch  from  Later  Chemicals  levels  of  in  soils  collected  and  organochlorine  the drainage  by  sediment  manufacturing plant  several  sediments  data  the  of  EPS  the  ditch containing  Pesticide  abandoned  in Richmond. pesticides  and  of  Particularly high  were  3200  site  detected  mg/kg  1020 mg/kg total chlordane, 120 mg/kg aldrin, 110 mg/kg  total  with DDT,  heptachlor,  15 mg/kg methoxychlor, 21 mg/kg dieldrin and 13 mg/kg lindane.  Despite the local concern that is warranted by this latter case, it is concluded that organochlorine pesticides are not a significant concern to the management of dredged sediments in the Lower Mainland. was  never  extensively  used  in  British  banned in Canada in the early 1970's.  Columbia,  and  its  DDT  use  was  Other organochlorine pesticides  are more than an order of magnitude more soluble and less persistent in  the  environment.  phosphates,  which  Most have  pesticides  very  low  in  current  association  use  are  organo-  tendencies  with  sediments.  Polychlorinated Biphenyls (PCBs)  Polychlorinated biphenyls guantities the  Fraser  have been detected in  in the sediments River  of almost  downstream  from  all the  low  but  measurable  industrially active areas of Port  Mann  Bridge,  and  in  higher concentrations in False C r e e k and Burrard Inlet (Garrett, 1983). Although the manufacture of P C B s was  terminated in North A m e r i c a  45  in  the  early  restricted,  1970's  PCBs  and  remain  the  a  allowable  ubiquitous  uses  have  pollutant  been  deserving  severely  substantial  environmental concern.  Garrett  (1983)  conducted  a  comprehensive  review  of  the  sources and distribution of P C B s in the British Columbia High sediment  concentrations, often exceeding  environment.  1.0 mg/kg dry  were reported off certain industrial facilities in the Lower These include levels of up to 4.46 mg/kg  Concentrations of up to  sediments of Coal Harbour.  weight,  Mainland.  in the east basin of  Creek and up to 6.9 mg/kg under the roller bearings Street Bridge.  potential  False  of the Granville  16.8 mg/kg were reported in  Very high levels were also found in the  vicinity of the various shipyards and wharves of Burrard Inlet.  The sediments of the Fraser River generally have low levels of P C B s , except in localized areas adjacent to paper and paperboard mills certain of Delta's  land drainage  pump stations  (Garrett,  1983).  and High  levels of P C B s  in these sediments  are probably a reflection of  local  contamination.  Concentrations away from point sources are generally  low.  The  extreme  1974) of trations  toxicity  PCBs found  in the in  and  persistence (up  environment,  the sediments  of  to 30 years; Horn  together  with .the  areas  Vancouver's  of  justify very high concern for these compounds within the of dredged materials from the Lower  Mainland.  high  et al., concen-  waterways, management  46  Polychlorinated terphenyls (PCTs) and polybrominated biphenyls (PBBs) are  related  compounds  under the Canadian  which  are  also  listed  as  Environmental Contaminants  closely resemble P C B s  Act.  manufacture  banned in Canada However  PBBs  (Jamieson,  and  importation  of  1977a),  previously  while  plasticizers, adhesives,  these  PCTs  widely  served  a  Mainland.  PBBs  under the Environmental  were  Each of  However no information was found describing  their usage or possible distribution in the Lower  use,  pollutants  in chemical structure and their environmental  e f f e c t s may be similar.  The  priority  and  PCTs  Contaminants used  as  variety  has  Act  flame of  been  (1979).  retarders  uses,  including  lubricants, caulking compounds, in printing  and as fire retarders (Jamieson,  1977b).  inks  There is conseguently a need  to determine the levels and extent of distribution of these compounds within Vancouver sediments.  Chlorinated Phenols  Chlorinated  phenols  are  used  extensively  in  the  Lower  Mainland,  primarily as wood preservatives and as slimicides in paper production. Other  uses  cides.  The  include most  chlorophenol (PCP). in wood  preserving  Vancouver region.  germicides,  mildewcides,  environmentally Both P C P operations  persistent  insecticides  and  herbi-  is  penta-  chlorophenol  and tetrachlorophenol (TCP) at  numerous  foreshore  sites  are used in  the  There are more than twenty mills using chlorinated  phenols for wood protection located along the foreshore of the lower Fraser River alone (Garrett,  1982).  47  Maynard  and  Vigers  (1979)  analysed  sediments  from  number of chlorophenol users in coastal areas of B.C., wood  preserving  from  all  sites  operations contained  pentachlorophenol. weight of P C P  in  the  Fraser  detectable  Maximum  River.  to  a  including three  Sediment  concentrations  sediment  adjacent  of  samples  tetra-  and  levels of up to 70 ug/kg dry  and up to 60 ug/kg T C P  were found adjacent to the  Crown Zellerbach M i l l .  Garrett toring that  (1980) of  reported data  sediments  showed  high  off  levels  from  Waste  Management  Koppers  International  pole  of  (525  and  PCP  mg/kg)  Branch  treating TCP  monifacility  (90  mg/kg).  Garrett (1980) also described the results of tissue analyses of fish from the Fraser River, which found that chlorinated phenol compounds were identified with greater freguency and at higher concentrations in fish from  the  industrial  areas  of  concentrations did not exceed  the  lower  Fraser.  PCP  and  125 ug/kg and 62.0 ug/kg wet  TCP  weight,  respectively.  The  high  Lower tion.  usage  Mainland Relative  of  pentachlorophenol by  persistent  industries  justifies continued concern for sediment to  the  other  halogenated  concern to ocean dumping management, less  foreshore  in the sediments.  PCP  However  organic  in  the  contamina-  contaminants  (and especially T C P ) the likelihood that  of is  there  are regular and substantial discharges or spillages of this compound to the coastal  environment requires routine monitoring of P C P  sediments proposed for ocean dumping.  levels in  48  Chlorinated Benzenes  Chlorinated  benzenes  Contaminants (HCB)  Act  are  list  listed  of  priority  that  has  been  found  sediments of the Lower Mainland U.S. E P A ' s  was  disease  Canadian  chemicals.  used  extensively  Current  environment  Environmental  Hexachlorobenzene  significant  (Garrett,  agriculture  1980).  of  release  of  for  HCB  residues  HCB  is among the  prevention use to  within  in  1979).  from  HCB  may  electrolytic  and Teshendok,  is  virtually  sediments. preserving HCB  weight)  also  chlorine  storm  fungus  (Garrett,  Vancouver's  aguatic  water  be a component production  1977), and may  data  their  the  of  describing  survey  industry, Maynard  Chemicals in  no  During  in sediments  Later  of  1971  be  of  run-off  of  formed  the Fraser River  L t d . , and vicinity  of  HCB  (1979)  by  Johnson et al. (1975) found H C B  of  Bloedel  the  to  White  chlori-  1976).  in  Vancouver  from  the  to.Domtar  up  dis-  (Quinlivan,  found trace  adjacent  concentrations MacMillan  levels  contamination  and Vigers  waste  facilities  nation of sewage effluents (Kopperman, Juehl and Glass,  There  in  1977).  were placed on such  sources  concentrations  discharges, e.g., from producers of chlorinated solvents  (Safe et al.,  Ghassemi  in  include tire-rubber  industrial  charges  in  129 Priority Pollutants (U.S. E P A ,  until restrictions  1980).  and  the  is the most persistent compound of this class, and is the only  chlorobenzene  HCB  in  1.9  levels  of  L t d . and  ug/kg  Pine  wood  (dry  Division.  in tissues of a wide range of  fishes  49  collected  from  Concentrations  throughout were  low  the Fraser however  River  (mean  downstream  =  10 ug/kg  from  wet  Hope.  wt.),  and  there was no apparent variation with location.  No other information was found describing H C B  levels in sediments of  the Fraser River, and there was a total absence of data pertaining to HCB  levels  in False  Creek  and  Burrard  Inlet.  Given  the  lack  of  evidence to the contrary, and with regard to the numerous potential sources  of  HCB  contamination  compound must be assumed dumping  along  Vancouver's  to be a contaminant  shoreline,  this  of concern to ocean  management.  Polyaromatic Hydrocarbons (PAHs)  R e f e r e n c e to P A H s includes a large class of compounds which  consist  of  cluster  two  or  more  arrangements.  fused  benzene  rings  Other terms commonly  in  linear,  coastal which similar  are  ubiquitous  in  nature,  but  high  to  PCBs,  particularly chemicals  used are  persistent  under  the U.S. E P A ' s  industrial  anthropogenic  not in  compounds  naturally the  the Canadian  occurring  environment. Environmental  129 Priority Pollutants,  with  are  hydrocarbons.  environments warrant appreciable concern. are widely  or  used for these compounds  polycyclic hydrocarbons and polynuclear aromatic  PAHs  angular  inputs  to  Chlorinated P A H s , physical compounds PAHs  are  Contaminants  16 are P A H s .  properties and  are  priority Act.  Of  50  There are few data pertaining to P A H sediments.  Hall, Parkinson  concentrations  among  and  Ma  sediment  concentrations in Vancouver's  (1983)  samples  analysed  locations in False Creek and Burrard Inlet. samples  from  False  71.69 mg/kg, with  Creek a  mean  ranged of  reported high  Total P A H  from 3.86  21.36  from  mg/kg  mg/kg.  In  total  unidentified  levels in nine  (dry  the  weight)  nine  to  Individual  1551.99  mg/kg,  with  a  mean  value  of  to  sediment  samples analysed from Burrard Inlet, concentrations ranged from mg/kg  PAH  314.96  1.62  mg/kg.  P A H s identified in particularly high concentrations included  naphthalene,  acenaphthene,  fluorene,  phenanthracene,  anthracene,  fluoranthene, pyrene and benzo(a)anthracene.  Lower  concentrations  sediments.  Dunn  of  and  PAHs  have  Stich  (1976)  concentrations on Sturgeon Bank Island sewage  treatment  120 ug/kg (dry wt.).  plant  been  reported in Fraser  reported  that  River  benzo(a)pyrene  increased with proximity to the lona outfall.  Concentration maxima  were  Garrett (1980) reported Department of Fisheries  and Oceans data showing naphthalene concentrations of up to 22 ug/kg in the same been  found  area.  Low  in sediments  concentrations of adjacent  benzo(a)pyrene  to creosoted pilings  have  also  in the Fraser  Estuary (Garrett, 1980).  The  largest source of P A H s to the environment is the combustion of  coal, wood and oils. responsible within  for  localized  management.  more  However point source contamination is generally substantially  areas,  so  is  of  elevated more  sediment  interest  to  concentrations ocean  dumping  51  Contamination  of  the aquatic  can be a significant 1977). resin  environment by crude and refined oils  source of P A H s , particularly  Other significant manufacturers,  sources  timber  products  formulators and iron foundries. levels  in timber  (U.S. E P A ,  The  U.S.  cessing  products  EPA and  Borneff  processors,  wastewaters  (1980) Treatability Manual  automobile  products  and  Man-made  and  Kunte  and  other  sources  paint  and  and  ink  of  up  to 45  mg/L  lists timber  products  pro-  laundries of  as  major  flouranthenes  sources  include  of  shipping  and industrial effluents from oil refineries,  processors,  industries  source of  include plastic  A U.S. E P A survey found naphthalene  processing  and harbour oil discharges  dyestuff  (Lee,  1978).  benzo(a)pyrene.  timber  of naphthalenes  naphthalenes  coke  industries  (1965)  production  industries,  using  high  temperature  road  runoff  indicated that  flouranthenes as a result of  bituminous  plastic  can  and  furnaces. also be  road surfaces,  a  car  tire wear and vehicle exhausts.  Matins  et  al.  (1980)  reported  samples  from Puget Sound.  sources  of  halogenated  leaching  PAHs  from  halogenated  PAHs  in  sediment  Although there are very limited data on  sources appear to be discharges (Halowaxes),  26  to  the  aquatic  environment,  possible  from motor vehicle washing facilities  landfill  sites,  discarded  capacitors  and  cable insulation. Historical usage of chlorinated P A H s included rubber substitutes, cutting oil additives and fabric dyes.  52  Polyaromatic tions  hydrocarbons  in sediments  of  have  been found  urban and  in very  high  concentra-  industrialized embayments  in  Puget  Sound, where they have been linked to tissue abnormalities in resident fish and crabs (Malins et al., can  be  established  must be assumed  for  1980).  sediments  Until  from  to be contaminants  dumping management  evidence to the contrary  the Vancouver  of significant  region,  PAHs  concern to  ocean  in Canada.  Phthalate A c i d Esters (PAEs)  Phthalate esters have a variety of uses ranging in  the  paper  However  industry  they  polyvinyl  are  to  mainly  chloride.  perfume  vehicles  used  plasticizers  Within  as  some  plastic  in  from antifoam cosmetic in  the  agents  production.  production  formulations,  PAEs  of can  comprise up to 6 0 % of the total weight of plastic, depending on the degree  of  plasticity  required.  The  extremely diversified, including use packaging occur  industries.  through  leaching  of  of P A E s  Phthalate  is  therefore  Contamination of the environment by P A E s  can  of  effluents  from  substances  such  from  industries,  land  or  disposal  As a result, there are many potential  by sites  sources  in the Vancouver region.  acid  Environmental Pollutants  PAEs  and  containing  (Johnson et al., 1977).  for  in clothing, home furnishings  discharge PAE  market  List.  esters  are  priority  Contaminants Of  the wide  Act  chemicals and  variety of  the PAE's  under U.S.  the  Canadian  EPA's  Priority  manufactured,  di-2-  53  ethylhexylphthalate  (DEHP),  diethyl phthalate  (DBP), butyloctylphthalate (BOP)  (DEP),  dibutylphthalate  and di-isononylphthalate appear to be  of the most significant environmental concern (Garrett,  L i m i t e d data were found  from  levels in Vancouver sediments. for  PAEs  in sediment  the  describing  PAE  Hall, Parkinson and Ma (1983) analysed  samples  Creek and Burrard Inlet.  literature review  1980).  from  unidentified  locations  in  False  Total phthalate concentrations ranged from  below detection up to 33.10 mg/kg (dry weight) to 20.96 mg/kg in Burrard Inlet.  Individual  in False Creek and up  PAEs  found in the highest  concentrations were D E H P (up to 25.2 mg/kg in False Creek and 7.82 mg/kg  in Burrard  tively). mg/kg  Dimethyl  Inlet) and DBP phthalate  in two of the samples  (7.9 mg/kg and 4.27 mg/kg respec-  concentrations  were  found  to  be  8.7  from Burrard Inlet, but were undetect-  able or in trace amounts at all other sites.  Garret (1980) reported that an extensive survey of contaminant in biota in the lona Island mudflats analysed.  DEHP  ug/kg wet weight low  but  was  present  in flounder).  guantifiable  in  region found P A E s highest  concentrations  Cain, Clark  concentrations  of  in all  a  and Zorkin range  of  samples  (up (1979)  PAEs  levels  to  696  found in  the  effluents from the Annacis Island, lona Island and Lulu Island primary sewage treatment plants. Total P A E concentrations ranged from 2.0 50.0 ug/L.  54  PAEs  have  lower  recorded  toxicity  than  the  other  nominated  con-  taminants of concern to ocean dumping management. The concern for PAEs  in  the  environment  is  a  result  of  their  high production  and  subsequent release into the environment, and their persistence within aquatic  sediments.  The  high  concentrations  of  PAEs  found  in  sediments of False Creek and Burrard Inlet by Hall, Parkinson and Ma (1983), and the probability that other areas of Vancouver's  waterways  also contain substantial concentrations of P A E ' s , justify their inclusion as contaminants of concern to ocean dumping  management.  Chlorinated Butadienes  No data was  found describing chlorinated butadiene contamination of  Vancouver's  sediments.  hexachlorobutadiene, production of methanes,  and  chlorobutadiene  are  chlorine, other  However significant  compounds,  the  hexachlorobenzene, chlorinated ethylenes  and  is  also  by-products  industries used  as  (U.S. a  of  particularly from  chemical  (HCBD)  these  wastes  EPA,  solvent  1975). for  Hexa-  natural  and  synthetic rubber and other polymers, as a washing liquor for removing hydrocarbons and as a hydraulic fluid (Verschueren, 1983).  Chlorinated  butadienes  have  been  found  in  high  concentrations  in  sediments of urban and industrialized embayments in Puget Sound (up to 3.3 mg/kg dry weight of H C B D ; Malins et al., 1980; Riley et al., 1980).  The likelihood of comparable  levels in Vancouver's  sediments  55  cannot be discounted.  The high probability of chronic effects in biota  that  very  are  exposed  to  low  levels  of  HCBD  has  justified  its  inclusion in the Canadian Environmenal A c t list of priority chemicals.  Polychlorinated Dibenzafurans  No  data  nation  was  of  tionally  found describing  Vancouver's  for  chlorinated  (PCDFs)  any  sediments.  purpose,  phenols  polychlorinated  but  (Norstrom  PCDFs  are  are  common  et al.,  dibenzafuran not  produced  impurities  1976).  Other  contami-  in  inten-  PCBs  possible  and  sources  include coal tar used as an anticorrosion coating on sub-aguatic  pipes  and in fly ash from municipal or industrial incinerators.  The primary cause for suspicion of P C D F waterways which  is  is  used  terminals during  and  the  (Norstrom  Although  its  presence  widely pulp  in  and  burning  as  of  impurities  local  paper PCP  contamination in Vancouver's in pentachlorophenol  sawmill mills.  facilities,  PCDFs  contaminated  may  hogfuel  lumber also  be  from  (PCP), shipping formed sawmills  et al., 1976).  PCDFs  are  not  nominated  as  priority chemicals  under  the  Canadian Environmental Contaminants  A c t , the identification of three  PCDFs  (Malins  in  Puget  Sound  sediments  appreciable concern in British Columbia. similar  et  PCDFs  al„  1980)  justifies  are structurally very  to chlorinated dibenzodioxins, which are among the most  chemicals  known.  Recent  findings  suggest  that  small  toxic  amounts  of  56  P C D F s found along with P C B s in contaminated rice oil may have been the principle factor causing 1968 (Koroki and Masuda,  mass  food poisoning  in Yusho,  Japan  in  1978).  Organotins  The  major  sediments minor  concern derives  for  from  tri-  its  and  use  tetra-organotins  in antifouling  paints.  local usage in wood preservation (Garrett,  are used extensively as stabilizers in P V C  Information  on  environmental  analytical methodology  is still  levels  in  Vancouver's  There is  1982).  also  Di-organotins  plastics.  of  organotins  in the developmental  is  lacking  stage.  as  However  high levels are suspected for sediments underlying boat and ship repair facilities, during  where  the  paint.  concentrations  removal  Recent  of  have  antifouling  innovations  in  accumulated  paint  and  analytical  improved our ability to monitor organotins EPS, pers. comm.,  via  leaching  the application  of  and new  techniques  have  greatly  in sediments  (C.  Garrett,  1985).  Conclusion  It  is  concluded  that  chemicals  identified  pesticides,  warrant  each in  of  Table  concern  the  classes  VIII,  in the  except  of for  management  toxic the of  and  persistent  organochlorine  dredged  material  from the Vancouver region. Organochlorine pesticides have never been extensively  used  in British  Columbia,  and  have  only  been found  at  57  significant  levels in the aquatic sediments of the Lower Mainland  one isolated HCB,  occasion. However  HCBD,  suspected specific  PCDFs,  distribution  consideration  PAHs  and  within in  the  toxic PAEs  Vancouvers  the  trace metals, each  sediments  PCP,  documented  demand  a scientifically  rational  is a requirement that routine  analyses  of  so  or  each  formulation  dredged material management  have  PCBs,  on  program.  Implicit within this conclusion  of sediments proposed for ocean dumping should be extended from the present cursory examination  to cover this broad range of  substances.  In practice however, analysis costs (especially when considered in the light  of  requirements  for  sample  replication  necessary  to  provide  adequate sediment characterization over an area such as False will  prohibit  the  conduct  of  this  breadth  of  analyses  on  a  Creek) routine  basis.  A tiered structure of sediment analyses may provide some reduction in the  suggested  dredged should  analytical  from not  sediments  requirements.  Vancouver's  require from  waterways  detailed  the  Fraser  The are  Main  of  relatively  characterization. River  majority  Arm  For do  sediments  unpolluted,  example, not  backwater  areas.  If  an  initial  assessment  indicates  coarse  warrant  detailed assessment that should be required of " o o z e " sediments that  so  the from  sediments  proposed for ocean dumping may be significantly contaminated, then a requirement for scientifically informed management responsibility  to  demand  substantive  and  practices implies a  comprehensive  characterization data before the issuance of a permit.  sediment  58  I will  return to this question subsequently.  however, it  is concluded that  dredged sediments of  the  contaminants  contaminants  processes  effecting  from disposed dredged  e f f e c t s of the contaminants for  portion of  purpose  ocean  dumped  from the Vancouver region may contain any or all  nominated  environmental  a significant  For the present  in a comprehensive  of the  concern. release  material, and  Therefore, of the  any  of  the these  environmental  that may be released, must be accounted  management scheme.  the objectives of the following two sections.  These  tasks  comprise  59  4.0  TRACE  METAL  MARINE  4.1  PATHWAYS AND  P R O C E S S E S IN  THE  ENVIRONMENT  Introduction  Trace  metals  occur  naturally  in  the  marine  environment.  Their  distribution in seawater was first compared and discussed by Fabricand et al. (1962) and Shutz  and Turekian (1965).  considerable fluctuation observed  in coastal  They showed  waters  that  the  can be attributed  partly to man's influence and partly to natural biological cycles.  Only  in  data  the  past  few  years  however,  have  reliable  experimental  become available.  Natural centrate very  processes trace  soluble  in  riverine  metals  in  and  in bottom  water  under  the  marine  ecosystems  sediments. conditions  Trace that  tend  to  metals  normally  con-  are  not  occur  in  oxygenated uncontaminated surface waters, so the introduction of high concentrations of metals  into aquatic ecosystems  in a equilibrium condition where most of (adsorbed  or  absorbed)  deposited on the bottom time  necessary  physiochemical  by  suspended  when  to achieve  this  the  will generally  metals  particulate  the suspended  will  matter  material  be  result sorbed  and  then  settles.  The  equilibrium condition depends on the  conditions of the aquatic system  duration of contaminant introduction.  and the quality  and  60  Society's  awareness  environment  is  a  of  trace  recent  prominence in the early resultant  human  Minamata Bay seabirds the  It  was  in  the  first  marine  brought  to  1950's by a mysterious neurological illness and  in Japan.  among  the  subsistence  fisherfolk  of  Since this disease also prevailed among local  and household cats, of  contamination  phenomenon.  fatalities  consumption  metal  investigations  high  led to the discovery  concentrations  of  mercury  that  compounds  accumulated in fish and shellfish had evoked disasterous end effects in the  nutritional  food  chain.  Society  became  existence of toxic metals in the environment. human since  poisoning Minamata  suddenly  aware  of  the  Four other tragedies of  due to toxic metals have been documented in Japan (Table  XI).  In  each case  the concentration of  the  metals in a sediment phase and subsequent release and transfer to the food chain was a factor (Kester et al., 1983).  Consequently  good cause to understand the behaviour of metals  there is  in the disposal  of  contaminated dredge spoil.  The  release of trace metals  water  column  chemical relating  and to  from disposed dredged materials  is complex, being biological  the  influenced by a number of  factors.  transformation  Although and  or  the  physical,  the fundamental  release  to  concepts  retention  of  trace  metals in the aquatic environment have long been developed, it is only in  the  last  disposal  that  operations.  conducted release  decade  of  sediments.  by  the  The  U.S.  chemical Although  they  have  Dredged  Army  Corps  contaminants the  been  Material of  of  a  wide metal  dredging  Research  Engineers,  from  magnitude  applied . to  have  variety release  and  Program,  studied of is  the  dredged largely  61  TABLE X I .  Summary o f I n c i d e n t s o f Human P o i s o n i n g by T o x i c i n t h e A q u a t i c Environment  Location  o f Japan ( F o r s t n e r  Year  and W i t t m a n ,  Metal  Minamata Bay  1953-1960  Mercury  Ni i gata  1964-1965  Mercury  1973  Mercury  Goshonoura Fuchu  1947-1965  Tokyo  1975  Metals  Cadmi urn Chromi um  1981).  62  specific  to  general  the  dredged  principles  have  material been  and  derived  the  receiving  which  should  environment,  be  applied  to  environmental regulation.  4.1.1  T r a c e Metal  Speciation  The  of  action  metals  is highly  the sediments. are  chemical  processes  effecting  the  release  of  trace  dependent upon the speciation of  the metals  within  Most trace metals  sedimentary  "sink"  in the natural  incorporated into the crystalline  lattice of  their  mineral  carrier  (Brannon et al., 1976).  Because this incorporation is by metal bonding  and  in  is  predominantly  inert  positions,  these  trace  e f f e c t i v e l y removed from the aquatic and biological  metals  are  systems.  T r a c e metals associated with parts of the dredged material other than the  mineral  crystalline  lattice can  biologically unavailable.  also be essentially  immobile  Metals associated with crystalline F e and  oxides in dredged sediments are a case in point.  and Mn  For example, most  sediment As is usually associated with these highly crystalline F e and Mn  oxides  and  is  chemically  immobile  and  biologically  unavailable  (Brannon et al., 1976).  However  there  is  aquatic  sediment,  mineral  lattice.  the  cation  crystalline,  a  diverse  some  of  range which  of  other  metal  are  only  weakly  associations bound  to  in the  Metals in sediment interstitial waters or adsorbed to  exchange amorphous  complex, Fe  and  and Mn  metals  associated  oxides, are  the  most  with  poorly  mobile  and  63  potentially Engler,  available  1978).  associations  in  contaminants  dredged  material  (Burks  and  Forstner and Patchineelam (1976) characterized metal both  natural  bonding processes (Table  A  in  and  polluted  aquatic  systems  by  the  XII).  number of studies have been conducted to characterize the ability  of a sediment to release material to the overlying water. used  in  these  interstitial  studies  water)  to  have total  ranged acid  from  filtration  digestion.  In  Procedures  (to  determine  addition,  several  intermediate operationally defined sediment extraction procedures have been used  to assess sediment  procedures  are similar  constituent  to soil  availability.  These  extraction procedures that  latter  have  been  used for many years to define exchangeable, available and extractable constituents in soils (Jackson, 1958; Black,  No  single  defining  extract  has  chemical  been  shown  exchangeability  to  1965).  be  (Jenne  universally and  successful  Luoma,  seguently, a variety of extraction procedures ranging  1977).  in  Con-  in severity from  distilled water or a dilute salt solution to strong oxidizing agents such as  hydrogen  define jointly  peroxide  sediment by  the  Environmental  to  a  strong  geochemical U.S.  phases.  Army  Protection  acid  Corps  Agency  solution The  of to  have  been  used  to  elutriate test, developed Engineers  evaluate  and  the  .proposed  U.S.  dredged  material disposal operations, is similar to the weaker extractant used in elemental partitioning studies except that disposal site water rather than distilled water leaching agent.  or a  well  defined salt  solution  is  used  as  the  64 TABLE X I I .  Mechanisms o f Trace Metal Bonding (from F o r s t n e r and Patchineelam,  1976)  Carrier  Bonding Metal  C r y s t a l l i n e mineral  Process  bonding p r i m a r i l y a t  inert  positions Hydroxides  P r e c i p i t a t i o n as a r e s u l t o f  -,  Carbonates  exceeding s o l u b i l i t y  Sulfides  in s i t u  Hydroxides and  pH  dependent  product  Physico-sorption Chemical s o r p t i o n (exchange  Oxides o f Fe/Mn  H  +  in fixed  of  positions)  C o p r e c i p i t a t i o n as a r e s u l t o f exceeding s o l u b i l i t y Bitumen, Humic  Lipids,  pH  dependent  Residual  Physico-sorption Chemical s o r p t i o n  substances,  H+  organics  product  i n COOH", OH"  (exchange  of  groups)  Complexes Calcium carbonate  pH  dependent  Physico-sorption Pseudomorphosus C o p r e c i pi t a t i o n  (incorporation  by e x c e e d i n g t h e s o l u b i l i t y product)  65  Another  commonly  adopted  strategy  developed by Brannon et al. (1976).  of  selective  leaching  This procedure partitions  was trace  metals within the sediments into six phases as follows:  1.  Interstitial  water,  which  is  subject  to  diffusive  exchange  with  benthic organisms or the overlying water column.  2.  Easily exchangeable phase, which may release dissolved cations in response to pH and salinity  3.  Easily  reduceable  phase,  changes.  which  may  be  released  with  a  slight  decrease in redox potential.  4.  Organic  plus sulfide phase, which could be mobilized by exposure  to oxygenated conditions.  5.  Moderately  reduceable  phase,  which  could  be  mobilized  if  the  redox potential substantially decreases.  6.  Residual phase, which is tightly bound and unlikely to be released to the marine environment or biota upon dredging and disposal.  However  neither  the  elutriate test  nor selective  leaching  strategies  provide complete information describing the lability of trace metals in disposed dredged material.  This failing is perhaps more the result of  the complexity of _in situ transformation processes than inappropriate analytical  procedures.  The receiving environment  includes  not  only  66  the  bulk  seawater  column,  micro-environments interfacial  as  transition  digestive  tracts  of  following  discussion  but  also  the  interstitial  zone  between  particulate the  such water solid  feeding  emphasis  is  complex of  the  and  variable  sediment,  and  solution,  and  the  benthic  animals.  In  the  placed  on  the  environmental  conditions which induce metal transformations and remobilization. phase partitioning of trace metals within individual sediments the susceptability of those sediments  the  to the described  The  effects  transformation  processes.  T r a c e Metal Release During Water Column Passage  The remobilization of  trace metals  caused by four types of chemical  1.  from  dredged  material  is  mainly  changes.  Elevated salt concentrations, whereby the alkali and alkaline earth cations can compete with metal ions sorbed onto solid particles.  2.  Changes in redox conditions. and  manganese  releasing  part  hydroxides of  the  Under more reduced conditions iron partly  or  incorporated or  completely sorbed  dissolve  trace  metal  thus load.  Under more oxidized conditions, metal sulfides may be oxidized to more soluble forms.  3.  Lowering  of  pH  which  leads  to a  dissolution  of  carbonates  and  hydroxides, as well as to increased desorption of metal cations due to competition with H+  ions.  67  4.  Increased  concentrations  of  complexing  agents  in solution,  which  can compete for trace metals adsorbed to solid particles and form soluble metal complexes, sometimes with high stability.  4.2.1  Salinity  Alteration  Concern from  that  salinity  riverine  alteration  sediments  may  disposed  cause  into  trace  the  marine  primarily based upon research on trace metal However  estuarine  interactions  that  chemistry  displays  a  metals  desorption  environment  behaviour in estuaries.  very  complex  system  are still not completely understood, especially  respect to the behaviour of trace metals. in an estuarine system  of with  Turekian (1977) noted that  there is continuous movement of some  in and out of solution, but  is  little is actually  lost out of  the  metals system.  The loss that does occur is primarily in the form of fine particles.  Experiments conducted by Kharkar, Turekian and Bertine (1968) on the desorption  of  molybdenum freshwater  absorbed  show  that  competitive  sodium of  ions.  standard  solid  where  the  silver, trace  selenium, metal  chromium  was  absorbed  and from  it was always released to a greater or lesser extent upon  contact with seawater. was  cobalt,  organic  They concluded that the mechanism  displacement  of  adsorbed  Sholkovitz (1976) argued that clays  and  matter  distilled water, and  the  failure  ions  by  to  magnesium  the use • by these  the absence monitor  involved and  authors  of  dissolved  and  pH  restricts  the  68  conclusions  that  Nevertheless,  can be drawn  desorption  did  from  these a r t i f i c i a l test  seem  to  occur  and  conditions.  this  has  been  der Weiden, Arnoldus and Meurs (1977) resuspended  Rhine  confirmed in other studies.  When Van  River sediments in seawater they demonstrated significant desorption, primarily due to chloride and sulfate complex formation.  The order  of decreasing desorption of metals in the experiments was  Cd  > Mn  > Ni  found.  > Co  > Cu  Zn  >  == C r ; for F e and Pb no desorption  was  However, in a more recent series of experiments on suspended  Rhine River sediments in seawater, Patchineelam and Calmano (1981) concluded that none of the investigated elements (Zn, C o , C r and Fe) released  more  than  10% of  the original  metal  concentration in the  seawater.  In the Columbia River estuary, similar studies by Evans and Cutshell (1973)  observed  minor  desorption  of  Mn  and  changes, but saw no loss of C r , Sb or Sc.  Zn  due  to  salinity  T r e f r y and Presley (1976)  conducted extensive studies in the Mississippi River estuary, comparing river  suspended  mouth.  They  matter showed  to  that  that  in  seawater  individual  differently upon mixing with G u l f of  Mexico  concentrations were very similar  matter  whereas  content  generally  outside  particulate  and C r  Mn  just  water.  the  metals  river  behave  F e , A l , C o , Ni  in river and gulf  decreased (i.e. was  suspended released)  seaward and Zn, Pb, C u and C d concentrations were either similar or higher  in gulf  samples.  These observations  argue  desorption of any of these metals except for Mn.  against  extensive  The decreased Mn  69  concentrations  in gulf suspended matter, which were up to 4 0 %  lower  than those in the river, suggest desorption of Mn similar to Evans and Cutshell  (1973).  concentrations  In  a number  were  higher  of  instances,  in the gulf  the Zn, Pb, C u  suspended  matter,  and  Cd  suggesting  that under certain conditions (e.g. following pH changes from less than 8.0  to 8.5, or during  phytoplankton  blooms) uptake of  these  metals  may occur.  Similar  studies of the effects of the sediment  exchange reactions in  the Fraser River estuary on zinc and copper distributions in the Strait of Georgia concluded that both these metals desorbed from suspended sediments Grill,  when  1977).  which  (Thomas  and  De Mora (1981) showed that this also occurred for  Mn,  exhibited  the  a  river  water  maximum  mixed  dissolved  River estuary at salinities ranging  Bindra (1983) used static tigate  with  seawater  concentration  in  the  from 4 to 12 ppt.  and agitated  water  column  tests  to  inves-  the effects of salinity alteration on desorption of copper, iron,  manganese,  lead and zinc from sediments of the Lower  Variable  copper  to a static, aerated water column due to a salinity 0 ppt  water  column  agitated  test  increases. column  to  results  14.5 with  were  ppt,  but  further  measured  achieved.  much  of  increases  negligible  There was  Fraser  shed.  from  Fraser  this  in  release  Analyses of zinc concentrations  showed  release  of  zinc  increase to 14.5 ppt, subseguent  into  was  release of  removed  salinity. of  minor  copper  In  water  increase from  the  contrast,  the  due  to  salinity  in a static, aerated water  solution  following  a  readsorption after a salinity  salinity increase  70  to 21.5 ppt, then slow release after salinity was 29.5 ppt. zinc  at  In the agitated higher  further increased to  test, high organic sediments  salinities,  but  low  organic  sediments  release due to a very slight salinity increase (to from  solution  at  higher  salinities.  removed from solution due to  Iron  released more showed  high  I ppt), and removal  and  lead  increased salinity,  were  generally  whereas  manganese  was released.  It  is perhaps  not  surprising  that so much seemingly  conflicting  data  have been published on marine adsorbtion-desorption phenomena in view of  the  likely  centration  of  equilibrium, detail  importance both  such  dissolved  and  variables  and  temperature, etc.  in O'Connor  then, that  of  as  suspended  These matters  Kester  the  matter,  and  pH,  (1975).  con-  time  are discussed  (1975) and Parks  each dredged material and disposal  nature  It  environment  in  of  some  may will  have  to be considered individually if there is concern for minor changes the  chemistry  However  it  of  seems  the  material  unlikely  that  expected as a response to salinity  in  response  major  to  chemical  changes  alone.  be  in  salinity  changes.  changes  can  be  Changes in redox  conditions and pH are of much greater significance.  4.2.2  Alteration of Redox and pH  Conditions  The redox potential (Eh) and the pH are two of the primary that  control  the chemical  behaviour  of  metals  in marine  variables sediments.  The redox potential of the water column or sediment is a measure of the  availability  of  electrons  and  thus  the  intensity  of  oxidation  or  71  reduction of a sediment-water system.  Similarly, the pH indicates the  activity  aqueous  of  the  hydrogen  ion  in  the  phase  measure of the degree of acidity or alkalinity. pH  act  in combination  zation or of  to  influence processes  immobilization of metals  these processes  and  is  thus  Redox potential and affecting  the  mobili-  in sediment-water systems.  can be described from  a  Some  thermodynamic considera-  tions (e.g. valence state), but many processes do not lend themselves to mathematical description.  In situ, the fine-ground " o o z e " sediments that are of primary concern to this review are generally other substances from  organic  matter  and  that did not completely oxidize before being cut off  the overlying  organics  reduced, containing  water  by  burial.  Microbial  degradation  in anaerobic conditions results in the formation of  of  the  sulfides,  ammonia and reduced forms of iron and manganese.  T r a c e metals are  normally  Typical  stabilized  as  insoluble  metal  sulfides.  conditions are a low redox potential (Eh <-50  chemical  mV) and pH (usually  in  the range of 6.8 - 7.5).  The  waters  (Waldichuk,  in  Georgia  1957).  Strait  are  generally  oxidized  throughout  Marine environments that contain dissolved  oxygen  usually have E h values greater than 400 mV with pH values generally in the range of 7.5 - 8.4. tional  areas  of  the  Strait,  The sediments such  as  might  within  low energy  be suitable  for  deposidredged  material disposal, may have an oxidized surface veneer (to a depth of a few centimetres or less), underlayed by anaerobic sediments.  72  The degree to which dredged sediments become oxidized upon disposal depends  upon  the  oxygenated water.  extent  of  contact  between  the  material  and  Clam-shell dredged material which is disposed from  a bottom dumping scow  tends to remain cohesive during  through the water column, so contact will be minimal.  its  passage  In contrast,  hydraulically dredged material entrains large volumes of water during both the dredging and the disposal operation, so may be substantially oxidized.  When reduced sediments are mixed with oxygenated water, the metal sulfides  are oxidized.  The oxidized forms  of  the  metals,  with  the  exception of manganese and iron, are somewhat more soluble than the sulfide compounds.  In  addition, the oxidation of  sulfides  to  sulfate  may reduce the pH, resulting in increased dissolution of exchangeable trace metal cations.  However the  the release of  dissolved  manganese  cations  trace metals  onto  hydrous oxides.  the  is counteracted by sorption of  surface  of  poorly  soluble  The hydrous oxides of iron and  form colloidal particles that  precipitate and exhibit  a  iron  and  manganese  large,  active  surface area that scavenges other trace metals from the water column (Burks and Engler, 1978). compensates degree relative  of  the  The extent to which this scavenging  release of  oxidation  of  the  soluble  metal  sediments,  phase concentrations of  cations  the  the various  pH  depends upon  conditions  metals.  and  Freshly  pitated colloidal hydrous oxides are especially e f f i c i e n t in for trace metals (Lee, 1973).  process the the  preci-  scavenging  73  The above theoretical framework is substantially complexed in natural sediments  by  sediments. heavy  the  Chelation  metal  centration insoluble  activity  solubility  of  with to  soluble  organics  is  of  soluble  levels  free an  organic  material  organic  considerably  ions.  within  compounds greater  Conversely,  important  sink  for  the  dredged  may  enhance  than  the  con-  complexation  many  with  metals.  Redox  potential, and to a lesser extent pH, influence both of these processes by  guantitatively  present  and  (Gambrell  et  qualitatively al.,  1976).  affecting The  the  organic  structurally  compounds  complex,  molecular weight organic compounds characteristic of humic in reduced environments  are  large  materials  reported to be altered to smaller,  less  complex molecules with less metal binding capacity as a sediment oxidized  (Patrick  and  Mikkel sen,  1971).  Though  metal  ions  may  is be  released from insoluble humic materials as a consequence of oxidation or acidification, it is likely that such release would occur only where a reduced dredged material was subjected to an oxidizing environment for  a  considerable  period  of  time  (Gambrell,  Khalid  and  Patrick,  1976).  Numerous  researchers  have  investigated  trace  metal  release  under  varying E h and pH conditions using the elutriate test described by L e e (1975).  This test involves the mixing of one volume of sediment  four volumes of seawater for a 30 minute shaking period. considered that  this will  induce greater  L e e (1975)  mobilization of trace  than will occur under actual dredged material disposal  with  metals  conditions.  74  Bindra the  (1983) investigated  release of  Fraser  the effects of varying  copper, lead and zinc  watershed.  Generally  a  pH conditions  from sediments  high  release  of  observed at extreme pH conditions (pH of 5 and  of  all  10).  the  upon Lower  metals Under  was  normal  pH (between 6.5 and 8) and both oxic and anoxic conditions, release of  copper  and  lead  was  very  low  and  release  of  zinc  was  slight.  Physical characteristics of the sediments (organic matter, particle size distribution) appeared to a f f e c t the release pattern.  Chen, L u and Sycup (1976) tested release of A g , C d , C r , C u , F e , Hg, Mn,  N i , Pb  and Zn  from  sediments  taken  from  Angeles Harbor and released into oxidized (DO oxidized (DO  = 0-1  Neutral  pH  was  immediate  an  subsequent  conditions  environments.  or  from  The  of  metal  metals  that  and N i , with C r ,  all  The  of  mg/L), slightly conditions.  conditions  there  either  gradually  in  reducing  slightly  oxidized  or  oxidized  significantly  C u , Pb  and  metals  released Zn  being  > in slightly in  the  in  by  this  released  for each of  these  oxidizing >  equilibrated  were very low, in the parts per billion range or less. release of A g , C d or Hg.  Los  followed  in reducing conditions  concentrations  of  seawater,  were  the  areas  = 0 mg/L)  Under  to  solution, in  = 5-8  The release phenomena behaved similarly  metals, with release oxidizing.  maintained.  immediately  were F e , Mn  slightly.  were  release  removal  environments,  study  mg/L), and reduced (DO  seven  water  There was  no  75  Other and  investigations  coastal  inlets  testing have  released in substantial  a variety of  shown  that  sediments  manganese  from U.S.  is  the  rivers  only  metal  quantities during the Elutriate Test conducted  under fully aerated conditions (Brannon et al., 1976; L e e et al., 1975; Lee  et  al.,  Wright, (0.01  1978;  1978).  Brannon,  Plumb  and  Smith,  Transitory release (a matter of  - 0.05 ug/L),  1978; Shubel, minutes)  of  1978;  mercury  lead (< 40 ug/L), cadmium (0.08 - 2.5 ug/L)  and  nickel (5 - 20 ug/L) have been observed on occasion in the field (Lee et al., 1978, Wright, higher very  1978).  Iron is usually released initially in much  concentrations than metals rapid oxidation and  other  than  Mn,  but  precipitation in the water  is  subject  column  to  (Wright,  1979).  The iron oxide precipitates have been generally found to result  in  removal  the  of  most  other  soluble  metal  constituents  from  the  water column (Lee et al., 1975, Brannon et al., 1976).  Brannon et al. (1976) observed large releases of zinc during elutriate tests on Mobile Bay sediments However  run under anaerobic acidic conditions.  these releases have not been observed by others conducting  aerated elutriate tests on similar sediments.  4.2.3  Field  In  Monitoring  field  monitoring  during  disposal  by  barges  and  hopper  dredges,  releases of trace metals have been found to be minor and of limited duration.  Such  effects  water  Even  on in  releases quality  continuous  should or  not  marine  discharge  exert  even short-term  organisms  pipeline  at  the  disposal  in  adverse  disposal areas  site. where  76  sediments found  contained  no  plumes  elevated of  levels  dissolved  background  levels.  ciated with  particulate matter  of  most  metals  Trace metals  in  and  metals,  significantly  the disposal  were  rapidly  Shubel,  (1978)  greater  than  plume were  asso-  removed  from  the  water column.  It thus seems unlikely that metal release to the water column during the  disposal  operation  would  have  significant  biological  effects.  Clam-shell dredged materials that are disposed by bottom opening scow remain  relatively  cohesive  as  they  fall  (discussed subsequently in Section 6.0).  through  the  water  Because seawater entrainment  within the falling mass is small, the release of trace metals within  the  pore  water  should  column  be minimal.  The  dissolved  limited extent  and  duration of contact between the disposed sediments and the seawater should  also  mitigate  contaminants. has  largely  occurs  oxidative  dissolution  of  trace  metal  Concern for metal release during dredging and disposal  been  during  against  based  hydraulic  on  the  dredging  extended and vigorous operations.  In  mixing  recognition  which of  the  reduced concern attached to clam-shell dredging, L e e (1977) proposed a short-contact "plop test" as a more reasonable simulation of metal release under these conditions than the elutriate test.  trace  77  4.3  T r a c e Metal Release from Settled Sediments  4.3.1  C h e m i c a l Release  After near  the  Processes  sediment  neutral pH  settles  it normally  condition.  oxidized to a shallow  The  depth.  returns  surface  to an  sediment  anaerobic  will  and  probably  be  The vertical extent of the oxic zone is  a function of the natural sediment  accumulation  rate (Shokes,  1976),  the concentration of metabolizable organic matter (Berner, 1971), and the nature and extent of  biological  activity.  If  sizeable amounts  of  anoxic dredged material are deposited in oxygenated water there will be  a  limited  sediment  oxygen  supply  where biological  except  mixing  in  the  occurs.  surface  With  centimetres  freguent  disposal  of of  high organic content waste material, it may be possible to generate a completely reducing, anoxic sediment column.  Hoos' organic  (1976)  study  content  core samples  of  the  Point  in the disposed  was  Grey  disposal  sediments  site  (maximum  1.61%), despite the high volume  debris and fibrous material at the site.  of  evidenced value  low  from  disposed  50  wood  It is assumed that appropriate  dredge spoil sites in Georgia Strait will be generally anoxic, overlayed by a variable but shallow oxic zone.  In the anoxic interstitial  region, some  water  whereas  data has shown that and variable.  chemical species may others  may  be released to the  be rendered immobile.  partitioning within settled sediments  On the basis of solubility product constants  Field  is complex for metal  78  sulfide  compounds,  reducing  trace  sediments.  metals  Thomson,  should  remain  Turekian and  essentially  McCaffrey  fixed  (1975)  in cal-  culated that trace metals should remain immobile in pore waters with a sulfide ion concentration of (1976) reported that very  high;  Hallberg  up  to  (1974)  IO 9  trace metal  1000  times  ascribed  mole per litre.  -  concentrations  higher  the  high  than  However  in pore water  the  solubility  Manheim  overlying of  trace  were  seawater. chemicals  measured in pore waters of reducing sediments to the stabilization of metals  leached  from  silicates  and  oxides  onto  soluble  organic  complexes.  Nissenbaum  and Swaine (1976) analyzed the metals bound to dissolved  organic  complexes  Saanich  Inlet, B.C.  from  interstitial  water  of  reducing  sediments  in  The results showed that all of the Zn, almost all  of the C u and a major part of the F e , Ni and C o are bound to humic material. under  Experimental  data  reducing conditions  of  Lu  and  Chen  the concentrations of  (1977) suggests C d , Hg  that  and Pb  are  controlled by sulfide complexes with organic complexes controlling F e , Ni  and Zn, chloride complexes  for  Mn  and  hydroxide complexes  for  Cr.  High  pore  water  concentrations  of  trace  metals  will  establish  a  concentration gradient between the sediments and overlying seawater, which will promote upward diffusive migration. complexes that migrate sediments,  so  release  Dissolved trace metal  upward will reoxidize in the aerobic surface to  the  overlying  seawater  controlled by the solubility of the oxidized species.  will  generally  be  79  Large  molecular  slowly  degrade  weight  organic  to simpler  molecules  (e.g.  fulvic compounds  humic  in an oxic  compounds) environment.  F r o m a colloid chemistry point of view, metal ions in large molecular weight  molecules may be included in central hydrophilic "cavities" of  the molecule, and would then be prohibited from leaching. higher  molecular  these  metals  pounds  may  (Reddy  release  weight be  fractions  released  and Patrick,  process  exhibit  following  colloidal oxidation  1975; Chen et al.,  properties, to  1976).  simpler  will be countered by the higher complexing  functional  groups  metals  can attach.  organic  molecules  (i.e.  Also, will  OH,  COOH)  with  slow  rate of  the very  generally  mean  that  released trace metals onto iron and manganese surface  sediments  water column.  will  substantially  counter  which  com-  which have the  released of  absorption  of  hydroxides within  release  this  capacity  oxidation  the  and  However  of many simpler organic molecules (e.g. fulvic compounds) more  Only the  large any the  to the overlying  Long-term incubation tests (3 and 5 months) conducted  by L u and Chen (1977) showed that, with the exception of C r and Hg most  trace  seawater  metals  were  found  concentrations.  sub-ppb  to  release  was  ppb the  levels.  to  However The  scavenging  be  released  total  relative  release  explanation  offered  effects  Fe/Mn  of  to  original  remained for  the  in  the  negligible  hydroxides  or  clay  minerals and the formation of insoluble humic complexes.  Studies  by  Windom  (1976)  on  the  exchange  of  metals  sediment and water from marshes and estuaries in the Gulf of similarly showed no significant C u and Hg above ambient  between Mexico  increases of heavy metals such as Pb,  levels.  It was concluded that the slowness  80  of the diffusion processes and the rapid absorption of released metals by F e / M n hydroxides resulted in insignificant contribution to the water column.  In contrast  to these results, studies  Mississippi  River  dredged  by  sediment  Gambrell  indicated  et  that  al. (1977) with Cd  release  was  heavily pH-redox dependent, and that significant release may occur in time under low pH, oxygen rich conditions. (1976)  found  that  prolonged oxidation of  can result in significant C d release. it was  Gilbert, C l a y and Leighty reduced polluted  sediments  Due to the high toxicity of C d ,  concluded that care must be exercised with polluted dredged  material.  Khalid,  Patrick  and  Gambrell  suspensions  containing  cadmium,  streams  oxygenated  gas  of  with high and low oxygen than  gases with an  was  that  organics;  a a  (1978)  subjected  sulfides  mixtures. contents  and  reduced  other  inorganics  They found that gas  solubilized more Pb, C d  intermediate oxygen  content.  Their  low  oxygen  regime  favoured  metal  high  oxygen  regime  supported  conversion  sediment to  mixtures and  Cu  explanation  solubilization of  by  insoluble  sulfides to soluble sulfates as E h rose from -170 mV to +600 mV, and the  concomitant  decrease  soluble cadmium species. oxides  of  iron  and  in  pH  promoted  the  formation  of  more  Khalid et al. (1978) suggested that hydrous  manganese  acted  as  scavengers  for  cadmium at moderate E h , but could release absorbed soluble as sediments became slightly acidic and oxidizing.  dissolved cadmium  81  4.3.2  Biological Release  The  laboratory  Processes  studies  cited  above  provide  no  measure  of  the  processes by which the biological community that colonizes a dredged material  disposal  site may  e f f e c t trace metal  release.  With  time,  biologically induced release of trace metals to the water column may be significant. several across  Wood  mechanisms  (1974) and Petr  responsible  the sediment-water  important.  for  (1977) suggested  the  movement  interface, diffusion  is  of  that  of  trace  probably  the  the  metals least  The movement of certain biota and release of gases from  microbial activity were considered of greater significance.  Macrofaunal and microbial activity in the seafloor sediments can each significantly e f f e c t trace metal release.  Bioturbation  Burrowing  and tunnel building influence trace metal  release rates by  active and passive regulation of pore water exchange with the water column.  Although  little  e f f e c t s of biologically (1980) contend  that  it  is  known  about  the  mechanisms,  induced pore water exchange, Swartz is  more  important  in  pore  water  exchange  include  Biogenic  burrowing  organisms and irrigation by vagile and stationary fauna. the  transport  of  feeding purposes.  water  through  a  tube or  tunnel  for  or  and L e e  than particle transport  controlling the flux of many dissolved compounds. resulting  rates  in  activities by  vagile  Irrigation is respiratory or  82  Unfortunately few studies have investigated the influence of organisms on the rate of exchange the  water  column.  of contaminants  Tube  irrigation  enhance ammonia  flux  to  Burrow  was  also  irrigation  methane  (Martens,  Irrigation  1976)  by  overlying shown  and  by A r e n i c o l a marina  from a  water to  marine  polychaete  was  (Aller  Yingst,  and  influence the  manganese  sediments  (McCaffrey  (Gordon, Dale  and  shown  benthic et  to  1978). flux  al.,  Kerzer,  to  of  1980).  1976) and  U c a pugnax (Pemberton, Risk and Buckley, 1976) may have contributed to the dissipation of buried oil.  Bryan metals The  (1976) suggested that burrowing organisms would release heavy dissolved  only  Renfro  study  in interstitial water, but provided no substantiation. that  (1973), where  could  be  found  to  the addition of  support  this  belief  was  by  the polychaete (Nereis diversi-  color) to contaminated sediments increased the loss rate of &$Zn three to seven times compared with sediments without  It  is considered that  the scavenging  worms.  properties of  Fe/Mn  hydroxides  probably plays a significant role in counteracting biogenic trace metal release due to mechanical processes.  Burrowing and tube construction  do increase the depth and surface area for passive or active exchange of pore water and seawater. of  However  the sediment-water interface  the burrows or tubes will generally be oxidized..  metals  within  the  pore  water  that  diffuses  or  is  Dissolved  pumped  into  aerated layer will generally adsorb and coprecipitate with the hydroxides.  trace this  Fe/Mn  83  A l l e r (1978) determined that sediments with the polychaete Clymenella torquata  had  higher  pore water concentrations  of F e and Mn  surface 2 c m , but lower concentrations from 2 - 1 2  cm.  an  the pore  increased  flux  of  F e , Mn,  NH4  and HPO4 from  in the  There  was  waters  due to diffusive exchange of ions through the polychaete tubes. A l l e r (1978) reasoned that closely spaced tubes of  the  sediment-water  distance  these  However  the coprecipitation of  tated  Fe/Mn  ions  column  had to  hydroxides  increased the surface  interface and  travel  was  decreased  area  the  average  to diffuse into the water  column.  dissolved  trace  believed  to  metals  have  with  precipi-  counteracted  the  expected release of trace metals to the water column.  Although  trace  metals  release  to  the  water  column  may  not  be  increased by mechanical processes of biological activities, it is noted that  these processes  concentrations reworking,  do result  in the  surface  aerated  sediments  in substantially surface  may  be  elevated trace  sediments. ingested  metal  In  areas  of  high  several  times  a year.  Passage through the gut of invertebrate exposes particulate and sorbed trace  metals  to an acidic environment (pH  organically and inorganically sorbed metals. that  the  structure  of  some  clay  minerals  < 5), which may  release  Pryor (1975) demonstrated is  modified  by  digestive  processes.  The nature and extent of chemical alteration of trace metal through  digestive  elimination High  in  processes,  feces  concentrations  effects of  and  the  trace  organic  degree  metal  pollutants  to  release, have  which  trace  remains been  species metal  unknown.  measured  in  84  invertebrate benthic  feces  filter  biodeposition  (Lee  feeding of  and  Swartz,  populations  water  borne  1980),  can  and  be  trace  a  fecal  deposition  significant  metals  by  source  (Kraueter,  of  1976).  Presumably, digestion chemically alters trace metal speciation in feces vis  a v[s  the sediments,  but  the nature  and  relative  importance  of  deposition  by  this process is not known.  Of  possibly  macrofaunal stantially and  greater  significance,  organisms  that  irrigation  colonize  the  and  fecal  disposal  mound  can  sub-  increase microbial density in the sediments (Rhoads, M c C a l l  Yingst,  1978).  The  importance  of  microbial  processes  in  the  remobilization of metal components from the sedimentary reservoir is frequently  stressed  in  the  literature,  but  the  kinetics  are  poorly  leading to the mobilization of  metals  understood.  Microbial  Processes  There are two major processes  from marine sediments by microbial activity:  1.  The destruction of organic  2.  The  conversion  metal-organic  of  matter.  inorganic  compounds.  metals  into  soluble  or  volatile  85  The  first  of  these  is essentially  the acceleration of  organic  matter  decomposition in aerobic environments, described in Section 4.3.1. The structurally  complex,  large  molecular  weight  organic  compounds  characteristic of humic materials in reduced environments are altered to  smaller,  microbial Kaplan  less  complex  degradation  molecules  (Reddy  (1972) showed  that  and  (e.g.  Patrick,  fulvic  compounds)  1975).  humic compounds  by  Nissenbaum  and  are a major  component  of the organic matter reservoir in recent marine sediments,  comprising  up to 70 percent of the organic material.  F r o m a colloid chemistry  point of view, metal ions may be included in the central hydrophilic "cavities"  of  leaching.  Only the higher molecular weight fractions exhibit colloidal  properties,  humic  and  the  molecules,  metals  may  oxidation (Chen et al., 1976). tially  countered by  the  compounds,  which  than  compounds.  humic  and  be  then  released  be  more  metal  complexing  functional  prevented  following  However this process  higher  contain  would  groups  (i.e.  The net rate and significance  release from the sediments  microbial  will be  capacity  from  substanof  OH,  fulvic COOH)  of metal  ion  to the water column as a conseguence  of  these counteractive processes is highly dependent on Jn situ conditions and  is  largely  microbial  unstudied.  degradation  of  However humic  it  is  substances  generally  considered  that  in marine sediments  is a  relatively slow process and that the resulting desorption of metals the  water  column, should  (Chen et al., 1976).  it  occur, will  be  in very small  to  guantities  86  Considerably  more  research  effort  methylation of inorganic metals.  has  been  dedicated  Bacterial methylation  to  bacterial  is a form  of  detoxification within the bacteria, but the products are released from the  sediments  and  are  readily  partitioned  into  organisms.  This  is  particularly true for the bacterial production of methylmercury, which is highly toxic to higher life forms.  The  inorganic  forms  of  mechanisms  (Ladner,  extent  rates  and  including growth  mercury may  1971; Wood,  of  rate  and  Kennedy  methylation  concentration and  be methylated by at least  are  activity  Rosen,  effected  availability  metabolic  and  of  of  by  mercury  the  1968).  many  two The  factors,  ions;  abundance,  methylating  organisms;  temperature and pH (Bisogni and Lawrence, 1973; Baker  et al., 1981).  Methylmercury  in  may  also  (Spangler et al., 1973).  be  demethylated  Thus the amount  by  bacteria  sediments  of methylmercury  released  from the sediments is dependent on the combined reaction kinetics of the methylating and demethylating  processes.  Methylation of mercury involves the conversion of H g dimethyl-mercury. conversions  are  synthesized  from  + +  to methyl-and  The reactions and enzymes required to make these described  in  Wood  methylmercury,  (1974).  with  the  Dimethylmercury  rate  of  synthesis  of  is the  former being about 6000 times slower than the latter.  Windom sediments  et  al.  (1976)  in Georgia.  sulfide, strongly  sorbed  studied  the  transfer  of  mercury  in  Mercury was primarily present as an to  the sediments.  Bacterial  marine insoluble  methylation  in  87  sediments increased mercury mobility but the rate of methylation very slow:  was  annual production of methylmercury was calculated to be  50 ug for each gram of total mercury.  The relationship of bacterial  numbers and activity to the production of methylmercury has not been studied,  but  may  be  an  important  consideration  in areas  receiving  sewage effluent (e.g. Point Grey) where the density of bacteria in the sediments is extremely high.  The  ability  of  micoorganisms  to  detoxify  organometallic  transformation  is  not  their  environment  restricted to  through  mercury.  It  has  been established that the mechanism is also e f f e c t i v e in the formation of volatile metal-alky I compounds of As, Pb, Sn and Se.  Relatively have  high concentrations  been  found  in  seawater  Southern C a l i f o r n i a (Andreae,  The  results  of  Chau  of  et  mono-  overlying  and  di-methyl  contaminated  (1976)  selenium may also be a significant  showed  process.  that  acid  sediments  1978) and Florida (Braman,  al.  arsenic  1976).  biomethylation  However  in  Thompson  of and  C r e r a r (1980) reported that methylation of lead may not be significant in  marine  underwent  sediments.  Only  methylation  in that  confirmed this B.C.  finding  0.03%  of  study.  in the field at  lead  added  Thompson Saanich  as  (1981)  Inlet  lead  nitrate  subsequently  and A l i c e  Arm,  88  Biological  The  Uptake and Transfer  initial uptake of  metals  by marine biota can occur  from  water  through the respiratory or digestive surfaces, or from ingested food or particles. many  Absorption of metals  metals,  rates  of  occurs  absorption  by passive  are  directly  levels of availability in the environment (Bryan,  Although able  to  marine  animals  regulate  normal  levels  the concentration  through  molts (Bryan,  readily absorb  1979).  excretion  of  via  This occurs  diffusion  the  to  the  they are  also  1979).  metals  gills,  for  proportional  trace metals, many  and  gut,  more commonly  in  the  body  to  feces,  urine  or  with the  essential  and relatively abundant metals such as C u , Zn and F e rather than the non-essential When  metals  uptake  of  such as  essential  Hg  and C d  metals  (Connell  exceeds  the  and  Miller,  levels  1984).  necessary  to  maintain biochemical functions, excretion, induction of metallothionein synthesis sites  and storage  (e.g.  tissue  bone,  exoskeleton),  concentrations.  metals,  if  in the kidneys or  uptake  is  can  However, excessive  liver, or storage  provide with  the  at  homeostatic  essential  homeostatic  and  inactive  control  of  non-essential  mechanisms  are  inhibited and bioaccumulation in soft tissues and body fluids proceeds as uptake exceeds the loss rate (Connell and Miller,  The  ability  tissues  of  means  example, H o m e  many that  organisms  to  bioaccumulation  control is  metal  species  1984).  concentrations dependent.  in For  (1969) quoted a copper bioconcentration factor of 80  89  for  fish,  and  nudibranchs,  3,000  and  4,300  respectively.  factors of 3,000 and  for  Mussels  bottom and  dwelling  oysters  had  scallops  and  concentration  13,700.  Bryan and Hummerstone's  (1973) classical study of the response of the  polychaete Nereis diversicolor to metal contamination  in estuaries  of  southwestern England concluded that adaptation of this species to zinc and  copper  are  different, appear  to be genetically  have probably evolved separately. lead  tolerance  of  the  isopod  determined, and  Similarly, Brown (1976) showed that  Asellus  meridianus  may  be  genetically  determined.  Physico-chemical sediment characteristics and the geochemistry of the trace  metals  also  substantially  Hall  and  Bindra  nisms.  (1979)  affect  metal  examined  sediment trace metal geochemistry  accumulation  the  relationships  in  orga-  between  and accumulation of copper, lead  and zinc in benthic invertebrates from four areas of the Lower Fraser watershed. between  L e a d was the only metal to show some  the  accumulation, studied.  total and  Copper  concentration this  varied  in  with  the the  linear correlation  sediment sites  and  and the  organism organisms  levels in organisms were correlated with copper  in  the exchangeable and easily reducible phases, demonstrating that these phases  were apparently  more  available  or  retained by the  No single phase of zinc appeared to regulate organism  organism.  concentrations.  90  Despite  this  biological  apparent  uptake appears  Thomann (1978). a  complexity  balance  to fit  and  confusion, the net  within a simple  model  process  of  described  by  The accumulation of metals by marine organisms is  between  organism  and  the  comprise  the  base  the  intake  rate,  elimination of  the  the  rate.  food  storage  For  chain,  capacity  smaller  net  metal  of  the  organisms  that  accumulation  is  essentially the result of diffusive exchange between the organism and the  water  directly  column.  from  maintenance the  the  of  biota  water.  tendencies  is  low.  may  sediments,  equilibrium  surrounding  sorptive  Residues  but  levels  Because  for biological  If  a  metal  is  be  accumulated  diffusive  exchange  in organisms most  forms  tissue,  from results  relative of  food  to  metals  in  preferencial sorption  present  in  solution  the  levels  have  simply  or  in  weak within as  an  uncomplexed ion, it will not tend to be lipid soluble and (in the case of  fish)  may  accumulate  in the gills rather than  in internal organs.  R e l a t i v e to sediment concentrations, bioaccumulation  factors  are  less  than unity for most metals.  Aquatic  food chain  postulated that  for  in the most  simplification  enrichment  literature.  metals (see  this  Prosi,  of  trace metals  However mechanism  has  accepted  confused  by  organic  forms.  methyl  metal  biomagnification  over-  The exception to this is trace metals that occur in lipophilic a  that  been  generally  metals  If  and  is now  been frequently  of  does not occur (Kay,  1979)  it  has  1984; Biddinger and Gloss, 1984).  is  present  in  lipid  soluble  form  (e.g.  mercury), then accumulation in internal organs is enhanced.  The high  91  sorptive  tendency  to  organic  tissue  results  in  very  high  capacities within organisms, and low elimination rates.  storage  For example,  although Young et al. (1980) found no evidence for biomagnification of Ag,  C d , C r , C u , F e , Mn,  southern  California,  Zn, Ni  mercury,  and  notably  Pb  in several  the  organic  ecosystems  forms,  in  generally  increased with trophic levels.  The  bioaccumulation  of  lipophilic  substances  extensive research over the last decade. trations  in several  and body  weight  organisms  have  species  rather a  of  than  small  has  been  subject  The high mercury concen-  fish may be more a function of trophic  exchange  to  level  surface  (Phillips,  1980).  relative  to  time  Larger  their  body  volume, so exchange with the surrounding water is less important than intake from food and elimination with excretia.  Because elimination  via the latter route is relatively inefficient, concentrations in animals resident in contaminated areas tend to increase with residence time.  The role of biological metals  from  insignificant.  a  dredged  For  dependent  upon  organisms  affects  column. Benthic  uptake and transfer in the transport material  smaller  dissolved a  net  disposal  organisms, metals.  removal  mound  bioaccumulation  Biological of  is  trace  uptake  metals  of  trace  accordingly is  essentially  by  epibenthic  from  the  water  infauna accumulate metals from trie interstitial and  easily exchangeable fractions in the sediment system (Hall and Bindra, 1979) but bioconcentration factors rarely exceed unity.  Renfro (1973)  estimated that a population of Nereis diversicolor at a density of 50 worms/m2  would accumulate only  0.08%  of  the zinc content of  the  92  upper  2 cm  of  the sediment  within  biological  metals  from  tissue  is  the dredged  layer.  The fact  insignificant  to  material disposal  that  the  this  fraction  transport  mound.  of  is  trace  Biomagnification  of trace metals is essentially a misnomer, and accumulation in larger predator  species  is  dependent  upon  the  duration  of  exposure.  Appropriate selection of disposal grounds in areas of low productivity, augmented by the expected reduction in disposal site biomass of prey species due to dumping  activities, will  unattractive to migrating  predators.  ensure that  It  disposal  are  is thus expected that dietary  uptake of contaminants by predatory species will remain  4.3.3  sites  insignificant.  Conclusion  It  is  concluded  release,  dredged  preferably terized  that  by  for  material  be within fine,  a  chemically most  be  minimized  controlled  mound  will  by  metals  oxidation  and  surface veneer.  from Fe/Mn  pore  in  in a  low  trace  Georgia  by  metal  Strait  environment  energy  release  disposal  of  a  will  charac-  permanently  water  hydroxide  environment.  trace  onto  metals  reduced  The  will  be  sediments  Maintenance of a low redox potential  tend to maintain  and humic bound trace metals. trace  sites  and overlayed  induced  overlayed by oxygenated water. in the disposal  minimizing  Erosion and dispersion of particulate-bound  biologically  effectively  of  energy, depositional  reduced sediments  will  and  purpose  disposal  low  oxygenated water column. trace metals  the  the stability  of  The diffusive migration of will  be  mostly  co-precipitation  sulfide  dissolved  counteracted  within  the  by  aerobic  93  Although  appropriate  disposal  site  selection will  substantially  reduce  the potential for trace metal release, the extent of release over long term defies accurate prediction.  A  the  large number of studies have  been conducted to elucidate the geochemical processes effecting trace metal  transport  and fate, yet a high degree of uncertainty  remains.  The data are often conflicting, and the dominant processes appear be  largely  teristics  site  of  specific,  different  each  responding  regimes  e.g.  to  the  particular  differences  in  charac-  minerology  particulate phases and in the amounts and/or types of organic Thus  it  is  not  possible,  even  in  laboratory  testing,  Further  matter. a  sediments  Strait.  uncertainty  influences of  of  to determine  priori which of these processes are applicable to Vancouver disposed in Georgia  to  abounds  biological  when  activities  we  attempt  upon  these  to  account  geochemical  for  the  processes.  Numerous biogenic processes that promote the release of trace metals have  been  identified,  but  the  kinetics  and  significance  of  these  processes remain poorly understood.  Recent  investigations  in  controlled  microcosms  information on the chemical and biological  provide  valuable  behaviour of trace  metals  in sediments, but have also served to confirm the complexity of system.  Hunt  and  Smith  (1981)  presented  the  results  of  a  the  study  conducted in cylindrical tanks (2 m diameter and 5 m deep) containing a 30 c m  layer of sediments and associated benthic organisms.  tanks were filled with seawater  from lower Narragansett  Bay,  These Rhode  Island, and they simulate many features of the planktonic, benthic and  94  bacterial  components  of  collected  from  locations  three  the  bay  ecosystem.  along  a  The  sediment  was  pollution gradient:  highly-,  Hunt and Smith's (1981) study shows release of some metals  from the  slightly-, and uncontaminated.  sediments  and  in some  instances, trapping of metals.  tration in the water column varied during the and  during  much  showed similar flux  of  of  results.  the  experiment  During  copper and cadmium  the  the summer  Metal c o n c e n -  17 month experiment,  three  types  of  there was  a  substantial  from the highly contaminated sediment  that was greater than those observed from the other two The  sediment  sediments.  study showed that the release of metals from sediments is not a  continual process, but is episodic and perhaps seasonal.  The causes of  the episodic variation in release rates could not be determined.  However except  the for  release rate of  cadmium,  very  trace metals  slow  (sub-umole  from m 2 _  the sediments day '). -  Hunt  was, and  Smith (1981) estimated the times required to purge the upper I c m of the  sediments to be decades or centuries.  When dredged material is  disposed into a depositional area of Georgia Strait, burial by naturally deposited sediments or by capping the disposal  mound with clean fill  may counteract this release rate. I  I.  Sediment deposition rates at the current Point Grey dumpsite and elsewhere in the Strait of Georgia are currently unknown. Near-sediment oceanographic studies are a priority topic for 1985-86 R.O.D.A.C. (Pacific Region) research projects (R. Kussat, EPS, pers. comm., 1985).  95  Thus, the conclusion drawn by Engler (1981) in his review of research conducted  by  the U.S.  Army  Corps  of  Engineers,  that  "contaminant  releases (from dredged material) are usually limited to nutrients with negligible releases of toxic metals", and Smith's (1981) work.  is essentially confirmed by  The exception is cadmium.  Similar  Hunt  results  by Gambrell et al. (1976), Gilbert, C l a y and Leighty (1976) and and  Smith  sediments  (1981) can  have  shown  that  induce significant  prolonged  cadmium  oxidation  release.  of  In  Hunt  polluted  light  of  the  high toxicity of cadmium, this aspect requires very careful evaluation in the local context.  The other significant concern in the British Columbia context pertains to the methylation of mercury.  The present Point Grey disposal  site  is within five nautical miles of  the lona Island sewage outfall.  The  high  of  mercury content  of  some  our  dredged  sediments,  combined  with the very high bacterial densities that might be expected within Point G r e y sediments, provides cause for substantial  concern. Parsons,  Bawden and Heath (1973) found mercury levels in crab from Sturgeon Bank  ranged  Forrester, mercury  to  3.7  Ketchen and levels  Methylmercury studies.  up  ppm  Wong (1972)  in dogfish content  dry  from  was  not  weight  (0.74  similarly  specimens measured  ppm  wet  recorded their  collected off in  weight).  either  of  highest  Point these  Grey. two  96  4.4  Environmental E f f e c t s of Released T r a c e Metals  There is an extremely abundant environmental effects of It  trace metals  is well beyond the scope of  current  state  of  knowledge  known to be toxic. available  and diverse  this  literature describing  the  released to the water column.  review to attempt  pertaining  to  Wood (1974) listed  each of  to define the  the trace  metals  19 metals that are relatively  to marine biota in dissolved forms and which are known  be highly toxic.  Connell and Miller (1984) have conducted a  to  thorough  review of the principles of ecotoxicology.  This  review  subsequent  has to  shown  the  that  disposal  principal of  concerns  contaminated  toxicity  Through  reviewing  provided  on  the  data  for  the  toxicity  difficulty  these  of  metals  of linking  metal  dredged  Georgia Strait pertain to cadmium and mercury. the known  for  materials  in  This section reviews  in the marine  these  release  metals,  toxicology  ecosystem.  insight  and  is  also  environmental  effects.  4.4.1  Cadmium  There  is  cadmium  a  general  lack  to marine biota.  of  information  on  The 96-hour L C 5 0  the  acute  values  toxicity  for marine  of fish  are generally quite high, i.e., for larval A t l a n t i c silversides, the L C 5 0 was ug/L  1600 ug/L (U.S.  insensitive  and for juvenile mummichog,  EPA, with  1978). LC50  Gastropod  values  above  the L C 5 0  molluscs 1,500  are  ug/L.  was  114,000  generally  quite  However,  other  97  invertebrates are more sensitive, with the L C 5 0 for the mysid shrimp being  15.5 ug/L.  Inhibition  of  costatum, was observed at  growth  rate of  175 ug/L (U.S. E P A ,  the alga,  Skeletonema  1978).  Low levels of cadmium are capable of causing various chronic effects. Nimmo  et al. (1977) reported that mysid shrimp exposed to 6.4  cadmium  exhibited  48-hour  delays  in  brood  formation  decrease in the number of young born per female. observed at 4.8 ug/L. alterations days  to  5  a  57%  No e f f e c t s were  Calabrese et al. (1975) demonstrated  in gill-tissue  exposure  and  ug/L  significant  respiration rates measured j n vitro after 60 ug/L  cadmium.  The  significance  of  this  to  zinc,  observation has not been evaluated.  It  has been suggested that  cadmium  may  displace  because  zinc  in  of  its  certain  chemical  enzymes,  kinship  thereby  disrupting  normal metabolic functions (Callahan and Slimak, 1979).  Bioaccumulation actively  is an important  accumulated  significant  differences  accumulation. accumulation as 250,000.  by in  Chapman,  fate process  marine the  organisms.  literature  Fisher  and  for cadmium, which There  concerning  Pratt  (1968)  are, the  is  however, degree  reported  of bio-  factors of cadmium within marine invertebrates as high The U.S. E P A  (1978) indicated that bivalve molluscs most  actively accumulated cadmium  and a bioaccumulation  was observed after 280 days exposure. 700-fold bioaccumulation of cadmium  factor of  2600  Vernberg et al. (1977) reported by grass shrimp and N i m m o  al. (1977) reported a 57-fold bioaccumulation by pink shrimp.  et  98  Cadmium  uptake  studies  require  long-term  experimentation.  (1979) in his studies with the A m e r i c a n oyster, Crassostrea  Frazier virginica,  found continuing cadmium accumulation even after 280 days exposure. Uptake  is  affected  between tissue Engel  by  level  and Fowler,  speciation;  accumulation  1979).  Uptake  an  inverse  and water  relationship  salinity  (Frazier,  1979;  is also a f f e c t e d by ambient  temperature with increased uptake at higher temperatures. rates are slow.  exists  water  Depuration  Greig and Wenzloff (1978) and Zaroogian (1979) found  no decrease in cadmium concentration to C. virginica when transferred from  metal  temperature  impacted  waters  regime.  However,  concentration and weight Although  the  of  cadmium  to  the  cleaner the  waters  latter  oysters  concentration  or  worker  in  a  found  declined during  stayed  the  declining that  both  depuration.  same,  the  total  amount of cadmium in the organism decreased.  In a study of the relationship between toxicity and bioaccumulation in aquatic  invertebrates, Spehar, Anderson  the 28-day amphipods  LC50 were  values  for  effects  could  periods.  values II  these  Data  for cadmium-exposed  and 4 times metals,  occur  at  and Fiandt (1978) found  lower  than  respectively.  lower  snails and the 7-  The  concentrations  during  lead-exposed  and 4-day  results  that  indicate  longer  LC50 that  exposure  are not available on the relationship between toxicity  and accumulated body burdens of metals  in aquatic, invertebrates and  research into this area is required for marine species.  Since concerns  over ecological  are  impacts  of  heavy  metal  contamination  commonly  developed from environmental surveys that identify contaminant  levels  in biological  metal  tissues,  relationships  between  toxic  effects  and  99  burdens  in major body organs must be established.  would provide much needed fundamental  Such  information  data for the development  of  sediment criteria.  4.4.2  Mercury  Mercury  is  one  of  environment. chemical  the most  The  toxicity  hazardous of  trace metals  mercury  form (Luckey, Venngopal  varies  present  greatly  and Hucheson,  1975).  in the  with  its  Monovalent  mercury is relatively non-toxic due to the low availability of its salts. However divalent mercury and organic mercurials are highly toxic.  Alkyl  or methylmercury poisoning  from  inorganic  weeks  or months  effects  may  permanent hearing,  be  poisoning.  after acute irreversible.  neurological  sensory  disorders have  mercury  loss  in higher  Symptoms  exposure, and Alkyl  damage in  limbs,  resulting ataxia,  as  mental  retardation  occurred  in  infants  whose  during  pregnancy.  and  mothers  Fetal  sensitive to methylmercury (Grant,  nerve  be  brain  damage  tremor.  convulsive  tissue  caused  vision  and  Neurological cerebral  exposed may  for  occurs,  have  impaired  were  somewhat  dormant  poisonings  in  and  differ  may  if  mercury  such  mercury  animals  to  be  palsy  methyl-  especially  1971).  The U.S. E P A (1978) Ambient Water Quality C r i t e r i a recommended an upper  limit  24-hour time  of  average  for  the  0.19 and  ug/L a  inorganic  maximum  protection  of  mercury (mercuric chloride) as concentration of  saltwater  life.  1.0 The  ug/L  a  at  any  criterion  for  100  methylmercury is more stringent with 0.025 ug/L as a 24-hour average and a maximum concentration of 0.26 ug/L at any time. animal  species, especially at early  Invertebrate  life stages, are noted to be more  sensitive to inorganic mercury than are fish species.  The E P A I  ug/g  recommended a maximum permissible tissue concentration of  for protection of wildlife.  The present U.S.  Food and  Drug  Administration and Canadian Food and Drug D i r e c t o r a t e administrative guidelines for protection of mercury  in edible portions  mercury  in  fish  that  human health are 0.5 of  have  fish (I.J.C, been  killed  1977). by  ug/g  (wet  weight)  Concentrations of  chronic  exposure  to  methylmercury ranged from 9.5 to 23.5 ug/g ( M c K i m et al., 1975).  Fish have been shown to accumulate other  aquatic  mercury compounds  organisms, both directly from seawater  through the food chain.  Concentrations of  mercury  more  than  and indirectly up to 9.8  ug/g  have been recorded from fish taken from contaminated environments (Keckes  and Miettinen, 1972).  The position of the fish  in the  food  chain was found to be an important factor in relation to its mercury content.  Ratkowsky, Dix and Wilson (1975) found that in the Derwent  estuary, Tasmania, approximately 5 0 % of consisted predominantly of excess  of  0.5  ug/g.  wet  other  fish  weight.  In  the fish species whose diet  had mercury concentrations contrast,  24.% of  in  invertebrate  predators and only 7% of individuals of herbivorous habit had mercury concentrations  above  the  0.5  ug/g  level.  A  similar  correlation  between the mercury concentrations and feeding habits was reported for fishes in the lower Fraser River (Northcote, Johnston and Tsumura  101  1975). and  Mercury  prickly  levels  sculpins)  feeders, which  in piscivorous  were  greater  fishes (i.e., northern  than  in turn were greater  mercury  than  levels  levels  squawfish in  benthic  found in planktonic  and surface feeders.  Methylmercury  is  the  by estuarine fish.  form  of mercury most  readily bioconcentrated  It has a long biological half life, i.e., 400-700 days  for flounder in brackish water (Keckes and Miettinen, 1972).  Hartung  (1976) calculated that elimination half lives of methylmercury in pike and eel were in the order of 600 to 1,030  days.  Uptake  is  and  factors. Atton uptake from  bioconcentration of  Studies  and  I0°C  dependent  on rainbow trout (MacLeod  Royer,  rate  mercury  1973)  of  mercury  to  20°C  have into  shown fish  increased  that  and Pessah, temperature  muscle. the  upon  various  1973; Uthe, affects  the  Increases in temperature  biological  magnification  factor  (mercury concentration in fish divided by the mercury concentration in water)  from  uptake  of  (Uthe  et  10  to  mercury al.,  22  times  (MacLeod  occurred during  1973).  Luoma  (1977)  the  and  Pessah,  first  warm  showed  concentrations in biota from a small Hawaiin nearly  two  orders of magnitude  that  the  1973).  Rapid  summer  months  total  mercury  estuary, fluctuated over  during one year.  Shrimp  (Palaemon  debilis) rapidly concentrated soluble mercury which periodically entered the estuary from storm runoff. remaining  in the estuary was  Between rainstorms, minimal mercury available.  The net loss of mercury in  102  tissues was  slow relative to the rate of uptake, and  time  necessary  were  to  lower  the  levels  of  long periods of  mercury  accumulated  during the short rain storms.  Luoma  (1976)  mercury  studied  the  in the carnivorous  uptake  and  inter-organ  crab (Thalamita  distribution  crenata).  of  The rate of  increase of mercury in muscle vs. uptake in the viscera was  used  an  mercury  indication  of  the  relative  importance  (i.e., from water or food) to the crab. gills were observed after portioning season,  which  mercury Luoma  of  from (1976)  location,  mercury  changed  suggested the  rainstorms.  suggested  short-term  that  laboratory  McGreer  (1981)  reported  from lag  some  because  the  time  slowly  of  the  experiments  potential for contamination of such  source  High mercury  seasonally  to  the  of  levels in crab  The body muscle-chela  a considerable  environment  of  wet  to  were  may  in  dry of  tissues.  metal  trans-  underestimate  the  tissues.  seasonal  reported  the  exchanging  variation  in  concentration  mercury from crabs on Roberts Bank (Strait of Georgia). concentrations  muscle  in translocation  lag  as  from  winter  and  The  spring  of  lowest  sampling  occasions, while higher concentrations were reported in samples  taken  in late summer to fall.  Based on studies of uptake with mercury, it can be seen that all field studies on contaminants should assure standardization of the sex, size, and age of the organism, period of collection, and analytical to assess the rates of accumulation and changes  methods  in body burdens over  103  a period of of  time.  excretion  It  and  organisms (Bryan,  is also important  regulation 1976).  in  Dungeness  crab, the destruction  excretory  progressively (Sloan,  capability  accumulation  organs  was  after  and  or  heavy  invertebrates metal  binding is  in  various  1974).  exposure  have  as  to  some  in  of  a  body  Bank (Brown et al.,  species  of  The term biomagnification  of  pathways  in  mechanism  leading  to  free mercury Deterioration  mercury  in the of  would  protection  from  weight  crabs  excretory  lead  low  marine  protein  to  higher  level  chronic  involving  metal  metallonthionein  invertebrates  1977) and is instrumental  against high body burdens of  tissues  animals.  The low molecular  in several  marine  enzyme  pollution by a detoxification mechanism  proteins.  present  mercury blocking  concentrations in the oldest, largest  Marine  metals  to eliminate  Larkin,  chronic  of  suggested  reduced ability  Thompson  heavy  mechanisms  For example, in studies of the role of metal  regulation  the  the  of  to recognize the  from  in providing  Sturgeon protection  metals.  refers to a specific phenomenon in which a  compound is concentrated through consumption  by progressively  higher  food  increase  tissue  chain  organisms,  concentration  at  and  results  each successive  in  a  net  trophic  level.  in  the  Biomagnification  of  mercury occurs, especially, in long-lived predatory fish species such as swordfish, trations food  of  chain  tuna, and pike. mercury to  In this way,  even relatively  in the environment  mercury  levels  concen-  can be built up through  exceeding  concentration considered safe for human  low  the  0.5  ug/g  consumption.  wet  the  weight  104  5.0  ORGANIC POLLUTANT PATHWAYS  AND  P R O C E S S E S IN  THE  MARINE ENVIRONMENT  5.1  Introduction  Rachel for  Carson's  "The Silent  research into  environment. DDT  Spring"  the fate  and  (1971)  provided a major  effects of  organic  stimulus  chemicals  in  the  That this popular work was specifically concerned with  led to much of  the  initial  research effort  directed towards organochlorine pesticides. effort has expanded rapidly  in  this  field  being  In more recent years  to include a very wide  range of  this  organic  chemicals.  The  work  is  a  formidable  hundreds, if not thousands, can  reasonably  be  future environment.  and of  considered  complex  task:  anthropogenic likely  there  organic  components  of  are  literally  compounds  that  the present  and  F o r example, in excess of 200 organic  compounds  considered to be toxic have been identified in the water, sediment and biota of Puget  Sound  and/or  in effluents  (E. Long, N O A A , pers. comm., 1985). analytical nants  nor  techniques for the  routinely  toxicological  discharging  into  the  Sound  Neither convenient, inexpensive  monitoring  information  to  this  host  even  of  contami-  estimate  potential hazards to biota and their consumers are available.  their  105  Despite gation  this has  apparent  complexity  determined  properties of  organic  interest  processes  to  many  pollutants  processes and pathways particular  that  and uncertainty, scientific  bound  environmental biological  chemical the  that e f f e c t their fate in the environment.  Of  the  conditions is  and  of  present  thesis  a  which  is an  release  contaminants.  system  physical  permit a broad understanding  that e f f e c t water column  sediment  shared  investi-  understanding  and biological  Cognisance promote  prerequisite  and  contaminant  to  of  uptake  avoidance release  appropriate  the  to  of of the  environmental  management.  The schematic representation of contaminant transport and fate in the marine environment that was described above in Figure 3 (see Section 2.3) applies equally to organic contaminants  as to trace metals.  The  sediments act as a "sink" to the organic contaminants of concern, but the water  column  and  biota can  taminated dredged materials new  equilibrium between  also become  are disposed  the  respective  ments, the water and the biota may metals,  the  operations  important shift  question  organic  When  con-  into a new environment, a concentrations  be established.  is whether  pollutant  enriched.  dredged  equilibria  in  As  the  sedi-  with  trace  material  enough  to  disposal  release  bio-  logically harmful concentrations of those pollutants.  A s was outlined in Section 2.4, the contaminants dumping  management  are  the relatively  of interest to ocean  insoluble  organic  compounds  which preferentially accumulate and persist in the sediments. 3.2  reviewed  information  describing  the  documented  and  Section suspected  106 contamination  of  taminants  concern  of  polychlorinated  Vancouver's in  biphenyls,  sediments  the  present  to  compile  instance.  hexachlorinated  a  list  These  butadiene,  of  con-  included  polychlorinated  dibenzofurans, pentachlorophenol, hexachlorobenzene, halogenated  and  non-halogenated polyaromatic hydrocarbons and phthalate esters.  The  present  section  reviews  the  tendency  of  these  contaminants  to  be  released to the water column or to be accumulated by marine biota subsequent to the marine disposal of dredged sediments.  Release of Organic Contaminants to the Water  The water solubility of an organic pollutant  Column  is an important c h a r a c -  teristic not only for determining its susceptibility to dissolution, but for  establishing  its  overall  potential  environmental  distribution  and  fate (Hague et al., 1980).  Substances with higher water solubility are  less  more  likely  ments.  to  Water  adsorb  and  solubility  can  likely  also  to  effect  desorb possible  from  marine  sedi-  transformation  by  hydrolysis, photolysis, oxidation, reduction and biodegradation in water: hydrophobic organic compounds are less susceptible to degradation than hydrophilic compounds.  The  partitioning  tendency  adsorbed and solution  phases  of  an  organic  pollutant -between  is described by the equilibrium  cient (K), as in the expression:  the  coeffi-  107  K  =  Cone, of pollutant in sorbent Cone, of pollutant in water  The  Freundlich equation  quently  used  describes  in discussions  of  adsorption  adsorption  and  equilibria  and  desorption  is  fre-  phenomena.  This equation:  C  s  = K  (Cw)'/n  enables  a  water.  C  Cw  prediction of  the  adsorption  tendencies of  a pollutant  in  is the amount of adsorbed chemical per unit of adsorbent,  s  is the equilibrium solution concentration of the chemical and  l/n  is a constant describing the degree of non-linearity (see Figure 4).  In  dilute  systems,  adsorption  isotherms  approach  linearity  (n—1 = 1).  How dilute the system must be to show this limiting behaviour from  system  to system,  depending  sorbent, and the type of sorption Scott  (1979)  determined  that  isotherms for natural sediments phase  pollutant  concentration  on  interaction. for  are is  the nature of  low  loading isotherm  and  K a r i c k o f f , Brown  and  organics,  linear if the eguilibrium I0"5  half of the solute water solubility (whichever substantiate  the solute  hydrophobic  below  varies  sorption aqueous  mole/litre  or  less  than  is lower).  Other works  linearity for a range of hydrophobic  organics (Hassett et al., 1980; Mearns et al., 1982; Rogers, McFarlane and  Cross,  1980).  This  low  loading  limit  is  typically  met  in most  108  FIGURE 4.  Freundlich Adsorption  Isotherm.  Equilibrium Concentration of in Solution  (Cw).  Solute  109  environmental situations.  Thus, the tendency of  pollutants to enter the adsorbed state  hydrophobic  organic  is inversely proportional  to  its  solubility.  From  pesticide-soil  studies,  numerous  soil  properties (organic  carbon  content, particle size distribution, clay mineral composition, p H , cation exchange and/or  capacity)  degree  However, sorption  of  the of  have  been  pesticide  sorption  predominance uncharged  identified as  of  (Mingelgrin  organic  organic  affecting and  carbon  compounds  the  in  has  mechanism  Gerstl,  1982).  "controlling" been  the  extensively  documented for soils (e.g. Kenaga and Goring, 1978) and more recently confirmed for sediments (Karickoff, Brown and Scott, Flagg,  1981).  for  sediment  a  This suggests that the equilibrium partition c o e f f i c i e n t consisting  of  multiple  sorbent  components  reduced to a form containing only sorption to organic  The  1979; Brown and  experimental  distribution  of  an  organic  can  be  matter.  compound  between  the  organic solvent n-octanol and water is now widely used to predict the adsorption of organic compounds  to the organic portion of  sediments.  The log of the distribution coefficient is referred to as "log  P".  It is emphasized however, that the sorbed state concentrations and the thermodynamic variables  derived therefrom are operationally defined.  Seldom can the actual distributional volume of the sorbate be defined. The  actual  dependent  degree not  only  of on  adsorption the  to  sediments  characteristics  of  in the  any  instance  pollutant  is  (e.g.  110  polarity  or  solubility)  and  sorbent  (e.g.  surface  area  content), but also on the characteristics o f . the water,  and  organic  most  notably  temperature, salinity, pH and redox potential.  Under  static  taminants  environmental  conditions,  in undisturbed sediments  hydrophobic  have a strong  organic  con-  tendency to remain  associated with solids so are not free to volatilize into the air or be dispersed as a solute. limited  to  However alters,  if  or  microbial the more  Their ultimate environmental fate is essentially degradation  environmental particularly  and/or  burial  character  if  it  is  of  within  the  sediments.  the surrounding  altered  by  medium  relocation  of  the  sediments into a different medium, then the kinetics of adsorption and desorption need to be considered.  A  great  deal of confusion exists  adsorption-desorption  kinetics.  in the sorption  Sorption  is  literature  often  regarding  described as  rapid  and readily reversible (times to reach equilibrium of minutes to a few hours).  Y e t as Karickhoff  (1985) has pointed out, analytical  chemists  commonly encounter extreme difficulty extracting pollutants from field soils or sediments. require  lengthy  Highly  sorbed  extraction  periods  hydrophobic (days),  chemicals  multiple  frequently  solvents  and  abrasive mixing techniques for quantitative chemical recovery.  A  concept  recently  long  held  revamped  Horzempa,  for  by  soil  pollutant  1982) distinguishes  desorption process.  chemists  (see  sorption  to  Rao  et  al.,  sediments  1982)  and  (DiToro  and  the relative rates of the adsorption and  D i T o r o and Horzempa (1982) found that  for  the  Ill  sorption  of  hexachlorobiphenyl  to various  sorbents  silica), the adsorption process was rapid (minutes  (sediments,  clays,  to hours) but for the  reverse process most of the sorbed chemical was "highly resistant" to release.  Hiraizumi,  Takahashi  laboratory  and  bed sediments. be  field studies  were  Nishimura of  PCB  (1979)  conducted  adsorption  and  extensive  desorption  from  P C B adsorption was found to occur rapidly, and could  approximately  rates  and  much  described  by  a  Freundlich  slower:  seabed  mud  isotherm.  released  Desorption  only  1%  of  total  adsorbed P C B during the first 24 hours, and a further 0.8% during the next five days.  Karickoff  (1980) reported a similar  hydrocarbons.  Also,  finding  for  he freguently observed a  polynuclear drastic  aromatic  change  in the  ease of extraction of sorbed chemical with increased incubation time. After  short  (greater  incubation  periods  (less  than  5  minutes)  essentially  than 90%) of the sorbed chemicals could be easily extracted  from the sediment by direct extraction of the suspensions for  approximately  3  minutes.  The  fraction  of  with hexane  sorbed  chemical  recovered by this brief extraction decreased to 5 0 % after 3-5 of  all  incubation  and  continued  to  decrease  slowly  over  the  next  hours few  days, levelling out in the range of 20-40%.  Karickoff  (1985) concluded that  these  findings  suggested a  diffusion  controlled process in the sorbed state where sorbed chemical is slowly incorporated  into  release  resistent  components  of  the  sorbent.  112  Accordingly,  it  hydrophobic  has  been  contaminants  generally from  assumed  resuspended  that  desorption  dredged  material  of  is  a  relatively minor pathway of contaminant release.  The  likelihood of insoluble organic chemicals  desorbing  from riverine  sediments disposed into the marine environment is further reduced by the  "salting  reactions. the  PCB  out"  effects  Wildish  increased  salinity  upon  hydrophobic  et al. (1980) studied the adsorption-desorption of  mixture,  salinities.  of  Aroclor  Adsorption was  1254,  by  sediment  over  a  range  of  found to increase with increasing salinity.  Concentration factors (i.e. sediment versus water concentrations) for I gram of  silt-clay  exposed to 0.2  deionized water; 2710 strength greater  seawater. than  for  for The  half  ug/L  1254 were:  strength seawater;  concentration  adsorption,  Aroclor  and  factors  sediment  and  for  810 for  4240  for  desorption  adsorption  of  full were  PCBs  in  seawater was considered to be essentially irreversible.  F i e l d confirmation of these observations as they pertain to disposal of dredged sediments has been difficult due to the d i f f i c u l t y in obtaining a  water  Insoluble  sample material  for  analysis  cannot  be  that  contains  removed  by  only  soluble  filtration because  organics. of  probability of soluble organic contaminants adsorbing to the filter.  the A  preferable method is high speed centrifugation, but the results of this methodology  can be substantially  exaggerated  by contamination  with  suspended particles and oil that have specific gravity equal to or less than the water phase (Hartung and Klinger,  1970).  113  Fulk,  Gruber  and  Wullschleger  (1975) conducted extensive  studies on the desorption of a variety of organohalogens materials present  sampled in  59  commonly  of  present  from the  throughout 64  the  samples.  and aldrin and  United  2-4-T  were  from dredged  States.  Dieldrin  and  laboratory  PCBs  DDT  were  were  also  each detected in  two  samples.  The objectives of the study were to determine the transfer  of  materials  these  to  the  water  column  during  simulated  disposal  operations.  A  significant  finding of this study was that pore water concentrations  of hydrophobic organics in the dredged sediments were extremely low: the maximum concentrations were 0.15 ug/L for P C B s and D D T .  With  such low concentrations, the release of some of the pore water to the surrounding  environment  during  disposal  operations  would  result  in  negligible contaminant release.  Analysis of the water column after simulated disposal found no soluble pesticides or P C B s . all  associated  with  concentrations. ug/L  Pesticides suspended  and P C B s particulate  The maximum  for dieldrin.  agueous  organohalogens  solution  upon disposal.  and  and  tend  are to  rapidly  remain  were  in  were low 0.04  The relative release of  support and  released  determined were  1.8 percent of the total P C B  in the sediments. These results strongly hydrophobic  material  concentrations  for P C B s and 0.004 ug/L  P C B s ranged from 0.4 -  which were  the assumption  strongly  associated  concentrations  with  sorbed the  that from  sediments  114  In their review of research studies conducted by the U.S. A r m y of Engineers (1978) was  Dredged  concluded  negligible,  Material  that and  Research Program,  desorption of that  any  behaviour  is generally  Elutriate  Test.  material  would  Engler  and be  PCBs rapidly  L e e et al. (1978) showed that  the case for  However  and  chlorinated pesticides  desorbed  resorbed by suspended particles.  Burks  Corps  chlorinated pesticides during  releases of  PCBs  ranging  from  1.3 to  this the 6.9  times the concentrations in the receiving waters were found by these authors  in some tests.  Lee et al. (1978) found that the release was  inversely related to the oil and grease content of the test sediments, i.e. sediments  low in oil and grease released the largest quantities of  PCBs.  In  field  studies  organohalogen highly  Lee  pesticides  et or  al. PCBs  (1975), was  no  significant  detected  contaminated dredged sediments.  the P C B field  by  during  release  of  disposal  of  The authors concluded that  release shown in the E l u t r i a t e Test was not detected in the  due  to  rapid mixing  and dilution of  the very small  quantities  which may have been released.  Blazevich et al. (1977)  reported the results of the U.S.  toring  of  Sound. the  of In  the  disposal  contaminated  1974 there was a spill of almost  maintenance  extremely  PCB  dredging  contaminated  area  sediments  of  the were  sediments  EPA's  moni-  into  Puget  1000 litres of P C B s into Duwamish  hydraulically  River. dredged  placed into an impervious upland containment area, while  The and  I 14,000 m3  115  of the remaining contaminated material was  removed by a clamshell  dredge and disposed from barges at an experimental disposal  site  in  E l l i o t t Bay, Puget Sound.  Water quality monitoring showed that there were very slight increases in  water  column  operation.  PCB  These  concentrations  changes  associated  occurred  with  with  increases  the in  disposal suspended  particulate matter and, when the particulate matter decreased, so did the P C B  concentration.  less than 30 minutes. fish  or  most  operations.  to  tically  There was  invertebrates  no significant  analysed  during  or  uptake of after  PCBs  the  by  disposal  In addition, caged animals were held at the disposal  for up to 3 weeks. PCBs  The increases were of short duration, usually  site  Mussels in cages at the disposal site accumulated  levels above background,  significant.  It  was  animals  collected from  stantial  amounts  but  the  pointed out  Elliott  Bay  prior  increase  however, to  was  that  disposal  not  some  statisof  contained  the sub-  of P C B s , so an appreciable uptake would have been  necessary for statistical significance.  Similar studies by A r i m o t o and Feng (1983) in Long Island Sound were confounded by P C B an adjacent occurred  river.  coincident  levels in the water column due to discharge Although  significant  with  disposal  the  uptake of P C B s  operation, multiple  from  by mussels regression  analysis could account for only 20 - 4 0 % of the observed variance in concentrations.  The authors concluded that dumping was only a minor  influence on the P C B  concentrations of the monitoring animals, even  for those living on or adjacent to the dumpsite.  116  Boehm and Fiest (1983) conducted extensive analyses of water from  New  disposal  York  Bight prior  operation.  concentrations  The  ranging  to, during dredged  from  3700  and after a  material -  6900  samples  dredged  contained  ug/kg.  material  total  PCB  Individual  PAH  concentrations ranged from 800 - 7000 ug/kg.  Sampling  at  15 minutes  after  the dump  detected negligible  concen-  trations of P C B s or P A H s in the water column, except at one station within the particulate plume near the seafloor.  Within this plume, the  concentration of P C B s was 0.058 ug/L and total P A H s were After  2.5  remained were 0.45  hours,  concentrations  detectable:  PCB  at  levels  this were  station  had  0.038 ug/L  1.8  ug/L.  decreased and  total  but  PAHs  ug/L.  For perspective, the U.S. recommends  that  for  EPA  (1978) Ambient  the protection of  Water  marine  life,  Quality C r i t e r i a PCB  concentra-  tions should not exceed a 24 hour average of 0.024 ug/L nor 0.20  ug/L  at any one time.  PAH  compounds prominent water The  analysed  average  by  for P A H  Boehm  in both the source  column  U.S.  Similarly  EPA  sediment (1978)  seawater  ug/L at any time.  plume criteria  and  levels: Fiest  material  (1983),  (5.8 - 6.9  15 minutes for  of  the  individual  flouranthrene mg/kg) and  after  disposal  (0.1  flouranthrene  suggest  a  was  in  24  the  ug/L). hour  concentration of 0.30 ug/L with a maximum of 0.69  117  It is concluded that available evidence concurs with the general theory that  hydrophobic  organic  pollutants  are  not  readily  solution subsequent to dredged material disposal. operations  F i e l d monitoring of  dumping  ficant  release  state.  However the confidence that can be expressed in these results  these  not  into  ocean  of  have  released  pollutants  detected environmentally  in either  the sorbed or  signi-  desorbed  is low considering the background interference that was often present. Laboratory  tests  environmental  indicate  impact  that  there  from disposing  resuspension of sediments.  is  a  significant  potential  contaminated sediments  It is therefore strongly  for  due  to  recommended that  the disposal of dredged materials contaminated with organic pollutants should be managed  to  minimize  losses of  suspended  or  resuspended  particulates to the water column.  Biological Uptake of Organic  Contaminants  Accumulation  tissue  hydrophobic environment. released  into  within organic  biotic  contaminants  Relative solution,  is  significant  within  to the very the  a  low  the  fate  aquatic  of  and  concentrations that  absorption of  many marine  may  hydrophobic chemicals  be into  biotic tissue, and their subsequent transport from the disposal site via the  food chain, may  disposed manner  sediments. are  be The  an  important  fact  incorporated within  that  source of  their release  contaminants  animal  tissue  mental significance of this release process.  adds  released to  in  from this  the environ-  118  Contaminants  may  enter  marine  the sediment, or their food. of  fundamental  (MacKay,  o  events  organisms  from  the aqueous  phase,  Whatever the source of entry, a number  are  involved  in  the  accumulation  process  1982):  partitioning  of  the  pollutant  compound  hetween  the  source  and  some surface of the organism o  diffusive  transport  membranes.  of  the  (Klaassen  pollutant  (1980)  also  compound describes  across  various  cell active  transport mechanisms which have been postulated), o  transport mediated by body fluids, such as exchange between blood vessels and serum  o  lipoproteins  concentration of the compound in various tissues, depending on its affinity for certain biomolecules, such as nerve lipids  o  The  biodegradation of the compound.  bioaccumulation  kinetic  (diffusional,  (partitioning) marine  by  tissues (MacKay,  their  is  transport  processes.  environment,  determined  process  For  biological relative  and  seen  to  be  a  biodegradation)  persistent uptake chemical  organic  and  result and  in  both  equilibrium  pollutants  accumulation  activities  of  in  is  water  the  largely and  in  The time required to approach steady  state  tissue concentrations is determined by kinetic processes, and can  range  from a few et  al.,  1982).  thus  hours to several weeks  1975).  However,  the  more  (Southward  et al., 1978; Branson  hydrophobic  greater is its tendency to move through biological  the  compound,  membranes.  the  119  The  rate  and  the extent of bioaccumulation of organic  molecules  thus greatest for lipophilic (or hydrophobic) compounds.  is  Although the  pharmaceutical industry first drew attention to the link between lipid solubility and biological effectiveness of organics at about the turn of the  century  (see  Tute,  environmental sciences in  the  last  fifteen  1971  for  a  review  of  this  topic),  have only turned their attention to this  years.  The  uptake  and  location  of  the topic  persistent  organic compounds in the marine fauna has now been shown to depend upon the amount and Meade, tissue  and distribution of lipid content (McFarland,  1984).  Stout (1980) and Schneider  concentrations  of  hydrophobic  chemicals  could be directly correlated with lipid content. concluded chemicals  that  differences  in  biological  Gibson  (1982) observed  that  in field sampled  fish  Schneider (1982) also  concentration  factors  in different organisms were due to differences in the  of lipid  pool.  McFarland, Gibson and Meade (1984) found that the equilibrium  levels  of  PCBs  in  fish  and  clams  were  equivalent  when  expressed  relative to lipid content.  The  common  approach  to  a  quantification  of  lipid  solubility  is  to  determine the experimental octanol/water partition c o e f f i c i e n t (P), the alcohol  being  the  model  for  biological  (1975) correlated the bioaccumulation pounds  (tri-  benzoic  acid, anisole,  ecosystems  tetra-  with  the  and  of  lipid tissue. a  number of  pentachlorobiphenyls,  nitrobenzene, aniline) octanol/water  limited number of compounds  DDT,  from  partition  the  Metcalf  et al.  organic  com-  chlorobenzene, fish of  coefficient.  model  For  the  included the correlation was excellent.  Konemann (1979) reported a non-linear relation between log P and the  120  log  of  the  guppies.  bioconcentration  factor  chlorobenzenes  in  fat  of  Bioaccumulation approached a maximum value when log P =  6.5, further bioaccumulation being 5).  for  limited by uptake kinetics (Figure  Mackay (1982) considered that for high log P values (i.e. greater  than  6) bioaccumulation  potential data  is uncertain.  Reasons  given  were that:  o  direct  equilibrium  measurement  of  partition  coefficients  are  difficult due to the very low water phase concentrations o  time  to  reach steady  permeability  state  resistance  to  is extremely large  long  due to  molecules.  This  membrane  means  that  growth and lipid deposition need to be considered in the analysis.  For  compounds  evidenced  an  with  log  essentially  and P values (Figure 5). by  Mackay  accepted between dicted  P  linear  for  than  6,  Konemann's  relationship  lipophilic  and  Moser (1982).  organic  compounds  2 and 6, bioaccumulation potential  from  Institute of  the octanol/water Biological  between  (1979)  results  bioaccumulation  This relationship has since been confirmed  (1982) and Esser  that  less  Sciences  may  It  is now  with  log  generally P  values  be reasonably  partition c o e f f i c i e n t . (1978) A q u a t i c Hazards  pre-  The  American  of  Pesticides  Task Group has recommended that compounds with log P greater than 3 be considered to have high bioaccumulation potential.  Currently the state of the art is such that theoretical calculations of log P can be made solely from consideration of the structure of the organic molecule.  The derived log P is expressed in terms of additive  121 FIGURE 5 . . B i o a c c u m u l a t i o n o f S i x C h l o r i n a t e d Benzenes (from Konemann, A.  in  Guppies.  1979.)  R e l a t i o n s h i p between l o g b i o a c c u m u l a t i o n and l o g P.  Log P  B.  R e l a t i o n s h i p between uptake r a t e c o n s t a n t and l o g P.  122  structural  contributions  from  different  parts  earlier experimental data as sources of  of  log P contributions  different molecular parts (Verschueren, 1983). of organic compounds predicted  through  the molecule, using for  these  Similarly, the behaviour  in the aquatic environment can increasingly  theoretical  application  of  established  be  structure-  reactivity relationships (Wolfe et al., 1980).  The  overall  encouraging,  performance but  the  of  such  application  theoretical  of  estimates  experimentally  or  has  been  theoretically  derived log P values for predicting contaminant concentrations in biota in field situations contaminants  is not  from  the  straightforward.  environment  The  correlates  uptake with  of  the  lipophilic  partitioning  characteristics of the chemical, but the resulting tissue concentrations in biota  are  strongly  influenced by  characteristics of  the  individual  organisms.  Thomann  (1978)  proposed  a  mechanistic  model  which  allows  inter-  pretation of the variability between different organisms within a single coherent  framework.  contaminants  According  to  this  model, the accumulation  in organisms is a balance between the intake  storage  capacity  smaller  organisms such as  taminant  residues  rounding  water  Residues  may  of  the  are and  be  organisms  zooplankton,  capable the  and  of  internal  accumulated  facile  the the  data  food  sites, but  the  rate, the  rate.  indicate  exchange  sorption  from  elimination  For  that  con-  between the primarily facile  of  sur-  lipids.  exchange  results in the equilibration of the residue levels in the organisms with  123  the  levels  in the surrounding  water. The ultimate body  burden  thus  reflects essentially a partitioning of the residues between the lipid and water phases (i.e. log P for the contaminant).  A t the other end of the scale, larger organisms do not have as an  exchange  surface  internal  environment  external  medium.  which do not  great  relative  to  their body  volume, so  maintain  an  which  has  greater  independence  from  the  This is particularly true for the marine  have gills, an e f f e c t i v e exchange  organ  mammals,  in fish.  For  these organisms, exchange with the surrounding water is considerably less important  than  is  intake of  nation primarily with excretia.  contaminants  from  food and  elimi-  Since elimination via the latter route  is relatively inefficient (e.g., seal scat were found to have about the same P C B  levels as observed in fish food; Calambodikis et al., 1978),  some portion of the residues in food is retained. in these animals  The concentrations  consequently tend to increase with time, reflecting  the consumption of greater guantities of food.  Studies  in Puget  especially  for  transfer.  In  Sound  the one  two  appear  to  extremes  study,  confirm of  Thomann's  equilibration  the concentrations of  PCBs  (1978) model,  and  food  chain  in zooplankton  (copepods, euphausiids and ctenophores) were analysed as functions of a variety of habitat and physiological variables (Clayton et al., 1977). The  lipid weight  normalized data  the concentrations of P C B s relative  accumulation  higher log P).  was  yielded rough correlations between  in the water and in the organisms. greater  for  more  chlorinated P C B s  The (i.e.  124  Similar the  behaviour was noted in studies on the depuration of P C B s by  mussel  Mytilus  lected from a  edulis  (Calambodikis  et  al.,  heavily polluted area of Puget  1979).  Sound  placed in a relatively pristine area of the Sound. P C B s originally present in the mussels  decreased  Mussels  col-  were caged  and  The high levels of logarithmically  with  time of exposure to the cleaner environment. More highly chlorinated PCB  isomers  were  mated to range  retained  longer,  with  depuration  half  lives  esti-  from 3 days for d i - and tri-chloro compounds  to 50  days for hexa- and hepta-chlorobiphenyls.  At  the  other  end  of  the  blubber of Harbour seals  scale,  the concentrations  1978).  PCBs  in the  from Puget Sound and the Washington  were found to increase with the age et al.,  of  The concentrations  of  the individual  in the blubber  coast  (Calambodikis  were greater  than  observed in the fish species known to provide food for the seals, even when the latter levels were normalized to a lipid weight basis. and Teal (1979) similarly  found more oil residues  Burns  in the herring gull  than was contained in their food after exposure to the West Falmouth oil  spill,  but  no  evidence  for  this  food  chain  magnification  among  invertebrates or fish in the study area.  According bration  to  and  Thomann food  chain  (1978),  between  transfer  there  the  two extremes  exists  a  continuum  tionships, primarily dependent on the size of the organisms. (1978) considered that the continuum shifts as a function of  of of  equilirela-  Thomann increasing  125  size of the organisms from the dominance of facile sorptive/desorptive equilibrium  exchange  to  dominance  by  food  intake  and  reduced  elimination rates relative to the rate of accumulation.  Although recent data have  shown  that  has generally confirmed Thomann's  he over-estimated  the  role  of  dietary  model, they intake  and  under-estimated the role of facile desorptive equilibrium exchange large  water  breathing  (i.e. non-mammal)  organisms.  Relative  to  in air  breathing animals, all water breathing organisms have large respiratory surfaces  in proportion to their body size. The solubility of oxygen in  water, especially seawater, is low. Therefore large quantities of water must be passed over their gill surfaces to provide adeguate oxygen for respiration, eguilibrium  simultaneously exchange  of  increasing  contaminants  the with  opportunity  for  the surrounding  facile medium.  Even when dietary intake of contaminants is high, the opportunity for desorptive equilibrium exchange via the gills will also be high.  In  addition  minated  prey  contaminants items  to  this, items  the that  consistent results  are successively  food pathway  the  in  intake  food-chain  of  magnified  predominant  that  at  flow  contaof  levels in prey  trophic levels) rarely  Food-chain biomagnification reguires  is essentially  energy  successive  highly  biomagnification  in terrestrial systems (where contaminant  occurs in the marine ecosystem. a  dietary  from  linear and highly lower  to  higher  structured, with trophic  levels.  Most marine food webs are rather weakly structured and do not have trophic levels as clearly defined as those of terrestrial systems. species  may  occupy several trophic levels during its  One  lifetime due to  126  different  feeding habits at different stages of its life cycle.  Energy  flow in marine food webs is multidirectional with, for example, crabs being both prey to and scavengers of fish; a large component of the energy in marine systems is bound with the sediments.  The combination of intimate physical contact with the external medium and a complexly interactive trophic web is why trace contaminants do not increase nearly as much with trophic levels in aquatic systems as in nonaquatic  systems.  Kay  (1984)  and  Biddinger  and  Gloss  (1984)  provided comprehensive reviews of the potential for persistent organic compounds where  to biomagnify  biomagnification  up  the  food  chain.  They  did occur amongst gill  concluded  bearing  that  organisms,  produced concentrations in the order of only one to ten times  it  higher  in the upper trophic levels than in the lower ones, in contrast to the tens or hundreds of times  higher as  has occurred with D D T  in  fish  eating birds.  The  application  compounds sideration  in of  of  the  Thomann's marine  contaminant  (1978)  system transfer  equilibrum partitioning processes. considerations  discussed  culate matter.  for  model  therefore  sorption  that  involve  onto  different  mostly  processes These  to  organic  involves  con-  are dominated the same  the sediments  by  energetic and  parti-  Irrespective of the source of intake, the potential for  contaminants to concentrate in biological tissue will essentially reflect preferential  accumulation  hydrophobic  pollutants  management  this  of  that  potential  less are  will  be  soluble of  compounds.  concern  high.  to  dredged  Information  For  the  material  describing  the  127 partitioning  characteristics  and  exampling  the  bioaccumulation  potential of each of the organic contaminants identified in Section 3.2 is therefore summarized below in Section 5.5.  Biological Transformation  Abiotic  transformations  photolysis) are generally (Larson, phobic  Blankenship compounds  of  compounds  (e.g.  hydrolysis  high energy reactions involving  and  in  organic  Hunt,  the  1976).  aguatic  For  sediment  environment,  heat or sorbed  these  and light  hydro-  processes  are  generally considered to be negligible (Verschueren, 1983).  However  biological  pollutants potentially Recent  by  transformation  microorganisms  more  research  and  significant has  shown  and  biodegradation  higher  marine  modification that  most  and  organic  of  organic  organisms  release  processes.  contaminants  can  transformed in organisms by several major reaction pathways they  are  oxidized,  hydrolyzed  or  reduced  (Phase  I  (Connell  and  Miller,  the  1984).  reaction  When  products  a  pollutant  differ  or  reactions undergoes  chemical  change,  compound  in toxicity, bioaccumulation potential, solubility, volatility,  etc., so such changes may be of great importance.  from  be  in which  reactions),  conjugated (Phase II reactions), or both Phase I and Phase II occur  are  the  parent  128  5.4.1  Microbial  Many  Degradation  marine  and  estuarine  microorganisms  rapidly  oxidize the  complex fractions of petroleum hydrocarbon mixtures (e.g.  less  n-alkanes),  eventually to carbon dioxide and water.  But while the n-alkanes are  oxidized quite readily, the  process  with  increasing  rate  branching.  of  this  GESAMP  (1977)  decreases  markedly  conducted  extensive  research into the microbial degradation of petroleum hydrocarbons, and found that alkanes  and  Furukawa have  the rate of degradation of complex fractions (e.g. c y c l o PAHs)  and  can  Matsumura  limited capacity  chlorinated P C B s . sorption  of  compounds  exceptionally  (1976)  to  esters  suspended  slow.  similarly  degrade  Steen, Paris  phthalate to  be  Gibson  determined  complex  arenes  and  other  sediments  that  and  and Baughman (1980)  (1976)  them  bacteria  more  highly  found that the  nonhalogenated  rendered  and  industrial  unavailable  for  degradation in the adsorbed state.  Concentration  gradients  of  organohalogen  contaminants  cores from polluted embayments of Puget Sound generally rates,  i.e.  correspond  with  increasing  Dexter et al., 1979).  levels  concentrations  of  in  probable more  long  recent  sediment  have been shown term  historical  sediment  (Horn,  to  input 1978;  The same profiles would tend to be produced by  more complete degradation the cores did not  the  in  with  time of  burial, but  the residues  in  indicate the preferential reduction in the relative the  induced by metabolism.  less  chlorinated components  which  should  be  129  The concentrations of non-halogenated P A H s in Puget Sound sediment cores showed similar general decreases to low levels at depths in the sediments Fairhall, varied  corresponding 1979).  to  However  many  of  the  cores  individual  PAH  components  felt  be  clearly  established  that  maxima.  and  readily explanable from input concentrations, and the investigators not  subsurface  (Carpenter  not  could  showing  in dated  This was  it  with depth, some  pre-1900  PAH  levels  had  not  been  significantly altered by metabolism.  No data could be found on the microbial metabolism of many of the contaminants  of  concern to ocean  dumping  management.  However,  studies of the kinetics of microbial degradation of organics in natural water samples have shown significant correlations between degradation rates and chemical structure (Paris et al., 1975; Wolfe et al., 1980). These correlations tend to confirm the generally more  highly  chlorinated or more complex  held belief that  organic  are of concern to ocean dumping management)  compounds  the  (which  are not susceptible to  appreciable degradation by microbial organisms.  5.4.2  Metabolism by Higher Organisms  Many  higher  pathways  organisms,  capable  of  particularly  substantial  vertebrates,  alteration  of  The general mechanism for biotransformation of consists  of  two  phases:  mixed-function oxidations, and  formation  of  organic  metabolic  contaminants.  hydrophobic  metabolites,  transformations  conjugates (Connell and Miller, 1984).  possess  into  more  organics  usually  by  hydrophilic  Although the majority of these  130  reactions result in detoxification of the contaminants, some can form reactive gens,  metabolites  mutagens  biologically dredged  that  and  active,  material  have been  cytotoxins. hydrophilic  disposal  site  degradation  of  implicated  The  formation  metabolites may  as  by  primary and  biota  conseguently  carcino-  excretion  that  be  of  inhabit  of  a  ecological  significance.  Metabolism and  and  vertebrate biota  specific.  is  highly  organic  contaminants  complex,  and  by  appears  invertebrate  to  be  Although our understanding of the multiplicity of  species  processes  that occur is far from comprehensive, it is generally understood the rate  of  metabolism  of  organic  contaminants  in any  that  organism  is  related to the chemical structure of the contaminant.  While there is  probably  alteration, the  more  no  compound  highly  appear  to  chlorinated  be  less  marine organisms, capable  of  and Malins, essentially 1976).  totally and  prone  to  resistant more  to  metabolic  complex  metabolism.  organic  For  contaminants  example, while  particularly vertebrates, possess metabolic  rapidly  altering  simple  petroleum  many  pathways  hydrocarbons  (Varanasi  1977), P C B s containing more than four chlorine atoms resistant  Sundstrom  to  metabolism  (Sundstrom,  et al. (1976) also suggest that  Hutzinger for  and  are  Safe,  less chlorinated  P C B s , the stereochemistry of the individual molecule has a significant impact on the metabolism  Circumstantial  evidence  process.  indicates  that  the  biological  degradation  several of the hydrophobic contaminants of concern to ocean may  be  significant.  For  example,  studies  by  Malins  et  of  dumping  al.  (1980)  131  showed that while tetrachlorobutadienes often dominated in sediments of  Puget  tissue.  Sound, This  hexachlorobutadiene  latter  component  was  butadiene in groundfish tissue.  generally  dominated  often the only  in  biotic  detected chloro-  These data were interpreted to show  selective metabolism of the less chlorinated butadienes.  It  is concluded that  halogenated unlikely  and/or  the  release of  complex  to be a major  metabolites  organic  of  the  contaminants  fate process.  However  more  of  highly  concern  the fact  that  is  meta-  bolites which are formed will be released to the water column as a more  hydrophilic conjugate  significance of this release.  substantially  increases  the  environmental  Information describing the metabolic and  degradation products of each of the organic contaminants  identified in  Section 3.2 is therefore summarized in the following section.  Properties, Bioaccumulation and Metabolism of  Organic  Contaminants of Concern  The  foregoing  release of  review  organic  of  environmental  contaminants  from  processes disposed  which promote  dredged  material  the has  identified three potentially significant release pathways:  o  the  erosion  and/or  resuspension  of  particulates  to  which  the  contaminants are sorbed o  accumulation of contaminants the food chain  in biological  tissue  and release via  132  o  biological transformation and release of soluble metabolites to the water column.  The  most substantial  of  these pathways  and it is recommended in Section 5.2 be managed  is potentially the foremost,  that disposal  to minimize these losses.  operations  should  The degree to which this  is  possible is considered in Section 6.  The  significance  dependent section  of  latter  upon the chemistry  therefore  properties, pathways  the  of  summarizes  bioaccumulation  two the  processes  is  highly  individual contaminants.  information potential  describing  and  the  This  relevant  metabolic/depuration  of each of the contaminants that were identified in Section  3.2 to be of concern to ocean dumping  5.5.1  release  management.  Polychlorinated Biphenyls (PCBs)  Properties  There  are  209  possible  compounds  chlorination of biphenyl with PCB  mixtures, about  I to  and  isomers  resulting  10 chlorine atoms.  from  the  In commercial  100 individual compounds and isomers have been  detected (Hutzinger et al., 1974).  PCB  is  producer  no of  longer PCB  manufactured mixtures  was  in the  North  America.  Monsanto  The  Company,  major which  marketed P C B mixtures for closed electrical system applications under  133  the A r o c l o r trademark. Aroclor products.  A numbering code was used to designate  The first  compound is biphenyl.  two digits,  12, indicate that  the  the parent  The last two digits specified the percentage by  weight of chlorine.  Solubility data for P C B s vary considerably for individual isomers. example,  a  review  solubility  values  by  for  Tulp  and  Hutzinger  2-chlorobiphenyl  that  (1978) varied  found  For  published  between  900  and  5,800 ug/L and for 2,2',3,3',4,4',5,5 ,6,6'-decachlorobiphenyl the variation ,  was  from  0.016  to  15 ug/L.  Tulp  and  Hutzinger  (1978)  expressed  their concerns about some of the methodologies used for determination of P C B data  on  solubilities. Aroclors  chlorinated  is  They stated that most of the published solubility based  components  on  from  selective the  solubilization  mixtures.  If  the  of  the  lower  solubilities  of  individual components of a mixture are not identical, the solubility of such a mixture in water cannot be defined as a physical  Nonetheless, the reported solubility values of P C B  mixtures and their  components illustrate their hydrophobic tendencies. solubilities  of  PCB  mixtures  in fresh water,  investigators, vary between 200 - 340 ug/L  as  constant.  The experimental  reported by  various  for Aroclor 1242 and 2.7 -  25 ug/L for A r o c l o r 1260 (MacKay and Leinonen, 1975).  Solubilities in  seawater would be less than those reported for freshwater.  The partition coefficients of P C B s also extremely monochlorinated  lipophilic. isomers  Reported to  as  indicate that the components  are  log P values range from 4.0 for  high  as  6.85  for  pentachlorinated  134  isomers (Callahan reported  for  chlorinated n-octanol  Aroclors,  it  compounds  phase;  components (1978)  and Slimak, 1979).  of  should  will  Where partition coefficients are  be  more  noted  selectively  therefore, partitioning  Aroclor  concluded  that  considered as physical  mixtures. log  P  that  As  will a  values  of  the  more  partition  differ  result,  within  for  each  Tulp and  PCB  highly  mixtures  the  of  the  Hutzinger cannot  be  constants.  Bioaccumulation  Bioaccumulation  of  PCBs  in  pelagic  organisms  primarily through direct uptake of P C B s dependent  1254  food were 950:1.  106 amplification levels  observed  of in  (Mytilus  function  of  the  Zitko  Clayton  chlorinated biphenyls Puget  Heesen (1976), reported a mussel  in organisms.  strongly  with juvenile A t l a n t i c salmon, the accumulation ratios of A r o c l o r and  levels  is  occur  that  water  lipid  from water and  to  (1974) showed  from  upon  appears  Sound  by zooplankton  waters.  McDermott,  This  fraction  in  amplification  the  organisms.  was  above  the  Young  10^ bioconcentration of A r o c l o r  californianus). lipid  et al. (1977) recorded a  and  1254 in the considered  Food  chain  a  bio-  magnification was determined not to be a controlling factor.  There  is uncertainty concerning  benthic species such as clams, Rollwagen  (1979) studied  the  the uptake  mechanism  crabs, and polychaetes. uptake  of  PCBs  by  for  PCBs  Stainken  three  species  in and of  bivalves (C. virginica, M. arenaria, and M. mercenaria) from sediments of  Lower  New  York  Bay.  No  valid  relationship  could  be  found  135  between  sediment  silt-clay  content  between tissue P C B  content  tissue  sites  levels  sediments.  at  all  and  sediment  and sediment  were  greater  PCB  than  PCB  content  content. the  Generally,  residue  However, Malins et al. (1980) found that  nor  values  in  bottom-dwelling  fish and benthic invertebrates sampled from areas in Puget Sound with the highest P C B  levels in sediments  PCBs.  Uptake  obviously  uptake  occurred  via  does  absorption  had the highest  occur, from  but  it  is  tissue  levels of  uncertain  interstitial  waters  whether or  from  in the uptake of  PCBs  ingestion of solid materials.  Although dietary intake may not be important by  fish,  marine  mammals  can  readily  within diet.  Herman and Calambodikis  mg/kg  in blubber  PCBs  of  a  killer  accumulate  PCBs  (1978) reported a  whale  which  was  contained level of  found  38  washed  ashore in 1977 in the Strait of Georgia.  Few,  if  any,  direct, acute  effects  a  PCB  recorded  as  However  PCBs  organisms.  Such  result do  of  have  effects  on  aquatic  contamination  sublethal  effects  include eggshell  organisms in  on  thinning  have  North  higher of  been  America.  food  chain  fish-consuming  birds; behavioural alterations in birds; and reproductive failure of such wildlife as mink (Stendell,  1976).  136  Metabolism and Depuration  Sundstrom, Hutzinger and Safe (1976) prepared an extensive review on biological  metabolism  of  chlorobiphenyls.  Generally  speaking,  biphenyls with four or fewer chlorine substitutions can be metabolized by a number of test organisms. species  are  predominantly  Metabolites of P C B s by  monohydroxy  and  mammalian  di hydroxy  compounds.  Highly chlorinated compounds do not appear to be metabolized. and  Harvey  biphenyls  (1978)  in  environments found  that  sediments aerated  found  anaerobic may  the of  as  percentage  of  for  mud,  long-term  Norwegian sand  evidence  marine  serve  the  marine  no  metabolism  indicating  sinks  that  for P C B s .  suggesting  a  was  greater  chloro-  anaerobic Eder  lower-chlorinated P C B s Depression  of  Carey  in  (1976)  anaerobic  higher  than  degree  of  in  well-  biological  degradation in the aerated sands, if the input ratios were identical for both areas.  5.5.2  Hexachlorobutadiene (HCBD)  Properties  Callahan  and  Slimak  solubility (2 mg/L)  (1979)  and high  reported  that  lipophilicity (log  HCBD  has  p = 3.74).  low  water  Studies  in  Puget Sound showed that H C B D tends to be associated with suspended particles at concentrations about four orders of magnitude the surrounding  water  (Riley  et al.,  1980).  Pearson  and  higher than McConnell  (1975) described H C B D as being "tenaciously adsorbed" on sediment.  137  Bioaccumulation  There does not appear of  HCBD  in  Confined  marine  uptake  contaminated factors.  to be a pattern of extensive food  studies,  areas,  chains  such  have  (Pearson  as  and  laboratory  generally  shown  or  jn  situ  1975).  studies  in  bioconcentration  For example, Laseter et al. (1976) exposed crayfish in cages  bioconcentration factor  by the  and found that the  varied from 7.8 to 300 among  animals during the same time period.  the  McConnell,  erratic  to waters and sediments contaminated with H C B D ,  The  bioaccumulation  different  test  No explanations were suggested  investigators.  log  P  of  chlorinated butadienes  compounds  McConnell days and  by  (1975)  biota  in  the  suggests moderate  marine  environment.  exposed dab and plaice to  106 days,  respectively.  1.6 ug/L  retention of Pearson  and  H C B D over 39  They recorded H C B D  accumulation  in the livers of dab by a factor of 7,000, and in plaice by a factor of 10,000. period  Negligible uptake was observed via contaminated food over a of  88 days.  The  lack  of  bioaccumulation  of  HCBD  via  the  food chain was also observed by Goldbach et al. (1976) and Leeuwangh et al. (1975).  Pearson and McConnell (1975) found that mussels exposed to 1.6  ug/L  H C B D bioconcentrated the compound by factors of 900 - 2,000  within  a  HCBD  period  occurred  of  up  in  the  to  50  days.  digestive  The  gland  occurred in the foot of the mussel.  largest  and  accumulation  relatively  less  of  accumulation  138  Laseter et al. (1976) showed that crayfish exposed to 2.97 ug/L  HCBD  concentrated the compound primarily in brain tissue (11,875 times) and the green gland (737 times).  Concentration factors in hepatopancreas  were 58; gills, 56; and muscle,  15.  Bass exposed to 33 ug/L  HCBD  had highest concentrations of H C B D in its gut (1610 times) with lower concentrations in liver, kidney and brain. concentrations  of  HCBD  in  liver of  It is uncertain if the lower  the test  organisms was  due to  metabolism by the liver.  Metabolism and Depuration  No experimental studies regarding biological metabolism of chlorinated butadienes were found in the literature.  However as was described in  Section 5.4.2, circumstantial evidence by Malins et al. (1980) indicated selective metabolism by fish of less chlorinated butadienes.  5.5.3  Polychlorinated Dibenzofurans ( P C D F )  Properties  There are al.  1978).  chlorinated  135 possible isomers of chlorinated dibenzofurans (Rappe et No  information  dibenzofurans  in  was  found  water.  on  the  However  solubilities the  of  any  solubilities  are  expected to be lower than 3.1 mg/L, the solubility of dibenzofuran in freshwater  at  25oC  (Lu  et  dl.,  1978).  On  the  basis  of  the  log  139  n-octanol/water  partition coefficient of 4.12 for dibenzofuran (Leo et  al.,  tetra-  1971), the  and  pentachlorodibenzofurans  are  theoretically  very lipophilic.  Bioaccumulation  Few  studies  PCDFs.  were  found  in  the  literature  on  bioaccumulation  L u et al. (1978) followed the passage of dibenzofuran through  a model aquatic system by applying this compound to sorghum which, when eaten by salt into  water  larvae,  containing  and  relatively  mosquito  water  determined  An  for  octanol/water  marsh caterpillars, resulted in its  plankton, fish.  The  found  Daphnia, that  snails,  the  magnification  authors  noted  a  factor  magnification  release mosquito  good  fit  be  was  substantial  of  947  was  between  partition coefficients and bioaccumulation  ecological  leaves  dibenzofuran  not degraded, and exhibited  ecological  fish.  algae,  They  soluble, was  accumulation.  higher  of  by  factor  would  mussels  (Mytilus edulis)  log  fish.  expected  A for  chlorinated dibenzofurans.  Lake  et al. (1981)  exposed  areas of Narragansett  caged  in various  Bay, Rhode Island, and found from 643 to  1,180  ug/kg (dry wt) of 2,4,8-trichlorodibenzofuran in the mussel tissues from the areas of the Bay  described as  highly  polluted. • Lobster  hepato-  pancreas from the lesser polluted areas where mussels  had a 52 ug/kg  level  ppb  of  trichlorodibenzofuran,  dibenzofuran.  contained  1,260  trichloro-  The authors concluded that "the high toxicity generally  140  associated  with  PCDFs  tributions throughout  calls  for  the coastal  futher documentation of United States and for  their  rapid  dis-  identi-  fication and abatement of their sources".  Metabolism and Depuration  Information structural  on metabolism similarity  dibenzofurans  would  to  of  PCDFs  was  dibenzofurans,  not  sparse.  On  appears  that  it  be appreciably biologically  the basis of chlorinated  degraded  in the  environment (Lu et al., 1978).  5.5.4  Pentachlorophenol  (PCP)  Properties  The  fresh water  White,  1965).  solubility  of  PCP  is 20 mg/L  at  25oC (Bailey  and  The log P for pentachlorophenol has been reported to  be 3.4 (Lu and Metcalf,  1975).  Bioaccumulation  Lu,  Metcalf  sisting  Cole  (1978) used  of a 3 liter flask  mosquito PCP.  and  a  model  aquatic  containing Daphnia, mosquito  fish and green algae,  to study  the uptake  A f t e r 48 hours exposure to 0.01 to 0.1 mg/L  organisms  were  factor  the fish was  in  found  to  ecosystem  contain  the  tracer.  calculated to be 296.  con-  larvae, snails, of  radiolabeled  levels of P C P , all  The  bioaccumulation  The other  organisms  141  took  up  less quantities and  had bioaccumulation factors of  165; mosquito larvae, 16; snail, 121; and algae, reported  that  goldfish  exposed  to  0.1  1.5.  mg/L  of  Kobayashi  PCP  showed a bioaccumulation factor of approximately  Daphnia,  for  (1978)  120  hours  1000.  Metabolism and Depuration  Kobayashi clams,  (1978) showed  was  guickly  excreted into  pentachlorophenyl-sulfate. 10 hours,  and  clean water.  that P C P  absorbed by goldfish, and also by the  surrounding  water,  mostly  as  Tissue concentrations dropped to half after  approximately  one-fifth after  20  The author concluded that P C P  concentrations in fish and shellfish for a  hours  depuration  will not remain at  long  time without  in  high  causing  death.  Schimmel, Patrick and Faas (1978) similarly found that oysters  purged  themselves  cessation  of  PCP  of  PCP  delivery.  in  tissues  Microbial  been shown to be relatively rapid (K.  within  four  degradation  days of  after  the  has  also  PCP  H a l l , Westwater,  pers. comm.,  1985).  5.5.5  Chlorinated Benzenes  Properties  No  solubility  found  in the  freshwater  values  for chlorinated benzenes in marine waters  literature, but  where  they  they  range  dichlorobenzene down to 6 ug/L  are  from for  expected to approximately  be  less  140  were  than  in  mg/L  for  hexachlorobenzene (Callahan  and  142  Slimak,  1979).  Increased  chlorination  and increased lipophilicity.  results  in decreased  solubility  The log P for hexachlorobenzene has been  reported to be 6.18 (Callahan and Slimak,  1979).  Bioaccumulation  Few data for bioaccumulation of chlorinated benzenes by marine biota were  found  in  concentration  the  literature.  factors  from  Veith  60 to  et  al. (1980)  89 for  benzene in bluegill sunfish during a  determined  three  isomers  14-day test.  Macek  of  bio-  dichloro-  et al. (1977)  investigated the relative significance of aqueous and dietary uptake of 1,2,4-trichlorobenzene using source  for  the  bluegill  exposed to 3 ug/L L.  macrochirus  the water flea, Daphnia magna, as a food  sunfish,  Lepomis  macrochirus.  D.  magna  in water accumulated up to 0.44 mg/kg in tissues.  accumulated  to  0.53  mg/kg  from  water  alone,  mg/kg from food alone, and 0.57 mg/kg from water and food. the authors concluded that the dietary contribution was  Similar  and  from  food  were  in  importance of the water (1977) salmon.  reported  an  the  accumulation  study  on  Amounts adsorbed from water  proportion  medium  Thus,  insignificant.  results were shown by Zitko (1977) in a freshwater  juvenile A t l a n t i c salmon (Salmo salar).  0.03  82.6%/17.4%  indicating  to bioaccumulation of H C B . coefficient  for  HCB  of  the Zitko  753  by  143  The highest bioaccumulation value found in the literature was 44,000, which was reported by Laseter et al. (1976) for juvenile bass.  In field  experiments, Laseter et al. (1976)  found that resident crayfish which  were exposed to 44 ug/L  in natural  waters  had whole  body  chlorinated  benzenes  are  dependent upon the degree of substitution on the benzene ring.  For  levels of  of H C B  1164 times this level.  Metabolism and Depuration  Depuration  rates  of  bioaccumulated  example, V e i t h et al. (1980) benzenes  in  tissue  Tetrachlorobenzene  of  showed  bluegill  had  a  that  sunfish  half  life  the half were  less  between  2  lives of dichlorothan and  4  one  day.  days  and  pentachlorobenzene had a half life greater than 7 days.  Lu  and  chemical  Metcalf  (1975)  which  is not  suggested  (1975)  microbial  found  chlorobenzene is a  readily biodegraded  they are already growing Agg  that  1,2-  on another and  by  persistent  microorganisms  hydrocarbon source.  1,3-dichlorobenzene  to  be  unless  Thorn and resistant  to  biodegradation.  Safe et al. (1979) found that in higher organisms, chlorinated benzenes are  metabolically  lites.  degraded  These authors  chlorophenol  in frogs.  metabolite of H C B  found  to  hydroxylated  that  and  conjugated  metabo-  tetrachlorobenzene can form  Pentachlorophenol  (Koss et al., 1977).  is  produced  by  rats  tetrdas  a  144  5.5.6  Polyaromatic Hydrocarbons  There  is  a  very  diverse  (PAHs)  range  of  compounds  within  chemicals, not all of which could be reasonably scope of this study. the  general  this  reviewed within  Therefore, following some observations  properties  of  PAHs,  the properties and  benzo(a)pyrene,  and  the  commonly  detected  of the  regarding  bioaccumulation  potential of several common P A H s , benzo(a)anthracenes, and  class  flouranthenes  polychlorinated  naphthalenes, are reviewed as examples.  General Properties  Solubilities seawater of  and  partition  are generally  coefficients  of  PAHs  in  freshwater  dependent upon molecular weight.  Alkylation  a parent aromatic compound will decrease solubility and  lipophilic properties.  the solubility of naphthalene in seawater  2.4 mg/L  (Rossi and Neff,  decreased the solubility to also a f f e c t  1978).  was  from 20 mg/L  Addition of a third methyl  1.7 mg/L.  solubility.  benzo(a)anthracene  increase  For example, the addition of two methyl groups  decreases  may  and  Hollifield  approximately  Positions  to  group  of the added groups  (1979) showed three times  that  9  methyl  more soluble  than  Eganhouse and Calder (1976) found that mixtures of hydrocarbons  may  10 methyl benzo(a)anthracene.  a f f e c t the solubilities of various P A H s .  For example, naphthalene and  phenanthrene enhance  of  acenaphthene.  is  essentially  hand, the solubility  of  the solubility naphthalene  On the other  unaffected  by  the  145  presence of other P A H s .  A r o m a t i c hydrocarbons are "salted out" by  increasing  of  concentrations  inorganic  salts,  with  the  result  that  solubilities in saltwater are lower than in freshwater.  Bioaccumulation  Higher  molecular  weight  PAHs  are  generally  bioaccumulated  to  a  greater extent by aquatic biota and are retained for longer periods of time.  For  example,  deposit  feeding  Roesijadi  clam  Macoma  from water by a factor of anthracene  by  1349, and  (1978) observed similar pulex.  et al. (1978) found inguinata  that  concentrated  the  phenanthrene  10.3; chrysene by 694; dimethyl  benzo(a)pyrene  trends for P A H  by 861.  benthic  benzo(a)-  Southworth  et al.  bioconcentration with Daphnia  Uptake and elimination rate constants varied considerably with  no discrete pattern.  Naphthalene,  however,  had  the  lowest  uptake  degraded  PAHs.  rate and the highest elimination rate.  Metabolism  Microbes  in  However,  the  slowly  (Lee,  water-sediment higher 1977).  interfaces  molecular Gibson  weight  effectively PAHs  (1976) stated  than three rings, microbial degradation  that  were  degraded  for P A H s  is difficult. •  with  more more  146  Benzo(a)anthracene  Callahan  and  Slimak  (1979)  reported  log  octanol  water/partition  coefficients for benzoanthracenes between 5.6 and 6.4.  Oysters which were suspended in enclosures for 8 days were found by L e e et al. (1978) to have accumulated benzo(a)anthracene at a 18,000 times greater than the ambient water concentration.  level  When the  osyters were transferred to uncontaminated waters, benzo(a)anthracene was slowly released and its half life in the oysters was 9 days.  Roesijadi to  et al. (1978) exposed the benthic species Macoma  marine  sediments  found  that  factor  of  dimethyl 1349 above  anthracene  had  the  contaminated  with  Prudhoe  benzo(a)anthracene concentrations highest  in  was  Bay  crude oil  bioconcentrated  water.  bioconcentration  inquinata  Dimethyl factor  of  and  by  a  benzolthe  PAHs  studied, which included phenanthrene, chrysene, and benzo(a)pyrene.  Gardner et al. (1979) used a laboratory ( 2 0 ° C ) flowing seawater to  study  the  degradation  of  effects  and  microbes  benzo(a)anthracene.  benzo(a)anthracene ments  of  1.4%  were per  1.5  week  -  1.8% in  and  polychaete  Microbial per week  coastal  marsh  worms  degradation in coastal  system on  the  rates  of  sand  sediments.  sedi-  In  the  presence of the benthic polychaete worm, C a p i t e l l a capitata, which is associated  with  areas  of  high  oil  input,  degradation  increased to 2.7 - 3.0% per week in sand sediments and marsh  sediments.  Two  reasons  were  postulated  for  rates 1.8%  the  were in the  increased  147  degradation improved mixing  in  the  presence  conditions  of  the  in the sediments  the sediment  distributes  polychaete: for  microbial  field  tests  with  with  produced after  C-14  72  system enclosures"  Studies  of  the  aguatic  organisms  hours  labeled  in the  of  complicated  al.,  naphthalene oxygenated  can  be  readily  not  1980)  found  shown  of  no  in  I4CC>2  "controlled  benzanthracenes  by  (described  et  waters  the  mechanisms.  Malins  have  eco-  Inlet.  elimination/detoxification in  compounds.  benzo(a)anthracene,  located in Saanich  are  (i.e.,  For example, L e e et al. (1978),  exposure  bioaccumulation  worms  degradation  benzo(a)anthracene  detectable microbial degradation. experiments  the  nutrients to subsurface areas); and/or,  2) the worms metabolically degraded the  Short-term  I)  the For  found  converted  presence  of  dietary  flatfish  into  higher  metabolic  example, Varanasi that  by  in  et  al.  radio-labelled a  variety  of  metabolites that remained in tissues for extended periods.  Fluoranthenes  Fluoranthenes  are  coefficients. 0.12  mg/L  solubility  of  characterized by  low  solubility  and  high  partition  Hollifield (1979) reported a solubility of fluoranthene of in  distilled  fluoranthene  water.  Rossi  in saltwater  and  Neff  (1978)  as 0.1 _+ 0.06 mg/L.  and Slimak (1979) reported log octanol/water  reported  a  Callahan  partition coefficients of  5.33 and 6.57 for fluoranthene and methyl fluoranthene respectively.  148  Fluoranthene was one of the P A H s added to the controlled ecosystem enclosures by L e e  et al. (1978).  mulated  fluoranthene  ug/L  5 mg/kg  fluoranthene. A f t e r  Oysters  in the enclosure bioaccu-  in 2 days from  23 days  anthene remained in the tissue.  water  containing  depuration time, 0.4  mg/kg  7.2  fluor-  A half life of 5 days was calculated.  Benzo(a)pyrene  Benzo(a)pyrene  has a solubility in freshwater of approximately 4 ug/L  (MacKay and Shui,  1977) and a  log P value of  6.04 (Radding et al.,  1976), so is highly susceptible to adsorption to organic sediments  and  to biological uptake.  Biological uptake studies of benzo(a)pyrene have predominantly utilized invertebrate test species.  Vertebrate species such as fish metabolize  polyaromatic hydrocarbons, hence complicating interpretation of uptake data.  Roesijadi  et al. (1978) exposed  the bivalve  days to oil contaminated sediments  Macoma  and found that  inquinata  for 7  the concentration  factor for benzo(a)pyrene uptake from sediment was 0.09 compared to an  uptake  concentration  factor  from  water  of  861.  Long-term  exposure of M. inquinata to contaminated sediment^ showed continuing increases  of  benzo(a)pyrene  quantities of BaP  within  the  bivalves,  despite  decreasing  in the sediments, indicating that equilibrium was not  quickly reached with benzo(a)pyrene and that benzo(a)pyrene would be relatively persistent in tissue of exposed bivalves.  149  Freshwater  studies  by  benzo(a)pyrene about unextractable  Lu  "as  et fast  products".  degradation of BaP after 3 days.  al. (1977) as  it  is  However,  found adsorbed  the  that  fish  and  authors  metabolize  converts noted  it  to  minimal  in snails, with a 2177-fold concentration observed  Therefore, studies of uptake of benzo(a)pyrene indicate  that it is rapidly metabolized in fish livers, explaining the low values of BaP  found in fish livers during the Puget Sound studies by Mai ins  et al. (1980). may  Nonetheless, these authors considered that  metabolites  remain in fish tissue and possibly a f f e c t physiological  processes.  The implications of the metabolites are unknown.  Chlorinated Naphthalenes  Callahan  and  Slimak  (1979)  naphthalene to be 0.007 ug/L be 4.12.  calculated  the  solubility  of  2-chloro-  in freshwater at 2 5 ° C and the log P to  Increased chlorination will result in decreased solubility and  increased log P.  Bioaccumulation four  or  more  environmental shrimp, Halowax 1000  of  chlorinated naphthalenes,  chlorine  fate.  Palaemonetes  a  Green  and  puqio,  to  Neff 40  ppb  is  probably  (1977) (ug/L)  those  a  exposed levels  (monochloro-  and  factor  of  dichloronaphthalene)  was  with  significant adult of  1099, 1013, and 1000 for periods of up to 16 days.  factor of 63; Halowax by  substitutes,  particularly  grass  each  of  Halowax  accumulated  by  a  1013 (tetrachloro- and pentachloronaphthalene)  187; and  Halowax  1099 (trichloro- and tetrachloro-  150  naphthalene) by a factor of 257. in the  first  3 days.  In each case accumulation was rapid  Depuration  was  rapid  in  clean  water;  tissue  levels were generally reduced to I mg/kg or less within 5 days.  The bioconcentration factors grass shrimp U.S.  EPA  are  (1976)  much for  reported by  lower  brown  than  Green and N e f f  the 2300  shrimp.  factor  Halowax  (1977) for  reported by the  1014,  a  mixture  of  tetra-, penta-and hexa- chloronaphthalene, was used for the U.S.  EPA  (1976) studies and the increased number of substituted chlorines  may  have contributed to increased bioaccumulation levels in these studies.  The U.S. E P A (1978) in its review of chlorinated naphthalenes reported that  metabolism  metabolism  of  decreases  naphthalenes  with with  increasing five  or  chlorine  more  levels.  substituted  No  chlorines  was observed.  5.5.7  Phthalate Esters (PAEs)  Properties  Individual  PAEs  vary  considerably  in  solubility  and  partitioning  tendency, dependent upon molecular weight and substituted groups. The most persistent P A E s  include di-butyl phthalates (DBPs), butyl benzyl  phthalates (BBPs) and di-ethyl hexyl phthalates (DEHPs). Callahan Slimak (1979) determined log P's and 5.3 - 8.7 respectively.  and  for these compounds as 5.2, 4.8 - 5.8  151  Bioaccumulation  There  have been few systematic  by marine biota. difficulties  in  Giam  studies of bioaccumulation of  et al. (1978)  analytical  capabilities  PAEs  attributed the lack of data  to  -  to  some  of  which  are  due  contamination of dilution waters, reagents, and possibly equipment.  K i n e t i c uptake studies of phthalate esters found during this literature review  all  used  (1973) showed  freshwater  that  aquatic  I4C-labeled  test  DEHP  organisms.  was  Sanders  6500 after equilibrium was reached, generally within 7 days. publication  by  the  same  authors  and  for  1900 to However  the same  test  species, much lower bioconcentration factors were reported (Mayer Sanders,  1973).  concentration  and  Accumulation studies were apparently dependent upon  the concentration of concentrated  al.  taken up rapidly and bio-  accumulation factors for six invertebrate species varied from  in another  et  within of  PAEs  in water.  the scud  0.1  ug/L  by  and  a by  For example, D E H P  factor a  of  factor  13,400 of  270  was  bio-  using  a  water  using  a  water  concentration of 62.8 ug/L.  Metabolism and Depuration  Biological al.  (1973)  elimination of accumulated P A E s to  be  accumulated 5.4 rapidly activity.  during  rapid. mg/kg  4 days  Scud  exposed  in 3 days.  was  to  0.1  Residual  in phthalate-free water  found by Sanders ug/L  of  radioactivity to 2 0 %  of  et  14C-DEHP decreased the initial  152  Rapid  depuration  Gledhill at  rates  were  also  determined  within  bluegills,  by  et al. (1980) who observed a bioconcentration factor of  equilibrium  I^C-uptake.  (21  days)  for  butylbenzyl  phthalate,  663  based  on  The depuration half life was less than 2 days.  Giam et al. (1978) found low levels of phthalates in biota in the Gulf of  Mexico  despite  elevated  levels  of  phthalates  in  water  and  sediments. This observation was attributed to rapid metabolism by the organisms. Also, concentrations in liver were lower relative to muscle levels indicating the presence of metabolic degradation of  PAEs.  Conclusion  The persistent organic contaminants  that accumulate  in sediments  concentrations that warrant concern to dredged material have  strong  sorption  tendencies  evidence  suggests  that  sediments  upon  disposal  significant contaminant  they  will  in  the  with not  the  marine  management  sediments.  appreciably  Available  desorb  from  environment.  release from the disposal  to  the  However,  site may  occur via  dispersion of contaminated particulates that become suspended in the water column.  The  potential  for  contaminated  particulate  material  to  become  suspended into the water column during or subsequent  to disposal  dependent  material,  upon  the  characteristics  disposal  methodology,  and  disposal  site.  that  Given  the  of  the  oceanographic  contaminants  dredged  is the  characteristics  of  the  preferentially sorb  to  fine  153  grained sediments (Boyd et al., 1972), and that fine grained sediments are the most susceptible to resuspension and transport away from the disposal  site,  disposal  be managed  The  it  is  oceanographic  of  primary  importance  to minimize sediment  characteristics of  that  dredged  losses  disposal  via  sites  material  this  where  pathway. suspended  sediment losses are minimized, and the extent of suspended sediment losses  at  such  sites,  are  considered  in Section  6.  Section  identifies potential disposal areas within the Strait  7  of Georgia  then where  resuspended sediment losses will be minimal.  The potential role of biological uptake and transfer of hydrophobic contaminants be significant. have (vis  a vis_ water PAHs)  centrations  from disposed dredged material may also  E a c h of the reviewed organic contaminants of concern  a high potential  PCP,  in the transport  bioaccumulation.  concentrations)  up to that  for  range  106 (e.g. PCBs).  may  be  released  from  Bioaccumulation  factors  approximately  103  (e.g.  Relative to the very  low  con-  into  solution,  the  adsorption  of  hydrophobic chemicals into biotic tissue, and their subsequent release from the disposal chain,  may  site via migration of the organism or via the food  conseguently  release from a disposal in  this  manner  are  provide  mound.  an  important  pathway  for  The fact that contaminants  incorporated within  animal  tissue  adds  their  released to  the  environmental significance of this release process.  The extent of contaminant uptake from disposed dredged material to the biological system exposure  to  the  is directly dependent upon the degree of biotic  material.  Demersal  fish and benthic invertebrates  154  that  reside at  lating  high  a disposal  body  site will be particularly prone to a c c u m u -  burdens.  Their  relatively  sedentary  and  benthic  habits, and in the case of groundfish, their long life span, will result in direct and prolonged exposure to the material. chemicals  have  been shown to  Hydrophobic organic  rapidly accumulate  to  high  levels  in  these organisms.  However  the contribution of bioaccumulation to the actual  of contaminants from a disposal of  food  chain  contaminant apparently  biomagnification,  concentrations ineffective  contaminant  area remains at  in  concentrations  which  can  issue.  result  The in  in  predatory  terrestrial  the  marine  environment.  in  gill-bearing  marine  transport process  very  high  animals,  is  Because  organisms  are  effectively moderated by equilibrium partitioning exchange, they rarely exceed sediment concentrations by more than an order of magnitude.  The concern for bioaccumulative contaminants from a disposal thus  largely  dependent upon the physical  migration  of  site is  contaminated  organisms from the area.  The extent to which this occurs is specific  to the biotic assemblage.  Groundfish are more mobile than infaunal  vertebrates, so possibly release.  Migrating  contribute more substantially  predatory fish that  prey at  to  contaminant  a disposal  site  may  also accumulate then transport contaminants from the area, but their contribution will be limited by their length of habits at the site.  residence and feeding  155  It  is concluded that the contribution of bioaccumulation as a pathway  of possible contaminant release defies definative prediction on present knowledge.  It is probably substantially  less than release via suspended  particulate dispersion, but is potentially much greater than desorptive release  to  solution.  bioaccumulation  Minimizing  requires  the  selection  of  environmental  implications  disposal  where  sites  of  resident  biota are relatively sparse and of low ecological and economic value. These reguirements will be applied in a review of appropriate disposal sites in the Strait of Georgia in Section 8.  Biological  transformation  contaminants Vertebrates accumulated  is are  a  and  further  particularly  contaminants.  release  fate  of  process  efficient at Although  metabolites of  potential  excreting  metabolites  are  generally  the  philic  implicated  some  cases  have  been  significance. and  they  in  organic  metabolizing  less toxic than the parent compounds, and  of  are usually  more  hydro-  with  carcinogenic,  The rate at which higher organisms metabolize organic  contaminants  mutagenic and cytotoxic effects.  appears to be related to chemical structure: and  more  degradation.  complex  compounds  are  less  more highly chlorinated susceptible  to  metabolic  Rapid depuration of contaminants by fish has been shown  to occur with less chlorinated phenols and benzenes, and with the low molecular weight lites are unknown.  PAHs  and P A E s .  The implications of  the  metabo-  156  Ocean  dumping  persistent  management  organic  metabolism.  primarily  contaminants  However  transformations  regard.  Minimizing  transformation  and  disposal  where  that  the uncertainty  metabolic  sites  is  requires  the release  that  are  resident  the  are  to  our knowledge  implications requires  relatively  requirement is coincidental with that for minimizing  more  resistant  caution be exercised  contaminants biota  with  relatively  surrounding  environmental of  concerned  of  in  of this  biological  selection sparse.  of This  bioaccumulation,  and is applied in the review of appropriate disposal sites in the Strait of Georgia in Section 8.  157  6.0  PROCESSES EFFECTING DISPOSED D R E D G E D  6.1  T H E P H Y S I C A L DISTRIBUTION O F  MATERIAL  Introduction  It  has been concluded that  the primary pathway  of potential release  of trace metals and organic compounds from ocean dumped materials is through the dispersion or erosion of the particulates to which the contaminants  are  bound.  Particulate  release  from  ocean  dumped  material may occur from frictional forces during passage through the water  column, or  from  erosion of  the settled  either case, the advective loss of contaminants  disposal  Section  2.1,  this  imposes  unpredictable  and  In  will extend the area  of potential impact of the ocean dumping activities. in  mound.  As was outlined  possibly  substantial  environmental risk.  The  finer  particles  dispersive forces. dispersion contain  is  a  are  the  most  susceptible  to  resuspension  and  The environmental risk associated with fine particle  accentuated  by  disproportionately  the high  fact  that  these  contaminant  fines  frequently  loading.  This  is  because, other factors being equal, contaminant adsorption is a surface phenomenon: ratio  tend  coarser  fine particulates with a high surface to  contain  fractions  (Boyd  higher et  al.,  contaminant 1972).  For  area  concentrations example,  to  volume  than  the  Brothers  and  158 Sullivan (1984) determined that the more highly contaminated dredged materials  from  False  Creek  could  be  visually  distinguished  dredged  material  on  the  thus  of  basis of colour and texture.  Determination of  the physical  fate  c r i t i c a l environmental concern.  of  is  In the selection process for a disposal  site, consideration must be given  to the eventual disposition  of  the  dredged material in order that adeguate determination of the zone of impact can be made. then  be  calculated  The conduct of to  maximize  the disposal  the  assurance  operation that  the  should impact  boundaries do not extent beyond a confined and acceptable area.  Nittrouer  and  Sternberg  (1975)  investigated  the  fate  of  dredged  material in Puget Sound, and concluded that the controlling factors of fine  grained  sediment  movement  were  the  degree  of  water  entrainment during dredging; the water depth at the disposal site; and the energy regime of the near bottom environment at the site. following  describes  the  processes  through  which  these  The  factors  are  e f f e c t i v e , then defines operational procedures by which fine material release may be controlled.  During Water Column Passage  Dredged deposited  material that is released at the sea surface from a scow on  the  seafloor  in  three  steps  1974).  Upon  release, the dredged sediment descends rapidly (> 100 m/min)  through  the water column as a high density jet.  (Gordon,  is  If the disposed sediment  has  159  a moisture content of fall essentially any 67%  intact rapidly through the water column with little if  entrainment  of  seawater.  for silts or 7 5 %  ambient depths may  less than 5 0 % , then the bulk of material will  water  will  exceeding  be  for  be  clays  the initial water content then  entrained  20 metres  increased  If  several  the  it  will  act  during  the  descent  total  fold  volume  before  it  of  as  a  is  above  dense  fluid:  phase,  and  the descending  reaches  the  seafloor  in jet  (JBF  Scientific Corp., 1975).  Dredging Lower  of  heavily  Mainland  Disposal  contaminated  is  primarily  sediments  conducted  British  using  Columbia's  clam-shell  dredge.  is usually by bottom dumping scows with a capacity of up to  1000 m3.  On the basis of the Gordon and J B F studies, this material  will pass through a shallow  water  column  water, this dense mass may entrain a  in  neutrally  bouyant  plume.  In  relatively intact.  In deep  enough ambient water to create  this  case,  maximum  water  column  interaction occurs and less bottom impact will occur.  Upon  impact  impact outward  with the bottom,  area,  but  some  of  from  the  impact  large blocks of  the  point  released as  a  sediment  material  density  stay  in the  spreads  rapidly  This  bottom  plume.  plume may be several metres thick, but slows and thins as it travels outward. particles  Initially away  sufficiently observed  to  the  from  the  to permit run a  point (Gordon,  plume  impact  deposition.  few  1974).  moves  hundred On  a  swiftly  point  until  Over metres,  sloped  a  and, carries its  flat  at  bottom,  velocity bottom  most,  from  density  sediment is  it  reduced has  the  plumes  been  impact with  a  160  suspension  concentration greater  than  10 g L - l  have been observed to  retain their integrity over much greater distances, and move down the slope as a gravitational flow (Meagher and Gorham,  1982).  These three steps - descent of the jet, impact on the bottom, and the spread wide  of  range  the bottom of  density  hydrological  plume -  conditions  have been observed under a and  dredged  material  teristics (Bukoniewicz et al., 1978; Cusstar and Wakeman,  charac-  1977).  The  limiting conditions under which these steps will occur have not been determined.  They have been documented in water depths up to  metres, but cannot be arbitrarily applied to deeper water sites as exist in the Strait of Georgia.  125 such  The Point Grey dumpsite is in 240  metres of water.  Literature limited  in  discussing amount  deeper and  water  scope.  disposal  mechanics  Yamamoto  and  is  extremely  Alcauskas  (1975)  monitored the disposal of 4,000 cubic yards of material dredged from San Francisco Bay into 183 m of water. of the material fell the resultant  much  in clumps throughout the water column, but that  disposal  depth of 0.3 metre.  They determined that  mound covered only 4000 m2 with an  average  This accounts for only one third of the disposed  material.  A similar study was conducted by R.M. 250,000 cubic yards  of  water of Kauai, Hawaii.  spoil  disposed  Towill Corp. (1972) to monitor into  1,300  -  1,600  It was calculated that maximum  metres  of  deposition  thickness was approximately 0.02 mm, at a distance of no less than  161  20 km downstream may  be  reasonably  from the disposal site. concluded  that  the  In this depth of water, it disposed  material  disperses  completely during its passage through the water column.  In deep water disposal sites in the Strait of Georgia, shear effects on the  falling  mass may  result  in considerable erosion of  during water column transit.  fine material  Although the bulk of material  disposed  will probably impact the bottom, a significant proportion of fines may be  lost  to  the  water  column.  Given  that  most  contaminants  are  associated with the fine fraction (Boyd et al., 1972), this loss may be of high environmental significance.  6.3  Subsequent to Settling  6.3.1  Physical Factors E f f e c t i n g Sediment  Resuspension  Settled sediments may be physically remobilized and dispersed by wave and  current  turbulence.  Studies  by  Bokuniewicz  et  al.  (1977)  of  post-depositional movement of dredged materials in Long Island Sound determined principal  that  cause:  disturbance  from  direct, wind-driven  tidal  current  flow  depths greater than 20 m is usually weak.  over  fluctuations  the bottom  in  is  the  water  This determination would  equally apply to Georgia Strait, which is well protected from sea-wave disturbances.  162  The  sediment  particle size  largely  determines  the speed of current  required to erode, transport or deposit naturally settled particles (see Figure  6).  For  substantially,  disposed  dredged  dependent on  the  materials,  mode  of  this  scheme  disposal  and  may  vary  the  resultant  which  simulate  material.  Examples  profile of the disposal mound.  Numerous physical  computer transport  models  dynamics  have of  been  disposed  developed dredged  include those of Koh and Chang (1973), Brandsma Krishnappan  (1975)  important factors column  were  and  Hunt  pertaining  known,  there  (1984).  and Divoky  However,  even  to the dredged material appears  to  be  no  if  (1976), all  and the  universally  the  water  applicable  model for quantitatively predicting the time history and ultimate fate of material released in the sea.  Resuspension of disposed dredged sediments occurs when the boundary shear  stress exceeds the critical  former  is  related to the water  stress of the disposal velocity profile but  mound.  the  latter  The is  a  complex function of the geometry of the sediment-water interface and the texture of the sediments.  No  quantitative testing of dumpsite erosion subsequent to disposal  dredged material has been conducted in British Columbia.  of  The seabed  water current regime at our major ocean dumping site at Point Grey has not even been studied (H. Nelson, EPS, pers. comm., 1985).  Hoos  (1977) determined that the majority of disposed material at the Point Grey  dumpsite  was  located  up  to  3  km  to  the  northeast  of  the  163  FIGURE 6.  R e l a t i o n s h i p between C u r r e n t S p e e d , P a r t i c l e D i a m e t e r , Sediment E r o s i o n , T r a n s p o r t ,  or Deposition ( a f t e r  and  Kennett,  .  •)  100 ErOS'On  -90 Water Content (%)  Deposiiion  SILT  CLAY 4  i 20 60 PARTICLE DIAMETER  SAND l 200 (^m)  2000  1982).  164  designated site, but concluded that  this was  dumping rather than bedload movement.  the result of inaccurate  This dumpsite has received a  diverse and often unrecorded variety of sediment types, so it cannot be determined whether erosion of the fine materials has occurred.  Studies  conducted  elsewhere  have  shown  that  clam-shell  dredged  material deposited in low or moderate energy environments in coastal waters mostly  remains where it settles.  the water content  and  cohesiveness  influences the erosion potential. disposed tend  from a bottom  For clay and silt sediments,  of  the  are  therefore  dumping  reguired  mound  strongly  Sediments dredged by clam-shell and scow  have  to remain cohesive upon deposition.  regimes  disposal  to  low water  Relatively  resuspend  them  content  and  strong current  once  they  have  settled.  Substantial mounds of sediment have accumulated at dumpsites over a number of years. site  in  shoaled  A bathymetric study of a dredged material disposal  Narrangansett by  about  6  Bay, metres  Rhode after  sediment (Saila, Pratt and Polgar, agreed  to  within  have been dumped. Island  Sound  2.4  percent of  Island, the  showed  disposal  1972).  of  that  the  8  I0*> m3  x  The volume of this  the volume  that  was  bottom of  mound  estimated  to  Precise bathymetric mapping of the Central Long  disposal  site  similarly  accounted  estimated volume of disposed material (Morton,  for  1983).  97%  of  the  165  Morton (1983) did find that newly deposited dredged materials in Long Island Sound hurricane  lost  approximately  passed  through  hurricane were small  at  12 percent of  the  area.  their volume  However  losses  neighbouring older disposal  when a  due  sites,  to  the  where  the  disposed sediments had consolidated over time and under the influence of less extreme forces.  Bed sediment distributions provide a simple and accurate reflection of sediment transport conditions at a prospective disposal especially where  true  for  clam-shell  dredged  the disposed  sediments  are  dredged condition.  A  study  by  and  scow  structurally  area.  dumped  similar  This  is  sediments,  to  their  pre-  Dexter et al. (1979) confirmed that  clam-shell dredged silty-sand deposited on a predominantly sand bottom in E l l i o t t Bay, Puget Sound, did not significantly erode.  6.3.2  Biological Factors E f f e c t i n g Sediment  In  addition  metal  to  release  the  above  from  remobilization may  described physical disposed  occur.  construction activities of  Resuspension  factors  sediments,  effecting  biologically  trace  induced  Feeding, burrowing, excavation and benthic organisms each result  in  tube  transport  and reworking of the sediments.  However, the degree to which these  activities  a  alter  the stability  of  never been definitively studied. disposal  mound  stability  have  disposed  dredge  spoil  mound  has  The aforementioned studies describing been  of  insufficient  duration  determine the effects of recolonization upon material erosion.  to  166  The  biota  at  reduced as  dredged  material  a consequence of  cases the biological  disposal  disposal  large  is usually  activities.  community at the disposal  recover to pre-disposal abundances. noted  sites  densities  of  burrowing  substantially  However  in  mound will eventually  Hoos (1977) and Packman and deposit  most  (1980)  feeding fauna at  the  Point Grey dumpsite.  At  least  two effects of biogenic processes can significantly decrease  mound stability.  1.  An  increase  velocity  These are:  in water content.  necessary  water content.  to  initiate  Figure 6 shows that erosion  decreases  the current  with  increasing  Feeding and burrowing activity breaks up sediment  aggregates and counteracts compaction, creating an open sediment fabric.  2.  A  modification of surface topography. at  the  Microtopographic  sediment-water  interface  features  increase  turbulence  and  hence  erosion.  Rowe (1974) demonstrated that burrows and fecal mounds  can act as "catalysts" for erosion by periodic bottom currents.  The  extent of  predicted. that  after  these effects on any given disposal  Laboratory studies by Young  mound cannot  and Southard  (1978)  be  showed  60 days of reworking by a natural assemblage of benthic  organisms, critical  erosion velocity decreased by  approximately  60%  167  from the initial value.  They found that bioturbated muds had  lower  threshold shear velocities than fine sands, which is contrary to Figure 6.  However  these researchers were unable to translate  these studies  to  accurate field predictions in the intensively studied Buzzards Bay. This suggests  that  we  are  a  mechanisms  influencing  dredge spoil  mounds.  long the  way  from  transport  of  understanding  the  biogenic  from  disposed  clam-shell  dredged  particulates  Conclusion  It  is  concluded  material that Georgia  Because because  a  will  The  be  loss  contaminants fine  significant  proportion  of  is disposed by bottom opening scow  Strait  operation.  that  particles  lost will  to  the  consist  water  be  column  predominantly  preferentially may  into deep areas  sorb  transported  before resettling, the environmental  during of  a  fine  to  finer  for  substantial  implications  of  of  dumping fractions.  fractions,  and  distances  this loss warrant  considerable concern.  A t shallow to  the  emanates  water disposal sites, clam-shell dredged sediments will fall  bottom from  as the  a  coherent  point  of  mass.  impact  The  should  bottom for more than a few hundred metres.  density  not  spread  plume over  which a  flat  168  Upon settlement sediments will  situ  disposed  appreciably  metres For  and consolidation in moderate  erode.  these areas  the energy  sedimentary  depositional  Strait  areas  turbulence is  regime  regime.  In  it is unlikely that  depth, low-energy  Water  depth in Georgia  on the bottom  below  uneffected by is reasonably  shoal  areas  depositional  areas  approximately occasional  20  storms.  reflected by the in  (i.e. < 20  m),  may be periodically eroded by storm  low  energy  driven  wave  deep  that  turbulence that reaches to the bottom.  Suitable  disposal  deposited  sites  sediments  are  will  therefore  protected  be  sufficiently  from  both  that  water  disturbance, yet sufficiently shallow  regular  and  irregular  entrainment and  the  resultant disaggregation of the disposed sediments during water column passage will be minimized. suitable disposal  sites  On the basis of the available information,  in Georgia Strait  will be within a low energy,  depositional environment and in a water depth of not less than 30 m or deeper than  Dredging  125 m.  and disposal of contaminated sediments should be restricted  to clam-shell dredge and bottom dumping scow. restricted  to during periods of negligible  conditions.  should be  tidal current and calm  sea  Johansen et al. (1976) investigated the potential of placing  dredged material depositional  Dumping  in borrow pits or depressions  stability  of  the  dredged  material  to enhance the  post-  deposit.  offer  They  guidance on how to use a barge or hopper dredge to release dredged material  into  subaqueous  volumes,  navigation  depressions,  techniques, and  including  maneuvering  suggested  effective  and position  main-  169  tenance over the pit during disposal. modifications  to  disposal  Their study suggests that proper  equipment  and  careful  handling  of  the  material may reduce the potential for erosion and resuspension of the dredged material deposit within the borrow pits.  A  desirable  taminated lateral  or  dredging  strategy  for  sediments  can  vertical  project.  uncontaminated  disposal  that  be  realized  pollution  gradients  Sequential  dredging  sediments  bio-chemically active zone.  promotes  secures by  taking  which and  burial  confinement advantage  often  disposal of  the  exist of  of  con-  of  the  within  a  polluted  and  former below  the  Capping of contaminated sediments  with  clean sands (e.g. from the Fraser River main channel) would achieve the  same  possible.  effect.  This  process  should  be  considered  whenever  170  7.0  D I S P O S A L SITE O P P O R T U N I T I E S WITHIN G E O R G I A  7.1  Recommended Disposal  The  important  STRAIT  Site Characteristics  physical  oceanographic  criteria  for  dumpsite  are water depth and circulation/dispersion potential.  selection  On the basis of  depth alone, the Point Grey dumpsite is an unsuitable location for the disposal of contaminated material. site will result in substantial  The water depth of 240 m at this  disaggregation of disposed material as  it  falls through the water column. The disaggregated mass will be f r a c tionated  by  materials areas.  particle  will  size,  disperse  in  and  the  the  water  more  highly  column  The extent and distribution of  to  contaminated contaminate  the spread of  nates from this site are unpredicatable, but probably  As  was  concluded  disposing  of  in  the  contaminated  last  section,  material  toxic  fine other  contami-  substantial.  the  preferred  locations  should  meet  the  metres  but  for  following  oceanographic c r i t e r i a :  o  water  depth  should  be  greater  than  20  less  than  100-125 meters o  bottom topography should be flat, or preferably concave  o  water the  circulation should be sufficient to maintain oxygenation  bottom  water,  but  insufficient  to  resuspend  fine  of  material.  Natural sediments at the site should be predominantly mud, or silt and clay (i.e., less than 0.063 mm).  171  In such areas, the disposal of contaminated materials would potentially have  substantial  adverse  effects  on  resident  organisms,  but  these  effects will be restricted to as small an area as possible.  There are very few areas within the Strait of Georgia that meet the bathymetric c r i t e r i a for dumpsite suitability.  The Strait is a glaciated  marine valley comprising a series of deep basins and troughs separated by shallower  ridges  and banks.  Average  depth in the Strait  metres with deeper waters frequently exceeding 250 metres.  is  157  Few of  the shallower banks are expansive, and most are steep-walled.  On  the other  ciently  well  hand, virtually circulated to  waters (Waldichuk, common water  in  is  many  not  1983). inlets  all  areas  maintain  substantially  Georgia  Strait  high oxygenation  The Strait and  in  coastal  impeded.  lacks seas,  a shallow  of  are the  suffibottom  threshold sill,  and replacement of  Although  there  are  few  deep data  describing bottom-water circulation within the Strait, it can reasonably be assumed  for  the present purposes  that  oxygenated  water  will  be  maintained at the sediment surface of even the most stagnant shallow water areas.  This assumption would need to be confirmed previous to  disposing of contaminated sediments at any site.  The  upper  disposed  limit  fine  to  the criterion for  sediments  may  be  monitoring.  The large tidal range  in  waters  southern  and  five  water  resuspended)  circujation (i.e., requires  where  more careful  in the Strait (up to three metres  metres  in  northern  waters)  generates  172  strong  tidal  northern,  currents.  central  and  Waldichuk southern  (1957)  areas  divided  based  on  the  the  Strait  surface  into  current  regime, and reported that:  o  the northern region (north from southern Texada Island) has weak (<0.2  knots) and variable surface currents.  Speeds  rarely exceed  one knot, although they may be faster in some channels. o  the central region (to a line joining Point Roberts and the Saanich Peninsula) water  has strong  movement  tidal currents and exhibits complex  under  the  wind, tides and Coriolis force.  influence  of  Fraser  River  surface run-off,  Currents in excess of one knot are  common. o  the southern region  has  tidal currents typically greater  than one  knot.  There  is virtually no data on bottom current velocities for anywhere  within Georgia Strait.  Reference is frequently made in the literature  to bottom current measurements bottom data required. in measuring  but these data were not the type of  " B o t t o m " is frequently used as a relative term  water column profiles, and may  two or even five metres above the sea bed.  refer to data collected Such data are of  little  or no value for bedload movement calculations, which require data at a maximum  of one metre above  the sea bed.  Accurate  describing sea bed current velocities at potential disposal fundamental  importance  to  the  management  of  information sites is of  dredged  material  173  disposal,  and  is appropriately  funded investigations  during  a Priority  Research  1985-1986 (R.  Topic for  Kussat, EPS,  RODAC  pers.  comm.,  1985).  In the absence of appropriate bottom current data, existing characteristics rents.  must  used  to  reflect  maximum  resuspension  cur-  Local geology and sediment sources profoundly e f f e c t sediment  characteristics. particles regime. an  be  substrate  However  in the substrate  the predominance is a reasonable  of  mud or silt  and  clay  indication of a low current  Conversely, where a sea bed is characterized by sand despite  abundant  speculate  supply  that  fine  of  silt  and  grained  clay  into  sediments  the  would  area, be  it  is  safe  removed  (or  to not  deposited) by bottom currents.  Identification of Potential Disposal  Sites  A  charts  detailed review of bathymetric  only  four  areas  suitable disposal 7-11.  The  large  potential dumping Figures 8-11  The  enclosed  They are described in Table XIII and  sites  Area  within  basin  Stuart  De  Vancouver Island (Figure 8). by strategically  dumping  it. 2.5 x  Channel  between  3  site  has  criteria  permitted  The area of  for  identified  sites.  of  bathymetric  Strait  met  is approximately  Northern  Georgia  which  size  the  of  potentially  delineation  Figures of  two  the circles shown in  lO^m?.  is  located  Courcy  Island  in and  a  shallow, Flewett  semiPoint,  The basin could readily be fully enclosed  clean sediments  in the channel extension  to  174  TABLE X I I I .  P o t e n t i a l Disposal S i t e s i n the S t r a i t of Georgia meet the Recommended B a t h y m e t r i c  S i t e  Site  Latitude  that  Criteria.  Longitude  Number  Approximate D i s t a n c e Depth (m)  p  t  r  ™  1.  N o r t h e r n S t u a r t Channel  49°05'28"N  123°45'12"w  64  25  2.  McNaughton  49°33'27"N  124°00'36"W  122  45  Point  3a.  Denman I s l a n d  49035'54"N  124°46'30"W  91  60  3b.  Comox  49°39'54"N  124°49'22"W  77  65  Smelt Bay ( C o r t e s I s . )  50°02'30"N  125°00'30"W  100  90  4.  e y ( n m )  © '175  125° ,  ^  ^  ^  t  ?f f  X *  123°  124°  '  r  '41  FIGURE 7.  Georgia S t r a i t -  L o c a t i o n o f Proposed Dumpsites  1a  ^  1. S t u a r t Channel 2. McNaughton P o i n t 3*. Comox - Denman Is 4 . Smelt Bay  'itfedonda Ba/  nttiiaski O  50°  v  50° Garth»l<JI-  \ \ v  . V  .  ,-'^VPowffll Kiver  --'-''7?  ffi *<!••)• '<t-  Woe. i f V V v V ' ' ^ ' r t i CoWc [tile Rivet\ \^^\^*=^^\Billingi^NelSo^Y/ ' oysWTK  ' ^ b - . i a is/  \  l  4 \ V 3  Union BayU  N  Gillies TEXAD^N y V \ TEXADA  e x a d a  i  % . H  S  L  A  N  \\\  Island  D  Sjjiiamish  N  v  oS,\Madeira Pat* : \  f  £  ^ktkpenirtsylai ;|  '  . <?  r si- i  Port Mellon y^^-  IVp  89l\  W (loen\an Island  V ^ f K  Hallmoon\  Buccaneer <  A  (I  I \  lambief. lslan(i, \ ;  AasqueliVVSj \  „v /..  v. <t •  {'•', ,\ ,«  ft \ ft *;  .  iORTH I 'ANCOU  ^nsmui,  a.DL-UM!  i  r e  ^W  NANAIMO | I Qualicum Beach ^ /> 4. fe^^^^Paxksville * L  ^, . 419  ,--V(ESryANC  "\^*-<2?;:.-.^-"  .riu.  VANCOUVER^ illingWn*  3 )  M"  O Gabnola  rctsland  \ '  \\yaldes  \  Q\  ^-S^island  '  v  \  49° 49  c  ©  pe Beale*-4y0'. (  •fender  ^ *r  Pachena Point  Carmanah Poiriri^V--, /'  . ».ii!^,."tB-  ^ry^art  ^jua  ir--A..  Compiled from Canadian E n e r g y , Mines and Resources Map NM-9/10 VIII)  125°  124°  123°  3577  48'  Adjoining Chart/Carte adjacent e  42'  40'  -1X7-  124°oc/  \< /27M 3535  Francis \ I \7r\ Peninsula  ,0<  x  [too"  S :  E  C  H V E Li,  i H".V  -'••'•.91 fl(3 • 1  VII.  ^  ! <4? '  i  J5--LH  V> i \f \ ,'ii  ^  N \  NI  I\  S \ U  A 0 7 H  ' :i 3  v. so , ~ ' 7.v ' '•.  Hires'  ;  6  ,  ,  ' l•• v '.'.  1  . is:  7 0 ; -*t <\ i> i  80  E  'P  V'«r' v, •  ;  U9  "  .5V5  ^'4'  "  ^  \  " > &4. ~ -. '-.''V  BjerPeShoalV;^  \  ^  (SITE 67  • 13  o  M NajigKcon P.. c  o(  27 . 67 *3v  58fc. 65 Turnagain Ii V  X  fi  \ 48\54FIGi„':„  1  i•  V '9>. ^ 6 vt»»_v^ v  54 I  FIGURE 9 .  \T/ {  *6  S  • 2i  5  5?;  .. ; i. 2  Tomnham Gfr S\ 2  [H  M , 16). ^ ':'9j *  \  .' . ,t:<  I / /;' •' '.'-. 6  _ jj ; ^ L p T * Chart 3535 535  {  45 VyiefiA ;f ';^:b<LSmuK'V'"A 6  ••'••.^.-iy^/iM>  ^ ^ ' L '.|4,  I ;  Epsorn"Pi' 2i. Fl Buccaneeri -6- •'  ! is i. V  r  15  II  L o c a t i o n o f Proposed  Bill  McNaughton P o i n t Dumpsite (Area 2 ) . Area d e s c r i b e d - 2 . 5 x 10 Soundings i n fathoms.  m .  ' 4 . -41 3. 60 ° «B  .1A  ,  Chan 3535  Kg. Compiled from C a n a d i a n ' ^ - n 46 ^sJ" Hydrographic S e r v i c e s , : N a u t i c a l C h a r t s , 1985 7 S s  124°otr  :  J  s  se: x c^" ^ 4 ^ x>  p  , 173  50'  91'  92  76  Ajax  *° V-.. ••-.U  z;  22i 1  • * \ ' k.  ? 33  .-.^ v " i 7 \  15  15  »  i1%Islets^^-*V..^ .  37  ;  8 1.  14  V  16  S.  .V,**. V'\ ?7 FIGURE 10.  Location of  Denman I s l a n d - Comox (Area  Proposed  $•'-4  , s . • sc  Dumpsites  3).  Area d e s c r i b e d • 2.5 x 10 Soundings i n fathoms.  m .  Compiled from Canadian ^ Hydrographic S e r v i c e s , N a u t i c a l C h a r t s , 1985 50'  a*' i  125°00l79  FIGURE 11.  L o c a t i o n o f Proposed  Smelt Bay Dumpsite - (Area  4).  2 . 5 x 10 6 m 2 . Area d e s c r i b e d Soundings i n fathoms  Compiled from Canadian ^ Hydrographic S e r v i c e s , ; N a u t i c a l C h a r t s , 1985 ;  125*00'  8? SS'  180  the  southwest  of  the proposed  site.  The resultant  basin  approximately five metres deep and could accommodate  would be  up to 20 x  106 m3 of dredged material.  Although Stuart in  surface  waters  Service,  1983),  probably  weak.  sediments 1981).  Channel  at  is subject to relatively strong tidal currents  (1-3  the  knots  bathymetry  This  is  during  indicates  supported  the proposed disposal  However  given  floods;  by  Canadian  that the  sea fact  Hydrographic  bed currents that  the  are  existing  site are mud (Lands Directorate,  the strength of  the surface currents in  this  area, ocean dumping at this site would need to be restricted to during tidal slacks.  The potential site at McNaughton Point is within a submarine trench running between Bjerre Shoal and the Sechelt Peninsula (Figure 9). The narrow  entrance  to  the  trench (south  readily be closed using clean fill.  of  the  proposed  The resultant  basin  site)  could  would be  at  least five metres deep and could accommodate at least 30 x 10^ nr)3 of dredged material.  There are no data describing water currents inside Bjerre Shoal, but the bathymetry suggests that sea bed currents in this area are low.  The  existing  Directorate, 1983).  sediments  at  the  proposed  site  are  mud  also  (Lands  181  The Denman  Island and Comox sites are both located within a trench  between the Comox Bar and a shallow from Cape  L a z o (Figure  10).  bank  that extends  The trench has  a narrow  southwards opening  to  deeper water at its southern end, which could be readily closed with clean within  sediments. the  Although  resultant  basin,  Figure  10 describes  the entire basin  criteria for a potential dumpsite.  two  meets  specific  the  bathymetric  The basin could be easily designed  to accomodate a ten metre mound of spoil throughout. to approximately  There  Tsolum  at  the Comox  River  This  eguates  The  existing  120 x I0& m3 of dredged material.  are no appropriate current data  sediments  sites  (Lands  for  this  area.  site are silts and clays, probably from the  Directorate,  1981).  At  the  site  outside  of  Denman Island, the sediments are mud (Lands Directorate, 1981).  The Smelt  Bay  site comprises  a  natural submarine  basin  embayment between Marina and Cortes Islands (Figure  II).  within  the  The basin  is approximately 20 metres deeper than the shallow sill at the mouth of the embayment and could accommodate approximately 50 x 10^ of  dredged  Directorate,  material.  The  basin  has  mud  sediments  1981), indicative of a low current regime.  (Lands  182  8.0  R E S O U R C E S IN  8.1  Introduction  CONFLICT  The Strait of Georgia is of c r i t i c a l environmental economic and social importance  to  British  Columbia.  moderate climate, rich coastal and marine waters, have  attracted  activity  to  and  advantages  fluvial soils,  of  accessibility,  productive estuarine  and diverse aesthetic and recreational amenities,  most  its  The  of  British  perimeter.  Columbia's  The  Strait  population  lies  between  and the  economic two  major  centres of population in the province, Vancouver and the other urban communities Nanaimo,  the  Lower  Mainland  and other Vancouver  Islands and base.  of  the Sunshine  to  the  east  and  Island towns to the west.  Coast  also contribute  to  this  Victoria, The  Gulf  development  Approximately 80 percent of the provincial population now live  within 80 km of the Strait.  The marine resources of Georgia Strait are abundant and diverse. High nutrient inflows  from riverine (mainly  oceanic sources  promote  rich  for  foundation  variety habitats marine  of  estuarine,  algae,  high primary productivity.  organisms  higher  protected and  in Georgia Strait 200 species  the Fraser River) and upwelled  in open  the  This provides  food  web.  shoreline,  and open  support more than 500 species of of  fish, 300 species of  The  a  wide water  attached  invertebrates,  130  species of marine-associated birds and 10 families of marine mammals  183  (Barker, great  1974).  deal  This  abundant  animal  to the commercial and  and  plant  life contributes  recreational attractiveness  of  a  the  region.  Important commercial and recreational resource uses in Georgia include  the  goeduck  salmon,  fisheries,  ational  herring,  the  activities  groundfish,  culturing  such  as  of  shrimp,  salmon  boating,  and  crab,  each  extent,  of  these  upon  the  resources  is  maintenance  dependent, of  a  to  high  and  and  recre-  swimming,  scuba  diving, oyster and c l a m digging and beachcombing. of  clam  oysters,  sportfishing,  Strait  The exploitation  a  greater  level  of  or  lesser  environmental  protection.  The  potential  dredged material disposal  the preceding section that  will  assure  taminants.  minimal  oceanographic  long-term present  as  small  biological section  long-term  an area  degradation provides  a  as  release  possible,  will  occur  review  of  of  substantial at the  the  to assess their vulnerability  degradation.  to severe  but  and  disposal  current  potential resource uses in the vicinity of the proposed ocean sites,  criteria  from  to  or  identified in  Although this will restrict the environmental impacts  possibly  The  the physical  were  con-  operations  short-  that  toxic  disposal  site.  each meet  sites  and  dumping  localized biological  184 TABLE XIV.  S p e c i e s Names o f Organisms c i t e d i n S e c t i o n 8 .  Groundfish  Pelagic  Mol1 uses  P a c i f i c cod English sole Lingcod Walleye pollock P a c i f i c hake Spiny d o g f i s h Rockfish  Fish Chinook salmon Coho salmon Chum salmon Pink salmon Sockeye salmon Cutthroat trout Pacific herring P a c i f i c anchovy Eulachon Surf smelt  B u t t e r clam Japanese l i t t l e n e c k Native l i t t l e n e c k Geoduck P a c i f i c oyster  Crustaceans Dungeness Prawn Shrimp  crab  Marine mammals K i l l e r whale Harbour s e a l S t e l l a r sea l i o n C a l i f o r n i a sea l i o n  Gadus macrocephal us Parophys v e t u l i s Ophiodon e l o n g a t u s Theragra Chalcogramma M e r l u c c i u s productus Squalus o c a n t h i a s Scorpaenidae Oncorhynchus t s h a w y t s c h a 0. kisutch 0. keta 0 . gorbuscha 0 . nerka Salmo c l a r k i c l a r k i Clupea harengus p a l l i s i i E n g r a u l i s mordax Thaieichthys p a c i f i c u s Hypomesus p r e t i o s u s Saxidomus g i g a n t e u s Venerupis j a p o n i c a P r o t o t h a c a staminea Panope generosa Crassostrea gigas Cancer m a g i s t e r Pandalus p l a t y c e r o s P. j o r d a n i P. b o r e a l i s P. h y p s i n o t u s P. danae Pandalopsis dispar Orcinus orca Phoca v i t u l i n a Eumetopias j u b a t u s Zalophus c a l i f o r n T a n u s  185  Groundfish  Demersal  fish  that  are  commercially  exploited  by  a  bottom  trawl  fishery in the Strait of Georgia include P a c i f i c cod, English sole and other flounders, Lingcod, and Walleye pollack. dogfish plement  have also been increasingly declines  groundfishery offshore  in  is  areas  the  minor to  the  traditional  trawled  P a c i f i c hake and Spiny in recent years  species.  The Strait  compared  with  the  activity  west  north  of  Vancouver  and  retains a high commercial importance due to markets.  Georgia  between  900  Oceans,  1980).  Longlining provide  of  a  Recreational  -  Strait  1200  tonnes  Rockfish,  minor  trawl per  year  of  that  harvesting  is  in  Georgia in  Island, yet  it  its close proximity  to  Pacific  (Department  fishery  sup-  occurs  cod  of  Lingcod, P a c i f i c cod and Spiny  commercial  groundfish  landings  of  to  the  Strait  directed  alone  are  Fisheries  and  dogfish also of  primarily  Georgia. towards  Rockfish and Lingcod.  Demersal fish that reside within the vicinity of an ocean dumping site are particularly vulnerable to adverse contaminated sediments.  impacts  from  the disposal  of  Their relatively sedentary and benthic habits  result in prolonged and direct exposure to sediment contaminants. The major potential impacts of ocean dumping upon groundfish include:  186 Toxicity.  A c u t e and/or chronic toxic effects of contaminants upon  groundfish stock  or their prey may impact  in the area.  Groundfish spawning  susceptible to toxic effects.  McGreer  that contaminated sediments substantially cod.  areas  are particularly  and Munday  (1982)  of  fertilized  eggs of  the P a c i f i c  hatching of larvae was virtually eliminated when  the eggs were covered to a depth of only  I  mm with c o n t a m i -  nated sediment, or exposed to suspended sediment  concentrations  of 7.5 g/L or greater (cf. 30 g/L for " c l e a n " sediments). the young  found  from Roberts Bank and False Creek  e f f e c t e d survival  Successful  the size of the groundfish  of fish species  are usually  the most  Although  sensitive  to the  toxic e f f e c t s of contaminants, mortalities of mature groundfish or their  prey  occur. lesions  species  Malins of  at  dredged  et a l . (1980)  varying  severity  material  disposal  reported high in groundfish  areas  may also  incidences of  Puget  of  tissue  Sound,  and  related the occurrence of these to the distribution of high levels of sedimentary contaminants.  Bioaccumulation. may  Prolonged and direct exposure to contaminants  result in their accumulation  in groundfish  which endangers the health of human consumers.  tissue  to a  level  Adult groundfish  are bottom-feeding, relatively stationary and have a long life span (up  to  15 years  contamination, significant.  in many  contaminant For  example,  species). levels  In areas in  elevated  older  of  high  individuals  mercury  levels  sediment may  that  be  were  187  consistently Sound  detected  in the  in groundfish  and crab species  I970's forced the closure of  this  area  from  Howe  as  com-  a  mercial and sport fishery (Garrett, MacLeod and Sneddon,  o  Habitat  Alteration.  Changes  to  the  physical  and  1980).  chemical  character of the sediments at a disposal site may induce dramatic changes  in  (Levings,  o  benthic  community  upon  which  groundfish  feed  concrete rubble,  wood  1982).  Fishery debris  the  Interference. or  dredging)  wire  Ocean  cables  will  dumping  (which  interfere  of  freguently  with  the  litter  areas  operational  requiring  logistics  of  a  groundfish trawl fishery.  The  commercial  value  of  the Strait  of  Georgia  groundfish  together with the high vulnerability of groundfish species impact spawning  from  contaminated  or fishing  sediments,  deem  areas as unsuitable  for  to  important  the disposal  resource, adverse  groundfish of  contami-  nated sediments.  The  Lands  Directorate  reviews  of  coastal  pilation  of  available  showed  that  follows:  (1981;  resources data  utilization of  1983)  has  in the Strait  describing  conducted of  Georgia.  groundfish  the proposed  ocean  comprehensive  stocks dumping  Their  com-  in the  Strait  sites  is  as  188  1.  N o r t h Stuart areas  of  Channel.  The proposed dumpsite and adjacent deep  northern Stuart  Channel  are productive spawning  for English sole and other flounders.  areas  The reef area to the north  of Ruxton Island is a Lingcod spawning area.  Walleye pollock are  believed to also spawn in Stuart Channel, since mature individuals have  been  observed  there  in  February,  imminent  spawners  in  M a r c h - A p r i l , and spawned out pollock in May.  Commercial flounders, Channel  trawling  and (i.e.  for  Walleye where  Pacific  pollock  suitable  cod,  is  English  conducted  substrate  sole  and  other  throughout  occurs),  Stuart  including  the  proposed disposal area.  2.  McNaughton  Point.  Bjerre Shoal.  There are no groundfish stocks recorded inside  The drop-off zone to the west of Bjerre Shoal  is  included within the Spiny dogfish longline fishery that occurs along the entire Sunshine  Coast.  Mid-water  trawling  for  Pacific  hake  occurs further offshore in central Malaspina Strait and south into Georgia Strait.  However neither of these fisheries are considered  sufficiently proximate to  impact  from  to the proposed dumpsite to be vulnerable  contaminants.  Bjerre  Shoal  forms  a  natural  barrier to sediment flow into deeper waters.  3.  Denman  Island - Comox,  Both of the proposed sites in this area  are within the principal spawning ground for the northern Georgia Strait stock of P a c i f i c cod (the major stock in Georgia Strait) and the Cape L a z o stock of English sole (one of two major stocks  in  189  the  Strait).  The  these species.  area  Pacific  supports  a  months  from Cape L a z o to Hornby Island. water  of  trawl  fishery  for  hake have also been recorded to be very  abundant during the summer  deeper  productive  the  central  in the 50 -  100 metre zone  These fish apparently winter in Strait,  then  migrate  inshore,  especially to the area east of Comox Bar, each summer.  4.  Smelt Marina  Bay.  There  and  are  Cortes  no  Islands.  groundfish  stocks  Recreational  recorded between  fishing  for  Lingcod  occurs around the shallow reefs to the north of Marina Island, but this is well distant from the proposed dumpsite.  Benthic Crustaceans  F i v e shrimp and one prawn species are fished commercially in British Columbian waters.  The major shrimp fishery is by bottom trawl over  muddy or sandy bottoms  in 95 to 135 metres of water, whilst  are predominantly taken by trap.  Recreational harvesting of  prawns shrimp  and prawns is minimal.  The Dungeness crab provides a small  trap fishery in shallow (<40  sand areas of the Strait.  This fishery is minor  harvest  C r a c o f t and G i l f o r d Islands, K i n c o m e  in waters  around  m),  relative to the crab Inlet  and Knight Inlet, which provides 9 0 % of the provincial catch (Ministry of  Lands, Parks and Housing,  popular among  the boating  (Lands Directorate, 1981).  1984). Recreational fishing for crab  public, but  the numbers  taken are  is  small  190  Subsequent to settling from their pelagic larval phase, shrimp, prawns and  crabs  are  sedentary.  Populations  within  a  dredged  material  disposal site will consequently suffer direct and prolonged exposure to contaminant  materials.  sedimentary  contaminants  lacking,  they  contaminant  are  Although to  often  effects.  benthic  among  Shuba,  data  describing  marine  the  most  Tatum  and  the  toxicity  crustaceans  sensitive Carrel  is  often  organisms  (1978)  of  found  to the  shrimp Paleomonetes pugio to suffer high toxicity from a wide variety of sedimentary contaminants. sensitivity  of  a  benthic  Chapman (1984) similarly noted the high  amphipod  to  contaminated  sediments  and  recommended its use in sediment bioassays for toxicity testing.  Benthic crustaceans have also been recorded to accumulate high levels of sediment contaminants within their body tissues.  The accumulation  of sediment bound mercury by crabs in Howe Sound, which forced the closure of the area for  fishing, was  noted above.  Mercury c o n c e n -  trations above the guideline for human consumption have also be found in  crab  on  Sturgeon  Bank  (Garrett,  MacLeod  and  Sneddon,  1980).  Garrett (1983) similarly reported high concentrations of P C B s in crabs from this area.  Nimmo  et al. (1971)  demonstrated that  shrimp  and  crabs can accumulate high hepatopancreas concentrations of P C B s from ingesting contaminated sediment particles.  Shrimp,  prawn  or  crab  fisheries  proposed for ocean dumping. Hornby three  occur  commercial  three of  the  four  areas  The area north and west of Denman and  Islands (including proposed sites major  at  shrimp  3a and 3b) forms one of the  trawling  grounds  in  the  Strait  of  191  Georgia.  Shrimp  (proposed site  trawling  is  also  conducted  in  I), which is part of the general grounds  Stuart  Channel  comprising  the  larger channels of the Gulf Islands.  The  major  prawn  trapping  activity  in  the  Strait  occurs  at  the  numerous 50 metre banks along the Sunshine Coast, including the area around  Bjerre Shoal  Sunshine  Coast  (proposed  site  is conducted well  2).  Shrimp  trawling  along  to the south of McNaughton  the  Point,  beyond Sechelt.  Minor  crab  fishing  activity  occurs  in  shallow  water  along  northwestern shore of Stuart Channel (west from proposed site  the  I)  and  north of the proposed Comox dumpsite (site 3b).  Molluscs  The  Strait  oysters,  of  Georgia  geoducks  between  the  mariculture  supports  rich  and other clams.  less  intensive  operations.  Wild  harvest stocks  stocks  of  molluscs,  Commercial of are  wild  activity  stocks  also  and  commonly  including is  divided intensive  harvested  recreationally, especially near population centres and more accessible locations.  The commercial clam  fishery has traditionally included Butter  Japanese Littleneck clams and the Native these species Georgia  inhabit  Strait.  Littleneck c l a m .  intertidal areas of suitable substrate  Landings  of  geoduck  clams,  first  clams,  E a c h of throughout  reported in  1977,  192  now  exceed the annual  average  landings of  traditional species.  The  main populations of geoducks are found in sub-tidal sand or sand-mud, and are fished from the high subtidal to a depth of approximately  15  metres.  P a c i f i c oysters were initially introduced into B.C. from Japan and now provide a substantial inhabit  intertidal  local fishery and culture industry.  flats  grown in the lowest  of  firm  mud,  sand  intertidal area (bottom  and subtidally (off-bottom  culture).  They normally  or gravel, or  but  are  near-bottom  often  culture)  C o m m e r c i a l permit harvesting of  wild stocks is limited to scattered populations sustained through local spatfalls.  Most wild stocks  in the Strait  of Georgia are reserved for  recreational use.  The major oyster harvest in the Strait comes from c o m m e r c i a l culture operations.  Spat are c o l l e c t e d from Pendrell and Hotham  Sounds and  grown in leased shoreline areas elsewhere on the coast.  In the Strait  of  one  Georgia  the  oysters  grow  to  market  size  in about  to  four  years, depending on culture technigues, temperature and a variety of other factors.  Clams  and  oysters  are  filter  feeding  items on the basis of particle size. are  within  ingested dietary  the  size  with the  range  food.  of  suspended in the water column.  which  select  food  Suspended sediment particles that  their  planktonic  Consequently,  intake of contaminants  organisms  these  feed  animals  items  will  be  are  prone  to  that are sorbed to sediment  material  193  Reid  et  al.  staminea)  (1981)  and  found  mussels  elevated  (Mytilus  levels  edulis)  of  from  cadmium False  i n clams  (P.  Creek.  E.V.S.  Consultants (1984) reported similar body burdens i n the c l a m  Macoma  balthica after six months exposure to sediments from the same area. This species was also shown to bioaccumulate lead from sediments of Vancouver  Harbour.  under  Burrard  the  Garrett and  (1983)  Granville  reported that  bridges  mussels  contained  collected  only  low  PCB  concentrations (<20 ug/kg), but mussels from industrial harbour regions in C a l i f o r n i a have been reported to contain up to tendency trations  for of  filter  feeding  contaminants  molluscs  has  to  1300 ug/kg.  bioaccumulate  encouraged  their  use  The  high c o n c e n as  integrative  indicators of water pollution levels i n many coastal areas.  The toxicity of Vancouver sediments to the c l a m M . balthica has been assessed by numerous  researchers.  M c G r e e r , Reid and Nelson  (1981)  found no elevated mortalities i n adult clams after 30 days exposure to Vancouver negligible Creek  Harbour toxicity  sediments.  sediments. to  this  Reid  species  However  et  from  al.  (1981)  60 days  E.V.S. Consultants  similarly  exposure  (1984)  to  more  found False  recently  documented 2 8 % and 2 4 % mortality i n M . balthica after exposing them for  six  months  to  the  Harbour, respectively.  sediments This was  of  False  significantly  Creek  and  Vancouver  higher than  mortalities  i n a cleaner control sediment.  From  data  compiled  by  the  Lands  Directorate  (1981;  1983)  the  utilization of areas adjacent to the proposed ocean dumping sites for the cultivation or harvesting of oysters and clams is as follows:  194 1.  Northern Stuart Channel. in False Narrows Gabriola  The only oyster leases in the area are  and Degnen  Island, which  is  Bay  remote  on  the  from  southern shoreline  the  proposed dump  of  site.  Recreational digging for clams is popular in sandy intertidal areas near to the proposed site, particularly along the Vancouver Island shoreline. shallow  Geoduck nearshore  Geoducks  are  in  clams region  higher  are to  found the  in  west  abundance  low of  further  abundance the  in  proposed  south,  near  the site.  Yellow  Point.  2.  McNaughton  Point.  There are no harvested mollusc populations in  the immediate vicinity of this proposed site. harvesting  of  clams  occurs  at  Thormanby  Minor recreational  Island,  12 km  to  the  eastern Denman  Island  and  Island  the  south.  3.  Comox-Denman the  area  to  Island. the  Comox  north  of  Bar,  Hornby  important c o m m e r c i a l clamming  region  comprise  in the Strait  of  most  Georgia.  Barnes Sound (between Comox Bar - Denman Island and Vancouver Island) and L a m b e r t Channel (between Denman Island) are among cultivation.  the Strait's  most  Island and Hornby  productive areas  for  oyster  The shallow subtidal zone throughout the region also  supports a rich harvest of geoducks.  4.  Smelt having  Bay. major  Cortes  Island  potential  western shoreline of  for  Cortes  was  identified by  off-bottom  Valiela  culture of  Island (north from  (1979)  oysters.  Marina  as The  Island) is  195  currently  under  extensive  use  for  bottom  culture  and  it  is  presumed that Valiela (1979) was referring to these more sheltered waters.  Closer  to  the  proposed  dredged  material  disposal  site,  there is minor use of the shoreline adjacent to Mansons Landing and along the eastern side of Marina Island for oyster cultivation. C o m m e r c i a l oyster picking permits have been issued for a section of shoreline i n Smelt  Bay.  Geoducks are in low abundance i n the immediate vicinity of the proposed  disposal  Charman,  1980),  site but  (I-10 are  in  clams  per  square  higher  abundance  metre; C o x (11-50  and  clarns/m2)  further to the north and west.  Despite  the  high sensitivity  and  bioaccumulation  potential  of  filter  feeding molluscs for sedimentary contaminants, the vulnerability of the above  described  populations  to  contaminant  loadings  sediment disposed at the proposed sites is relatively low.  from  dredged  E a c h of the  proposed dump sites are i n more than 60 metres of water and meet c r i t e r i a that will ensure minimum short or long term loss of material  from the immediate dumpsite area.  disposed  The oysters and beach  clams described inhabit intertidal areas near the dumping grounds,  so  are  45  remote  metres  from  depth,  direct  but  exposure. Geoduck  commercial  harvesting  clams is  are  found  restricted  accessible depths between the intertidal and 15 metres.  to  to  more  196  The  primary  molluscs  to  potential  source  contaminants  of  from  exposure disposed  of  these  dredged  shallow  material  water  is  from  contaminated fine materials dispersed in a near-surface plume during the  disposal  ensure that  operation. disposal  Caution  resources  therefore be  exercised  to  operations near valuable oyster or c l a m popula-  tions should minimize water mollusc  should  in  the  column vicinity  losses. of  Adequate protection of  proposed  areas  I,  3  and  4  therefore requires that dumping operations should only be conducted during slack lihood of  tides and relatively calm sea conditions when the like-  onshore  transport  of  contaminated  particles  in the  water  column is minimized.  Pelagic F i s h  Pelagic fish in the Strait of Georgia that are subject to c o m m e r c i a l , recreational or native Indian harvesting include five species of salmon, Pacific  herring, Coastal  cutthroat  variety of other species.  trout, Eulachon, Surf  smelt  and a  The salmon and herring fisheries far exceed  the values of other fisheries in the Strait.  In contrast to groundfish, pelagic fish are not especially vulnerable to adverse feeding  impacts  from  sediment  and migratory, so  contaminants mercury  from  are not normally  They  exposed  either directly or for prolonged periods.  concentrations  British  contaminants.  Columbia  in salmon, are  herring, anchovies  generally  very  low  even  are  to  surface  sedimentary F o r example,  and in  eulachons areas  highly contaminated sediments (Garrett, M a c L e o d and Sneddon,  with 1980).  197  Nix  and  salmon  Chapman juveniles  (1984)  in  regularly  False  Creek  sampled  herring, anchovies  throughout  dredging  and  and  disposal  operations by B.C. Place and Expo '86, but noted no adverse impacts.  The  eggs, larvae  prone  to  and young  fry  many  pelagic  species  extended and direct exposure to sedimentary  than are their adults.  Many  their  resident  fry  often  remain  approach maturity. shallow  of  subtidal  their first 6-8 spawning  pelagic  fish  in nursery  F o r example, P a c i f i c  areas months  grounds.  of  have  areas  eggs, until  and  their  fry  bays and inlets proximate  Thereafter, most  and they  herring spawn on kelp  the protected coast,  in shallow  more  contaminants  demersal  rearing  are  Georgia  Strait  in  spend  to their  herring  migrate  out of the Strait to the open ocean and do not return until they are mature fish of 3-4 years.  Pacific  herring,  and  also  anchovies  and  surf  smelt,  are  virtually  exclusively surface feeders throughout their life, so are only indirectly exposed  to  sediment  residence. benthic  However  organisms  contaminants other  during  even  pelagic  their  during  fish  early  life  periods of  feed  prolonged  predominantly  stages.  Benthic  upon  feeding  habits place the fish in immediate proximity to sediment contaminants and  increase  the  likelihood  taminant loadings.  that  prey  organisms  contain  high  Coho and chinook salmon in the Strait of  con-  Georgia  are primarily benthic feeders during their fry residence in estuarine areas,  then  switch  gradually  to  an  exclusively  dependence when they move into coastal waters.  surface  feeding  There is a period of  198  uncertain juvenile  duration salmon  as  they  retain  a  first  move  into  high  dietary  coastal  waters  dependence  on  when  benthic  organisms.  The  eggs  sensitive Sherk  and  larvae  of  many  to contaminants  in  pelagic  fish also appear  the sediments  than  are  to be  their  more  parents.  et al. (1974) reviewed the effects of suspended and deposited  sediments on a wide range of estuarine species of surface fish, and concluded sensitive  that life  eggs  history  and  larvae  stages  are  tested.  almost  universally  Messiah,  Wildish  the  and  most  Peterson  (1981) showed that contaminated sediments deposited onto the spawn of  Atlantic  herring  (Clupea  harenqus)  increased  egg  mortality.  Chapman et al. (1983) exposed eggs of surf smelt in the laboratory to contaminated Sound.  sediment  slurries  collected  at  22  stations  in  Puget  Adverse effects on development, which included reduction of  hatching success, premature hatching and reduced larval survival, were recorded at 20 of the 22 sites tested.  Thus, although it is extremely unlikely that the localized contaminant effects due to ocean dumping at any of the proposed sites in Georgia Strait  will impact migratory and surface feeding adult populations of  pelagic  fish species, caution  dumping  sites  grounds.  Seasonal  during spawning  does  not  dumping  is required that  conflict  with  restrictions  the  their to  location of  spawning  protect  is a Common p r a c t i c e (Levings,  or  resource  ocean nursery species  1982), but these do  not address the persistent nature of sedimentary contaminants.  Con-  199 fidence  that  stocks  is  ocean  only  dumping  achieved  will  by  not  ensuring  adversely that  impact  disposal  pelagic  sites  are  fish geo-  graphically remote from important spawning and nursery grounds.  P a c i f i c herring  P a c i f i c herring are the dominant fish species (in terms of biomass) in Georgia Strait. spring  They support a lucrative roe fishery during their early  spawning  months.  They  and a smaller also  provide  food and bait  a  major  food  fishery during the fall source  for  larger  fish,  marine mammals and seabirds.  Herring spawn between low water and 10-15 metres depth in a limited number  of  locations  areas  and  scattered  intensities  of  throughout spawning  the  vary  Pacific  from  coast.  year  to  The  year,  but  within the Strait of Georgia, the Comox to Nanaimo region (including areas proximate to proposed ocean dumping held  the  most  assessments of  the  productive  spawning  area 3) has  grounds.  consistently  Spawning  ground  have indicated that this region produced between 45 - 6 0 %  Georgia  Strait  herring stock  (Lands  Directorate,  1981). The  coastline near Y e l l o w Point (adjacent to proposed site I) has also been productive, Strait  stock  proposed  accounting  for  (Hourston,  dump  sites  an  1972). 2  estimated  10 -  Herring  spawning  (McNaughton  Point)  20%  and  of  the  Georgia  in  the vicinity  4  (Smelt  Bay)  of is  negligible, but data compiled by the Lands D i r e c t o r a t e (1983) indicates  200  that  Bjerre Shaol  (adjacent  to proposed site  2) and southern  Island (to the south of proposed site h) do support  Cortes  rearing areas  for  herring juveniles.  Salmon  Salmon  stocks  in the  Strait  of  Georgia  Sockeye, pink and most chum stocks  have  diverse  life  histories.  from rivers entering the  Strait  generally migrate to offshore waters soon after leaving the rivers.  In  contrast, most chinook and coho stocks, as well as some chum stocks, prolong  their  nearshore  departure  from  the  Strait  residence in protected coastal  with  indefinite  waters.  During  periods this  of  early  period, these fish eat benthic as well as pelagic prey, so are prone to dietary uptake of  Some Strait,  chinook but  contaminants.  and  their  coho  stocks  nomadic  take  lifestyle  up permanent and  residency  in the  surface  feeding  exclusively  habits ensure minimal exposure to localized contamination during their post-juvenile life.  Of  the four proposed ocean dumping  Channel area (site of  young  salmon.  high numbers  in  areas, only the northern  I) has been reported to support significant Coho the  juveniles  vicinity  of  have been sampled Yellow  Point.  Stuart  numbers  in particularly  Further  north  and  closer to the proposed disposal site, chum juveniles were predominant. This area also supports  lesser numbers of chinook, pink  salmon (Lands D i r e c t o r a t e , 1981).  and  sockeye  201  Juvenile salmon utilization of the other three proposed dumpsite areas has not been reported, and is unlikely. waters Strait  Salmon fry prefer protected  and have rarely been found in more open water areas of the such as  these sites.  Each  of  the  proposed  sites  2 - 4  are  nearby to alternate areas of protected waters where salmon fry from the rivers of the immediate region may be expected to preferentially congregate.  Commercial  salmon  fishing  activity  in the  vicinity  of  the  proposed  ocean dumping sites is listed by the Lands D i r e c t o r a t e (1981; 1983) as moderate  in  the  Comox-Denman  region  (area  3)  and  low  at  McNaughton Point (area 2) and southern C o r t e s Island (area 4). Sports fishing a c t i v i t y is described as moderate at proposed areas and low at proposed areas  Other Pelagic  There  are  2 and 3,  I and 4.  Fish  very  few  data  describing  the  use  of  areas  near  to  the  proposed disposal sites by pelagic fish other than herring and salmon. Rivers  utilized by  Coastal  cutthroat  trout  are  listed  in the  D i r e c t o r a t e reviews (1981; 1983), but none are sufficiently to  the  proposed sites  to warrant  concern.  No  data  Lands  proximate  were  found  in  these reviews or elsewhere indicating utilization of areas proximate to the proposed sites by Eulachon or Surf smelt. Parks  and  Housing  (1984)  also  distribution of these species.  noted  the  The Ministry of Lands, dearth  of  data  on  the  However, given the low vulnerability of  202 these surface  feeding and nomadic species to impact  from  sediment  contaminants, this information reguirement is considered to be of  low  priority for the present purposes.  Marine Mammals  There are ten families of marine mammals that utilize Georgia Strait. The most abundant  are Killer  and C a l i f o r n i a sea Georgia  Strait  are  whales,  lions.  Although  now  harvested  Harbour  seals and the  Stellar  none of the marine mammals of by  humans,  they  provide  high  recreational amenity value.  Killer  whales  nautical  miles  are nomadic, cruising at  approximately  3-4  throughout knots.  a range The  of some  200  known  area  only  where prolonged residence occurs is north of Georgia Strait in Robson Bight.  The  Killer  whales  migratory  offshore where they are thought and smaller marine  The  Harbour  seal  routes  deltas,  tidal  commonly  1 - 5 km  to prey primarily on salmon, herring  mammals.  populations  in  Georgia  residents but are nomadic between haulouts. river  are  rocks  and  shallow  Strait  are  permanent  They frequent estuaries,  sublittoral  areas,  and  feed  predominantly on littoral fish.  Sea  lions  are  resident  in  Georgia  Strait  only  during  months, when the two species intermix on tidal rocks.  the  winter  They feed on  a wide range of fish, including numerous groundfish species.  203  Marine  mammals  potential nants.  to  warrant  accumulate  particular high  concern  concentrations  with of  regard  to  persistent  their  contami-  They do not have gills, an e f f e c t i v e exchange organ in fish, so  contaminant exchange is a function of intake via food and elimination primarily with excretia.  The elimination of persistent contaminants by  the  been  latter  route  (Calambokidis  has  et al., 1978).  found  to  relatively  inefficient  A s a result, a portion of the persistent  chemicals  from contaminated food may  tions  tend to  will  be  increase with age.  be retained, and c o n c e n t r a Although  contaminant burdens in marine mammals  remain  the effects of  high  unknown, high  PCB  levels (38 mg/kg wet weight) in the blubber of a K i l l e r whale which was washed ashore in Georgia Strait (Herman and Calambodikis,  1978)  support high scientific and public concern in this regard.  The likelihood of contaminant accumulation in marine mammals  from  disposed dredged material  is dependent upon the mammal's freguency  and duration of exposure.  O f the four proposed ocean dumping areas,  Area  I  (Stuart  migration normal  Channel)  route, but  migrations  of  is  recognized as  a  the other proposed sites these animals  secondary are  Killer  remote  (Lands Directorate,  whale  from  1981;  The major migration routes of K i l l e r whales through the Gulf  the  1983). Islands  are well to the south of the proposed site in Stuart Channel.  Seal and sea lion populations are open to more direct and prolonged exposure to localized contaminant loadings than are K i l l e r whales.  In  areas proximate to the proposed disposal sites, the rocky foreshore of Link and Round Islands (near A r e a  I in Stuart Channel), and also the  204  Seal  Islets (near A r e a 3), are popular haulouts for seals and sea lions.  Their residency in these areas, and their high potential to accumulate substantial  contaminant  levels through food chain magnification  groundfish prey, warrant concern with the use of the areas posing contaminated sediments. haulouts  proximate  from  for  dis-  In contrast, there are no recognized  to  proposed  sites  Georgia  provides  a  2  or  4  (Lands  Directorate,  1983).  Marine Birds  The  Strait  of  environment for migrating  major  resting  and  overwintering  birds on the P a c i f i c flyway.  birds that reside and feed in the Strait are migrants.  Most of Myriad  the  habitat  types in the estuaries, inlets, coastal embayments and waters of  the  Strait  the  provide  abundant  many species that visit. shorebird  densities,  food  and  a  mild, sheltered winter  Vermeer et al. (n.d.) reported overwintering  based  on  aerial  surveys,  of  63.5  kilometre for the Gulf Islands (including proposed area per  kilometre along  170.2  birds  (including  per  the  for  Mainland  kilometre along  coast  (including  birds  I),  per  47.4 birds  proposed area 2),  the central Vancouver  Island  coast  proposed area 3) and 21.7 birds per kilometre in northern  Georgia Strait (including proposed area 4).  During the summer months the marine bird population in the Strait of Georgia is comparatively very low (Robertson, for  1977).  the few species that do breed in the Strait  Nesting  differs  habitat  substantially  among species and is usually associated with an immediate source of  205  food  (Lands  Directorate,  saltmarshes, eelgrass  1983).  In  this  sense,  intertidal  meadows and kelp beds are extremely  areas,  important  to their breeding success.  Data  describing bird populations  limited  to  broad-scale  aircraft  in the Strait and  boat  of Georgia  surveys  of  are  mostly  migrating  and  overwintering populations.  Although these do not provide the detailed  information  assess  necessary  contamination  to  the  potential  upon seabird populations,  impact  of  localized  they do indicate the relative  seabird use of the general regions of the Strait.  Vermeer et al. (n.d.)  summarized  the distribution and densities of marine birds over seven  sub-regions  in the Strait  surveys  of  bird  of  Georgia.  populations  D i r e c t o r a t e (1981, 1983).  has  Further  been  data  from  summarized  by  individual the  Lands  U t i l i z a t i o n of the shoreline and pelagic zone  proximate to the proposed disposal areas is indicated by these reports to be as  I.  follows:  Stuart the  Channel, Gulf  most popular  Islands.  The Gulf  overwintering  and  Islands provide some  nesting  habitats  for  marine  birds in the Strait of Georgia (Rodway and Campbell, 1976). surveys  in M a r c h - A p r i l of  1977 showed 300 shorebirds,  grebes and cormorants, 43 gulls, 3 auks and  Island  Directorate, Lands  1981)  Directorate,  supports and  is  28  nesting  rated  by  pairs  Parks  1981) as a moderately  (i.e. it received at rating of II  Boat  I 15 loons,  138 diving ducks per  kilometre of shoreline (Vermeer et al., n.d.). DeCourcy  of  The west coast of  seabirds  Canada important  of  (Lands  (described nesting  in a four point scheme from  in  area I =  206  least  significant  Mudge,  Link  to  and  IV  = most  Ruxton  significant).  Islands  The west  were also  recorded  nesting seabird colonies (Lands Directorate, 1981). areas were awarded a rating of surveys  by  the  B.C.  Ministry  I by Parks  of  coasts to  support  Each of these  Canada.  Environment  of  Waterfowl  (n.d.)  and  Ducks  Unlimited (n.d.) also identified moderate numbers of seabirds along the Vancouver  Island coast  of Stuart Channel during the fall and  higher numbers during spring.  2.  McNaughton  Point,  Sechelt  proximate to McNaughton  Peninsula.  Point  appears  The  coastal  to be of  region  relatively  importance to nesting or overwintering seabird populations.  low Boat  observations of overwintering populations along the entire Sunshine Coast  (i.e. from  Lund  grebes and cormorants,  to Gibsons)  noted 87 shorebirds, 2  10 gulls, 4 auks and 71 diving ducks per  kilometre of shoreline (Vermeer et al., n.d.). preponderance of these sitings Thormanby  Island,  loons,  which  is  It is likely that the  were made to the south of 5  km  south  This southern stretch of the Sechelt Coast  of  McNaughton  was  rated III  by  North Point. Parks  Canada, whereas the region north of N o r t h Thormanby Island did not earn a rating (Lands D i r e c t o r a t e , 1983).  A n aerial survey from  Francis  U n l i m i t e d (n.d.) noted  only  3.  Point  to Smuggler  C o v e by Ducks  102 overwintering birds along this  Denman very 1981).  Island-Comox.  important A  staging  The Sandy area  for  10 km tronsect.  Island - Seal shorebirds  Islets area is a  (Lands  Directorate,  linear survey by the B.C. Provincial Museum during the  207  winter  of  1976  reported 5600 seabirds,  including  especially  high  numbers of Surf scoters and Greater scaups, along a six kilometre transect between Comox and C a p e L a z o (Lands Directorate, 1981). Kye  Bay,  reported  immediately  to  provide  to  the  north  overwintering  coastline of  birds  densities  124 shorebirds,  Cape  support  kilometre (Lands D i r e c t o r a t e , 1981). overwintering  of  for  Lazo, 300  has  been  seaducks  per  Vermeer et al. (n.d.) report  along  the  central  18 loons, grebes  Vancouver  Island  and cormorants,  45  gulls, 5 auks and 52 diving ducks per kilometre.  4.  Smelt  Bay,  Strait  coastline  in M a r c h - A p r i l ,  birds,  2  grebes  diving  ducks  Surveys during  Cortes  loons,  per  Island.  Boat  and  surveys  of the northern Georgia  1977, documented only 21  cormorants,  kilometre  of  3 gulls,  shoreline  5 auks  (Vermeer  et  by the B.C. Ministry of Environment and Ducks October,  numbers  along  1979 the  and  January,  mainland  (Lands Directorate, 1983).  1980  coast  shoreand  al.,  n.d.).  Unlimited  recorded similarly  to the east  of  II  Cortes  low  Island  No information specific to the southern  Cortes Island coastline was uncovered by the literature review for this study,  but  it appears  likely that  utilization of  the area  by  marine birds is low.  Marine  birds,  like marine  regard  to  sistent  contaminants.  their  potential  mammals, to  accumulate  Seabirds  organisms  from  several  (primarily  with  ecretia)  trophic of  warrant  prey  on  levels.  dietary  particular concern with  high a  body  diverse  Because  accumulated  burdens array their  of  of  per-  marine  elimination  contaminants  is  208  relatively  inefficient,  a  portion  of  their  dietary  intake  of  these  substances  is retained and concentrations tend to increase with  age.  Very high tissue concentrations of persistent pesticides and P C B s have been  recorded  in  adult  seabirds  from  diverse  geographic  regions  (Kreitzer and Heinz, 1974).  Although  the  toxicity  of  persistent  contaminants  such  as  PCBs  to  most avian species is usually guite low, experimental work with P C B s has  shown  reproductive impairment  ability  (Cecil  Heinz,  1974), decreased egg  1973)  and  Lincer  and  cycles  by  et  al,  embryo Peakall  1974),  behavioural  stimulating  the  through  (Cecil  suggest  that  production  reduce circulating estrogen levels.  reduced hatch-  modifications  production (Tumasonis,  abnormalities (1970)  in birds  et  al.,  PCBs of  (Kreitzer  Bush and  1974). may  liver  and  Baker,  Studies  effect  by  breeding  hydroxylases  which  Other effects of P C B exposure in  birds include decreased avoidance responses (Kreitzer and Heinz, 1974) and  decreased  hatching  of  eggs  due  to  inadeguate  parental  care  (Peakall and Peakall, 1973).  Very little information is available on the effects of other persistent organic contaminants of concern, or on the effects of environmental pollutants in general, upon wild populations of marine birds. the potential for impact  is possibly  substantial.  Many  However  marine  birds  v survive by adapting one or all of the functions (e.g reproduction) to the behaviour of a prey species (e.g. herring spawn). A s  the popula-  tions of prey species are often subject to sharp fluctuations and shifts in  location, the populations  of  seabirds  can  also  fluctuate  substan-  209  tidily.  The .additional  consequences  of  unnatural  stresses,  such  as  reproductive failures or high adult mortality, may be catastrophic but may  not  high  natural  variability  be  of  revealed by  adult  population seabird  enumerations  decline.  populations  cating unnatural perturbations.  Until may  until during periods  this  occurs  the  e f f e c t i v e l y mask  of  inherent  the c o m p l i -  By the time the e f f e c t is unmasked,  the population may have entered an irrecoverable decline.  The high concern that is warranted by the above is moderated in the present case by regard to the very low potential for seabird exposure to sedimentary contaminants.  The principal feeding reliance of marine  birds is upon zooplankton, pelagic fish and intertidal benthos.  As  has  been outlined above, the disposal of contaminated dredged material at the locations proposed by this study should have minimal impact upon these prey items. least  60  metres  E a c h of of  water  the proposed disposal and  has  sites  been selected on  is within  the  basis  oceanographic c r i t e r i a which will minimize release and dispersion contaminants  to  effect  nearby  areas.  It  is  therefore  at of of  considered  unlikely that the controlled disposal of dredged material at these sites (i.e. during periods of slack  tides and moderately calm weather) will  significantly e f f e c t nearby marine birds.  Human Recreation  Recreational activities other than sports fishing that may be impacted by dredged material disposal scuba  diving  and  boating.  in the Strait of Georgia are The potential  impact  of  swimming,  ocean  dumping  210  upon the health of swimmers than  real:  a  very  large  contaminated  sediments  may  However  occur.  concerns, real between  or  water  and boaters is probably more volume  would the  of  need  high  to  accorded  that  recreational  containing  be swallowed  priority  perceived, requires  contact  water  imaginary  any  before  to  and  effects  human  potential  activities  suspended  health  for conflict  ocean  dumping  should be minimized.  Most of  the coast  of  the Strait  of Georgia  is rated by the  Canada  Land Inventory as having moderate to very high capability for outdoor recreation (Department of Environment, 1978). and  accessibility  appear  to  be  determinants  I and 2 have high recreational use, A r e a 3 has moderate 4  has  low  recreational  use.  This  ocean  actual  areas, Areas  Area  the four proposed  of  use.  and  of  primary  recreational  use  Accordingly,  the  Nearby population base  applies  dumping  equally  to  shoreline and waterborn recreational activities.  Popular  scuba  diving  sites  in the Strait  heightened environmental  protection as  biological  amenity  coincide.  proposed  dump  northern Stuart Woods Bay  sites, Channel  Pratt-Johnson (3 km  Georgia  sites  where  Of  the areas  (1977)  northwest  lists  perhaps  the best  deserve  recreational proximate Round  to  Island  from proposed site  on the Sechelt Peninsula (2 km southwest  site 2) among region.  values  of  from  I)  and the in and  proposed  141 dives in the Georgia Strait - Puget Sound  211  Parks and  Reserves  The Strait including  of  Georgia  several  has  30 Provincial  Provincial  Marine  Parks with water  Parks.  There  are  frontage, also  nine  Ecological Reserves preserved by the provincial government as part of the  International  areas  established  Biological by  Program,  regional  and  and  a  municipal  number  of  conservation  authorities.  These out-  standing scenic or ecological areas are preserved for public recreation and/or the protection of wildlife:  other uses are strictly controlled.  None of the proposed dredged material disposal  sites  impinge  upon established parks, reserves or conservation areas. are parks or reserves sufficiently proximate sites to warrant concern.  1.  However there  to each of the proposed  These are:  North Stuart Channel.  Mudge, Link and D e C o u r c y Islands, to the  east  I,  of  proposed  Islands Regional  site Plan.  are  conservation  Pirates  Cove  McNaughton within  Point.  Smuggler  Cove  areas  under  conservation  12 km  to  status but  ecological area.  the is  south  generally  of  Gulf  Park.  Provincial  Marine  10 km to the south of the proposed dump site.  Island, some  the  on the southeastern end of  D e C o u r c y Island, is a Provincial Marine  2.  directy  the site,, has recognized  as  Park  is  Thomanby no  an  declared important  212  3.  Comox-Denman  Island.  The  Sandy  Island  -  Seal  Islets  area  (approximately 4 km from each of the two proposed dump sites) is a  Provincial Park  this  park  are  (upland only).  recognized  as  The intertidal flats an  important  surrounding  staging  area  for  shorebirds, but have no reserve status.  4.  Smelt Bay, Cortes Island. park abutting a small Bay.  The  Smelt Bay Provincial Park is an upland  section of the southern shoreline of  Mansons Landing  Provincial  Marine  Park  mately 2 km north of the proposed dump site.  is  Smelt  approxi-  The boundary  to  this park corresponds closely with the 5 metre depth contour.  Although the potential impacts of the water disposal of contaminated dredge implicit  material  upon  requirement  upland  to  leave  parks a  and  reserves  suitable  buffer  is  negligible,  between  the  an park  boundary and waste disposal of any kind is recognized by the author. Of  concern  therefore,  Comox-Denman  is  the  proposed  ocean  dumping  in  Island area, within 4 km of the important intertidal  sandflats surrounding the Sandy Island -Seal Islets provincial park. slightly Bay  Of  less concern would be ocean dumping proximate to the Smelt  Provincial  Channel.  the  Park  and  The status of  the  conserved  islands  of  Northern  these reserves is not based upon  Stuart  important  marine associations.  The  marine parks  are substantially  dredged material disposal.  more vulnerable to  impact  from  Although the Mansons Landing marine park  (site 4) extends only to the shallow subtidal so should not be e f f e c t e d  213  by confined disposal water  depth,  recognized. minimize  concern  for  Disposal  during  the  particulates  at a site some 2 km distant and in 100 metres  likelihood  may  precautions may  be  a  transported  be necessary  potential  slack  that  parks near proposed sites  8.10  unforseen  water  or  surface  impacts  should  offshore  tides  plume  into shallow  of  water  to protect the  be will  contaminated  areas.  Similar  less proximate  marine  I and 2.  Conclusion  None  of  the  proposed  dredged  material  disposal  identified on the basis of bathymetric c r i t e r i a  sites  that  were  in Section 7 are  free  for use as disposal sites without c o n f l i c t with other resource uses of Georgia  Strait.  Although  where ocean dumping  may  other  areas  may  exist  in  Georgia  better avoid c o n f l i c t with other resource  uses at the immediate site, the unpredictable and perhaps impacts  of  non-confined  disposal  prohibits the use of these areas Therefore,  if  marine  Strait  disposal  upon  non-proximate  for disposing of  substantial resources  contaminated material.  contaminated  material  is  to  be  permitted within the Strait, the selection of a suitable location must be made from the nominated sites.  Table  XV  provides  a quantitative  summary  of  t h e potentially  con-  flicting resource uses near to the proposed disposal sites, and permits comparative  selection  to  be  made  between  the  sites.  Relative  activity scores have been awarded for each of the nominated resource uses at e a c h of the proposed sites.  These scores were derived from  214 TABLE XV.  Q u a n t i f i c a t i o n o f Resource C o n f l i c t s a t t h e Proposed Ocean Dumping S i t e s . Vulnerability Factor  Resource Use  Level o f Activity/Abundance Site 2  Site 1  (Potential  Impact)  Site 4  Site 3  Groundfish: -  spawning area  8  2  (16)  -  (-)  3  (24)  -  commercial  8  2  (16)  (-)  2  (16)  -  sport  8  2  (16)  -  (-)  1  (8)  8  2  (16)  3  (24)  3  (24)  -  - commercial  4  1  (4)  -  (-)  3  (12)  2  (8)  -  4  1  (4)  2  (8)  2  (8)  2  (8)  fishery  fishery  Crustacean  fishery:  (-) (-) (-) (-)  Molluscs: recreational  Herring: -  spawning area  4  3  (12)  -  (-)  3  (12)  -  (-)  -  r e a r i n g area  2  3  (6)  1  (2)  1  (2)  2  (4)  -  fishery  1  2  (2)  -  (-)  2  (2)  -  (-)  Salmon: -  r e a r i n g area  4  2  (8)  -  (-)  -  (-)  -  (-)  -  commercial  1  -  (")  1  (1)  2  (2)  1  (1)  -  sport  1  1  (1)  2  (2)  2  (2)  1  (1)  Marine mammals:  4  2  (8)  -  (-)  2  (8)  -  <->  Marine B i r d s  4  3  (12)  1  (4)  3  (12)  1  (4)  1  3  (3)  3  (3)  2  (2)  1  (1)  fishery  fishery  :  Recreation: Parks and R e s e r v e s : -  marine  8  1  (8)  1  (8)  -  (-)  2  (16)  -  upland  1  1  (1)  -  (-)  2  (2)  1  (1)  TOTAL  (133)  (52)  (136)  (44)  LEGEND SITE 1. 2. 3. 4.  LOCATIONS NORTH STUART CHANNEL, GULF ISLANDS MCNAUGHTON POINT, SECHELT PENINSULAR COMOX - DENMAN ISLAND SMELT BAY. CORTES ISLAND  VULNERABILITY FACTOR - A measure o f t h e d e g r e e o f e x p o s u r e and s e n s a t i v l t y o f t h e r e s o u r c e u s e t o disposed sedimentary contaminants. 1. NEGLIGIBLE 2. LOW 4. MODERATE 8. HIGH  LEVEL OF ACTIVITY / ABUNDANCE - The a c t i v i t y s c o r e s t h a t a r e awarded a r e d e r i v e d from c o n s i d e r a t i o n o f t h e r e l a t i v e i n t e n s i t y o f t h e r e s o u r c e u s e a c t i v i t y a n d / o r t h e a b u n d a n c e o f t h e resource,, and t h e g e o g r a p h i c p r o x i m i t y o f t h e r e s o u r c e t o t h e p r o p o s e d o c e a n dumping s i t e . 1. LOW 2. MODERATE 3. HIGH LEVEL OF POTENTIAL IMPACT - The p r o d u c t o f t h e V u l n e r a b i l i t y F a c t o r and t h e L e v e l o f A c t i v i t y / A b u n d a n c e .  215  consideration abundance resource  of  of to  the  the  the  relative  intensity  resource,  proposed  and  Island-Comox disposal  spawning  ground  for  the  disposal  Denmand  two  of  major  activity  geographic  site.  area  the  and/or  proximity  For example, the  of  In  comparison,  the  the  proposed  is directly within the principal  stocks  of  groundfish.  The  abundance and immediate proximity of this resource warrants rating.  the  Northern  Stuart  Channel  site  high  a high  is  within  productive spawning areas for minor stocks of groundfish, and is close to  (but  not  within)  spawning  areas  for  Lingcod.  The  moderate  abundance and proximity of this resource justifies a moderate Both of case  the  disposal minor The  these areas fishery  rating.  support a commercial groundfishery, but in each  extends  throughout small  area  fishery)  and  the  relative  to  groundfisheries  elsewhere  activity  of  this  therefore considered to  is  the  (i.e.  fishery  fishery  of  region  comprises  of  a  general  site  level  only  the  in  the  is  a  province. be  moderate.  Similarly  for  the commercial  Denman Island-Comox disposal important  clamming  and  harvesting  oyster  cultivation,  oyster  as  well  clams, oysters and geoducks. activities  are  relatively  molluscs.  The  proposed  area is in close proximity to the most production  Georgia, so warrants a high rating. for  of  region  in  the  Strait  of  Cortes Island has a high potential as  supporting  existing  harvests  of  However the productive areas for these  distant  from  the  proposed  disposal  site.  C o m m e r c i a l mollusc activity at Site k is therefore rated as moderate. In  Northern  Stuart  Channel  the harvesting  of  oysters  and  geoduck  216 clams is a low level activity and is primarily conducted at sites that are geographically distant from the proposed disposal site.  The level  of activity/abundance at this site is therefore rated as low.  Activity/abundance  scores  vity/abundance (score (score = 3).  =  awarded  I)  range  from  low  or  distant  acti-  to high and proximate activity/abundance  R e f e r e n c e by the reader to the narrative in Sections 8.2  to 8.8 is recommended to clarify the awarded scores.  Although the  scores that are awarded in each case are not beyond argument, they do provide a general indication of the relative potential for resource conflicts at the proposed dump sites.  Minor alteration of the activity  scores awarded has little e f f e c t on the overall outcome of Table X V .  Superimposed upon the relative activity of  each conflicting resource  use is a "vulnerability f a c t o r " which is dependent upon the degree of exposure and sensitivity of the resource use to disposed contaminants. Strait  vary  As  has been described above, resource uses in Georgia  substantially  disposal  of  disposal  sites.  sedimentary  in  their  sensitivity  and  exposure  to  the  contaminated material at confined, relatively deep water Consistent  dose-response nonessential  and  with  exposure  contaminants  and  the  scientific  time-response marine  literature  describing  relationships  organisms  (see  between  Connell  and  Miller (1984) for a review of this topic), a logarithmjc scoring system has been used. disposal  site  Thus, resident and benthic feeding groundfish at  have  arbitrarily been  determined to  be  twice  nerable as nomadic but benthic feeding juvenile salmon,  as  the vul-  who are  in  217  turn  twice as vulnerable as  temporarily resident but surface feeding  juvenile herring, and so on.  Vulnerability scores awarded range from  a low of  I to a high of 8.  The relative potential impact of dredged material disposal at each of the proposed sites is the product of the relative activity of  resource  utilization (or abundance of the resource) and the relative vulnerability of the resource. The  total  conflict  of  that  These values are shown in parentheses in Table X V .  these exists  potential at  impacts  each of  the  provides  proposed  an  estimate  sites  between  of  the  dredged  material disposal and other resource uses.  Comparison  of  proposed areas  the  potential  4) will c o n f l i c t  Strait  than disposal  Vancouver, stantial Channel)  Point may  conflicts and  scores  for  each  of  the  four  indicates that dredged material disposal at Smelt  (Area  McNaughton  impact  less with competing  resource uses in  at any of the other proposed sites. (Area  cause with  2),  which  marginally existing  3 (Comox-Denman  is  only  greater resource  half  the  conflict. uses  at  Bay  Georgia  Disposal  at  distance  from  There are  sub-  Areas  Island) and these areas  I  (Stuart  are r e c o m -  mended as inappropriate for dredged material disposal.  The costs of towing dredged material the considerable distances to the two recommended disposal sites are estimated in Table XVI. be seen from the Table, the costs vary substantially  As  can  depending upon  218 TABLE XVI.  Comparative Towing C o s t s f o r Recommended D i s p o s a l  Component  Disposal  Sites.3  Sites  McNaught on P o i n t  Smelt Bay  Low volume operation  High volume operation  Low volume operation  High volume operation  Tug r e q u i r e m e n t s  500 HP  3600 HP  500 HP  3600 HP  Tug h i r e  $3000/day  $14000/day  $3000/day  $14000/day  1000 m 3  7000 m 3  1000 m 3  7000 m 3  Barge r e q u i r e m e n t s Barge h i r e Trip  $300/day  Duration^  1.3  Trip cost Cost per metre  a.  3  Information Table  days  $1500/day 1.3  days  $300/day 2 . 5 days  2 . 5 days  $4290  $20150  $8250  $38750  $4.29  $2.88  $8.25  $5.54  d e r i v e d from e x t r a p o l a t i o n o f i n f o r m a t i o n p r o v i d e d i n  I.  b. Assuming a towing s p e e d , averaged over the r e t u r n j o u r n e y , T h i s f i g u r e i s based on i n f o r m a t i o n from T. comm.,  $1500/day  1985.  Hillier,  of 3 knots.  Rivtow,  pers.  219  the  scale  of  operation.  McNaughton Point Smelt  offers  In  either  considerable  case cost  however,  savings  disposal  over  the  at  use  of  Bay.  Despite  the value of Table X V  in selecting between possible  dredged  material disposal sites on the basis of potential impacts to conflicting resources, the Table does not permit final recommendation as to the suitability  of  the proposed sites  important  variable  that  ocean  dumping.  requires consideration  guantified in the above manner different  for  resource uses.  but  An  cannot  additional be  readily  is the relative value of each of  The value  of  a resource  the  is determined by  mutifarious and often intangible economic and social factors, some of which can only  be resolved by  the political process.  For  although the economic returns of the commercial salmon  example,  harvest  can  be readily quantified, salmon also offer an abstract social value based on romantic  perceptions of  jective and intangible  life  on the west coast  values. The recent controversy over  non-endangered  species  resource values  that accrue to some aspects  have  derived  willingness success.  to  and similar  of  whales  various  methods  pay  to  or  be  further exemplifies  for  of nature.  estimating  compensated)  the  but  these  sub-  harvesting intangible Economists  values  without  (e.g.  significant  U n t i l the relative value of each of the conflicting resource  uses listed in Table X V mination of disposal  can be accurately reckoned, the final deter-  site suitability  cannot be made.  In the present  case, a determination is reguired as to whether the impacts of ocean dumping ational  at  McNaughton  salmon  fishery  Point  and  upon  swimming  the and  prawn  fishery,  boating  the  activities  recreare  of  220  greater  environmental, economic and social cost  than the impacts of  dumping at Smelt Bay on the local mollusc stocks and the provincial parks.  This  issue  involves  subjective judgements  that  can  only  be  addressed by the political process.  A related but separate question that requires consideration pertains to the limits of sediment quality which might be disposed at any selected disposal a  site.  Dredged sediments from the Vancouver region comprise  continuum  minated  from  pristine  sediments  McNaughton  Point  could or  conflicting resources.  to  highly  polluted.  appropriately  the  Smelt  Bay  Relatively  be  disposed  sites  with  at  unconta-  either  minimal  risk  the to  However uncertainties prevent our prediction of  the ultimate impacts of highly contaminated sediments at these sites. Caution  in response to these uncertainties should reasonably  disposal  of  highly  our coastal  contaminated  waters.  authoritative  sediments  here  or  elsewhere  prohibit within  The uncertainty of ultimate impact also prevents  determination  of  the  degree  of  contamination  of  sediments at which such caution should be expressed.  The  means  and  of  potential  of  addressing  measuring for causing  the uncertainties of  sediment  quality  in  a  environmental manner  environmental degradation,  concluding section to this thesis.  impact,  reflecting  the  is considered in the  221  9.0  CONCLUSIONS  9.1  Introduction  The pressures to dispose of dredged material in Georgia Strait can be expected  to  continue, and  mentary material. been  reported  ments,  in  but  mercury,  will  not  be  limited  to  clean  to  contain  this  thesis  substantial  sediment  concentrations  as  likely  additional  hexachlorobutadiene,  pentachlorophenol, non-halogenated  of  a  Numerous other toxic compounds have been pollutants  of  the  for which analyses have not been conducted.  PCBs,  sedi-  Areas within Vancouver's extensive waterways have  range of toxic chemicals. identified  they  polychlorinated  polychlorinated benzenes, various  polyaromatic  hydrocarbons  and  sedi-  Cadmium,  dibenzofurans,  halogenated  phthalate  and  esters  are  identified as each reguiring particular concern in the management of the disposal of dredged material from the Vancouver region.  Concerns taminated  for  the  dredged  environmental materials  relate  contaminants  from the disposed  the  site  disposal  is  inevitable,  but  the contaminants  will  the  degradation.  ecological  the to  disposal  the  Biological  appropriate  site  release  economic  of  con-  of  degradation selection  within as small an area as  and  Without contaminant  from  primarily  materials.  confinement of minimize  impacts  conseguences  the of and  possible of  this  release, the question is essentially:  where do we relocate our pollution?  But  if contaminant  release  and  222  dispersion occur, the act of relocation accentuates the potential harm, adding  unpredictable and  perhaps  substantial  environmental costs  to  the dredging program.  Dredging  and  dredged  material  disposal  involves  the  mechanical  aggitation of the sediments, their exposure to the water column, and their  relocation into a physical, chemical and biological  that may  differ substantially  processes  may  induce  from the dredged site.  release  of  contaminants  environment  E a c h of  from  the  these  disposed  material.  This study has reviewed available information describing the processes, transformations  and pathways  of contaminant  release from  sediments  in the marine environment.  Desorptive release of contaminants to the  water  to  column  cadmium. the  was  found  Biological  more  soluble  be  negligible,  transformation  metabolites  to  of  the  except  contaminants water  for  perhaps  and release  column  is  of  potentially  significant for mercury and for some of the less chlorinated and lower molecular  weight  organic  compounds  molecular weight P A H s , P A E s ) . the disposal pathway  of  concern  (e.g.  low  Biological uptake and dispersion from  site via the food chain  is also a potentially  significant  for contaminant release, particularly for the highly lipophilic  organic contaminants and methylmercury.  However the primary route  of potential release and dispersion of both trace metals contaminants transport  PCP,  of  from disposed dredged materials contaminated particulates.  and  organic  is via the erosion and  Minimizing  the  resuspension  223  of material during and subseguent as  the  primary  objective  for  to disposal  the  selection  is consequently adopted of  disposal  sites  where  substantial contaminant release will be avoided.  A  review of the processes  particulate  material  from  that promote erosion and disposed  dredged  resuspension  material, and  of  the appli-  cation of this information to local oceanographic conditions, identified only four areas within the Strait of Georgia where particulate release from disposed dredged material may not be substantial. areas  are  sequently  adjacent deemed  to  valuable  unsuitable  biological  for  resources  dredged  material  Two of these and  were  disposal.  conOcean  dumping at the other two sites, one near Smelt Bay, Cortes Island and the other off result  in  relatively the  McNaughton Point on the Sechelt  localized degradation low biological  compliance  of  However  the  and economic value of these  resources,  and  areas  adjacent  with  ensure minimal release of contaminants these  two  sites  as  the  also  resources.  these  of  Peninsula, may  most  oceanographic  criteria  which  from disposed material, deem  environmentally  suitable  locations  for  ensure  the  contaminated dredged material disposal within the Strait.  The  principal  requirements  for  further  information  to  validity of the arguments presented in this thesis are considered to be the following:  I.  Oceanographic sea-bed  information  environment  at  is  the  required  to  recommended  characterize the disposal  sites.  near The  principal data requirements are the dissolved oxygen regime at the  224  sediment-water interface (to ensure the maintenance of oxygenated conditions that will minimize dissolution of trace metals);  sea-bed  current  will  profiles  (to  ensure  that  sediment  resuspension  be  minimal); and sediment deposition rates (to determine the need for capping the disposal sediment mound with clean sediments).  2.  An  ecologically  appropriate  required to measure be disposed  at  and  practicable  procedure  is  the quality of dredged material proposed  to  the recommended sites.  testing  Specifically, we need to  distinguish between dredged materials that can be disposed at the sites  with  negligible  ecological  impact  and  those  where  the  environmental risks remain unacceptable.  3.  Associated  with  this  second  information  reguirement,  research is required to define the potential long-term and  fate  of  toxic  into our coastal  contaminants  waters.  from  Substantial  dredged  distribution  material  uncertainties  further  of  disposed knowledge  have been identified by this review with regards to the long term potential  for  biologically  chemical induced  release release  of  toxic  of  trace  trace  metals  metal  and  and  the  organic  contaminants.  The  required  forward  and  investigation.  oceanographic well  within  the  information realms  of  is  comparatively  practicable  straight-  environmental  A n adequate data base could readily be obtained within  a twelve month research program, and should be a prerequisite to the use of any area proposed for ocean dumping.  225  The  latter  greater has  two  demands  witnessed  requirements upon our  a vigorous  dumping,  but  otherwise  inconclusive,  concerns. inherent  the  This  is  variability  for  information  present  research committment. research effort  results and  have  been  have  failed  primarily  a  into  The  the  calm  reflection  of  in the characteristics of  last  impacts  freguently to  considerably decade  of  ocean  inconsistent  our  the  or  environmental  complexity  both dredged  and  materials  and the receiving environment.  There  are  no  clear  case  studies  from  which  one  can  infer  contaminated dredged materials have impacted the food chain et  al.,  1983).  biologically may  But  it  is  clear  that  the  induced release of contaminants  be possible  reguired  to  their potential to deleteriously impact the disposal site. predicting,  from  assess  disposed  dredged  (Kester  chemically  in time and under certain conditions.  practicable procedures are  less  physically,  fate  and  Credible and materials  the environment proximate  effects  of  pollutants  or  sediments  The problem is that the science of measuring, the  that  in  the  for to  much marine  environment is in its infancy.  Dredged Sediment C r i t e r i a  Several  attempts  have been made to establish c r i t e r i a to  natural and contaminated sediments.  In Canada,  the Ocean  distinguish Dumping  Control A c t (1975) specifies bulk sediment concentrations for mercury (acid  digestible  fraction  <Q.75  mg/kg),  cadmium  (acid  digestible  fraction <0.60 mg/kg), persistent plastics (4% by volume) and oils and  226  grease  (10.0  disposal  mg/kg  of  n-hexane  is prohibited.  prohibits  ocean  exceeds 0.1  dumping  protocols.  poorly defined criterion for when  which  The  Act  arsenic,  flourides,  pesticides nickel for  organohalogens  the concentration of these  compounds to  sensitive  also  "restricts"  lead,  copper,  not  and  zinc,  prohibited  vanadium.  restricted metals  ocean  as  dumping  of  materials  organosilicon,  cyanides,  organohalogens,  Although  under  the  no  Act,  beryllium,  criteria  have  permitting  been  currently  relies on bulk concentration data (R. Kussat, EPS, pers. comm.,  It  ocean  there is no definition of test organisms or bioassay  containing  specified  beyond  parts of a concentration shown to be toxic  marine organisms:  chromium,  A  extractables),  1984).  is now well recognized that bulk chemical analyses provide a poor  basis for assessing the biological availability or mobilization potential of  contaminants,  particularly  example, Hirsch, Di was  little  or  no  trace  metals,  in  sediments.  For  Salvo and Peddicord (1978) concluded that there correlation  content and environmental  between  bulk  sediment  trace  metal  impact, and recommended development  of  site-specific toxicity evaluation procedures using sediment bioassays. In an extensive Lakes,  the  review Board  expressed similar  of of  the impacts the  of ocean dumping  International  concerns, stating  Joint  effect  sediment". as  that  may  result  Commission  Great (1978)  that research results "have shown  no relationship between bulk chemical content adverse  on the  from  open  for .sediment  water  disposal  and of  the that  And ..."in other words, dredged material may be classified  polluted on the basis of  bulk  analyses,  while in fact  contaminants may be available to the environment".  few of  the  The corollary of  227  this, that bulk chemical analyses may allow disposal of material where a low bulk concentration belies the environmental significance of  its  high  availability  occur.  to  Chapman  harbour  sites  toxicities  the  biological  and  Barlow  system,  (1984)  has  analysed  also  been  found  to  sediments  from  12  in British Columbia, and recorded some of the  in sediments  were comparatively  where the concentrations of  low.  highest  regulated  metals  The continued use of bulk concentrations to  characterize the potential environmental effects of  dredged  material  disposal merely confuses an already complex question.  Studies  which  have  attempted  to  devise  other  reliable  chemical  methods to predict biological and ecological e f f e c t s of trace metals in marine  sediments  have  had  1979; L u o m a and Bryan,  limited  success  even  more  Hall  and  Bindra,  1978) due to the extreme complexity of the  predictive relationship involved (Burton, 1979). become  (e.g.  difficult  to  compute  P r e d i c t i v e relationships  when  more  than  one  con-  taminant is present, as is invariably the case in the "real world". It generally  agreed  assessing  the  January, Canada,  no  ecological  (U.S. E P A / C O E ,  The c r i t e r i a  that  adeguate  effects  of  chemical  procedures  contaminated  sediment  are  much  more  comprehensive  and emphasize biological  disposal  than  142, No. those  7, 11  used  e f f e c t s of the contaminants  The cornerstone to these c r i t e r i a  the  dredged  Test,  mixed with disposal  where site  the  water  material  is  in  rather  than simple chemical presence. Elutriate  for  1977).  adopted in the U.S.A. (Federal Register  1977)  exist  is  is  experimentally  under defined operational  conditions,  228  then  the  liquid,  suspended  separated for evaluation.  particulate  and  solid  phases  are  each  The independent evaluation of the liquid and  suspended particulate phases is considered to correspond with potential contaminant  releases  via  desorption  and  erosion/resuspension  tively, with the solid phase containing residual  The their  evaluation  requirements  requirement for  testing  for  extensive  bioaccumulation  indicate overall  for  sediment  of  compounds,  as  as  between  chemicals.  Bioaccumulation  notable  for  toxicity  testing  and  including  toxicity  responses  both inorganic  synergistic/antagonistic testing  to be released from  entry into the food chain.  are  Bioassay  contamination  organic  for contaminants  bioassay  potential.  well  contaminants.  these three phases use  respec-  indicates  disposed  and  reactions  the potential  dredged  material  via  A s such, these tests provide data of more  direct relevance to environmental effects of ocean dumping  than  do  chemical analyses alone.  The principal objections to the adoption of the U.S. c r i t e r i a in Canada are  that  they oblige  prolonged  and  expressed  in  unreasonably  proponents  expensive the  U.S.  restricts  ocean dumping  sediment  that  the  ocean  (Brannon,  to waive  1978).  dumping  analyses.  strict  opportunities  culties by the U.S. E P A their authority  of  Concern  application  for  Implicit  to  of  conduct has  also  these  environmentally recognition of  very been  criteria  acceptable these  diffi-  has been indicated by their frequent resort to compliance with  the  evaluation c r i t e r i a , even in cases where substantial contamination  has  been suspected (Kamlet,  requirements of  1983).  strict  229  The  need  materials  for  credible and practicable procedures to assess  for  their potential  credible,  these assessment  relevant  and analytically  inclusion  within  economically  the  and  these  procedures reliable.  remains.  must be sensitive,  To  be  To  dumping  permitting  logistically  feasible,  and  the  process  data  be  ecologically  practicable, their  ocean  facilitate management  Obviously,  environmental effects  dredged  routine  must  produced  be  must  decisions.  objectives  are  more  easily  stated  that  achieved.  However a beginning would be made by discarding the requirement for bulk chemical analyses of sediments and replacing more  relevant  sediment genotoxic  evaluative  bioassay  criteria.  testing  endpoints.  Chapman  incorporating  Using  suitably  acute  sensitive  it with potentially  (1984)  has  suggested  lethal,  sublethal  and  indicator species,  the  sediment bioassay provides an integrated, rapid and inexpensive method of pollution assessment whose validity is not dependent on correlation with sediment chemistry.  Death as an end-point in acute lethal  tests  provides compelling and convincing evidence for decision makers, while sublethal  effects  determined  in  more  sensitive  tests  provide  more  subtle indications of possible ecological effects.  The lack of toxicity  in  bioassay  sediments  tested  provides similarly  by  a  range  of  sensitive  technigues  convincing evidence that the material is not prone  to causing gross ecological degradation in the marine environment.  Sediment  bioassay  testing  using  the  sensitive  benthic  amphipod  Rhepoxynius abronius, described by Swartz et al. (1982), is widely used by the U.S. E P A  as a screening tool in environmental monitoring, and  230  consistent results  have been determined in interlaboratory calibration  testing (A. Mearns, U.S. N O A A , pers. comm., 1985). larvae bioassay test (Chapman and Morgan,  It, and an oyster  1983), have recently been  adopted by the U.S. E P A as part of their interim decision c r i t e r i a for disposal of contaminated dredged material at Four Mile Rock in Puget Sound (U.S. lating  EPA,  which  will  1984).  Conseguently,  permit  detailed  substantial  evaluation  of  data  the  is  accumu-  relevance  and  appropriateness of c r i t e r i a based on these tests.  The principal failure of bioassay procedures is that they assume that e f f e c t s that cannot be readily measured in short-term laboratory tests either  are not occurring or cannot be of environmental significance.  They frequently underestimate the resourcefullness of the ecosystem; for example, the ability of microorganisms of  heavy  biological  metals  with  availability.  resulting Also,  to alkylate inorganic forms  enhancement  the  use  of  of  bioassay  their  toxicity  toxicity  and  tests  as  determinants of the suitability of dredged materials for ocean dumping emphasizes concern for environmental impacts at the disposal site. As was argued in Section 2.2 of this study, areally confined degradation at  a disposal  site  is of  less concern to ocean dumping  management  than is release and dispersion of contaminants.  The N e e d for F i e l d Assessment  The  bottom  dredged  line  material  is  that  disposal  the is  long-term only  truly  L o n g - t e r m degradation will first manifest  environmental assessible  in  impacts the  itself in the form of  of  field. sub-  231  lethal e f f e c t s occurring within the biological community that the  seabed  reguires  or  of  and  designed  studies  within  overcome  site. of  this  To  the  integrators  release.  Whatever  assess  of  the  these  physiology  community.  the short-term  represent  contaminant criteria  the disposal  organisms  successfully  burial  near  carefully  composition have  at  and  These  effects  of  analysis  effects  chemical organisms  turbidity  multifarious  sediment  inhabits  and  processes  procedures  are established under the permitting process,  of and  comprehensive  field monitoring should be conducted to coordinate and correlate with the laboratory tests.  Dependent on whether adverse effects are found  in the field, then the laboratory tests can be adjusted with suitable correction  factors  or  safety  margins  so  they  better  serve  their  predictive function.  The recommended disposal  sites at Smelt Bay and McNaughton Point  are  shallow  each  sampling many  in  sufficiently  water  that  intensive  remains within technical and financial feasibility.  uncertainties  that  preclude  definitive  biological Given the  prediction  of  the  environmental  e f f e c t s of ocean dumping, it is recommended that the  initial  the selected site should  scale  use of  field experimentation.  the perimeter of the disposal  be  Chemical  for  the  purpose  and biological  of  large  monitoring  at  site should emphasize guantification of  the nature and extent of contaminant release.  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