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Dynamics of temporal and spatial mercury contamination in an urban watershed 2005

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DYNAMICS OF TEMPORAL AND SPATIAL MERCURY CONTAMINATION IN AN URBAN WATERSHED by MATTHEW ROBERT MURARO B.A., University of North Carolina at Wilmington, 1996 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES Resource Management and Environmental Studies THE UNIVERSITY OF BRITISH COLUMBIA March 2005 © Matthew Robert Muraro, 2005 Abstract Mercury is a concern in aquatic environments because it can lead to accumulations of methylmercury in fish, which is the primary source of mercury exposure to humans. The Brunette Watershed is a highly urbanized watershed in metropolitan Vancouver with a rich record of monitoring (1973-2003) trace metal distribution and dynamics. This study was conducted to investigate the 294% increase in Brunette Watershed stream sediment mercury concentrations from 1973-1996. The project conducted analysis of field samples, laboratory experiments and examined previous data to determine if methylcyclopentadienyl manganese tricarbonyl (MMT) may play a role in the increase of mercury in the watershed. Little evidence compiled in this study supported the hypothesis that manganese, iron, sulfur or DOC is associated with mercury throughout the watershed. Thus, it is difficult to conclude or rule out that MMT or manganese oxides play a major role in the transport of total mercury. Laboratory experiments creating summer anoxic conditions released a significant amount of mercury from lake sediment into overlying waters. It seems that this release of mercury may be controlled by sulfate reducing bacteria. The study also found an analysis method used in the study caused 66.8% mean loss of mercury in stream sediment samples when the samples were dried. Temporal and spatial analysis of sediment data revealed that mercury concentrations have started to decrease since 1993. When sediment concentrations were adjusted for the 66.8% loss in stream sediment, 1993 mercury concentrations exceeded the Federal Interm Sediment Quality Guidelines at 12 locations; but in 2003, only 1 site exceeded the same guideline. The decrease in mercury concentrations may be linked to the increased public awareness and a large reduction of emissions from a nearby refuse incinerator. Effective imperviousness and mercury levels in stream sediment are significantly correlated throughout the period of high mercury releases from the incinerator. This may indicate that atmospheric mercury deposited on impervious surfaces connected to waterways may contribute to increases in stream sediment concentrations. ii TABLE OF CONTENTS Abstract ii Table of Contents iii List of Tables vi List of Figures ; x Acknowledgments xii 1. INTRODUCTION 1 1.1 STUDY GOAL 2 1.2 OBJECTIVES 5 1.3 MERCURY SOURCES AND ENVIRONMENTAL CONTAMINATION 5 1.4 ATMOSPHERIC PROCESSES AND TRANSPORT 9 1.5 AQUATIC PROCESSES AND TRANSPORT 10 1.6 GEOCHEMICAL PROCESSES OF MERCURY IN AQUATIC SEDIMENT 12 1.7 MERCURY AND METHYLMERCURY IN AQUATIC SYSTEMS 13 2. CHARACTERISTICS OF THE BRUNETTE WATERSHED 16 2.1 SITE DESCRIPTION 16 2.2 HISTORIC CONTAMINATION IN THE BRUNETTE WATERSHED 22 2.2.1 Trace Metal Contaminants 22 2.2.2 Organic contaminants 23 2.2.3 Microbial Contaminants 24 3. METHODS 25 3.1 STREAMBED SEDIMENT SAMPLING AND ANALYSIS 25 3.1.1 Streambed sediment locations 27 3.1.2 Sediment sample collection 27 3.1.3 Sediment sample preparation and analysis 28 3.2 L A K E SEDIMENT MICROCOSM EXPERIMENT 28 3.2.1 Microcosm sample collection 28 3.2.2 Microcosm Laboratory Experiment 28 3.2.3 Microcosm sampling 33 iii 3.2.4 Microcosm analysis methods 33 3.3 LABORATORY ANALYSIS 33 3.3.1 Aqua-Regia digest 33 3.3.2 Trace Metals 33 3.3.3 Mercury in Waters 34 3.3.4 Mercury in sediments 34 3.3.5 Percent Total Carbon in sediment 35 3.3.6 Total Sediment Solids 35 3.3.7 Water Quality Measurements ...35 3.4 STATISTICAL ANALYSIS 35 4. R E S U L T S A N D D I S C U S S I O N 3 8 4.1 DATA QUALITY 38 4.1.1 Variability between sample and methods: Determining the effects of drying samples 40 4.2 MICROCOSM EXPERIMENTS 41 4.3 SUSPENDED SEDIMENTS IN STILL CREEK AND THE BRUNETTE RIVER 48 4.4 BURNABY L A K E SEDIMENT 53 4.5 STREAM SEDIMENT...., -. 56 4.6 COMPARISON OF MERCURY IN STREAM SEDIMENT AND CATCHMENTS IMPERVIOUSNESS 63 4.7 COMPARISON OF VARIOUS ANALYSIS 69 4.8 POSSIBLE SOURCES 73 5 . S U M M A R Y A N D C O N C L U S I O N S 7 8 5.1 MERCURY'S CORRELATIONS WITH ORGANIC CARBON, IRON OXYHYDROXIDES, MANGANESE OXYHYDROXIDES, SULFUR AND OTHER TRACE METALS IN STREAM SEDIMENT, LAKE SEDIMENT, STORMWATER AND LABORATORY CONTROLLED REDOX CONDITIONS 79 5.2 LEVELS OF MERCURY, IRON, MANGANESE AND ORGANIC CARBON RELEASED FROM LAKE SEDIMENT TO OVERLYING WATER DUE TO SEDIMENT ANOXIA 79 5.3 TEMPORAL AND SPATIAL CHANGES IN MERCURY AND TRACE METAL CONTAMINATION SINCE 1973 78 iv 5.4 MMT 'S RESPONSIBILITY FOR THE INCREASE OF MERCURY CONCENTRATIONS IN THE BRUNETTE WATERSHED STREAM SEDIMENT 80 6. RECOMMENDATIONS 81 6.1 IMPLICATIONS FOR FURTHER RESEARCH 81 6.2 MANAGEMENT IMPLICATIONS 82 7. LITERATURE CITED 83 APPENDIX A Stream Sediment Sampling Locations 90 APPENDIX B Concentration of trace metals in Brunette Watershed stream sediment from 1973-2003 92 APPENDIX C Metal concentrations in sediment cores from Burnaby Lake 96 APPENDIX D Total metal concentrations within a Brunette Watershed stormwater event 97 APPENDIX E Microcosm data from Experiment 1, November 17 to December 9, 2002 ...98 APPENDIX F Correlations for 1973-2003 stream sediment in the Brunette Watershed ...100 APPENDIX G Correlations for Burnaby Lake composite core sediments 104 APPENDIX H Correlations for Microcosm #1 data 105 APPENDIX I Correlations for the February 28, 1997 stormwater event in the Brunette Watershed 106 APPENDIX J Quality control data for mercury in sediment 108 APPENDIX K Wilcoxon Paired Sample Signed Rank Test for mercury stream sediment data in the Brunette Watershed 109 APPENDIX L Mercury concentrations in stream sediment adjusted for a 66.8% loss caused by drying the sediment .111 L I S T O F T A B L E S Table 1.1 Estimate of annual releases of mercury from purposeful uses in Milwaukee, Wisconsin. The area is 420 square miles with population just over 2 million 7 Table 1.2 Estimate of annual releases of mercury from processes that release trace impurities in Milwaukee, Wisconsin. The area is 420 square miles with population just over 2 million 8 Table 2.1 Catchment name, number and imperviousness from Figure 2.1 18 Table 2.2 Average slope of catchments within the watershed 18 Table 2.3 Land use in the Brunette Watershed in proportion to the total area in 1973 and 1993 19 Table 2.4 Land cover in the Brunette Watershed in 1973 and 1993. 20 Table 3.1 Locations excluded due to urban development 27 Table 3.2 The following parameters were analyzed in the UBC Civil Engineering Laboratory 35 Figure 3.5 Box-whisker diagram. Adapted from 37 Table 4.1 Comparison of methods used in stream and lake sediment analysis in 1973, 1989, 1993 and 2003 38 Table 4.2 Quality control data for sediment metals analysis. Results in ug/kg, dry weight. 39 Table 4.3 Percent increase of mercury and iron in four microcosms over four weeks in experiment 1 .Manganese concentrations were all below the 50 wg/L detection limit. ..45 Table 4.4 Total metal concentrations in suspended solids collected with a continuous flow centrifuge during a February stormwater event on the Brunette River system, concentrations in mg/kg, dry weight 49 Table 4.5 Comparison of mercury concentrations in sediment from various locations. The Environment Canada guideline ISQC is 174 wg/kg. All concentrations in dry weight. 55 Table 4.6 Various federal guidelines, regulations and objectives for mercury for different water uses 58 Table 4.7 Adjusted mercury concentrations in stream sediment for a loss caused by drying that exceeded federal guidelines within the Brunette Watershed from 1973-2003 (Appendix L) [Concentrations in wg/kg, dry weight] 59 vi Table 4.8 Ratio of mercury concentrations in the Still Creek sub-basin and the Brunette River sub-basin in sediments and stormwater over a thirty-year period 61 Table 4.9 Comparison of sampling locations, matrix and methods for mercury determination in the Brunette Watershed 70 Table 4.10 Mercury median or mean concentration in various media throughout the watershed. (Water concentrations in wg/L and soil in wg/kg) 71 Table A- l Stream sediment sampling locations 90 Table B-l Streambed sediment, <180um fraction in the Brunette Watershed, total concentration in 1973. Values in dry weight. Nitric acid digest for all metals except Hg. Mercury analyzed with potassium permanganate digestion and cold vapor analysis 92 Table B-2 Streambed sediment, <180um fraction in the Brunette Watershed, total concentration in 1989. Values in dry weight. Nitric acid digest for all metals except Hg. Mercury analyzed with potassium permanganate digestion and cold vapor analysis 93 Table B-3 Streambed sediment, <1 SOum fraction in the Brunette Watershed, total concentration in 1993. Values in dry weight. Nitric acid digest for all metals except Hg. Mercury analyzed with potassium permanganate digestion and cold vapor analysis 94 Table B-4 Streambed sediment, <180wm fraction, in the Brunette Watershed, total concentration in 2003. Values in dry weight. Nitric acid digest for all metals except Hg. Mercury analyzed with pyrolysis digestion and AA detection 95 Table C-l Metal concentrations in sediment cores (depth < 2.0 cm) from Burnaby Lake [mg/kg dry weight]. Refer to Figure C-l for site locations. (C) indicates composite sample was analyzed 96 Table D-l Total metals within a stormwater event on the Brunette River, February 28, 1997 97 Table D-2 Total metals within a stormwater event on Still Creek, February 28, 1997 97 Table E-l Microcosm pH data from Experiment 1, November 17 to December 9, 2002. Note: Microcosm variables (1. Control, 2. DI water, 3. Oxic and 4. Molybdate ions).. 98 Table E-2 Microcosm conductivity data (uS/cm) data from Experiment 1, November 17 to December 9, 2002. Note: Microcosm variables (1. Control, 2. DI water, 3. Oxic and 4. Molybdate ions) 198 vii Tab le E-3 M i c r o c o s m d isso lved o x y g e n data ( m g / L ) data f rom Exper iment 1, N o v e m b e r 17 to December 9, 2002. No te : M i c r o c o s m variables (1. C o n t r o l , 2. D I water, 3. O x i c and 4. M o l y b d a t e ions) . . ; 98 Tab le E - 4 M i c r o c o s m disso lved organic carbon data ( m g / L ) data f rom Exper iment 1, N o v e m b e r 17 to December 9, 2002. No te : M i c r o c o s m variables (1. C o n t r o l , 2. D I water, 3. O x i c and 4. M o l y b d a t e ions) J 99 Tab le E - 5 M i c r o c o s m mercury data (wg/L) data f rom Exper iment 1, N o v e m b e r 17 to December 9, 2002. Note : M i c r o c o s m variables (1. C o n t r o l , 2. D I water, 3. O x i c and 4. M o l y b d a t e ions) 99 Tab le E - 6 M i c r o c o s m Iron data (ppm) data from Exper iment 1, N o v e m b e r 17 to December 9, 2002. Note : M i c r o c o s m variables (1. C o n t r o l , 2. D I water, 3. O x i c and 4. M o l y b d a t e ions) 99 Tab le E - 7 M e r c u r y concentrations o f B u r n a b y lake sediment used i n M i c r o c o s m #1 analysis, N o v e m b e r 1, 2002 99 T a b l e F - l Spearman's rho Corre la t ions w i t h Bonfer ron i Cor rec t ion- 1973 Stream Sediment i n the Brunette Watershed 100 Tab le F - 2 Spearman's rho Corre la t ions w i t h Bonfe r ron i Cor rec t ion- 1989 stream sediment data i n the Brunette Watershed 101 Tab le F-3 Spearman's rho Correla t ions w i t h Bonfe r ron i Cor rec t ion- 1993 stream sediment i n the Brunette Watershed 102 Tab le F -4 Spearman's rho Corre la t ions w i t h Bonfe r ron i Cor rec t ion- 2003 Stream Sediment i n the Brunette Watershed 103 Tab le G - l Spearman's rho Corre la t ions w i t h Bonfe r ron i Cor rec t ion- B u r n a b y L a k e composi te core sediments 104 Tab le H - l Spearman's rho Corre la t ions w i t h Bonfe r ron i Cor rec t ion for M i c r o c o s m #1 data 105 Tab le 1-1 Spearman's rho Correla t ions w i t h Bonfe r ron i Cor rec t ion for the February 28 , 1997 o n S t i l l Creek stormwater event 106 Tab le 1-2 Spearman's rho Corre la t ions w i t h Bonfe r ron i Cor rec t ion for the February 28 , 1997 o n the Brunette R i v e r stormwater event 107 Tab le J - l Qua l i t y control data for mercury i n sediment, analyzed on a L u m e x A A . Resul ts i n ug/kg , dry weight. Env i ronmenta l Resource Associa tes : Reference Sample Ca ta log #540 L o t # D 0 3 5 - 5 4 0 108 v i i i Table K-l Wilcoxon Paired Sample Signed Rank Test for 1973,1989, 1996 and 2003 mercury stream sediment data in the Brunette Watershed ....109 Table K-2 Test Statistics for data from 1973-2003 110 Table L - l Mercury concentrations in stream sediment adjusted for a 66.8% loss caused by drying the sediment (ug/kg, dry weight) I l l ix LIST OF FIGURES Figure 1.1 Location of the Brunette Watershed in Lower British Columbia 2 Figure 1.2 Map of Brunette Watershed (McCallum 1995) 3 Figure 1.3 Conceptual model of mercury cycling and pathways for a typical freshwater lake (Krabbenhofte/a/. 1997) ; 14 Figure 2.1 Map of the Brunette Watershed and tributaries and catchments (GVRD 2000a). 17 Figure 2.2 Cross section view of Brunette Watershed indicating slope (McCallum 1995). ..21 Figure 3.1 Brunette Basin stream sediment sampling sites. Adapted from Hall et al. (1976) 26 Figure 3.2 Diagram of a single microcosm with traps 29 Figure 3.3 Experiment I, four different microcosms were set-up for the initial three-week trial run 31 Figure 3.4 Experiment II, six microcosms were set-up with the same parameters as the first run for the six week analysis. Each contained 100 g of sediment and 1.2 L lake water. The following variables were in each microcosm: 32 Figure 4.1 Box-whisker plots comparing mercury concentrations in 2 mm wet vs dried stream sediment at 105°C (n=27) 41 Figure 4.2 Microcosm 1 containing lake sediment, lake water under anoxic conditions, for Experiment 1 42 Figure 4.3 Microcosm 2 containing lake sediment, de-ionized water and under anoxic conditions, for Experiment 1 : 42 Figure 4.4 Microcosm 3 containing lake sediment, lake water under oxic conditions, for Experiment 1 43 Figure 4.5 Microcosm 4 containing lake sediment, lake water with molybdate ions added under anoxic conditions, for Experiment 1 43 Figure 4.6 Diagram of Eh-pH for mercury in aquatic systems. Adapted from (Veiga and Meech 1998) 47 Figure 4.7 A Box-whisker plot of total mercury concentrations in stormwater over a stormwater event, units in ng/L [Data from Sekela et al (1998)] 49 Figure 4.8 Mercury concentrations in stormwater grab samples collected by Environment Canada in Still Creek on February 28, 1997 (Sekela et al. 1998). Bars indicate mercury concentrations and squares indicate flow 52 Figure 4.9 M e r c u r y concentrations i n stormwater grab samples col lected b y Env i ronmen t Canada i n the Brunette R i v e r o n February 28, 1997 (Sekela et al. 1998) Bars indicate mercury concentrations and squares indicate f l ow 52 F igure 4.10 B o x - w h i s k e r plot o f mercury concentrations i n B u r n a b y L a k e core samples, concentrations i n m g / k g dry weight [n=18] ( E n k o n 2002) [Envi ronment Canada ' s I S Q G guidel ine is 0.174 mg/kg] 54 F igure 4.11 B o x - w h i s k e r plot o f mercury concentrations (wg/kg dry weight) i n Brunette Watershed stream sediment f rom 1973-2003. O n e outl ier exc luded f rom 1993 at 870 wg/kg 57 F igure 4.12 B o x - w h i s k e r plot o f mercury concentrations i n the S t i l l Creek sub-basin stream sediment from 1973 to 2003 60 F igure 4.13 B o x - w h i s k e r plot o f mercury concentrations i n the Brunette R i v e r sub-basin stream sediment from 1973 to 2003 61 F igure 4.14 Spearman's correlat ion coefficients for mercury i n 180 « m stream sediment from 1973-2003. Data located i n A p p e n d i x F 62 F igure 4.15 B o x - w h i s k e r plot o f mercury streambed sediment concentrations (ug/kg) f rom s ix catchments i n 1993. O n e outl ier was exc luded from S t i l l Creek w i t h a value o f 2115 wg/kg. In 1993, three independent samples were analyzed at each site 65 F igure 4.16 Scatter-plot o f 1973 stream sediment mercury concentrations (wg/kg) vs effective impervious area (hectares) f rom 1973. L i n e indicates the l inear regression o f the s ix area's 66 F igure 4.17 Scatter-plot o f 1993 stream sediment mercury concentrations (wg/kg) vs effective imperv ious area (hectares) L i n e indicates the l inear regression o f the s ix area's 67 F igure 4.18 Scatter-plot o f 2003 stream sediment mercury concentrations (wg/kg) vs total imperv ious area (hectares) f rom 1996. Effect ive imperv ious area data was unavai lable for the per iod o f 1994-2003. L i n e indicates the l inear regression o f the s ix area's 69 F igure 4.19 M e t a l median concentrations i n <180 wm stream sediment f rom 1973-2003. M e r c u r y i n wg/kg. Iron i n m g / k g . Manganese i n wg/kg x O . l 76 F igure 4.20 M e t a l med ian concentrations i n <180 wm stream sediment f rom 1973-2003. ( A l l metals i n wg/kg) 77 F igure C - l L o c a t i o n o f Bu rnaby L a k e sediment core sampl ing stations. Photo adapted f rom ( E n k o n 2002) 96 x i Acknowledgments T h i s project was made poss ible b y the labor, d i rec t ion and funding o f D r . K e n H a l l . H i s experience and knowledge o f the Brunette Watershed over the last thirty years was invaluable . T h i s project w o u l d not have been poss ible wi thout the various laboratory support and guidance. D r . M a r c e l l o V e g i a p rov ided equipment and technical assistance w i t h the mercury analysis. D r . L e a h B e n d e l l - Y o u n g p rov ided more needed d i rec t ion and statistical advice. I w o u l d also l i ke to thank Pau la for her advice o n the m i c r o c o s m setup f rom the Envi ronmenta l Engineer ing and Susan Harper for the metals analysis. C a r o l and K a r e n , f rom the So i l s Laboratory, also p rov ided metals analysis . U B C - C E R M 3 prov ided funding for the mercury laboratory instrumentation and related supplies. x u 1. INTRODUCTION M e r c u r y is in t r iguing to study because its t ox ico logy , transformation and transport mechanisms are complex and not current ly w e l l understood. T h e U . S . Env i ronmenta l Protect ion A g e n c y is a l locat ing 4 0 - 5 0 % o f its mercury budget over the next 5 years to be spent o n transport, fate, and transformation, because it considers it a h igh pr ior i ty for research ( E P A 2003). M e r c u r y is the most c o m m o n contaminant i n aquatic ecosystems wor ldwide , however , its sources and pathways and tox ic i ty con t ro l l ing processes are ve ry complex (Krabbenhoft 1997). It 's behavior i n the environment is considerably different than other metals. Phys i ca l l y , it is unique because it is a l i q u i d at r o o m temperature and pressure. It and some o f its compounds , have a h i g h vapor pressure compared w i t h other metals. V a r i o u s complex processes affect mercury i n atmospheric and aquatic systems that are not fu l ly understood. Genera l ly , it is ve ry reactive i n the environment and read i ly undergoes phase and reduct ion-oxidat ion (redox) changes. It w i l l undergo many environmental processes, photochemica l reactions, chemica l ox ida t ion and redox reactions, m i c r o b i a l transformations, and phys io log ica l fractionation. M e r c u r y po l lu t ion is a complex p rob lem i n the w o r l d today and an incident i n the 1950's mercury po i son ing drew w o r l d w i d e attention when approximate ly 200 people d ied i n the Japanese F i s h i n g v i l l age o f M i n a m a t a . Later i n the 1980's , researchers found elevated levels o f mercury i n remote, isolated lakes where no sources cou ld immedia te ly be identif ied. T h i s lead to the d i scovery that mercury contaminat ion o f aquatic systems is general ly caused b y atmospheric transport and deposi t ion. O n c e i n an aquatic system it bioaccumulates i n organisms to levels m u c h higher then the surrounding atmosphere, water or lake sediment. In the past, analyt ical instrument technology was not able to reach a l o w enough mercury detection l i m i t to study it effectively. F i s h i n the remote lakes w o u l d have levels o f detectable mercury but a source cou ld not be detected i n water or air. O v e r the last fifteen years, improvements i n analyt ical techniques and technology have increased the capabi l i ty o f researchers. Recent ly , advances i n technology have made it possible to study levels as l o w as 0.005 n g / m 3 o f mercury, w h i c h is l o w enough for ambient atmospheric testing (Meyers 1998). 1 M e r c u r y is a concern i n aquatic environments because it can lead to accumulat ions o f methy lmercury i n fish. Seafood consumpt ion is the o n l y significant b io -accumula t ion pathway for humans and animals to become contaminated ( E P A 2003; U N E P 2003). Interestingly, due to the complex processes that control mercury c y c l i n g , total mercury concentrations i n air, water or so i l can not be an indicator o f methy lmercury concentrations i n water, sediment or biota . Thus , it is necessary to understand the c y c l i n g o f mercury i n aquatic systems. 1.1 Study goal T h e Brunette Watershed, a h i g h l y urbanized watershed i n metropol i tan Vancouve r , B r i t i s h C o l u m b i a w h i c h has been intensely studied over the last thir ty years (Figure 1.1 and 1.2). A weal th o f informat ion regarding the watershed has been created i n this t ime span and knowledge o f watershed condit ions and its processes has increased w i t h each study. M c C a l l u m (1996) noted a 2 9 4 % increase i n mercury and a 1 3 1 % increase i n manganese F igure 1.1 L o c a t i o n o f the Brunette Watershed i n L o w e r B r i t i s h C o l u m b i a 2  concentrations i n stream sediment f rom 1973-1996 throughout the watershed. It was presumed b y M c C a l l u m (1995) the increase i n manganese concentrations was due to the addi t ion o f methylcyc lopentad ienyl manganese t r icarbonyl ( M M T ) i n gasol ine after 1986, as a replacement for lead additives. T h i s concept was reinforced b y a 2 6 0 0 % increase i n di lute ac id extractable manganese f rom stream sediment, w h i c h is thought to be representative o f the manganese ox ide fraction ( B e n d e l l - Y o u n g and H a r v e y 1991). One possible explanat ion used b y M c C a l l u m (1995) for the increase i n mercury concentrations was its adsorption b y manganese oxides (Thabalas ingam and P i c k e r i n g 1985). Manganese , released f rom the exhaust o f an automobile w i l l o x i d i z e and then absorb or b i n d w i t h various materials, i nc lud ing mercury . M e r c u r y and manganese cou ld then be flushed into aquatic systems b y stormwater events. 2 M n + 2 + 0 2 = ( M n 0 2 ) " 2 ( M n 0 2 ) - 2 + H g + 2 = H g ( M n O ) 2 T h e geochemica l processes for con t ro l l ing mercury ' s associations i n an aquatic environment are different than other metals, due to its unique phys ica l and chemica l properties. M e r c u r y forms strong bonds w i t h c o m p l e x i n g agents or l igands. L igands are molecu les or ions that surround a metal i o n i n a complex . T h i s project is intended to investigate the poss ib i l i ty that manganese oxides cou ld be leaching mercury out o f the so i l and transporting it through the watershed; w i t h the hope o f expanding the current knowledge o f mercury dynamics i n the Brunette Watershed. It is suspected that these complexes transport mercury i n the " f lashy" S t i l l Creek system as particulate matter. Particulates eventual ly reach B u r n a b y L a k e and settle out. In the summer, B u r n a b y L a k e becomes anoxic . R e d u c i n g condit ions m a y release mercury and methy lmercury bound to i ron and manganese oxides back into interstit ial porewater and the o v e r l y i n g water co lumn . T h i s project was intended to determine i f metals, i nc lud ing mercury, bound to these i r on oxides (FeOx) and manganese oxides ( M n O x ) are released under anox ic condit ions i n sediment, interstitial water and o v e r l y i n g water. O n a larger scale, it w i l l investigate var ious processes to improve the understanding o f mercury transport i n the Brunette Watershed. 4 1.2 Objectives 1. Quant i fy current levels o f mercury and other trace metal contaminat ion i n Brunette Watershed stream sediment to identify temporal and spatial changes i n mercury contaminat ion since 1973. 2. Identify i f mercury correlates w i t h organic carbon, i ron oxyhydroxides , manganese oxyhydroxides , sulfur and other trace metals i n stream sediment, lake sediment, stormwater and laboratory control led redox condi t ions. 3. Identify i f mercury, i ron , manganese and organic carbon are released from lake sediment to ove r ly ing water under anoxic condit ions. 4. Investigate i f M M T cou ld be responsible for the increase o f mercury concentrations i n the Brunette Watershed stream sediment b y examin ing correlat ion 's between manganese and mercury. T h i s project used a combina t ion o f field and laboratory data a long w i t h h is tor ica l data. Labora tory m i c r o c o s m experiments was designed to ident ify mercury ' s reactions to various environmental condit ions i n an effort to identify geochemica l associations. Stream and lake sediment throughout the watershed was analyzed to determine temporal and spatial trends over the last thir ty years i n an attempt to locate sources and transport mechanisms. Stormwater was studied to identify features i n v o l v e d i n contaminant transport. 1.3 Mercury sources and environmental contamination Tota l releases o f mercury to the environment i n Canada is estimated at 20 tonnes per year (Hagreen et al. 2004) . Releases o f mercury are classif ied into two broad categories, natural and anthropocentric. A c c o r d i n g to E P A documents, the amount o f mercury i n the atmosphere is estimated to have increased b y 200 % to 500 % since the beg inn ing o f the industr ial revolu t ion (Obenauf and Skavroneck 1997). Recent estimates calculated that anthropocentric emissions have t r ip led the concentration o f mercury i n the ocean over the 5 last century ( M a s o n et al. 1994). Other reports indicate that there is 3 to 6 t imes more mercury today vs. pre-industrial t imes i n A t l a n t i c Ocean water, A t l an t i c b i r d feathers, peat bogs, soi ls and lake sediments (Obenauf and Skavroneck 1997). Current ly , atmospheric mercury originates f rom 25 -40% natural sources and 60 -75% anthropocentric ( M a s o n et al. 1994). Natura l sources o f atmospheric mercury are m a i n l y i n the gaseous elemental fo rm (Porce l la et al. 1996). These sources inc lude volcanoes, forest fires and o f f gassing o f soi ls , vegetation and the ocean. M e r c u r y is m i n e d and used because its unique phys ica l and chemica l properties make it very useful for industr ial processes. Its release into the environment is often unintended, accidental or a by-product o f industr ial processes. Anthropocent r ic sources to the atmosphere inc lude incinerat ion, ch lo ro -a lka l i plants, metal extraction processes, cement product ion, coa l , o i l and gas incinerat ion, (Table 1.1 and 1.2). Incinerat ion o f refuse is considered the second largest g lobal source o f atmospheric mercury, [Table 1.1] (Pacyna 1996). A recent report indicated that 1 i n 12 or 5 m i l l i o n people i n the U n i t e d States contain levels o f mercury above levels considered safe b y the U . S. Env i ronmenta l Protect ion A g e n c y [ E P A ] ( U N E P 2003). The U n i t e d States Research C o u n c i l estimated that about 60,000 6 Table 1.1 Est imate o f annual releases o f mercury f rom purposeful uses i n M i l w a u k e e , W i s c o n s i n . T h e area is 420 square mi l e s w i t h popula t ion just over 2 m i l l i o n . [Adapted from (Obenauf et al. 1997). Releases to M e d i a Sector A m o u n t (kg/yr) Percent o f To ta l A i r (kg/yr) S o l i d Waste (kg/yr) Wastewater (kg/yr) Refuse Incinerators 149 3 5 % 149 0 0 Fluorescent L a m p s 57 1 3 % 0 57 0 Genera l Industry 46 1 1 % 0 0 46 Denta l Fac i l i t i es 45 1 1 % 0 18 27 Switches - A u t o m o t i v e 32 8% 3 23 6 Thermostats 32 8% 0 32 0 Batteries 23 6% 0 24 0 Households 18 4 % 0 0 18 Switches - L i g h t i n g 7 2 % 0 7 0 Hospi ta ls and M e d i c a l Faci l i t ies 3 1% 0 0 3 Switches - App l i ances 2 <1% 0 1 <1 Crematories 1 <1% 1 0 0 Landf i l l s 1 <1% 0 0 <1 Vete r inary Faci l i t ies 1 <1% 0 <1 0 Septic 0 0 % 0 0 0 To ta l for Purposeful Uses (lb/yr) 418 ' 0 152 163 102 To ta l for Purposeful Uses (percent) 0 100% 3 7 % 3 9 % 2 4 % 7 Table 1.2 Est imate o f annual releases o f mercury from processes that release trace impuri t ies i n M i l w a u k e e , W i s c o n s i n . The area is 420 square mi l e s w i t h popula t ion just over 2 m i l l i o n . [Adapted f rom (Obenauf et al. 1997).] Releases to M e d i a Sector A m o u n t (kg/yr) Percent o f To ta l A i r (kg/yr) S o l i d Waste (kg/yr) Wastewater (kg/yr) C o a l C o m b u s t i o n Ut i l i t i e s 157 6 5 % 125 31 0 Secondary M e t a l Smel t ing 31 1 3 % 31 0 0 M o t o r V e h i c l e C o m b u s t i o n 22 9 % 22 0 0 O i l C o m b u s t i o n Industry 16 7 % 16 0 0 O i l C o m b u s t i o n Resident ia l 14 6% 14 0 0 C o a l C o m b u s t i o n Industry 0 0 % 0 0 0 L i m e Produc t ion 0 0 % 0 0 0 To ta l for Trace Impurities (pounds) 329 0 207 31 0 To ta l for Trace Impurit ies (percent) 0 100% 8 7 % 13% 0 % babies born each year i n the U . S . cou ld be at r isk o f b ra in damage w i t h possible impacts ranging f rom learning diff icul t ies to impai red nervous systems ( U N E P 2003) . H u m a n mercury contaminat ion has also been l i nked to cardiovascular problems i n c l u d i n g raised b l o o d pressure, palpitations and heart disease ( U N E P 2003). Effects o n the bra in can inc lude i r r i tabi l i ty , tremors, disturbances to v i s i o n , m e m o r y loss, impai red coordinat ion and other adverse effects ( U N E P 2003). Fetuses, the newborn and young ch i ld ren are par t icular ly vulnerable because o f the sensi t ivi ty o f their deve lop ing nervous system 8 ( U N E P 2003). Other effects have been found on the thyroid gland, w h i c h regulates growth, the digest ive system, the l ive r and the sk in inc lud ing pee l ing on hands and feet, i t ch ing and rashes ( U N E P 2003). A s o f December 2000, mercury was the contaminant responsible, at least i n part, for the issuance o f 2,242 f ish consumpt ion advisories b y 41 U S states (B ig l e r 2003). Furthermore, 7 9 % o f a l l fish and w i l d l i f e advisories issued i n the U n i t e d States are at least part ly due to mercury contaminat ion i n fish and shel lf ish (B ig l e r 2003). E P A advisories for mercury have increased 149% i n 7 years, f rom 899 advisories i n 1993 to 2,242 advisories i n 2000 ( B i g l e r 2003). O n January 12, 2001 , the E P A and U . S . Federal D r u g Admin i s t r a t i on ( F D A ) j o i n t l y issued a press release no t i fy ing the pub l i c o f a nat ional fish consumpt ion advisory due to mercury contaminat ion ( B i g l e r 2003). E P A ' s guidel ine recommends i f a person is pregnant, cou ld become pregnant, nurs ing a baby, or feeding a young c h i l d ; consumpt ion o f freshwater fish caught b y f ami ly and friends should be l imi t ed to one meal per week (B ig l e r 2003). F o r adults, one mea l is s ix ounces o f cooked fish or eight ounces o f uncooked fish; for a y o u n g ch i ld , one mea l is t w o ounces o f cooked fish or three ounces uncooked fish ( B i g l e r 2003) . The F D A has also released a consumer advisory recommending ch i ld ren and w o m e n , w i t h or p lann ing to have chi ldren, should avo id eating shark, swordf ish , k i n g mackere l , tuna steaks and t i le fish. Safeway, Kroegers , Trader Joe 's and W h o l e Foods , (large grocery store chains i n Cal i forn ia ) have vo lun ta r i ly agreed to post F D A warnings about mercury contaminat ion o f the p rev ious ly l is ted fish at seafood counters. 1.4 Atmospheric processes and transport Atmospher i c deposi t ion is considered the dominant pathway for mercury contaminat ion o f aquatic systems, wi thout a point source (Fi tzgera ld et al. 1991; Watras et al. 1996; E P A 1999). Fo rms o f deposi t ion inc lude direct wet /dry deposi t ion and indirect sources l i ke terrestrial runoff. Uncer ta in ty exists about h o w the c y c l i n g o f atmospheric mercury has changed w i t h the addi t ion o f anthropocentric sources. The major i ty o f uncertainty l ies i n assessing his tor ic levels and processes (Fi tzgerald et al. 1991; Guentze l 2001). 9 Current ly i n the atmosphere, 9 7 - 9 9 % o f mercury is i n the zero ox ida t ion state as gaseous elemental H g ( H g ° ) (Fi tzgera ld et al. 1991; L indqv i s t et al. 1991; Nater et al. 1992). The remain ing 1-3% is compr ised o f particulate H g ( H g p ) or reactive gaseous Hg( l l ) ) (L indqv i s t et al. 1991; Na te f et al. 1992). Gaseous elemental H g has a residence t ime i n the atmosphere o f up to 1 year (Fi tzgerald et al. 1991; L indqv i s t et al. 1991; Nater et al. 1992). H g ( l l ) and H g p can reside for days or weeks i n the atmosphere (L indqv i s t et al. 1991; Nate r et al. 1992). H g ° can enter the g loba l mercury cyc le and travel up to 10,000 k m (Porce l la et al. 1996). Hgp or H g ( l l ) are deposited near the emiss ion source (50 k m ) (Porce l la et al. 1996). W h e n deposited mercury is almost exc lus ive ly i n the H g p fo rm (Porce l la et al. 1996). It is diff icul t to predict residence t ime and distance transported due to l oca l va r iab i l i ty i n weather and the atmosphere (Porce l la et al. 1996). O f the estimated 158 tons o f mercury emitted annual ly into the atmosphere b y human activit ies i n the U n i t e d States, approximate ly 87 percent is f rom combust ion point sources, 10 percent f rom manufactur ing, and 3 percent is f rom a l l other sources (Obenauf et al. 1997). Speciat ion, c l imate and meteorology o f anthropocentric mercury determine the distance traveled (Guentze l 2001). 1.5 Aquatic processes and transport T h e intent o f this study is to analyze mercury transport i n an aquatic, urban e n v i r o n m e n t ^ a b i r z et al. 1998). U r b a n watersheds have shown higher y ie lds o f mercury than forested and rural areas (Hur l ey et al. 1995; M a s o n et al. 1997). T h i s is due to a lack o f so i l for b ind ing , h i g h stormwater fluxes and runof f due to imperv ious surfaces. Stormwater has been impl ica ted i n the movement o f particulate mercury i n aquatic systems due to the resuspension o f sediment, increased runof f and disturbance o f lake ' s h y p o l i m n i o n (Jackson 1982; M a s o n et al. 1997; Beno i t et al. 1998a). Inorganic mercury w i l l t yp i ca l ly enter a freshwater system bound to var ious inorganic and organic particles. There is some uncertainty as to what condi t ions govern b i n d i n g distr ibut ion. These particulates are predominate ly m o v e d under h igh - f l ow or stormwater condit ions un t i l particulates settle to the bot tom o f the system. Studies have concluded that h igh- f low events lead to increased mercury transport (Hur l ey et al. 1995; M a s o n e d al. 1997; B a b i r z et al. 1998; Beno i t et al. 1998b). A q u a t i c mercury transport 10 general ly occurs through a combina t ion o f two separate processes; mercury bound to suspended particulate matter ( S P M ) or bound to d i sso lved organic carbon ( D O C ) . A large b o d y o f research exists suggesting mercury i n an aquatic environment predominate ly bonds to organic carbon (Watras et al. 1994; M a s o n et al. 1997; Beno i t et al. 1998a; M e y e r s 1998). Organ ic matter has a strong affinity for mercury so it t yp i ca l l y correlates w e l l i n transport and sediment ( M e i l i 1997). Inorganic l igands, ( i ron and manganese oxyhydrox ides , reduced sulfur compounds and c lay minerals) general ly correlate i n systems w i t h l o w levels o f organic matter ( M e i l i 1997). Furthermore, some research indicates that i n eutrophic, c i rcumneutral waters, mercury w i l l predominate ly b i n d w i t h i r on and manganese oxides (Jackson 1982; Jacobs et al. 1995; Quemerais et al. 1998; R e g g n e l l et al. 2001). T h e role o f these different inorganic l igands i n d i sso lved and particulate mercury transport is important but not w e l l understood. H u r l e y et al. (1995) moni tored r iver sites i n W i s c o n s i n w h i c h exhib i ted strong seasonal variat ions. T h e y observed a strong correlat ion between filtered H g t and D O C (r 2 = 0.61) dur ing fa l l base f low but the relat ionship was reduced i n the spr ing ( r 2 = 0.14). T h i s reduced relat ionship is most l i k e l y due to higher spr ing f lows and increased S P M i n the spring. H u r l e y et al. (1995) also compared land-use to mercury concentrations i n 39 W i s c o n s i n rivers and found urban areas had the highest spr ing and overa l l concentrations. M e r c u r y bound to D O C is der ived f rom porewater i n "marsh l i k e " areas (Hur l ey et al. 1995; B a b i r z etal. 1998; Beno i t et al. 1998b). In urban watersheds, it seems that mercury transport is t yp i ca l l y associated w i t h S P M ( G i l l et al. 1990; M a s o n et al. 1997). S P M originates f rom run-off, suspended sediments and bank erosion (Hur l ey et al. 1995; B a b i r z et al. 1998). Sp r ing f lows are general ly higher, w h i c h w o u l d increase the amount o f suspended particulate matter. V a s i l i e v et al. (1996), analyzed mercury transport b y different fractions o f suspended sediments i n the spr ing and summer. T h e y found that particles i n the <0.45 « m fraction had the highest concentrat ion o f mercury w h i l e the >50 um had the highest overa l l contr ibut ion to transport. T h e m i d d l e fractions m i m i c k e d these overa l l relative trends. It is diff icul t to deduce the m o b i l i z a t i o n o f mercury b y examin ing the Brunette Watershed as a whole . T h i s is due to the various mechanisms that can control transport. T h e upper catchments o f the Brunette Watershed can be characterized b y h a v i n g a short 11 residence t ime. In these areas, it is l i k e l y that mercury transport is typ ica l o f other urban waters. 1.6 Geochemical processes of mercury in aquatic sediment Sediment plays an important role i n mercury transport and b iogeochemica l c y c l i n g . T h e b iogeochemica l c y c l i n g o f mercury i n sediment can be contro l led b y l igands. L i g a n d s are polar molecules or anions that surround a metal i o n i n a complex ( B r o w n et al. 1991). It is important to differentiate between mercury bound to l igands and other forms because l igands can determine sedimentat ion rates and b ioaccumula t ion rates i n animals . M e t a l oxides , i nc lud ing hydroxides and oxyhydrox ides are l igands that m a y di rec t ly or ind i rec t ly control the m o b i l i t y and transport o f mercury i n o x i c and anoxic environments. Iron and manganese oxides form labi le complexes i n particulate, c o l l o i d a l and d i sso lved forms. T h e stabil i ty o f these oxides are h i g h l y dependent o n p H and redox potential ( M e i l i 1997). R e d u c i n g condi t ions can create an increase o f mercury (Hg) and poss ib ly methylmercury ( M H g ) i n anoxic waters (Regne l l et al. 1996). Released i o n i c i r on and manganese m a y also compete w i t h mercury for sulfur b i n d i n g sites, increasing the quantity o f d isso lved mercury avai lable for methyla t ion. Therefore, under o x i c condi t ions sediment acts as a s ink for mercury and methylmercury . W h i l e under anoxic condi t ions, mercury cou ld be released f rom the sediment or converted to H g S . In an o x i c environment, M n O x and F e O x form strong bonds w i t h H g and organic matter. Po rce l l a et al, (1995) suggest that F e O x have a mass related affinity for H g ten t imes higher than organic matter alone. Quemerais et al, (1998) research indicates that organic carbon o n l y attracts mercury w h e n metal hydroxides are present, w h e n they are removed, no relat ionship can be found. A l s o , F e O x and M n O x can be the m a i n mercury c o m p l e x i n g agent w h e n their relat ive abundance is h i g h ( M e i l i 1997). T h i s is indicated b y coenrichment i n d i sso lved and anoxic waters and as so l id precipitates i n a var ie ty o f boreal , temperate and t ropical sediments. I ron and manganese ox ides m a y also regulate the potential for methyla t ion b y scavenging organic and sulfur b i n d i n g sites (Reggne l l et al. 2001). R e g n e l l etal (2001) have identif ied a correlat ion between Fe, M n and M H g i n water o f seasonally stratified lakes. Jacobs et al, (1995) studied an urban, eutrophic lake near Syracuse, N e w Y o r k , that experiences summer stratification, s imi la r condit ions to B u r n a b y L a k e and found a strong 12 relat ionship between M H g and manganese. T h i s is expla ined b y "The reduct ion o f F e (III) requires a l ower redox potential (or pe) than M n . In addi t ion, the ox ida t ion o f F e (II) i n the presence o f oxygen is t yp i ca l ly ve ry rapid; thus, F e diffusing across the redoxoc l ine is r ap id ly converted to the particulate fo rm [Fe (III)]. M n ox ida t ion kinet ics are s lower , and M n ox ida t ion has been attributed to M n - o x i d i z i n g bacteria that are present at the r edoxoc l ine" (Jacobs et al. 1995). 1.7 Mercury and methylmercury in aquatic systems A q u a t i c c y c l i n g o f mercury is a compl ica ted process that invo lves m a n y pathways (Figure 1.2). Inorganic mercury and organic mercury (forms o f methylmercury) are distributed and behave ve ry differently i n var ious aquatic systems (discussed i n section 1.5). Inorganic mercury i n a freshwater lake w i l l also bond w i t h a var iety o f substances and take m a n y forms. T h e major i ty o f inorganic mercury i n a freshwater system is bound to sediment. W i t h i n a lake system, it is possible for the top 3 mi l l imeters o f sediment to h o l d the equivalent mass o f mercury as the entire ove r ly ing b o d y o f water ( M e i l i 1997). W i t h i n water, mercury is bound b y sulfur, d i sso lved organic carbon ( D O C ) and inorganic complexes , such as M n O x and F e O x . O n l y a smal l fraction o f mercury is found i n b io ta ( typ ica l ly around 1%), relat ive to the rest o f an aquatic system (Porce l la 1994; M e i l i 1997). Converse ly , methylmercury does bioaccumulate i n b io ta b y b iomagni f i ca t ion and bioconcentrat ion ( M e i l i 1997). T h i s can create up to a 10 4 fo ld increase i n concentrations between upper and l ower b io ta i n the food chain ( M e i l i 1997). M e t h y l m e r c u r y ( M H g ) is general ly a h igh percentage (95-99%) o f the total ' 'mercury found i n fish (Porce l la 1994; M e i l i 1997). F i s h accumulate M H g through g i l l s and food; therefore, foraging habits and p r o x i m i t y to sediment regulates uptake (Porce l l a 1994). It is e l iminated ve ry s l o w l y f rom the l ive r , k i d n e y and spleen ( M e i l i 1997). T h e concentrat ion o f mefhymercury i n b io ta is thought to depend on the rate o f methyla t ion and demethylat ion w i t h i n the system and the substrate to w h i c h the ingested mercury is bound ( M e i l i 1997). M e r c u r y methyla t ion rates are the highest i n the presence o f steep redox gradients and h i g h m i c r o b i a l ac t iv i ty (Krabbenhoft 1996). T h e combina t ion o f steep redox gradients and h igh 13 Figure 1.3 Concep tua l m o d e l o f mercury c y c l i n g and pathways for a t yp ica l freshwater lake (Krabbenhoft et al. 1997). DEPOSITION u Hfflt) DEPOSITION IJ/ AND RUNOFF ifl: ii AQUATIC MERCURY CYCLE DEPOSITION VOLATILIZATION AND DEPOSITION VOLATILIZATION AND OEPOSSTIGM CH3HQ0ePOSmON AND RUNOFF J METrfMTlPK- SEDIMENTATION BIOMAGNIf (CATION- t • Uti I USIOt, SEDIMENT RESUBPENStON SEDIMENTATION m / M m i c r o b i a l act ivi ty are general ly located at the h y p o l i m n i o n or i n sediment w i t h anoxic and o x i c layers (Krabbenhoft 1996; M e i l i 1997). M e t h y l a t i o n seems to be a fa i r ly consistent process w h i l e demethyla t ion is var iable ( M e i l i 1997). Deme thy l a t i on tends to be highest i n o x i c waters (Watras et al. 1994). It has two pathways, i r radia t ion from sunlight and breakdown b y mic roorgan i sms (Krabbenhoft 1996). A l t h o u g h , i t is theorized that methylmercury p roduc t ion i n the o x i c zone is important to mercury c y c l i n g because overa l l levels m a y be masked b y demethyla t ion, the loca t ion o f product ion m a y increase b ioava i lab i l i ty . T h i s cou ld lead to an increase o f M H g b ioava i l ab i l i ty i n the o x i c zone. 14 T h e current paradigm o f aquatic contaminat ion is the loca t ion and leve l o f M H g i n the water governs the leve l o f b iota contaminat ion, not inorganic mercury . Therefore, lakes w i t h the highest net product ion o f M H g have higher contaminat ion i n p i sc ivorous fish. T y p i c a l water qual i ty characteristics o f these lakes include l o w p H , a lka l in i ty , hardness and l o w overa l l b io ta product ivi ty . H i g h product iv i ty , eutrophic lakes typ i ca l ly have l o w levels o f contaminat ion i n b io ta because mercury binds to organic matter and sediments out o f the system. O v e r a l l , eutrophic lakes general ly contain more mercury i n sediments than o l igot rophic . In eutrophic lakes, organic matter binds mercury and sediments it out o f the system. La rge quantities o f p lankton and algae biomass also di lute mercury concentrations. 15 2 . CHARACTERISTICS OF THE BRUNETTE WATERSHED 2 .1 Site Description T h e Brunette Watershed is a 73 square k i lometer urban area that f lows into the Fraser R i v e r i n N e w Westmins ter ( G V R D 2001). A t least a por t ion o f the watershed is w i t h i n the munic ipa l i t ies o f Vancouver , Burnaby , N e w Westminster , C o q u i t l a m , and Port M o o d y . Cent ra l ized i n the watershed is B u r n a b y L a k e , a r ece iv ing area for the upper catchments. F i v e m a i n streams S t i l l Creek, Eag le Creek, Deer L a k e B r o o k , R a m s a y Creek and Stoney Creek feed the lake (Figure 2.1 and Table 2.1). Sub-basins were delineated for S t i l l Creek and the Brunette R i v e r w i t h the Brunette Watershed. T h e S t i l l Creek sub-basin includes catchments 1,2,3 and 7 i n F igure 2 .1 . Brunette R i v e r sub-basin includes catchments 5, 6 and 10 i n F igure 2 .1 . S t i l l Creek carries approximate ly 5 8 % o f the f l o w to B u r n a b y L a k e ( H a l l et al. 1976). T h e upper reaches o f S t i l l Creek and most other streams have a steep slope, a long w i t h its channel ized banks and culverted stretches and produces qu ick stream veloci t ies (Table 2.2). T h e lower por t ion o f S t i l l Creek (be low G i l m o r e Street) has a decreased slope, increased channel w i d t h and backwater effects f rom the lake that contribute to l o w stream veloci t ies . Stormwater drainage systems and groundwater contribute to the bu lk o f the watershed f low. T h e stormwater f l ow is considered f lashy and carries a large particulate load i n stormwater events. 16 re 2.1 M a p o f the Brunette Watershed and tributaries and catchments ( G V R D 2000a). Table 2.1 Catchment name, number and imperviousness from Figure 2.1 ( G V R D 2000a) Catchment Catchment number Imperviousness (%) U p p e r S t i l l Creek 1 68 M i d d l e S t i l l Creek 2 58 L o w e r S t i l l Creek 3 52 N o r t h B u r n a b y L a k e 4 0 U p p e r Brunette R i v e r 5 37 L o w e r Brunette R i v e r 6 54 Beecher Creek 7 55 Eag le Creek 8 36 Deer B r o o k L a k e 9 38 Stoney Creek 10 33 R a m s e y Creek 11 33 Table 2.2 A v e r a g e slope o f catchments w i t h i n the watershed ( H a l l et al. 1976) U p p e r S t i l l Creek S t i l l Creek to G i l m o r e St. 15 m / k m slope Burnaby L a k e G i l m o r e St. to Ca r iboo D a m 0.5 m / k m slope Brunette R i v e r Ca r iboo D a m to Fraser R i v e r 2.5 m / k m slope B u r n a b y L a k e is 140 hectare i n area, sha l low and eutrophic, w i t h a large amount o f surrounding marsh (Fi tzgera ld et al. 1991). B o t t o m waters and sediments turn anoxic i n the summer, w h i c h has resulted i n f ish k i l l s ( G V R D 2001). M e a n water depth i n 2001 was 0.97 meters ( E n k o n 2002). T h e sediments are a m i x o f silt , c l ay and amorphous peat i n marsh areas ( E n k o n 2002). F o u r but o f f ive o f the larger catchments w i t h i n the watershed f low into 18 B u m a b y L a k e . T h e water l eve l i n the lake and f l o w i n the Brunette R i v e r are control led b y the Greater V a n c o u v e r Reg iona l Dis t r ic t ( G V R D ) lake outlet at C a r i b o u D a m . Wate r l eav ing C a r i b o u D a m f lows into the Brunette R i v e r , then into the Fraser R i v e r . T h e Brunette R i v e r slope and f l o w is i n i t i a l l y moderate, but decreases as it nears the Fraser R i v e r (Figure 2.2). T h i s is due to a decrease i n slope and t idal effects f rom the Fraser R i v e r . Surrounding Burnaby L a k e is a sma l l "green space" ca l led the B u r n a b y R e g i o n a l Nature Park. A m e d i u m density residential and commercia l / indus t r ia l land-use encompass the park. T h e watershed has a his tory o f trace metals contaminat ion ( H a l l et al. 1976; Duynstee 1990; M a c d o n a l d et al. 1996a). T h i s is attributed to large sediment loads, stormwater runof f and a h igh percentage o f imperv ious surfaces w i t h i n the watershed. Land-use and imperviousness can be useful indicators o f po l lu t i on sources. Land-use changes over the last thir ty years have been moderately increasing (Table 2.3). Impermeable cover has increased 7% from 1973-1993 (Table 2.4). S ince 1993, the densi ty o f development has undoubtedly increased, but it has not been quanitfied. Table 2.3 L a n d use i n the Brunette Watershed i n propor t ion to the total area i n 1973 and 1993 ( M c C a l l u m 1995). Land Use % 1973 % 1993 % Change Resident ia l 40.8 45.7 + 4.9 Industrial 11.9 13.2 .+ 1.3 C o m m e r c i a l 3.6 4.1 + 0.5 Institutional 6.6 6.4 - 0 . 3 A g r i c u l t u r a l 1.4 0 - 1.4 O p e n Space 32.9 28 - 5 19 Table 2.4 L a n d cover i n the Brunette Watershed i n 1973 and 1993. ( M c C a l l u m 1995) Land Cover % 1973 % 1993 Permeable 66 59 Impermeable 34 41 20  2.2 Historic contamination in the Brunette Watershed T h e Brunette Watershed has become h i g h l y contaminated w i t h a w i d e range o f pollutants due to its urban environment. Stormwater load ing calculat ions for nutrients, organic matter and a few trace metals ( C u and Z n ) were the highest when compared to 22 other extensively studied locations i n the U n i t e d States ( H a l l et al. 1998). A var ie ty o f organizations have col lected informat ion about the m i c r o b i a l , organic and trace metal contaminat ion over the last 35 years. The U n i v e r s i t y o f B r i t i s h C o l u m b i a ( U B C ) , S i m o n Fraser U n i v e r s i t y ( S F U ) and the B r i t i s h C o l u m b i a Institute o f T e c h n o l o g y ( B C I T ) have c o m p i l e d valuable research about the watershed. These groups have w o r k e d together to share informat ion and f ind solutions to various environmental problems. Federal , p rov inc i a l , regional and c i ty government agencies have also moni tored the area and p rov ided funding. These studies indicate the h igh levels o f contaminants have negat ively impacted the watershed ecology. T o x i c i t y bioassays demonstrated that stormwater runo f f were pe r iod ica l ly tox ic to Daphnia ( H a l l et al. 1988). Later, ch i ronomid (Chironomus tentans) bioassays indicated that elevated contaminants i n S t i l l Creek impacted their su rv iva l rate and weight , relat ive to an unimpacted site (Smi th 1994). ( 2.2.1 Trace Metal Contaminants Basel ine trace metal contaminat ion throughout the watershed was first quantified b y H a l l et al. (1976). M c C a l l u m (1995) analyzed B u r n a b y L a k e and Deer L a k e core samples for trace metals and found a steady increase i n C u , C r , C d , and N i f rom 1950-1970. T h i s increase is attributed to land-use changes and industr ial discharges throughout that t ime frame. S ince mon i to r ing began, surface water and sediment cri teria intended to protect aquatic l i fe have often been exceeded for Pb , C u , Z n and C r ( S w a i n 1989; M c C a l l u m 1995). C o m p a r i s o n studies b y Duynstee (1990) and M c C a l l u m (1995) identif ied m a n y variables that contribute to the increase i n stream sediment concentrations. These variables inc lude land-use, automotive traffic and imperviousness. Spat ial analysis o f stream and street sediment indicates traffic contributes a large propor t ion o f the Pb , C u , M n and Z n to the watershed. A l s o , imperv ious surfaces create a pa thway for trace metals and other contaminants to be transported into waterways. 22 H a l l et al. (1976), Duynstee (1990) and M c C a l l u m (1995) a l l indicated that S t i l l Creek is the largest source o f contaminants into B u r n a b y L a k e . Duynstee (1990) and M c C a l l u m (1995) attributed contaminat ion levels to h i g h levels o f industry, automotive traffic and imperv ious surfaces. U B C conducted mesocosm f low-through experiments w i t h benthic invertebrates i n the Brunette R i v e r (Richardson et al. 1998). T h i s study found that benthic invertebrates most sensitive to heavy metals exposure were la rge ly absent f rom the Brunette R i v e r watershed and concluded that heavy metal contaminat ion throughout the watershed contributes to the degradation o f the watersheds aquatic ecosystems. M e r c u r y contaminat ion data i n the Brunette Watershed dates back to H a l l et al. (1976), w h e n the first comprehensive survey o f stream sediments was conducted. Concentrat ions o f mercury increased 294 percent f rom 1973-1993 i n streambed sediments ( M c C a l l u m 1995). Correspondingly , M n increased 1 3 1 % i n total and 2 6 0 0 % i n extractable forms respectively. M c C a l l u m (1995) suspects this large increase i n manganese oxides is a result o f automobi le combus t ion o f the gasoline addi t ive methylcyc lopentad ienyl manganese t r icarbonyl ( M M T ) . In 1992, analysis o f mercury i n three carp l ivers f rom B u r n a b y L a k e resulted i n the f o l l o w i n g concentrations 114, 99 and 128 wg/kg d ry weight ( B C I T 1992). 2.2.2 Organic contaminants Organ ic compounds can have a strong effect on mercury transport and dis t r ibut ion due to there large s ize and b i n d i n g strength. H i g h levels o f po lychlor ina ted b iphenyls ( P C B ' s ) , 1,1-bis (4-chlorophenyl)-2,2,2-tr ichloroethane ( D D T ) and chlorinate phenols have been found i n S t i l l Creek and detected throughout the watershed ( H a l l et al. 1974; H a l l et al. 1976). These are a group o f synthetic chemicals that are h i g h l y stable and were c o m m o n l y used i n industr ial and commerc ia l processes. These chemica l compounds have been proven to cause negative effects o n animals and humans, i nc lud ing cancer, i m m u n e system, reproductive system, nervous system, endocrine system and other health effects. Chlor ina ted hydrocarbon ( D D E , D D T and P C B ' s ) levels i n stream sediment have been decreasing f rom peak concentrations between 1940 - 1 9 7 0 ( M c C a l l u m 1995). T h i s indicates that increased regulat ion has been effective i n reducing chlorinated hydrocarbon levels i n the aquatic environment. 23 P o l y c y c l i c aromatic hydrocarbons ( P A H ' s ) are k n o w n carcinogens w h i c h can be der ived f rom coa l , tar and petroleum and are emitted b y combus t ion related act ivi t ies . M o r t o n (1983) presented evidence o f P A H b io -accumula t ion i n fish and attributes the stream contaminat ion to automotive sources, street deposi t ion and runoff. L a r k i n (1995) used core samples to determine that total pet roleum hydrocarbon ( T P H ) concentrations have increased tenfold over the last 200 years. A n a l y s i s o f streambed sediments indicated indust r ia l ized regions had the highest hydrocarbon levels . Transport mechanisms were also identif ied from catchment land-use (automotive activit ies) , d i lu t ion o f street runof f b y stream v o l u m e and traffic intensity o n mean hydrocarbon concentration i n stormwater. O v e r a l l , pub l i c awareness and po l lu t i on prevent ion practices have been implemented to reduce the overa l l levels o f trace metals and hydrocarbons. A l t h o u g h , P A H ' s are l i k e l y s t i l l increasing due to r i s ing automotive use. 2.2.3 Microbial Contaminants Feca l co l i f o rm is a classif icat ion o f bacteria used to identify the presence o f human waste contaminat ion. H i g h levels o f fecal c o l i f o r m have been detected i n the watershed for sometime. T h i s is due to a combinat ion o f urban runof f and l eak ing or i l l ega l stormwater cross-connections to sewer l ines. M o n i t o r i n g has ident i f ied h igh levels i n S t i l l Creek and contaminat ion throughout the watershed. T h i s has caused the closure o f waterways throughout the watershed to pr imary contact recreational activit ies for sometime ( H a l l et al. 1998). 24 3. METHODS Labora tory analysis methods w i l l be described i n sub-section 3.3 (Laboratory analysis) . 3.1 Streambed sediment sampling and analysis A q u a t i c sediments b i n d trace metals, govern aquatic tox ic i ty and affect transport processes. The his tor ic var ia t ion o f trace metal contaminat ion i n streambed sediment 's were determined i n this urbanized watershed through streambed sampl ing , analysis and then compar i son to his tor ic data (1973-1993). T h i r t y streambed sediment samples were col lected and analyzed for a compar i son w i t h his tor ic data col lected over the last 30 years. S a m p l i n g locat ions and analyt ical methods used i n H a l l et al. (1976) were also used i n this study for data compatabi l i ty (Figure 3.1). Statistical analysis was then used to l ook for his tor ic trends and associations. Statist ical analysis was also used to ident ify correlations between metals and sediment quali ty. These correlations cou ld improve knowledge o f aquatic geochemistry w i t h i n the watershed. 25  3.1.1 Streambed sediment locations T h i r t y sampl ing locations were used to replicate previous w o r k b y ( H a l l et al. 1976; Duynstee 1990; M c C a l l u m 1995) b y us ing the same site locations and ident i f icat ion numbers. Some sites had to be excluded due to urban development (Table 3.1). Tab le 3.1 Loca t ions excluded due to urban development Site number Desc r ip t ion o f locat ion #5 S m a l l stream north o f Trans-Canada H i g h w a y . Wes t o f Har t St. between R o d e r i c k and Henderson St. Feeds Brunette R i v e r d i rec t ly above site #4. Appears to have been culverted for new housing. #23 S t i l l Creek at Sper l ing A v e n u e . Loca ted after the confluence o f Beecher Creek and S t i l l Creek. Inaccessible f rom the road. #28 Beecher C r at W e s t l a w n D r . Appears to have been culverted for new housing. #12, 18, 22 and 36 E x c l u d e d from ( M c C a l l u m 1995) due to cu lver t ing between 1973 and 1994. J 3.1.2 Sediment sample collection Sediment samples were col lected w i t h an a l u m i n u m pot attached to a three meter wooden pole from a m i n i m u m o f five composi te locations w i t h i n the site, ( H a l l et al. 1976). Excep t for site #1, i n w h i c h replicate samples were obtained w i t h an E k m a n Dredge. Samples were screened w i t h a 2 m m plast ic sieve to remove larger mater ial and sealed i n double layer, high-strength plast ic bags for storage. Samples were stored i n < 4 ° C refrigerator p r io r to sample preparation. S a m p l i n g occurred o n A p r i l 26, 27 and 30, 2003 . 27 3.1.3 Sediment sample preparation and analysis Sediment samples were r emoved from the refrigerator and a l l owed to w a r m to r o o m temperature before analysis preparation. Then , the samples were sub-div ided, w i t h a por t ion o f sediment r emoved for a wet vs dry compar ison. T h e other por t ion was used i n the metals analysis. Samples were analyzed wet, then dried at 105 ° C for 24 hours and reanalyzed to determine the percentage o f mercury lost i n the d ry ing process. Sample preparation for metals analysis was the same as previous studies ( H a l l et al. 1976; M c C a l l u m 1995) to a l l ow for a consistent compar i son o f data. T h i s por t ion was wet- s ieved w i t h a stainless steel 180 wm sieve; d i s t i l l ed water was used to increase particulate recovery. S i e v i n g was intended to reduce spatial bias created b y va ry ing part icle sizes at different locat ions when a composi te sample is taken. T h e <180 um sediment fraction was dr ied i n a 105° C oven for a m i n i m u m o f 24 hours. Sub-samples o f the dr ied sediment were prepared for var ious analyses. 3.2 Lake sediment microcosm experiment 3.2.1 Microcosm sample collection Sediment and water samples were col lected f rom the B u r n a b y L a k e r o w i n g center o n N o v e m b e r 17, 2002. Wate r samples were taken w i t h a large, ac id-washed plast ic container. Sediment samples were taken o f f the northwest corner o f the B u r n a b y L a k e R o w i n g Center ' s f loat ing dock w i t h an a l u m i n u m pot on the end o f a 3-meter wooden pole . Sediment was then p laced into double plast ic bags and frozen w i t h i n 6 hours o f sampl ing . 3.2.2 Microcosm Laboratory Experiment Labora tory experimentat ion was intended to replicate seasonal redox condit ions w i t h i n the lake. It a l l owed for a control led, contained setting w i t h l im i t ed variables. T h e experiment attempted to identify the reactions o f metal hydroxides b y compar ing releases i n anoxic and o x i c condit ions w i t h i n sediment and the o v e r l y i n g water. There was a three-week tr ial experiment from N o v e m b e r 17 to December 9, 2002 w i t h 4 separate mic rocosms (Exper iment 1), fo l lowed b y a 6 m i c r o c o s m study f rom February 9 to M a r c h 25, 2003 (Exper iment 2), [Figure 3.2]. 28 Figure 3.2 D i a g r a m o f a s ingle m i c r o c o s m wi th traps. gas flow intake to microsom 0 o o o I gas flow from microcosm to mercury traps water sediment gas flow exhaust mercury trap 29 T h e m i c r o c o s m setup process was s imi la r for both Exper iment 1 and Exper iment 2. T h e glass mic rocosms and traps had a respective 1.5 and 0.1 l i ter vo lume . T h e so i l was s ieved w i t h a 2 m m plastic screen to remove large particulates, then centrifuged at 4000 r p m for 30 minutes to remove most o f the interstit ial porewater. A 100 grams o f wet sediment was placed i n each m i c r o c o s m . The average concentrat ion o f mercury i n the sediment was 550.7 ppb. 1.2 L o f 20 um filtered lake water was gently poured into mic rocosms 1, 3 and 4. D e - i o n i z e d water was added to #2. M e r c u r y traps were filled w i t h 90 m L o f potass ium permanganate solut ion ( 0 . 5 M K M n 0 4 i n 10% ni t r ic acid) to capture any vo la t i l i z ed mercury. M i c r o c o s m 4 had 20 m m o l / L molybdate ions (4.84g @ 241.95 g/mol) added to inhib i t mercury methyla t ing bacteria (Regne l l 1994). T h e glass containers were wrapped i n b lack plast ic to prevent l ight induced vo la t i l i za t ion o f mercury. T h e mic rocosms were a l l owed to settle for one day before sampl ing and the gas f lows were started. A i r was pumped at a s l ow rate into the aerobic m i c r o c o s m 1. N i t rogen gas was b l ed into mic rocosms 2, 3, and 4 at a s imi la r rate to create anoxic condit ions i n the m i c r o c o s m . T h e mic rocosms were operated at ambient laboratory temperature ( « 2 0 ° C ) . Ind iv idua l m i c r o c o s m condi t ions for Exper imen t O n e and T w o d i sp layed respect ively i n F igure 3.3 and F igure 3.4. 30 Figure 3.3 Exper iment I, four different mic rocosms were set-up for the in i t i a l three-week tr ial run. 100 grams o f homogenized sediment and 1.2 liters o f water was placed i n each m i c r o c o s m . / 1 (1) (2) - L a k e sediment - L a k e sediment v - L a k e water - D . I . water - A n o x i c ( N 2 gas) - A n o x i c ( N 2 gas) 1 ^ (3) (4) - L a k e sediment - L a k e sediment - L a k e water - L a k e water - O x i c (air gas) - A n o x i c ( N 2 gas) - M o l y b d a t e ions added. 31 Figure 3.4 Exper iment II, s ix mic rocosms were set-up w i t h the same parameters as the first run for the s ix week analysis. E a c h contained 100 g o f sediment and 1.2 L lake water. T h e f o l l o w i n g variables were i n each m i c r o c o s m : 2) Bu rnaby L a k e sediment Burnaby L a k e water A n o x i c ( N 2 gas) 4) S t i l l Creek Sediment S t i l l Creek Water O x i c ( A i r gas) 6) Bu rnaby L a k e sediment B u r n a b y L a k e water A n o x i c (N2 gas) M o l y b d a t e ions added 1) S t i l l Creek Sediment S t i l l Creek Water A n o x i c (N2 gas) 3) S t i l l Creek Sediment S t i l l Creek Wate r M o l y b d a t e ions added A n o x i c (N2 gas) 5) Bu rnaby L a k e sediment B u r n a b y L a k e water O x i c ( A i r gas) 32 3.2.3 Microcosm sampling S a m p l i n g was performed w e e k l y b y us ing ac id washed plast ic syringe and tubing to wi thdraw 120 m L o f water f rom the m i d d l e o f each m i c r o c o s m . H a l f o f each sample was fil tered w i t h a 0.45 wm hydrophobic filter and then subdiv ided for metals, mercury and D O C analyses. E a c h mercury sample was preserved w i t h 2 m L / L H C I i n ac id washed bottles, metals w i t h 2 m L / L H N 0 3 and D O C w i t h 2 m L / L H3PO4 (Phosphor ic A c i d ) . Wate r qual i ty measurements were performed o n the D O C sample to avo id contaminat ion o f the metals or mercury sample. A l t h o u g h the U . S . Env i ronmenta l Protect ion A g e n c y (1999) requires "ul t ra-clean" procedures for sampl ing and storage o f mercury samples i n water; recent studies have indicated that storage i n P E T and H D P E plast ic bottles is acceptable for mercury samples at or above 0.5 ng/1 (Fad in i et al. 2000; H a l l etal. 2002). Therefore, P E T and H D P E plast ic bottles were used i n this study. 3.2.4 Microcosm analysis methods Speci f ic conductance, p H , d isso lved oxygen and D O C were analyzed accord ing to methods i n section 3.3.7, mercury i n waters 3.3.3 and mercury i n so i l 3.3.4. A l l samples were analyzed w i t h i n 7 days o f the m i c r o c o s m comple t ion . 3.3 Laboratory Analysis 3.3.1 Aqua-Regia digest T o prepare stream sediment for trace metal analysis, a 1.0 + 0.01 gram, homogeneous dry weight sample was digested w i t h and 4 m L o f (1+1) ni t r ic ac id and 10 m L o f (1+1) hydroch lo r ic ac id . The sample was ref luxed o n an 8 5 ° C hot plate for 30 minutes. Af te r coo l ing , the sample was brought to v o l u m e i n a 100 m L vo lumet r i c flask. The sample was g iven t ime to settle before analysis on the I C P (refer to 3.3.2). 3.3.2 Trace Metals S o i l samples were aqua regia digested and analyzed w i t h an I C P - A E S ( U B C S o i l Science L a b ) . Iron and manganese concentrations were determined b y ana lyz ing undigested m i c r o c o s m water samples w i t h a V a r i a n S p e c t r A A 220 flame A A ( U B C C i v i l Eng ineer ing 33 Laboratory) . A four-point curve was used for cal ibrat ion. T h e detection level for i ron and manganese was 50 ppb. 3.3.3 Mercury in Waters C o l d B r C l digestions o f water samples were analyzed w i t h a M i l l e n n i u m M e r l i n P S A 10.025 b y c o l d vapor a tomic fluorescence spectroscopy ( C V A F S ) ( A n a l y t i c a l 2001). T h e method detection l i m i t o f the instrument (4.1 n g / L ) was calculated as (n-1 @ 9 9 % confidence) mu l t i p l i ed b y the standard devia t ion o f 10 samples. A 30 m L sample was digested b y adding 7.5 m L o f 3 3 % H C 1 and 1 m L o f 0. I N potass ium bromate/potassuim bromide then brought to a 50 m L total v o l u m e w i t h de ionized water. T h i s solut ion was capped and a l lowed to stand for no less than 30 minutes. Immediate ly p r io r to analysis, 30 uL o f 4 5 % hydroxy lamine hydrochlor ide was added to remove any remain ing bromine . T h e instrument was calibrated w i t h a f ive point curve w i t h a m i n i m u m linear regression o f 0.995. A b lank and check sample, o f k n o w n concentration, was run after every 20 samples to ensure data qual i ty and reduce instrument drift. 3.3.4 Mercury in sediments Sediment samples were analyzed w i t h a L u m e x R A - 9 1 5 M e r c u r y A n a l y z e r w i t h a Z e e m a n processor used for interference and background correct ion ( L u m e x 2001). A 9 0 0 ° C pyro lys i s oven ionizes the undigested sediment sample before it was vacuum pumped into the A A ce l l . The instrument was calibrated w i t h var ious concentrations o f H g + 2 mercury standard i n methy l a lcohol . T h e methyl a l coho l so lu t ion was a l l owed to evaporate at r o o m temperature, l eav ing a mercury residue on the sample boat, w h i c h was then inserted into the instrument. A four-point curve was used for ca l ibra t ion w i t h a m i n i m u m linear regression o f 0.995. Instrument accuracy was measured b y the analysis o f certified reference soi ls and surrogate check samples. P rec i s ion was measured b y relat ive percent devia t ion ( R P D ) o f replicate samples. Af te r cal ibrat ion, 0.050-0.200 grams o f d ry sediment was analyzed. A blank and check sample ( o f k n o w n concentration) were analyzed after every 20 samples to ensure data quali ty. 34 3.3.5 Percent Total Carbon in sediment A L e c o induct ion furnace analyzer (model no. 572-200) i n the U B C Soi l s Labora tory was used to measure total organic carbon, us ing a sample size range o f 0.1-0.5 grams ( A P H A 1989). 3.3.6 Total Sediment Solids O n e gram o f wet sediment was weighed and dr ied for a m i n i m u m o f 24 hours at 1 0 5 ° C ( A P H A 1989). T h e sample was then re-weighted to calculate the loss o f moisture. 3.3.7 Water Quality Measurements Table 3.2 T h e f o l l o w i n g parameters were analyzed i n the U B C C i v i l Eng ineer ing Labora tory pH Measured w i t h a B e c k m a n 44 p H meter us ing "Standard M e t h o d s " ( A P H A 1989) Dissolved Oxygen. Measured w i t h a Y S I mode l 5 4 A us ing "Standard M e t h o d s " ( A P H A 1989) Specific Conductivity Measured w i t h a Radiometer C D M 3 us ing "Standard M e t h o d s " ( A P H A 1989) Dissolved Organic Carbon Samples were filtered w i t h a 0.45 wm hydroph i l i c M i l l i p o r e filter membrane and analyzed w i t h a S h i m a d z u m o d e l T O C - 5 0 0 us ing "Standard M e t h o d s " 1030 ( A P H A 1989). 3.4 Statistical analysis Non-parametr ic statistical methods o f analysis were used i n this project because the major i ty o f sample sets were not no rma l ly distributed. A l s o i n the case o f sediments, the interact ion between metals i s ve ry c o m p l e x therefore sediments cannot be considered independent variables. S u m m a r y statistics (mean, median , etc.) K r u s k a l - W a l l i s rank test and M a n n - W h i t n e y U test determined w i t h S-Plus 6.1 Student E d i t i o n . N o r m a l i t y tests were performed on 35 J M P I N vers ion 3.2.6. B o x - w h i s k e r plots and Spearman rank correlat ion coefficients were determined w i t h S P S S vers ion 11.5. B o x - W h i s k e r plots were used to d isp lay distr ibutions o f analyt ical values (Figure 3.5). T h e box contains 50 percent o f the values w i t h a l ine i n the b o x representing the median . The absolute difference o f the box ends are labeled Hspreads. The "whi ske r s " extend 1.5 Hspreads f rom either d i rec t ion o f the box . A n asterisk designates samples between 1.5 and 3 Hspreads, w i t h values greater than 3 Hspreads plotted w i t h an open ci rc le . T h e M a n n - W h i t n e y U test compares two non-parametric samples to determine i f they are from the same popula t ion. T h e K r u s k a l - W a l l i s test is a non-parametric method o f compar ing means/medians o f more than two populat ions. Spearman rank correlat ion coefficients a id i n the ident i f icat ion o f relationships between variables. Bonfe r ron i ' s Cor rec t ion was used to calculate the s ignif icance o f more than two correlations for Spearman's rank correlat ion coefficients. A n y data point b e l o w the detection l i m i t o f the instrument was g iven a value o f h a l f the instrument detection l imi t . A l t h o u g h there are more sophisticated and t ime-consuming methods that p rov ide a better estimate o f the true value (E l -Shaarawi 1989, Gi lbe r t 1987), this is also a standard method for addressing censored ("less-than" or " b e l o w detection l im i t " ) data. T h e mean was used for smal l populat ions (n<20) and the med ian was used for large populat ions (n>20) to l i m i t the inf luence o f ou t ly ing data points (Zar 1996). 36 Figure 3.5 B o x - w h i s k e r diagram. A d a p t e d from M c C a l l u m (1995) — whiskers K- hspread -̂ 1 median 37 4. RESULTS AND DISCUSSION 4.1 Data quality A n attempt was made to avo id deviat ions i n previous methods to a l l o w for v a l i d comparisons between data sets. In some cases, newer methods, instruments or technology were used to improve data qual i ty (Table 4.1). Depend ing o n the method or analyst, various data qual i ty control methods were used to ensure accuracy and precis ion. B l a n k s , sample spikes and check samples (o f k n o w n concentration) were used every 20 samples to ensure data qual i ty for mercury, water and so i l samples ( A p p e n d i x J). Sample spikes were used to check accuracy and determine the amount o f matr ix interference w i t h i n mercury samples. I f mercury data qual i ty objectives were not met, the instrument was re- calibrated and the samples were reanalyzed, (i.e. <20% relative percent difference ( R P D ) or between 75 -125% surrogate spike recovery) . Cer t i f i ed reference sediments were ana lyzed for trace metals sediment analysis (Table 4.2). A n t i m o n y and potassium were out o f range for sediment Q C reference samples but these are not elements o f p r imary concern i n this study. It should be noted that potass ium is k n o w n to be a diff icul t metal to analyze o n an I C P . C h e c k s and blanks were used to m i n i m i z e instrument drift and m a x i m i z e prec i s ion for a l l samples. Tab le 4.1 C o m p a r i s o n o f methods used i n stream and lake sediment analysis i n 1973, 1989, 1993 and 2003 ( H a l l , 1976; M c C a l l u m , 1995) Measurement Digest and Analysis Technique 1973 1989 1993 2003 Fe, M n , M g , C d , Pb , C u , Z n , N i HNO3-HCIO4/ F l a m e A A H N O 3 - H C I O 4 / I C P HNO3 / F l a m e A A Aqua-Regia digest / I C P C r Di rec t analysis / D C - a r c Spectrography HNO3-HCIO4/ I C P HNO3 / F l a m e A A Aqua-Regia digest / I C P H g H 2 S 0 4 - H 2 0 2 - K M n 0 4 H y d r o x y l a m i n e / C o l d vapour H 2 S 0 4 - H 2 0 2 - K M n 0 4 H y d r o x y l a m i n e / C o l d vapour H 2 S 0 4 - H N 0 3 - K M n 0 4 H y d r o x y l a m i n e / C o l d vapour L u m e x A A w i t h Zeeman processor and pyro lys i s attachment 38 Table 4.2 Qua l i t y control data for sediment metals analysis. Resul ts i n ug /kg , dry wieght . Envi ronmenta l Resource Associa tes : Reference Sample Ca ta log #540 L o t # D035-540 . Element/ M e t h o d L i m i t s mg/kg (from website) 5-Aug-03 7-Aug-03 10-Aug-03 A v e W i t h i n l imits A l 1 1000-50000 2614 3 3 2 2 3593 3176 Y A s 1 50-400 174.8 190.3 167.3 178 Y B ' 80-200 127.3 140.5 128.2 132 Y B a 1 80-3000 361.9 414.5 371.1 383 Y C a 1 1500-25000 3036 3334 2986 3119 Y C d 1 40-300 125.3 136.1 119.8 127 Y C o 1 30-200 53.11 57.75 52.46 54 Y C r 1 40-300 117.7 129.6 118.2 122 Y C u 1 40-200 85.53 93.88 85.18 88 Y F e ' 1000-22000 5069 6378 7292 6246 Y K 1 1400-25000 1070 1387 1469 1308 N M g 1 1200-25000 1260 1501 1509 1423 Y M n 1 150-2000 282.9 314.9 287.3 295 Y M o 1 5-250 56.70 62.19 57.89 59 Y N a 1 150-15000 248.8 282.1 296.0 276 Y N i ' 40-250 168.1 183.7 161.3 171 Y P 1 N / A 391.6 424.9 411.1 409 Y P b ' 50-250 155.6 170.1 153.9 160 Y Se 1 50-250 86.95 96.99 89.33 91 Y S i 1 N / A 560.9 594.8 884.8 680 Y S b 1 200-2000 144.0 161.3 144.7 150 N s 1 N / A 1.7 N / A N / A 1-7 N / A Z n 1 70-1500 223.1 245.6 220.1 230 Y H g ' 21.6-26.5 23.5 N / A N / A 23.5 Y Methods: 1. Aqua-Regia digestion analyzed with ICP 2. Lumex A A with pyrolysis oven 39 4.1.1 Variability between sample and methods: Determining the effects of drying samples M e r c u r y and some o f its complexes are vola t i le at r o o m temperature and pressure. Therefore, a por t ion o f mercury w o u l d be lost w h e n dr ied i n a 105° C oven, as described i n Sect ion 3.1.3. The effects o f d ry ing 2 m m sieved sediment samples were determined i n a smal l experiment w i t h 27 samples. W e t samples were analyzed before d r y i n g then there concentrations were adjusted based the percent o f moisture i n the so i l . T h i s was performed to estimate the amount mercury lost b y d r y i n g the <180 u m samples. T h e W i l c o x o n Pai red Sample S igned R a n k Test was used to determine that wet and d ry sample sets are s ignif icant ly independent. T h e wet samples lost a mean 66 .8% o f their mercury content w h e n dr ied (Figure 4.1). The h i g h var iab i l i ty i n the wet samples is not seen i n the dry samples. D r y i n g samples seems to normal ize the dis t r ibut ion b y l o w e r i n g the highest wet levels considerably. A compar i son o f <180 win and 2 m m fractions is diff icul t because o f the h i g h va r i ab i l i ty o f the wet samples relat ive to the dry. U s i n g smaller fractions o f sediment samples t yp i ca l l y increases the metal concentration o f the sediment ( W i l b e r and Hunter 1979). It is not l og ica l to assume the <180 um sediment fraction w o u l d have lost at least an equal percentage o f mercury as the 2 m m fraction. D u e to its higher concentrations, the <180 wm fraction is l i k e l y to have a higher bond ing strength than the larger fraction. Smal le r particles have a higher surface area, therefore a higher bond ing strength. 40 Figure 4.1 B o x - w h i s k e r plots compar ing mercury concentrations i n 2 m m wet vs dr ied stream sediment at 1 0 5 ° C (n=27) 140 120 100 Hg 80 (wg/kg) 4.2 Microcosm Experiments T h e intent o f the m i c r o c o s m experiments was to create control led reduct ion and ox ida t ion (redox) condit ions to m i m i c seasonal changes w i t h i n B u r n a b y L a k e . O x y g e n levels , bacterial ac t iv i ty and water chemistry were control led throughout the experiment. T h e d i sso lved oxygen ( D O ) i n the o x i c m i c r o c o s m was never recorded b e l o w 5.35 m g / L . In the mic rocosms filled w i t h ni trogen gas, the D O was never recorded above 0.50 m g / L after the first week. Regardless o f the type o f water or gas i n the m i c r o c o s m , mercury was released from the sediment into the water F igure (4.2-4.5). 41 Figure 4.2 M i c r o c o s m 1 conta ining lake sediment, lake water under, anoxic condi t ions, for Exper iment 1 11/18/02 11/25/02 12/2/02 12/9/02 Figure 4.3 M i c r o c o s m 2 containing lake sediment, de- ionized water and under anoxic condit ions, for Exper iment 1 0.0 -I r , , r - l 11/18/02 11/25/02 12/2/02 12/9/02 42 Figure 4.4 M i c r o c o s m 3 conta ining lake sediment, lake water under o x i c condi t ions, for Exper iment 1 2.5 ^ 2.0 o) 1.5 11/18/02 11/25/02 12/2/02 12/9/02 Figure 4.5 M i c r o c o s m 4 conta ining lake sediment, lake water w i t h molybdate ions added under anoxic condit ions, for Exper iment 1 2.5 2.0 O) 1.5 1.0 G) X 0.5 0.0 11/18/02 11/25/02 12/2/02 12/9/02 43 Leve l s o f mercury w i t h i n the mic rocosms were quite h igh (Table 4.3). T h e y ranged f rom 0.100-2.092 ug/L. T h e highest release o f mercury and i ron was i n M i c r o c o s m 1. The second chamber released less mercury than m i c r o c o s m 1 indica t ing the de ion ized water m a y have s l igh t ly inhibi ted the release o f mercury poss ib ly due to the lack o f c o m p l e x i n g substrate indicated b y is s l ight ly l ower D O C concentrations ( A p p e n d i x E-4 ) . T h e o x i c m i c r o c o s m (3) increased 2 2 9 % over four weeks. It is diff icul t to determine the sediments remained o x i c or anoxic throughout because o n l y the water was tested. Resp i ra t ion o f bacteria i n the sediment m a y have lowered the oxygen content i nduc ing the release o f the metals. T h e anoxic m i c r o c o s m (4) w i t h molybdate ions added had an increase o f 16%. M o l y b d a t e ions inhib i t bacterial g rowth and have been shown to el iminate product ion o f methy lmercury b y sulfate reducing bacteria (Regne l l et al. 2001). Therefore, o n l y geochemica l releases o f mercury w o u l d be observed i n the m ic r ocos m . T h i s cou ld indicate the increases i n the other mic rocosms were due to reduct ion o f mercury bound to sulfate b y methylmercury p roduc ing bacteria. 44 Table 4.3 Percent increase o f mercury and i ron i n four mic rocosms over four weeks i n experiment 1. Manganese concentrations were a l l be low the 50 wg/L detection l imi t . Microcosm Hg increase over 4 weeks (%) Hg increase over 4 weeks (t/g/L) Fe increase over 4 weeks (%) Fe increase over 4 weeks ML) 1. Anoxic with lake water 1912% 1.99 1974% 2.13 2. Anoxic w/ DI water 444% 1.33 29% 0.18 3. Oxic 229% 0.40 59% 0.27 4. Anoxic with bacteria inhibited 16% 0.03 8% 0.13 45 Data analysis reveals that i ron and mercury had a correlat ion coefficient o f 0.599 but it was not statistically significant due to the smal l sample size. D O C and p H had a statistically insignif icant posi t ive correlat ion coefficient o f 0.745, a= 0 .031. D O and p H had a stat ically significant inverse correlat ion o f - 0 . 6 4 9 , ct=0.006. T h e data for the m i c r o c o s m experiments is located i n A p p e n d i x E . Refer to A p p e n d i x E for m i c r o c o s m data. In a l l o f the mic rocosms , mercury was predominate ly associated w i t h the d i sso lved phase. Particulate concentrations ranged f rom 6 . 6 % - 1 4 . 2 % . Iron was associated w i t h the particulate phase f rom 54 .2%- 96 .3%. T h i s does not exclude mercury f rom b i n d i n g w i t h i r on because d isso lved i r on concentrations are s t i l l around 100 t imes greater than the d i sso lved mercury concentration. Manganese concentrations were a l l b e l o w the detection l i m i t o f 50 ug/L, ind ica t ing that ve ry l i t t le, i f any was released into the o v e r l y i n g water. Ei ther manganese oxides were not at h igh concentrations i n the sediment or they released then re-sorbed b y sulfur before they cou ld be dispersed into the water co lumn . Manganese has a higher reduct ion potential than i ron , therefore it w o u l d reduce first, a l l o w i n g it to f i l l up any o f the avai lable c o m p l e x i n g sites i n the so i l , p robably w i t h sulfur (Jacobs et al. 1995). In addi t ion, the ox ida t ion o f i r on is t yp i ca l ly ve ry rapid ( L a i m a et al. 1998). Therefore, i r on diffusing across the redoxcl ine is r ap id ly converted to the particulate form. Manganese ox ida t ion kinet ics are s lower compared to i ron , and manganese ox ida t ion has been attributed to M n - o x i d i z i n g bacteria that are present at the redoxc l ine (Jacobs et al. 1995; L a i m a et al. 1998). Regne l l et al. performed s imi la r m i c r o c o s m studies but also added radiolabeled 2 0 3 H g C l (Regne l l et al. 1991; R e g n e l l 1994; R e g n e l l et al. 1996; R e g n e l l et al. 2001). In 1991, they found s ignif icant ly more mercury i n the water for the anaerobic columns. O n average, 6 9 % o f mercury was i n the d isso lved form. T h e y concluded that the o x i c sediment was able to b i n d four t imes more mercury than anoxic sediment, most l i k e l y due to the presence o f hydrous ferric oxides . In 1996, they found an average 4 3 % increase i n mercury i n the anoxic water over the o x i c , compared to an average 69 .4% increase i n this experiment. Rad io l ab led 2 0 3 H g was found to constitute 80-90% o f the total methy lmercury i n anoxic water, but o n l y 40 -60% o f the extractable. T h i s m a y indicate that the product ion o f methy lmercury was occur r ing w i t h i n the mic rocosms 1-3 i n this experiment. 46 M e t h y l m e r c u r y analysis was planned for M i c r o c o s m Exper iment 2 samples but was not performed due to contaminat ion problems i n the experiment. F igure 4.6 indicates that mercury i n the mic rocosms under s l igh t ly ac id ic or neutral and o x i c condit ions associate predominant ly w i t h oxide/hydroxides . U n d e r reducing condi t ions, convers ion to meta l l i c mercury increases as p H decreases. Therefore, it seems j that i n the o x i c mic rocosms , mercury m a y have been converted f rom ox ide /hydrox ide to mercury (II) as the p H dropped o n December 2, 2002. In the anoxic mic rocosms , mercury was probably converted f rom oxide /hydroxide to meta l l ic mercury. F igure 4.6 D i a g r a m o f E h - p H for mercury i n aquatic systems. A d a p t e d f rom ( V e i g a and M e e c h 1998). 2 r—i— I II i — I I I — i — i — r — i i—T pH : results f r o m P o c o n e after S i l v a et al. (1991) 47 M e r c u r y was vo la t i l i z ed i n a l l o f the anoxic systems. T h e first two traps contained 242 and M l ug/L respectively. T h e fourth contained 104 wg/L, ind ica t ing that bacteria inhib i ted b y molybdate m a y have reduced mercury vo la t i l i za t ion . T h e o x i c trap became c logged and over f lowed w h i c h m a y have resulted i n contaminat ion o f the trap. In m i c r o c o s m experiment two, the s ix-week m i c r o c o s m was completed. H o w e v e r the mercury samples were r andomly contaminated before analysis. T h e mos t l y l i k e l y source o f contaminat ion was leaching from reused plast ic bottles. It is l i k e l y that al though the H D P E bottles were ac id washed and r insed thoroughly, contaminat ion s t i l l leached from or permeated into the plast ic bottles. 4.3 Suspended sediments in Still Creek and the Brunette River His to r i ca l informat ion f rom a February 28, 1997 stormwater event was used i n this analysis. S i x stormwater samples were taken every two hours, a long w i t h sediment col lected b y a Wes t fa l i a Separator mode l K A - 2 - 0 6 - 1 7 5 continuous f low centrifuge. A n attempt was made to col lect stormwater samples for this study to compare w i t h h is tor ica l data but was unsuccessful. In January 2003 , stormwater samples were col lected f rom S t i l l Creek and the Brunette R i v e r . T h e samples were not analyzed due to an in-operat ional f l ow meter and contaminat ion problems w i t h i n the trace mercury laboratory. Other stormwater sampl ing events were p lanned but never occurred due to insufficient precipi ta t ion throughout the 2003 summer. Seke la et al (1998) results o f the stormwater event indicated that the Brunette R i v e r had higher mercury concentrations i n suspended sediments than S t i l l Creek (Table 4.4). T h i s trend is not seen i n any o f the other metals tested except for manganese. T h i s is unusual because S t i l l Creek is k n o w n to have higher levels o f sediment contaminat ion than the Brunette R i v e r ( H a l l et al. 1976; M c C a l l u m 1995). It is also unusual because B u r n a b y L a k e is thought to act as a sediment and contaminant s ink for the watershed, as s h o w n i n l ower turbidi ty levels i n the Brunette R i v e r . Furthermore, i n the same storm event, S t i l l C reek ' s total mercury concentrations i n water were higher than the Brunette R i v e r ' s (Figure 4.7). 48 Table 4.4 To ta l metal concentrations i n suspended solids col lected w i t h a continuous f l o w centrifuge dur ing a February stormwater event on the Brunette R i v e r system, concentrations i n m g / k g , dry weight . [Data f rom Sekela et al. (1998)] Parameter Brunette R i v e r S t i l l Creek Suspended sol ids 34.3 47.6 H g 0.615 0.146 F e 54800 80800 M n 2900 1260 P b 175 254 Z n 557 772 F igure 4.7 A B o x - w h i s k e r plot o f total mercury concentrations i n stormwater over a stormwater event, units i n n g / L [Data from Sekela et al (1998)] 50 40 30 Hg 20 10 0 Brunette River Still Creek There are a few possible explanations for this anomaly. B u r n a b y L a k e acts as a settl ing bas in as indicated b y the lower concentration o f suspended sediments i n the Brunette I o 49 R i v e r (Table 4.4). T h e first poss ible explanat ion is a natural or anthropocentric source o f mercury either i n the Brunette R i v e r or Stoney Creek. T h e second poss ib i l i ty cou ld be contaminat ion samples, w h i c h is a lways a poss ib i l i ty when w o r k i n g w i t h trace metals analysis. C l e a n methods were not specif ied i n the report. F i n a l l y , it is also possible that the sediment is desorbing mercury and manganese into the o v e r l y i n g water when anoxic condit ions exist. T h i s w o u l d exp la in the increase i n mercury and manganese concentrations i n Brunette R i v e r suspended sediments. T h e oxides that bond manganese and mercury i n the sediment w o u l d b reakdown under anoxic condit ions, thus releasing o x i d i z e d metals into the interstitial pore water and ove r ly ing water where they w o u l d re-associate w i t h suspended particulate matter or D O C (Regne l l et al. 2001). Increased f l o w through the lake cou ld m o b i l i z e mercury reduced i n the lake ' s water, s imi la r to the releases seen i n the m i c r o c o s m experiments. Studies have shown that lakes w i t h marshes have higher mercury concentrations then those wi thout (Hur l ey et al. 1995; B a b i r z et al. 1998; Sonesten 2002). T h e mean mercury concentration o f stream sediments i n the S t i l l Creek sub-basin is 61.3 wg/kg. B u r n a b y L a k e has an average concentration o f 142 wg/kg ( E n k o n 2002). A l t h o u g h the lake sediment is less l i k e l y to be suspended i n a stormwater event, it w o u l d l i k e l y have an impact on downstream concentrations. T h e higher lake concentrations m a y be due to ver t ical movement o f reduced ion ic mercury. It seems that S t i l l Creek is behaving l i k e a typ ica l urban stream w h i l e the Brunette R i v e r m a y be showing the downstream effects o f a wet land environment i n B u r n a b y L a k e . T h e lake is ve ry sha l low, eutrophic and surrounded b y marsh. T h e Brunette R i v e r had 7 2 % less suspended sol ids and 109% more total organic carbon than S t i l l Creek (Sekela et al. 1998). It is possible that mercury deposited i n the lake m a y alter bond ing associations under the lake ' s anoxic condi t ions. M e r c u r y transported into the lake bound to oxides w o u l d be released under anoxic condit ions. Then , it cou ld associate w i t h d i sso lved organic carbon ( D O C ) i n the sediment pore water or the o v e r l y i n g water, were it w o u l d be resuspended under h i g h f low condit ions. R e g n e l l et al. (2001) found an increase o f total mercury, methylmercury , i ron and manganese s imultaneously dur ing a l ake ' s summer stratification. T h e y bel ieve that these processes m a y be mediated b y b i o l o g i c a l processes, due to the pos i t ive relat ionship o f the metal oxides and methylmercury. 50 Data for each stormwater sampl ing site is located i n A p p e n d i x D . Spearman R a n k correlat ion was performed o n the data from each stormwater sampl ing site but the smal l sample size (n=8) l imi t s detailed statistical analysis ( A p p e n d i x I). Iron and mercury i n stormwater were significant at 9 5 % w i t h a coefficient o f 0.829, a=0.042 for S t i l l Creek, but was not s ignif icant ly correlated i n the Brunette R i v e r . Contrary to the total values, mercury was not s ignif icant ly related to manganese at S t i l l Creek and negat ively correlated w i t h 9 5 % signif icance i n the Brunette R i v e r . Iron, lead and manganese are correlated w i t h 9 5 % signif icance i n the Brunette R i v e r . It is diff icul t to expla in w h y mercury has an inverse relat ionship to a l l other metals at the Brunette R i v e r site but it m a y be due to lake sediments releasing mercury f rom disturbed, anoxic porewater (Benoi t et al. 1998b; H a l l et al. 1998). F l o w for both systems increased over the eight-hour sampl ing per iod . S t i l l Creek had consistent concentrations, except for one spike at 4:33 (Figure 4.8). Brunette R i v e r exhibi ts a first f lush o f h i g h contaminants at the onset o f increased f l o w (Figure 4.9). T h e Brunette R i v e r had li t t le va r iab i l i ty i n concentrations except for a drop o f 5 0 % after the first hour. It is possible that the first hour concentrations are f rom the first f lush o f Stoney Creek and storm sewers b e l o w the dam, w h i l e the increase i n f l ow and mercury is a result o f higher f l o w f rom the lake. 51 Figure 4.8 M e r c u r y concentrations i n stormwater grab samples col lected b y Env i ronment Canada i n S t i l l Creek o n February 28, 1997 (Sekela et al. 1998). Bars indicate mercury concentrations and squares indicate f low. F igure 4.9 M e r c u r y concentrations i n stormwater grab samples col lected b y Env i ronment Canada i n the Brunette R i v e r on February 28, 1997 (Sekela et al. 1998) Bars indicate mercury concentrations and squares indicate f low. 52 4.4 Burnaby Lake sediment Recent studies have been performed examin ing sediment qual i ty or contaminat ion levels i n B u r n a b y L a k e . L a k e co r ing has been used extensively as an effective method o f sampl ing for temporal and spatial trends. H i s to r i ca l data was analyzed to examine trends w i t h i n the lake sediment. M c C u l l u m (1995) col lected three cores i n the lake, two at the mou th o f S t i l l Creek and one o n the north shore o f the lake to determine the impacts o f urbanizat ion. A s a f o l l o w up, H a l l and M a t t u (1998) col lected 7 sediment cores around the mouth o f S t i l l Creek and Eag le Creek and on the north side o f B u r n a b y L a k e . These cores were analyzed for lead, copper, n i c k e l , manganese, z i n c and i r on to determine temporal trends al though both studies d i d not determine mercury concentrations. In 1999, E n k o n col lected and analyzed eighteen sediment cores f rom B u r n a b y L a k e for trace metal concentrations as part o f a p i lo t dredging program ( A p p e n d i x C ) . T h e core sediments had a m a x i m u m depth o f < 1.2 c m and were a composi te samples. Cores had a mean mercury concentration o f 0.15 m g / k g (Figure 4.10) and most o f the cores at the mou th o f S t i l l Creek had a metal concentrat ion that exceeded Env i ronment Canada ' s I S Q G guidel ine (0.174 mg/kg) ( E n k o n 2002) . 53 Figure 4.10 B o x - w h i s k e r plot o f mercury concentrations i n Burnaby L a k e core samples, concentrations i n m g / k g dry weight [n=18] ( E n k o n 2002) [Envi ronment Canada ' s I S Q G guidel ine is 0.174 mg/kg] In general, studies have found that lake sediment is made up o f c lay-s i l t material m i x e d w i t h amorphous peat i n wet land areas ( M c C a l l u m 1995; E n k o n 2002). Sediment levels o f total organic carbon ( T O C ) ranges f rom 7-14% throughout lake sediment ( E n k o n 2002). H i g h T O C levels is thought to be a combina t ion o f anthropocentric load ing and natural ly occur r ing peat and plant material . H i s to r i c sampl ing has shown that most metal concentrations typ ica l ly decrease w i t h depth. T h e except ion was lead, w h i c h is expected to decrease since it was phased-out f rom gasoline i n 1974. G w e n d o l i n e L a k e is unimpacted b y development and was used as a reference site i n the M c C u l l u m (1995) study. T h e mean mercury concentration o f two cores taken b y ( M c C a l l u m 1995) i n 1993 at G w e n d o l i n e L a k e were 0.191 m g / k g and 0.231 m g / k g . T h i s is 0.084 m g / k g higher than the mean concentration found i n B u r n a b y L a k e . Therefore, its l eve l o f mercury contaminat ion should not be above background (Table 4.5). T h e mean concentrat ion i n two cores from Deer Creek L a k e ' s was 0.233 m g / k g and 0.219 m g / k g . A l l samples are composi te core data; s imi la r to the method used i n the E n k o n study for B u r n a b y L a k e . Cores a l l exhibi ted li t t le var ia t ion w i t h depth. B o t h G w e n d o l i n e and Deer Creek L a k e 54 average concentrations are over Env i ronment Canada ' s Interna Sediment Q u a l i t y G u i d e l i n e ( I S Q G ) o f 0.174 m g / k g . T h i s m a y be due to inputs o f atmospheric mercury without the Tab le 4.5 C o m p a r i s o n o f mercury concentrations i n sediment f rom various locat ions. T h e Env i ronment Canada guidel ine I S Q C is 174 wg/kg. A l l concentrations i n dry weight . L o c a t i o n Desc r ip t ion o f area Range o f mercury concentrations (ug/kg) G w e n d o l i n e L a k e Unimpac ted , forested 181-224 Deer L a k e U r b a n 221-238 B u r n a b y L a k e U r b a n 60-440 Sweden * Remote lakes 13-300 F i n l a n d * Stratified, forest 134-277 W i s c o n s i n * Prist ine, seepage lakes 1-140 W a b i g o o n R i v e r , Canada * W o o d treatment plant 1500-3000 * (Suchanek et al. 1996) d i lu t ion o f sediment found i n Burnaby L a k e due to its h igh sedimentation rates ( M c C a l l u m 1995). M e r c u r y was detected i n a l l o f the fifteen lake core sites f rom E n k o n (2002), w i t h the except ion o f two. T h e highest observed concentration was 0.44 m g / k g , w h i c h is more than double the I S Q G o f 0.174 m g / k g . H i g h mercury levels appear to be due to stormwater f l ow into the lake from S t i l l Creek, due to spatial dis t r ibut ion. Statistical analysis indicated that mercury, manganese, i r on and lead were a l l correlated w i t h each other at 9 5 % signif icance i n B u r n a b y L a k e sediments ( A p p e n d i x G ) . M e r c u r y was s ignif icant ly correlated w i t h a l l o f the parameters. Sulfur and T O C also had a significant, posi t ive relat ionship w i t h each other. M e r c u r y ' s correlat ion was pos i t ive and significant w i t h T O C but not sulfur. T h e posi t ive relat ionship o f mercury and lead is most l i k e l y due to load ing f rom streets and drainage systems. H i g h lead and mercury concentrations are assumed to be from anthropocentric sources. A l t h o u g h lead concentrations have been decreasing over the last 30 years throughout the watershed, it has 55 been l i nked to deposi t ion o f automotive exhaust ( M c C a l l u m 1995). M e r c u r y ' s strongest correlat ion is w i t h lead, (r =0.876). S i m i l a r transport processes f rom imperv ious surfaces are a l i k e l y explanat ion for this relat ionship. 4.5 Stream sediment His to r i c data f rom H a l l (1975) Duynstee (1990) and M c C a l l u m (1995) was compared to current data f rom this study for this analysis o f trace metal concentrations i n stream sediment ( A p p e n d i x A and B ) . The methods f rom previous studies were replicated to ensure data compat ib i l i ty . The median mercury stream sediment value i n 1973, 1989, 1993 and 2003 was 22.0, 90.0, 93.0 and 57.6 m g / k g respect ively (Figure 4.11). M a n n - W h i t n e y U tests were run to determine that the levels each year were s igni f icant ly different f rom the previous, except for 1989 and 1993 ( A p p e n d i x K ) . Therefore, the mercury sediment increased s ignif icant ly f rom 1973-1989, then levels remained stat ist ically unchanged from 1989-1993. M e r c u r y levels f rom 1993-2003 have s ignif icant ly decreased b y 35.4 m g / k g . A compar i son o f stream sediment mercury concentrations and Canad ian Guide l ines and U . S . regulations was made to determine i f contaminant levels i n stream sediment exceeded guidelines (Table 4.6). It should be noted that these concentrations do not accurately represent environmental condit ions for two reasons and therefore can not accurately be compared to any guidelines or regulations. Firs t , o n l y the <180wm sediment fraction was analyzed and this is not representative o f environmental condi t ions . Second, as part o f the method used i n this study, sediments were dr ied w h i c h has been shown to vo l i t a l i ze some metals l i ke mercury. Howeve r , since a mean o f 6 7 % o f mercury was lost f rom dr ied samples i n this study, these data can be considered " m i n i m u m " values (refer to section 4.1.1). There were three samples above the Interm Sediment Qua l i t y G u i d e l i n e ( I S Q G ) l eve l o f 174 wg/kg, a l l measured i n 1993 (Table 4.6). T h e highest overa l l site was 870.0 wg/kg i n 1993, was the o n l y sample tested over Envi ronments Canada ' s probable effects l eve l ( P E L ) o f 486 wg/kg (Table 4.6). E v e n i f the 2003 screened sediment was adjusted for the estimated 66 .8% loss from dry ing the screened sediment, the lake mean concentrations are s t i l l 155% more than S t i l l Creeks concentration. 56 Figure 4.11 B o x - w h i s k e r plot o f mercury concentrations (wg/kg dry weight) i n Brunette Watershed stream sediment f rom 1973-2003. O n e outl ier excluded from 1993 at 870 wg/kg. 60 60 o 1-4 -4—» o C o o 3 o 500 400 300 200 100 1973 1989 1993 2003 57 Table 4.6 V a r i o u s federal guidelines, regulations and objectives for mercury for different water uses Organization Criteria Fresh water Sediment/Solids US EPA Regulations (U.S. E.P.A. 2003) A m b i e n t water 0.144 ug/L Freshwater- acute exposure 2.4 ug/L p i s h consumpt ion ( F D A ) 1 ng/L me thy l mercury (wet weight) . Sludge/ pub l i c lands 17 p p m Environment Canada Guidelines (Canada 2002) A q u a t i c l i fe 0.1 ug/L I S Q G 174 ug/L P E L 486 ug/L F i s h Contamina t ion 33 ug/L me thy l mercury ' (wet weight) BC Guidelines (Nagpal 2001) D r i n k i n g water 0.1 ug/L A q u a t i c L i f e (30 day A v e . ) 20 ng/L w / M e H g <0.5% T H g 10 ng/L w / M e H g < 1 . 0 % T H g 4 ng/L w / M e H g <2.5% T H g 2 n g / L w / M e H g <5.0% T H g I S Q G - Interm Sediment Qua l i t y Gu ide l i ne P E L - Probable Effect L e v e l W h e n the 1989 sediment concentrations are adjusted for the loss o f mercury associated w i t h d ry ing , concentrations were over Env i ronment Canada Interm Sediment Qua l i t y Guide l ines (174 wg/kg) at 9 sites, and Env i ronment Canada Probable Effect L e v e l 58 (486 wg/kg) at 3 sites (Table 4.7). T h e 1993 sediment concentrations adjusted for the loss o f mercury associated w i t h d r y i n g had concentrations i n had 10 sites over Env i ronment Canada ' s Interm Sediment Qua l i t y Guide l ines (174 wg/kg) and 2 sites over Env i ronmen t Canada ' s Probable Effect L e v e l (486 wg/kg) (Table 4.7). Sediment f rom 1973 d i d not exceed any o f Env i ronment Canada ' s guidelines w h i l e 2003 had o n l y one that exceeded the Interm Sediment Q u a l i t y Guide l ines (174 wg/kg) [Table 4.7]. Tab le 4.7 Adjus ted mercury concentrations i n stream sediment for a loss caused b y d ry ing that exceeded federal guidel ines w i t h i n the Brunette Watershed f rom 1973-2003 ( A p p e n d i x L ) [Concentrations i n wg/kg, d ry weight] . Y e a r o f sediment sampl ing Envi ronment Canada Interm Sediment Qua l i t y Guide l ines (174 wg/kg) Env i ronment Canada Probable Effect L e v e l (486 wg/kg) 1973(n=26) 0 0 1989(n=29) 9 • 3 1993(n=29) 10 2 2003 (n=30) 1 0 F igure 4.12 and 4.13 are box -wh i ske r plots o f surface sediments mercury concentrations i n S t i l l Creek sub-basins and the Brunette R i v e r sub-basins; Tab le 4.8 is a ratio o f mercu ry concentrations i n S t i l l C reek sub-basins and the Brunette R i v e r sub-basins. In 1973 and 1989 the levels o f mercury i n the S t i l l Creek were double i n the lower Brunette R i v e r sub-basin. T h i s study seems to indicate that mercury levels have no rma l i zed throughout the sub-basins. T h i s m a y be due to a decrease i n point sources a long S t i l l Creek and/or the dis t r ibut ion o f mercury from the upper to the l ower bas in . T h e latter is re inforced b y the increased levels o f mercury i n Brunette R i v e r suspended sediment relat ive to S t i l l Creek (Refer to section 4.63, Table 4.9). 59 Figure 4.12 B o x - w h i s k e r plot o f mercury concentrations i n the S t i l l Creek sub-basin stream sediment f rom 1973 to 2003. 1000 DO 800i (30 a e o 1 "S D O a o o o <D 200 J 600 ^ 400- 10 1973 12 1989 12 1993 12 2003 60 Figure 4.13 B o x - w h i s k e r plot o f mercury concentrations i n the Brunette R i v e r sub-basin stream sediment f rom 1973 to 2003. 160 00 20 bfl a o "ia +-» c o cs o o 3 Table 4.8 Rat io o f mercury concentrations i n the S t i l l Creek sub-basin and the Brunette R i v e r sub-basin i n sediments and stormwater over a thirty-year per iod Media and year sampled * Still Creek / Brunette River Sub basins Stream sediment 1973 1.97 Stream sediment 1989 2.44 Stream sediment 1993 2.18 Stream sediment 2003 1.05 A Spearman rank correlat ion test w i t h Bonfe r ron i ' s correct ion was performed on trace metal data i n stream sediment f rom each year to determine the extent o f significant statistical correlat ion ( A p p e n d i x F ) . I ron and manganese were s igni f icant ly related w i t h 9 5 % confidence from 1974-2003. The highest mercury correlat ion was w i t h percent sediment organic matter (0.208). M e r c u r y exhibi ted a few trends over t ime. M e r c u r y was correlated 61 to lead, copper, n i c k e l and z inc w i t h 9 9 % signif icance f rom 1973-1993. It was correlated to c h r o m i u m w i t h 9 5 % signif icance from 1989-1993. F igure 4.14 presents temporal relationships (1973-2003) o f mercury to other trace metals found i n stream surface sediments. F igure 4.14 Spearman's correlation coefficients for mercury i n 180 wm stream sediment f rom 1973-2003. Da ta located i n A p p e n d i x F . L e a d , copper, n i c k e l , z i nc and c h r o m i u m were a l l s ignif icant ly related to each other from 1973-2003. M c C a l l u m (1995) found that Pb and C r had a direct relat ionship w i t h traffic v o l u m e i n street sediment i n 1993. A contaminant ident if icat ion study identif ied vehic le exhaust emissions, tire wear and brake wear as the most significant non-point source o f P b , C u and Z n i n their study ( W o o d w a r d - C l y d e 1992; A r m s t r o n g 1994). M c C a l l u m (1995) also l i nked imperv ious area or traffic v o l u m e to P b , C u , C r , N i and Z n enrichment i n 1993 stream sed iment . Consis tent ly h igh correlations over t ime indicates that some type o f relat ionship exists, poss ib ly due to s imi la r transport mechanisms. F r o m 1974-1993 the levels o f mercury 62 i n sediments increased throughout the watershed. T h i s coincides w i t h mercury ' s correlat ion w i t h P b , C u , N i and Z n ( A p p e n d i x F ) . Concentrat ions o f mercury decreased f rom 1993- 2003 a long w i t h its correlat ion to other metals. It seems that the processes that contributed to the increase o f mercury i n the watershed between 1993-2003, reduced the relat ionship to other trace metals. A l t h o u g h , the process that contributes these other metals to the watershed are s t i l l present. 4.6 Comparison of mercury in stream sediment and catchments imperviousness Atmosphe r i c transport is mercury ' s dominant pa thway for non-point source contaminat ion (Refer to section 1.3). Studies have shown that the catchment to lake ratio can be an indicator o f mercury levels i n f ish and sediment. Swed i sh studies have discovered a significant correlat ion between the catchment to lake area ratio and the levels o f mercury i n f ish (B i shop et al. 1997). A Canadian study used the same catchment/lake area ratio to s igni f icant ly correlate mercury concentrations i n sediment (French et al. 1999). B o t h o f these studies examined remote lakes, and their watersheds where the o n l y source o f anthropocentric mercury was from the atmosphere. U r b a n watersheds have been shown to have higher stormwater y ie lds o f mercury than other land-uses (Hur l ey et al. 1995; M a s o n et al. 1997; B a b i r z et al. 1998). U r b a n development has created impervious areas where precipi ta t ion is unable to penetrate ground cover and infiltrate into the so i l . Examples o f impervious areas inc lude bui ld ings , roads, compacted so i l and pa rk ing lots. Impervious area ( IA) has a negative affect o n water and sediment qual i ty due to the run o f f o f trace metals and other contaminants (Zandbergen et al. 1997; Zandbergen et al. 2000). M e r c u r y dis t r ibut ion i n a watershed is affected b y imperviousness due to its transport mechanisms. M e r c u r y resides and is transported i n the atmosphere before it is deposited on land. W h e n mercury reaches the ground or a waterway b y either d ry deposi t ion or rainwater, it is almost a lways i n the particulate form (Pacyna 1996). M e r c u r y has a strong aff ini ty for metal-oxides and organic carbon. I f mercury is deposited on a pervious surface, it is l i k e l y that it w i l l bond w i t h organic material i n so i l (B i shop et al. 1997). Impervious areas increase the amount o f runof f and mercury carried b y the runoff. 63 Catchments and there imperv ious area were delineated b y the G V R D i n 2001 us ing G I S and G P S systems. A l l o f the streams i n the catchments used i n this analysis are first order; except for the Brunette R i v e r , w h i c h has the lake as a source. Imperviousness decreases the l i k e l i h o o d o f mercury b i n d i n g to so i l and contributes mercury run-of f into a streams or lakes. Therefore, imperv ious areas create a pathway for mercury to reach streams. Effec t ive imperviousness area ( E I A ) is assessed b y quant i fy ing the impermeable area connected to or d ischarging into a catchment. F o r example , a r o o f is o n l y considered E I A unless the gutter is connected to the s tormdrain but i f the gutter runs onto the l a w n it is not considered E I A . Impervious area and effective imperv ious area per catchment was calculated b y M c C a l l u m (1995) i n 1973 and 1993. The G V R D (2000a) calculated imperv ious area i n 1996 (refer to Tab le 2.1). Average catchment concentrations was calculated w i t h data f rom A p p e n d i x B and f o l l o w the trends o f the overa l l watershed (Figure 4.15). M c C a l l u m (1995) d i v i d e d up the watershed into two sub-basins, S t i l l Creek and Brunette R i v e r , w i t h respective imperv ious levels at 5 2 % and 3 5 % . T h e same sub-basins were also used i n this study for compar ison . T h e sample range was at least three t imes larger for 1993 concentrations than 1973 and 2003. There are three times the number o f samples per catchment i n 1993 as the 1973, 1989 and 2003 since the samples were taken i n tr iplicate. The large number o f samples i n 1993 a l lows for a more detailed statistical analysis. Indiv idual mercury catchment concentrations are shown i n F igure 4.15. 64 Figure 4.15 B o x - w h i s k e r plot o f mercury streambed sediment concentrations (ug/kg) f rom s ix catchments i n 1993. One outl ier was exc luded f rom S t i l l Creek w i t h a value o f 2115 wg/kg. In 1993, three independent samples were analyzed at each site. 700 600 500 X3 Q . Q_ C o ro 400 c <D O C o o o \ CD 300 200 100 Brunette Still Stoney Eagle Deer Beecher Sediment concentrations from 1973, 1993 and 2003 were compared w i t h corresponding imperviousness and E I A data. T h e K r u s k a l - W a l l i s Test p rov ided sufficient evidence to conclude that catchment means were stat ist ically different i n 1973, 1993 and 2003. T h e l inear regression for the 1973 study year d i d not have a good fit w i t h E I A data due to the scattered data points and re la t ively l o w mercury concentrations (Figure 4.16). T h i s m a y indicate scattered point sources or natural background sources. 65 Figure 4.16 Scatter-plot o f 1973 stream sediment mercury concentrations (wg/kg) vs effective imperv ious area (hectares) f rom 1973. L i n e indicates the l inear regression o f the s ix area's 1000 800 600 400 co CD CD CO o '£ cu Q. . i 200 CD > LU 0 s Still • Dee? • D 3ruTrett» • Stoney • Eagle • Beecher • 25 50 75 100 Hg concentration 1973 T h e average mercury content increased 2 9 4 % i n stream sediment and a l l catchment concentrations increased substantially, between 1973-1993. A pos i t ive correlat ion was found between the effective imper ious area w i t h i n catchments and mercury i n 1993 stream sediment (Figure 4.17). Spearman's correlat ion coefficient is 0.371 and 0.257 for E I A and I A respect ively. T h i s seems to indicate that E I A is a better fit than I A , w h i c h is log ica l cons ider ing mercury ' s run-of f transport processes. Beecher Creek has the worst fit o f a l l the catchments i n the watershed, due to its h igh his tor ic mercury content i n a l o w imperv ious area. Beecher Creek is the most indust r ia l ized catchment and it is l i k e l y impacted b y a combina t ion o f atmospheric sources and point-source spills/releases. Spearman's correlat ion coefficient is 0.900 (a=0.037) w i t h the Beecher Creek point excluded. T h i s seems to suggest that the watershed is affected b y a combina t ion o f point source releases and runof f f rom imperv ious surfaces for a per iod before 1993. A t m o s p h e r i c mercury cou ld disperse re la t ive ly even ly over a 7200-hectare watershed. A possible h igh vo lume , loca l i zed source that fits into the 1973 to 1993 t ime 66 frame is the Burnaby Incinerator, w h i c h is located o n l y four k i lometers south o f B u r n a b y L a k e . Genera l ly , wester ly a i r f low f rom the Pac i f i c Ocean prevents the watershed f rom hav ing any h igh mercury concentration, l o n g distance sources. H i g h ra infa l l , typ ica l i n the coastal area w o u l d increase deposi t ion o f mercury released i n the area, w h i l e atmospheric and'particulate deposits o f mercury should decrease i n concentration away f rom the source (Nater et al. 1992). F igure 4.17 Scatter-plot o f 1993 stream sediment mercury concentrations (wg/kg) vs effective imperv ious area (hectares) L i n e indicates the l inear regression o f the s ix area's 1600-1 : : 1400- 1200-1 Hg concentration 1993 T h e B u r n a b y incinerator was fu l ly operational on M a r c h 1, 1988 and mercury releases peaked i n 1989 at 1.8 kg/day . Vegeta t ion and so i l samples moni tored for mercury near the incinerator f rom 1987-1989 d isp layed an increasing trend over t ime ( M c C a l l u m 1995). M e r c u r y releases from the incinerator have s ignif icant ly decreased since 1993 due to the instal lat ion o f an activated carbon inject ion system ( M c C a l l u m 1995). T h e average mercury discharge i n 1993 was 0.079 n g / m 3 ( A l l e n 2003). Estimates b y Horva te (1996) o f 67 globa l atmospheric concentrations o f mercury are f rom 0.5-10 n g / m 3 . W h i c h is s ignif icant ly more than currently discharged f rom the B u r n a b y Incinerator and since the system was instal led, discharges have averaged 0.031 ng /m ( A l l e n 2003). T h i s is over a 6 order o f magnitude decrease i n emissions since 1996. T h i s state o f the art system was the first to be instal led i n the N o r t h A m e r i c a and discharges are three t imes less than permits a l l o w ( H o l t 2003). A n attempt was made to draw inferences from the best avai lable data but due to insufficient data, the 2003 sediment data was compared to 1996 imperviousness . A l t h o u g h densif icat ion probably has occurred i n the area, it is assumed for this study that imperv ious areas and land-use has not s ignif icant ly changed over the last 10 years. M c C a l l u m (1995) noted that imperviousness i n the area had o n l y increased 7 % f rom 1973-1993. It is even more dif f icul t to assume that imperv ious levels have increased proport ionately w i t h i n each catchment but the correlat ion is wor th not ing for the purpose o f m a k i n g comparisons. T h e 2003 sediment concentrations compared to the 1996 imperv ious area had a Spearman's correlat ion coefficient o f 0.429, a=0.397 (Figure 4.18). S t i l l Creek is an outl ier w i t h a h igh imperviousness relative to its mercury concentration. T h i s cou ld be due to a combina t ion o f factors l i k e source abatement or effective use o f Best Management Practices ( B M P ' s ) storm-sediment containment systems. 68 Figure 4.18 Scatter-plot o f 2003 stream sediment mercury concentrations (wg/kg) vs total imperv ious area (hectares) f rom 1996. Effect ive imperv ious area data was unavai lable for the per iod o f 1994-2003. L i n e indicates the l inear regression o f the s ix area's 1600 Hg concentration 2003 4.7 Comparison of various analysis T h i s project was an attempt to determine h o w the majori ty o f inorganic mercury is be ing transported through the watershed, w h i c h inc ludes ascertaining its forms and associations. Th i s project examined var ious segments o f the watershed independently, i nc lud ing suspended sediments, stream sediments, lake sediments and redox changes o f B u r n a b y L a k e sediment. T h e intent o f this section i s to compare and examine these segments together to determine i f any significant trends exist. Suspended sediment, B u r n a b y L a k e sediment and stream sediment data was ana lyzed f rom the watershed w i t h Spearman 's R a n k Cor re la t ion Test and Bonfe r ron i ' s Cor rec t ion to ascertain i f s tat ical ly significant relat ionships exist between variables. It is diff icul t to compare concentrations due to the various methods used i n analysis, but it is 69 poss ible to discuss their relationships (Table 4.9 and 4.10). These relationships w i l l be characterized as changes o f transport mechanisms, geochemica l associations or s imi la r source locat ions. Characterist ics w i l l be differentiated b y evaluat ing literature, chemica l properties and watershed attributes. Tab le 4.9 C o m p a r i s o n o f sampl ing locations, mat r ix and methods for mercury determination i n the Brunette Watershed. Location Matrix Method L a k e Sediment M a x i m u m depth o f cores 1.2 c m Stream Sediment <180 wm surface stream sediment Suspended Sediments Sediment Centrifuge o f suspended stormwater sediments Suspended Sediments Water Stormwater 70 Tab le 4.10 M e r c u r y med ian or mean concentrat ion i n var ious med ia throughout the watershed. (Water concentrations i n ug/L and sediment i n wg/kg) Median / Mean Source Still Creek Sub-basin Burnaby Lake Brunette River Sub-basin Watershed Average Suspended Sediment '98 ( M e a n , n = l ) (Sekela et al. 1998) 146 - 615 - Stormwater '98 ( M e a n , n=12) (Sekela et al. 1998) 18.8 - 28.0 • - Stream sediment '73 (<180um) ( M e d i a n , n=27) ( H a l l et al. 1976) 46.0 - 23.3 30.2 Stream sediment ' 89 (<180 um) ( M e d i a n , n=29) (Duynstee 1990) 186.0 - 76.1 133.0 Stream sediment '93 (<180 um) ( M e d i a n , n=30) ( M c C a l l u m 1995) 205.6 - 94.2 132.9 Stream sediment '03 (<180 wm) ( M e d i a n , n=30) Current study 61.3 - 58.4 56.8 E n k o n ' 0 2 Compos i t e core ( M e d i a n , n=15) ( E n k o n 2002) - 142.0 - - Iron and manganese d i d not have a statist ically significant relat ionship to mercury i n B u r n a b y L a k e sediment. A l s o the relat ionship was not found i n stream sediment throughout the watershed. Iron was correlated to mercury i n S t i l l Creek stormwater but was inverse ly 71 related i n the Brunette R i v e r stormwater (Spearman correlat ion coefficient 0.829 and - 0 . 7 2 5 respect ively) . Manganese was inverse ly correlated w i t h mercury i n Brunette and S t i l l C reek stormwater, (Spearman correlat ion coefficient - 0 . 8 7 0 and -0 .143 respectively) . Iron and manganese were correlated w i t h each other i n lake sediment and every year o f stream sediment, the lowest s ignif icance o f 0.041 occurred i n 1973. Iron and manganese have s imi la r phys ica l properties due to their s imi la r a tomic weight and a tomic charges, yet behave differently under redox condi t ions. T h i s m a y indicate that correlat ion compar i son o f metals i n various segments can be representative o f geochemica l associations due to s imi la r transport mechanisms, even though k ine t ic redox rates differ. T w o elements that mercury t yp i ca l l y has a h igh degree o f correlat ion w i t h are sulfur and d i sso lved organic carbon (Shafer et al. 1997; Beno i t et al. 1998b; R e g n e l l et al. 2001). In this study, different methods were used to quantify organic matter m a k i n g it dif f icul t to make comparisons between methods. T h e m i c r o c o s m experiment w i t h Burnaby L a k e sediment resulted i n a Spearman correlat ion coefficient o f 0.651 and oc= 0.081 for D O C and mercury ( A p p e n d i x K ) . Bu rnaby L a k e cores were analyzed for total organic carbon and correla t ion confidence to mercury, (Spearman correlat ion coefficient 0.634, a=0.011) [ A p p e n d i x G ] . In stream sediment, total carbon was used as an approximate indicator o f total organic matter and the relat ionship w i t h mercury was found to be ve ry l o w . Organ ic matter was not analyzed i n stormwater. To ta l sulfur was o n l y quantified i n lake and 2003 stream sediments. N o stat ical ly significant correlat ion was found between mercury and sulfur concentrations. T w o separate environments exist w i t h i n the Brunette Watershed. T h e western por t ion o f the bas in is h i g h l y urbanized w i t h a steep e levat ion gradient. In these systems, mercury general ly associates w i t h suspended particulate matter ( S P M ) . T h i s section feeds Burnaby Lake , w h i c h is characterized as sha l low and dystrophic , more comparable to a marsh. In these systems, mercury is t yp i ca l ly found i n the d isso lved form or associated w i t h co l l o ida l particles (<0.45 um) (Hur l ey et al. 1995; B a b i r z et al. 1998; Benoi t et al. 1998b). L e a d general ly had the strongest relat ionship w i t h mercury throughout the var ious segments o f data. T h e y both were s igni f icant ly correlated w i t h 9 9 % confidence i n Burnaby L a k e sediment and every year o f stream sediment except 2003 (cc=0.071) [Append ix G and 72 F ] . It has the strongest relat ionship w i t h mercury out o f a l l the Burnaby L a k e core samples (Spearman correlat ion coefficient 0.876) [ A p p e n d i x G ] . N o significant correlat ion was found i n the stormwater event ( A p p e n d i x I). Th i s , combined w i t h a decreasing relat ionship i n 2003, cou ld indicate that sources or transport mechanisms are changing. L e a d w i l l not fo rm any strong chemica l associat ion w i t h mercury but m a y associate w i t h s imi la r particles. L e a d has a higher par t i t ioning coefficient (Kd) for S P M / D O C i n a variety o f watersheds than Z n , C d , C r and C u , but mercury ' s K d w i l l depend on the type environmental condit ions (Shafer et al. 1997). F r o m 1993-2003, it should be noted that concentrations o f lead and mercury decl ine throughout the watershed. L e a d concentrations i n the environment have been steadily dec l in ing i n N o r t h A m e r i c a since their phase out f rom gasol ine i n 1986. Copper , ch romium, n i c k e l and z inc appear to have the same temporal trend i n a l l m e d i a except for the stormwater study. It is poss ible that correlations i n stormwater were not observed due to a l o w number o f samples (n=8). In the watershed, copper, c h r o m i u m , n i c k e l and z inc a l l had a posi t ive, significant statistical relat ionship to each other. Copper is significant w i t h mercury at 0.001 i n lake sediment and stream sediment i n 1973 and 1989. Copper , chrome, n i c k e l and z i n c a l l have a s ignif icant relat ionship w i t h i r o n i n 2003. O v e r a l l , mercury i n sediments had the strongest relationships w i t h P b , C u , N i and Z n i n relative order. D u e to their va ry ing chemistries and sources, it seems that this relat ionship is p r i m a r i l y due to s imi la r sources and/or transport processes, i n w h i c h a l l o f these metals have been l i nked to automotive sources. It is diff icul t to expla in w h y the mercury ' s relat ionship to other metals decreased i n 2003 but the large reduct ion i n point source mercury concentrations f rom the incinerator m a y be one explanat ion. It seems very li t t le can be determined about the geochemistry w i t h i n the watershed w i t h the current data. M e r c u r y has o n l y weak relationships that can be ident i f ied for i ron , manganese, sulfur and organic carbon. These three parameters, based o n literature, are t yp i ca l ly found to geochemica l ly associate w i t h mercury. 4.8 Poss ib l e Sources M e r c u r y is found extensively throughout the w o r l d . G l o b a l studies ana lyz ing sediment cores concluded that mercury concentrations have increased around 3-5 t ime ' s since pre-industrial t imes (Krabbenhoft et al. 1997). The intent o f this section is to account 73 for the mercury source that led to an average 102.9 wg/kg increase i n stream sediment over twenty years (Hagreen et al. 2004). O v e r a l l , concentrations i n the Brunette Watershed range f rom l o w to moderately contaminated. G w e n d o l i n e L a k e is an undisturbed, forested site and mercury sediment concentrations there are higher there than i n Burnaby L a k e . A l t h o u g h increased lead concentrations i n core samples taken f rom G w e n d o l i n e L a k e indicate that atmospheric processes have transported lead, the same scenario is possible for mercury. Point-sources m a y have also increased the mercury concentration i n loca l i zed areas. M e r c u r y is c o m m o n l y used i n fluorescent l ights, electr ical switches, batteries, laboratory, med ica l facil i t ies and general industry processes. Da ta from 1989 and 1993 studies indicates that S t i l l Creek has the highest concentrations i n the watershed and sediment cores at the mou th o f the stream are also re la t ively h igh . B u r n a b y L a k e core and stream sediment samples taken from the watershed strongly correlate h igh levels o f H g , C u , Fe , P b and Z n . M e r c u r y is presumably released from a var ie ty o f industries a long w i t h C u , Fe , Pb and Z n metals, al though the 2003 dis t r ibut ion does not indicates any detectable point sources. It is poss ible that a pulse o f mercury was released i n S t i l l Creek and/or Beecher Creek i n the 1980's and 1990's and it is currently be ing distributed down-gradient. Sediment mercury concentrations have decreased since 1993 due to an increase i n awareness o f mercu ry ' s hazardous affects and controls on its use. M e r c u r y concentrations increased dramat ica l ly throughout the watershed between 1973 and 1993 and sources that cou ld un i fo rmly distribute mercury concentrations over the entire watershed are l imi ted . Source transport processes i nc lud ing mercury leached f rom the so i l b y M M T or deposited from the atmosphere are both poss ibi l i t ies . In theory, both scenarios w o u l d run-of f imperv ious areas and therefore should correlate w e l l w i t h effective imperv ious area. M e r c u r y i n street dirt has also increased s ignif icant ly from 1973-93 ( M c C a l l u m 1995). T h e source o f mercury i n street dirt is most l i k e l y a combina t ion o f atmospheric or automotive sources. B u t for the tentative assumption that M M T is leaching mercury out o f so i l to be true, there should be some type o f correlat ion between mercury and manganese i n sediment loading , geochemistry and transport, w h i c h was not observed anywhere i n the watershed. A l s o , the mic rocosms experiment released ve ry l i t t le , i f any manganese. T h i s also reinforces the idea that manganese oxides are not a dominant process i n the transport o f mercury. 74 M c C a l l u m (1995) suspects the nearby B u r n a b y incinerator is a contr ibut ing source o f mercury to the watershed due to its p rox imi ty , w h i c h released up to 1.8 kg /day i n 1989 ( M c C a l l u m 1995). M c C a l l u m (1995) also found a significant correlat ion "that traffic density is responsible for a large part o f Pb , C u , and Z n contaminat ion i n urban streams". M c C a l l u m (1995) associates a l l o f these metals w i t h automotive deposi t ion and runoff. Ano the r study indicated that y ie lds to aquatic sediment f rom atmospheric mercury o f urban watersheds are 4 0 - 1 0 0 % higher then forested, rural areas (<10%) ( M a s o n et al. 1997). Increased imperviousness , surf ic ia l runof f and the lack o f organic b i n d i n g sites are suspected processes for higher levels o f mercury i n urban areas. M e r c u r y deposited from atmospheric sources is almost a lways bound to particulate; regardless o f wet or dry deposi t ion (Pacyna 1996). It is h i g h l y l i k e l y that particulates released from an incinerator w o u l d be associated w i t h other metals l i ke N i , C u , Pb and Z n . H o w l o n g these associations w o u l d last through transport w o u l d depend on their bond ing strength and environmental condi t ions. I f the incinerator were responsible for the large mercury increase i n watershed concentrations, i t w o u l d have to be a rap id process. T h e incinerator became operational i n M a r c h 1988 and stream sediment sampl ing was next performed i n M a y 1989. It is feasible that mercury cou ld be released, deposited and washed into streams leading to a 68.0 wg/kg median increase i n concentrations f rom 1973-1989, especia l ly w i t h the regions h i g h l eve l o f precipi ta t ion (Figure 4.19 and 4.20). T h e decrease o f mercury f rom the incinerator cou ld also be related to the decreased l eve l o f mercury observed throughout the watershed sediment i n 2003. M e r c u r y fo l lows a s imi la r trend o f most other metals i n the watershed f rom 1973 to 1989. It is h i g h l y correlated w i t h lead, copper, n i c k e l and z inc through this t ime (Figure 4.20). T h i s m a y indicate s imi la r transport mechanisms because these other metals have been l i n k e d to automotive sources and they do not react geochemica l ly w i t h mercury . F igure 4.19 and 4.20 indicate that mercury is the o n l y metal that increases f rom 1989 and 1993. A l l other metal concentrations decrease from 1989. T h i s is probably due to an overa l l increased awareness o f the presence o f tox ic metals i n urban sediments and implementat ion o f sediment control best management practices b y the G V R D . Af te r 1989, mercury ' s correlat ion to most other metals drops and this trend continues unt i l 2003. 75 M e r c u r y concentrations peaked i n 1993, the same year that air scrubbers were instal led at the B u r n a b y Incinerator. F igure 4.19 M e t a l med ian concentrations i n <180 um stream sediment f rom 1973-2003. M e r c u r y i n wg/kg. Iron i n m g / k g . Manganese i n wg/kg x 0.1 76 Figure 4.20 M e t a l med ian concentrations i n <180 u m stream sediment f rom 1973-2003. ( A l l metals i n ug/kg) 77 5. SUMMARY AND CONCLUSIONS The results o f this project are summar ized i n the f o l l o w i n g sections. Contaminant levels f rom different m e d i a and t ime frames were compared and evaluated for trends. Tempora l changes are representative o f h is tor ica l trends i n watershed. D u e to problems w i t h laboratory results i n m i c r o c o s m Exper iment II, water qua l i ty parameters cou ld not be compared to sediment concentrations and other parameters. Therefore, focus was shifted to examine the temporal relat ionship between trace metals w i t h i n stream sediment. These conclus ions are discussed i n the f o l l o w i n g , Sec t ion 5.3. 5.1 Temporal and spatial changes in mercury and trace metal contamination since 1973 One important temporal trend identif ied i n this study is the overa l l l eve l o f mercury i n stream sediment has started to decl ine i n the watershed. T h i s decrease is p robab ly due a combina t ion o f increased pub l i c awareness and a decrease o f releases. O v e r a l l , the l eve l o f contaminat ion i n Burnaby L a k e is s imi la r to other nearby lakes, Deer L a k e and G w e n d o l i n e L a k e , both o f w h i c h are not connected to stormwater drainage systems. D u e to its remote locat ion , contaminat ion i n G w e n d o l i n e L a k e is p r i m a r i l y f rom atmospheric deposi t ion. M e r c u r y concentrations i n Brunette Watershed stream sediment are actual ly higher than reported i n this and other studies because it was found that an average o f 66 .8% o f mercury was lost i n the d ry ing process. W h e n sediment concentrations were adjusted for the loss 1973, 1989 1993 and 2003 sediments exceed n=0, n=12, n=12, and n = l o f the federal Interm Sediment Qua l i t y Guide l ines , i n respective order. Previous studies from 1973-1993 have shown that mercury concentrations were highest i n the S t i l l Creek Sub-basin. Current 2003 data indicates that S t i l l Creek Sub-bas in mercury levels are approximate ly equal i n the Brunette Sub-basin w i t h at ratio o f 1.05 (Sti l l /Brunette) . W i t h an overa l l decrease i n the watershed concentrations f rom 1993-2003, it is reasonable to conclude that source loadings are decreasing and mercury concentrations are be ing distributed downstream. T h e trends i n Sect ion 4.8 indicated the B u r n a b y incinerator was a probable source o f mercury to the watershed from 1988-1993. M e r c u r y seems to f o l l o w a trend s imi la r to other trace metals w i t h i n the watershed, except i n a smal l per iod from 1989-1993 when 78 every metal concentration decreased f rom 1989-1993, except for mercury. Consequent ly , the incinerator was releasing its highest concentrat ion o f mercury into the atmosphere for the same per iod. It is w e l l k n o w n that atmospheric mercury can lead to increased levels o f mercury contaminat ion i n waterways. M e r c u r y ' s transport mechanisms and geochemica l associations after deposi t ion are not as w e l l k n o w n . Catchment effective imperv ious area m a y p l ay an important role i n determining the transport mechan i sm relative to mercury runoff. A l t h o u g h this needs to be examined further, when the B u r n a b y Incinerator p rov ided a source, levels o f mercury increased i n stream sediment w h i l e a l l other metals decreased. A l s o , i n that same t ime frame, mercury ' s correlat ion w i t h the catchments effective imperv ious area was higher than wi thout the incinerator releases. 5.2 Mercury's correlations with organic carbon, iron oxyhydroxides, manganese oxyhydroxides, sulfur and other trace metals in stream sediment, lake sediment, stormwater and laboratory controlled redox conditions F r o m 1973-2003, mercu ry ' s correlations i n stream sediment and B u r n a b y L a k e sediment were highest w i t h lead, copper, n i c k e l and z inc . These four metals and c h r o m i u m were a l l s ignif icant ly related to each other f rom 1973-2003. T h i s m a y be due to their s imi la r anthropocentric sources and transport mechanisms, more than their geochemica l associations. N o consistent correlations were observed between mercury and organic carbon, i ron oxyhydroxides , manganese oxyhydrox ides and sulfur i n stream sediment, lake sediment, stormwater and laboratory control led redox condit ions . 5.3 Levels of mercury, iron, manganese and organic carbon released from lake sediment to overlying water due to sediment anoxia T w o separate m i c r o c o s m experiments were performed to determine i f anoxic condit ions w o u l d lead to increased levels o f mercu ry i n o v e r l y i n g water. T h e first t r ia l m i c r o c o s m , from N o v e m b e r 17 to December 9, 2002, d i sp layed a release o f mercury i n a l l four m i c r o c o s m chambers. T h i s release co inc ided w i t h a release o f i ron . T h e anoxic m i c r o c o s m w i t h lake water released 3 9 8 % (1.59 ug/L) more mercury and 6 8 8 % (1.86 ug/L) more i ron than the o x i c m i c r o c o s m w i t h lake water. It is suspected that methylmercury m a y have been 79 produced i n the mic rocosms due to lower levels o f mercury released when m i c r o b i a l ac t iv i ty was suppressed. S ince the mic rocosms were intended to replicate seasonal redox condi t ions w i t h i n Burnaby L a k e , it is l i k e l y that s imi la r releases o f mercury and i ron occur i n the lake. (The second experiment ran f rom February 9 to M a r c h 25, 2003 wi thout any results due to mercury contamination.) 5.4 MMT's responsibility for the increase of mercury concentrations in the Brunette Watershed stream sediment Li t t l e evidence compi l ed i n this study supported the hypothesis that manganese, i ron , sulfur or D O C is associated w i t h mercury throughout the watershed. Thus , it is diff icul t to conclude or rule out that M M T or manganese oxides p l ay a major role i n the transport o f total mercury. O v e r a l l , evidence that w o u l d lead to conclusions about mercury ' s geochemica l associat ion w i t h i n the watershed f rom this study was inconc lus ive . In this study, mercury does not correlate w i t h any substances typ i ca l ly found i n the literature to have geochemica l associations w i t h mercury. Therefore, co r r e l a t i on ' s i n stream sediment, lake sediment, stormwater and laboratory control led redox condit ions m a y not be the o p t i m u m method to examine a watershed's geochemica l associations. S ince a relat ionship between mercury and manganese was not observed i n field data, m i c r o c o s m experiments, stream sediment, and other studies were examined to determine other potential sources o f mercury to the Brunette Watershed. 80 6. RECOMMENDATIONS The conclusions d rawn f rom this study can be used to make better management decisions concerning the remediat ion and conservat ion i n the Brunette Watershed and urban watersheds i n general. Further research w o u l d enable improved understanding o f the source, transport and fate o f mercury and other trace metals i n urban environments. 6.1 Implications for further research T h i s project indicates source and transport processes to a waterway m a y be important to the dis tr ibut ion o f mercury i n stream sediments. Further research into effective imperviousness effect o n mercury dis t r ibut ion i n waterways and stream sediments is recommended. It m a y be an important component i n m o d e l i n g mercu ry ' s in termediary fluxes between air to aquatic transport. Other projects should examine the relat ionship between mercury i n waterways and point-source releases, i n c l u d i n g a detai led examinat ion o f mercury concentrations i n core samples f rom 1988- 1996 to ident ify temporal f luxes. Future w o r k should investigate the levels o f mercury and methy lmercury w i t h i n var ious med ia throughout the watershed. D u e to methodologica l errors, h is tor ic concentrations o f mercury i n sediment and waters are suspect. M o r e research is needed, u s i n g current methods, to determine levels o f contaminat ion throughout the watershed. M e t h y l m e r c u r y is a h i g h l y tox ic compound and the m i c r o c o s m Exper iment I indicated anoxic sediments might release methylmercury . Labora tory analysis should examine the relat ionship between M M T and mercury to reduce variables present i n the environment. Further research is needed to identify levels o f methy lmercury i n f ish and other biota w i t h i n the watershed. Then , i f necessary, investigate levels o f contaminat ion i n water and sediment. Further research is needed into mercury ' s geochemica l associations and the release o f mercury f rom anoxic sediments i n the B u r n a b y L a k e and other urban watersheds, poss ib ly G w e n d o l i n e L a k e cou ld be used for a compar ison . Bu rnaby L a k e has the environmental cond i t ions /cyc l ing that w o u l d make it possible for sediment releases o f stored mercury into the ove r ly ing sediment and thus downstream. F o r this invest igat ion, methodologies i n v o l v i n g mic rocosms to study mercury ' s geochemical relationships and stormwater sampl ing to study mercury ' s aquatic transport are recommended. 81 A l s o , it is important to determine i f the b i o l o g i c a l and eco logica l health o f the watershed has improved w i t h decreased trace metal contaminat ion. A n eco logica l assessment conducted i n 1998 b y the U B C c o u l d be used to p rov ide background informat ion o n contaminat ion (Richardson et al. 1988) There has been a focus on i m p r o v i n g the phys ica l and chemica l indicators w i t h i n the watershed for sometime. It w o u l d be interesting to determine i f improvements i n phys ica l and chemica l indicators resulted i n b i o l o g i c a l indicator improvements . 6.2 Management implications T h e G V R D is consider ing dredging B u r n a b y L a k e to improve the recreational and environmental condi t ions. T o prevent the need for further dredging, the G V R D and the Brunette B a s i n Task G r o u p ( B B T G ) should continue implement ing sediment control measures to reduce the in f lux o f contaminated sediment into the lake. Env i ronmenta l impacts o f dredging w o u l d be dependent o n the l eve l o f freshly exposed sediment. Enkron(2002) recommends the use sediment control devices to m i n i m i z e the impact o f suspended sol ids over a large area w i t h i n the lake. S m a l l mercury releases are possible f rom anox ic sediment due to sediment exposed b y dredging; al though mercury w o u l d have already had the opportunity for release when i t was o r ig ina l ly deposited. T h e planned sediment controls proposed b y the G V R D should reduce the release o f mercury and the transport o f mercury and other contaminants. 82 7. L I T E R A T U R E C I T E D A l l e n , C . (2003). 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Vancouve r , B . C . Zandbergen, P . , H . Schreier, et al. (2000). U r b a n watershed management C D . Institute for Resources and the Envi ronment , Un ive r s i t y o f B r i t i s h C o l u m b i a . Vancouve r , B . C . 89 APPENDIX A Stream Sediment Sampling Locations Table A - l Stream sediment sampl ing locations Stat ion N u m b e r Station Desc r ip t ion Genera l Remarks 1. Brunette R . at Spruce A v e . (bridge) A t r iver mouth , w o o d products industries 2. Brunette R . at C a m p h o r A v e . , near r a i lway bridge. W o o d products industry nearby. 3. Brunette R . at B r a i d St. (bridge) W o o d products industry nearby. 4. Brunette R . at Brunette R d . Potent ia l ly affected b y h i g h traffic vo lumes 6. Brunette R . at N o r t h R d . (east side) Sampled w i t h i n H u m e Park. 7. Stoney Creek at G r a n d v i e w H w y . , 100m west o f intersection o f Hunter and K e s w i c k Streets 8. Stoney C r . at Beaverbrook D r . and N o e l D r . , samples obtained upstream and downstream o f br idge. Res ident ia l area. 9. Stoney Creek at East B roadway , 5 0 m west o f Norcres t R d . Res ident ia l area. 10. Brunette R . at Ca r iboo R d . , samples obtained upstream and downstream o f bridge. Potent ia l ly affected b y h i g h traffic vo lumes . 11. S m a l l stream ar is ing f rom a s torm sewer, south side o f W i n s t o n St., east o f B r i g h t o n St. L i g h t industr ia l and residential area. 13. Eag le Creek o n P ipe r A v e n u e , south o f W i n s t o n St. Loca ted i n Werne r Boa t Park. 14. Eag le Creek at East B r o a d w a y (south side), bgetween L a k e C i t y W a y and Lawrence D r i v e . B e l o w g o l f course. 15. Tr ibutary o f Eag le Creek at Shel lmont St. (north side), east o f A r d e n D r i v e . Downs t ream o f pet ro leum tank farm runof f detention faci l i ty . 16. Tr ibu ta ry o f Eag le Creek at W o o d b r o o k Place , east o f P h i l l i p s A v e . Ups t ream o f g o l f course, w o o d e d stream buffer. 17. Rober t B u r n a b y Creek, near park entrance at 4 t h St. Loca ted w i t h i n Rober t B u r n a b y Park. 19. Deer L a k e B r o o k at G lenca i rn D r . (north side) N o r t h o f freeway south o f B u r n a b y L a k e . 20. Deer L a k e B r o o k at Deer L a k e A v e . , south o f Canada W a y , upstream and downstream o f br idge. Downs t ream o f Dee r L a k e . 21 . S m a l l stream at M o s c r o p St. (south side), Res ident ia l area downstream o f 90 between R o y a l O a k A v e and Oaktree C t . cemetery. 24. S m a l l creek at intersection o f Sper l ing A v e . and Jordan D r . Resident ia l area. 25 . Beecher C r . near G o r i n g A c e . , sampled on south side o f ra i l road tracks S m a l l tributary o f S t i l l Creek 26. Beecher C r . at Lougheed H w y . (south side) Ups t ream o f station 25. 27. Beecher C r . at Spr inger A v e . (east side). Ups t ream o f station 26. 29. S m a l l stream i n Wes tburn Park a long G i l p i n C r . 4 0 0 m upstream o f 1973 locat ion. 30. S t i l l Creek o n S t i l l Creek D r . , west o f W i l l i n g d o n A v e . Industrial area, heavy traffic. 31 . S t i l l Creek at G i l m o r e A v e . (east side). Industrial area. 32. N o r t h branch o f S t i l l Creek at Lougheed H w y . (south side) Af fec ted b y heavy traffic. 33. S t i l l Creek at G r a n d v i e w H w y . (south side) and R n d f e w St. (east side) Res ident ia l area. 34. S t i l l Creek at M y r t l e St., east o f Bounda ry R d . Industrial area 35. S t i l l Creek at Doug las A v e . Industrial area. 37. S t i l l Creek at A t i l i n St. and 2 7 t h A v e . W o o d e d ravine. 91 APPENDIX B Concentration of trace metals in Brunette Watershed stream sediment from 1973-2003 Table B - l Streambed sediment, <180um fraction i n the Brunette Watershed, total concentration i n 1973 ( H a l l et al. 1976). V a l u e s i n dry weight . N i t r i c acid digest for a l l metals except H g . M e r c u r y analyzed w i t h potass ium permanganate digest ion and c o l d vapor analysis . 1973 Stat ions Fe Hg Mn P b C u C r Ni Z n O M (mg/kg) (wg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) % 1 41600 44 716 104 52.3 175 41.1 136 6.4 2 36000 40 684 108 46.3 100 23.6 128 5.3 3 20800 52 652 134 44.4 50 15 117 6.3 4 25200 11 460 50 16.1 75 10 52 2.3 6 14000 11 165 50 12.3 100 7.4 47 2 7 22600 19 248 45 16.7 50 8.4 46 52.2 8 23000 • 14 444 .63 18.2 75 9 67 5 9 26000 20 275 39 17 100 9 60 2.3 10 19400 12 655 24 14.5 100 12.4 60 2.4 11 10800 10 196 14.5 13.9 50 5 32 7.4 13 24000 27 315 91 42 200 12.6 126 2.1 14 15200 30 325 10 12.3 0 8.4 65 2.5 15 50000 9 250 5 11.6 75 10 47 7.9 16 14800 13 205 26 15.8 700 11 47 2.5 17 23800 14 436 118 16.5 75 9.4 47 4.6 19 15600 18 242 292 48.6 50 14.4 136 2.2 20 24000 22 682 324 40.3 50 13.4 167 7.3 21 31800 18 875 58 40.4 125 20.8 118 7.9 24 24000 53 415 470 72.8 100 18.8 168 7 25 30800 29 328 950 82.9 100 194 199 2.2 26 23200 15 225 66 19 125 12 51.5 4.6 27 22600 22 468 48 17.8 100 8 69 9.4 29 73000 73 398 276 50.7 125 29 121 5.9 30 23800 101 211 440 684 100 33.6 206 6.4 31 2500 60 308 400 1765 150 23 168 1.8 32 22600 37 200 359 62.8 150 54 130 2.2 33 19400 34 294 34 52.7 50 10 100 3.8 34 36200 N A 114 600 95.1 200 19.2 305 29.7 35 33400 N A 425 840 816 N A 85 408 .00 N A 92 Table B - 2 Streambed sediment, <180wm fraction i n the Brunette Watershed, total concentration i n 1989 ( M a c d o n a l d et al. 1996b). V a l u e s i n dry weight. N i t r i c acid digest for a l l metals except H g . M e r c u r y analyzed w i t h potass ium permanganate digest ion and c o l d vapor analysis. 1989 Fe Hg M n P b C u C r Ni Z n Stat ions (mg/kg) (ug/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) 1 379000 120 1108 169 91 75 35 263 2 381000 110 1203 180 77 73 33 218 3 325000 80 1187 155 77 53 25 177 4 385000 45 1123 142 58 57 17 148 6 333000 80 1398 245 91 50 23 211 7 297000 80 726 113 85 75 19 126 8 291000 35 727 85 61 48 18 106 9 330000 45 720 82 48 55 20 104 10 344000 90 2118 159 85 55 20 205 11 N A N A N A N A N A N A N A N A 13 190000 40 506 36 53 34 16 83 14 540000 35 1090 48 53 55 17 130 15 455000 40 1007 60 72 50 18 306 16 277000 50 756 90 63 47 21 120 17 350000 25 757 47 50 65 28 95 19 266000 95 1093 247 151 55 22 227 20 324000 105 2513 132 69 58 25 178 21 261000 115 640 356 108 63 24 202 24 782000 350 4083 577 262 94 31 443 25 363000 55 1084 145 83 70 23 163 26 329000 65 1101 143 80 64 21 150 27 299000 70 899 93 61 54 21 138 29 332000 90 701 176 83 61 24 212 30 300000 160 1152 388 234 59 27 298 31 254000 90 649 140 102 46 18 155 32 530000 365 554 667 394 131 59 445 33 448000 415 8794 444 267 93 34 759 34 390000 200 845 267 157 81 40 252 35 282000 120 676 170 106 62 25 208 37 350000 175 767 479 155 76 24 285 93 Table B - 3 Streambed sediment, <180um fraction i n the Brunette Watershed, total concentration i n 1993. ( M c C a l l u m 1995). V a l u e s i n dry weight . N i t r i c ac id digest for a l l metals except H g . M e r c u r y analyzed w i t h potass ium permanganate diges t ion and c o l d vapor analysis . 1993 F e Hg M n P b C u C r Ni Z n O M Stat ions (mg/kg) (ug/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) % 1 32739 132 768 63 66 38 34 186 6.3 2 20929 132 534 62 51 41 24 134 5.4 3 26948 137 401 55 58 38 22 145 5.9 4 20199 51 1299 48 42 20 11 116 4.5 6 10437 57 561 48 31 15 7 111 3.2 7 20287 85 1009 37 32 24 13 87 4.6 8 13208 51 508 32 30 21 9 115 4.2 9 17474 115 807 96 51 26 12 95 4.7 10 30431 79 1435 407 141 35 19 310 8.1 11 22800 103 975 62 101 26 11 185 5.6 13 16994 45 1109 22 43 18 8 106 4.2 14 23872 50 791 39 34 18 9 93 3.7 15 44724 15 1553 24 45 19 6 163 7.8 16 28657 15 839 36 50 20 24 166 5.9 17 14822 60 474 40 97 40 14 161 4.8 19 9370 61 200 53 55 19 8 110 5.0 20 12923 69 1315 86 72 18 10 171 7.8 21 18421 95 906 60 52 30 17 146 6.3 24 27289 102 2004 190 119 45 21 391 5.0 25 13901 352 333 43 50 18 12 89 19.9 26 18178 64 869 72 55 24 11 128 4.2 27 21421 68 1273 73 56 29 16 196 6.5 29 11430 154 357 26 26 17 13 136 4.2 30 23219 121 346 127 195 34 28 262 4.6 31 23293 149 1334 141 279 33 16 341 r 7.1 32 12225 91 194 133 80 •31 15 140 10.6 33 23115 870 1440 307 162 33 19 278 5.2 34 21054 214 366 190 142 35 17 255 3.7 35 18787 137 287 116 142 37 18 , 283 5.9 37 14651 N A 722 207 199 38 19 271 3.0 94 Table B - 4 Streambed sediment, <180um fraction, i n the Brunette Watershed, total concentration i n 2003 . V a l u e s i n dry weight . N i t r i c ac id digest for a l l metals except H g . M e r c u r y analyzed w i t h py ro lys i s digest ion and A A detection. 2003 Fe Hg Mn Pb Cu Cr Ni Zn OM S Cd Stations (mg/kg) (wg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) - % (mg/kg) (mg/k 1 20163 72.4 461 43 32 12 12 140 1.57 268 2.6 2 4707 26.3 171 9 8 8 7 39 0.40 75 0.6 3 20539 65.1 210 7 29 27 29 60 0.60 66 1.9 4 22179 20.1 224 8 31 28 30 62 0.65 71 2.7 6 7571 102.9 294 22 14 7 4 49 0.36 105 0.7 7 12456 78.8 503 15 24 11 9 86 1.25 161 1.3 8 7805 59.6 373 33 15 7 6 57 1.45 157 0.8 9 11897 44.3 511 31 32 13 8 104 1.45 232 1.4 10 14695 56.1 1594 67 78 20 13 190 1.22 329 1.9 11 36853 58.4 1490 62 87 26 13 311 2.84 389 4.4 13 16189 10.9 1587 20 22 11 7 136 3.20 324 1.8 14 7990 32.7 402 3 8 4 3 45 0.55 112 0.8 15 17670 56.9 927 8 14 7 4 124 1.69 173 1.7 16 12575 79.4 790 50 50 17 . 8 143 4.24 352 1.6 17 10846 85.5 153 622 176 19 9 220 4.26 872 1.4 19 20831 101.2 1725 93 103 27 13 301 13.90 1773 2.8 20 11884 28.2 1438 50 48 10 18 126 5.74 619 1.4 21 8492 33.1 509 18 20 8 6 68 1.93 164 1.3 24 17187 99.6 990 157 99 22 17 181 3.44 345 2.3 25 21693 24.3 1076 60 53 18 13 181 3.38 360 2.6 26 9231 62.1 361 29 28 11 7 83 1.93 195 1.1 27 15006 48.7 633 44 49 18 13 129 1.82 243 1.8 29 23528 110.8 1662 33 41 16 13 160 3.09 312 2.7 30 15228 51.7 212 54 76 18 11 162 1.16 285 1.8 31 15516 69.1 306 102 107 19 18 152 1.46 261 1.8 32 38807 46.2 312 270 162 49 33 403 4.73 729 4.6 33 24247 71.1 1439 168 166 37 19 359 3.31 545 3.8 34 31769 17.8 1601 186 126 38 23 366 2.52 801 4.6 35 8609 32.2 160 27 46 11 9 96 1.32 205 1.0 37 11140 102.0 201 69 55 22 9 106 0.81 274 1.5 95 APPENDIX C Metal concentrations in sediment cores from Burnaby Lake Table C - l M e t a l concentrations in sediment cores (depth < 2.0 cm) from B u r n a b y L a k e ( E n k o n 2002) [mg/kg dry weight] . Refer to F igure C - l for site locations. ( C ) indicates composi te sample was analyzed. Site H g M n F e P b C u N i Z n T O C S A - C 0.16 240 13300 153 80.9 17.6 177 14 2210 B - C 0.28 394 25100 514 189 26.9 476 8.3 2210 C - C 0.05 443 25700 4 35.3 16 55.2 0.24 234 D - C 0.06 180 10400 5 20 13.3 48.2 9.1 3290 E - C 0.1 243 15700 62 35.7 16.8 152 8 1870 F - C 0.08 232 1500 50 39.8 39.5 91.3 7.3 2170 G 0.07 252 9850 6 16.2 14.9 56.7 14 2580 H 0.06 233 15300 4 29.3 17.9 60.4 7.8 2690 I 0.05 219 14200 12 24.9 14.9 62.2 7.7 2400 J 0.1 201 9720 30 23.6 12.5 80.5 12 2970 K - C 0.26 420 16800 277 125 33.6 412 14 5430 L - C 0.25 323 20900 209 175 22.6 426 9.7 2700 M - C 0.2 291 17300 70 38.6 16.1 172 14 2470 N - C 0.05 218 10600 58 28.4 12.5 98 7.3 1030 O C 0.44 424 31500 533 254 36 571 12 4330 F igure C - l L o c a t i o n o f Burnaby L a k e sediment core sampl ing stations. Pho to adapted f rom ( E n k o n 2002) . O Burnaby Lake sediment core locations. ft North 96 APPENDIX D Total metal concentrations within a Brunette Watershed stormwater event Table D - l Tota l metals w i t h i n a stormwater event on the Brunet te R ive r , February 28, 1997 (Sekela et al. 1998) Brunet te R i v e r Flow time Hg Fe Mn (cms) (hr) (ng/L) (mg/L) (mg/L) 1.57 1:00 22.0 0.882 0.075 1.80 2:00 11.0 1.600 0.087 3.92 3:00 18.0 1.830 0.117 6.30 5:00 19.0 0.983 0.085 6.58 7:00 22.0 0.986 0.083 6.88 8:15 21.0 1.120 0.086 Ave 18.8 1.234 0.089 Std Dev. 4.1 0.387 0.015 Table D - 2 Tota l metals w i th in a stormwater event o n S t i l l Creek, February 28, 1997 (Sekela etal. 1998) Flow Time Hg Fe Mn (cms) (hr) (ng/L) (mg/L) (mg/L) 0.38. 1:00 27.0 1.790 0.240 0.66 2:00 23.0 1.740 0.234 1.59 3:00 26.0 2.540 0.225 1.97 4:15 39.0 4.280 0.179 2.81 5:45 25.0 2.080 0.088 4.90 7:45 28.0 3.020 0.098 Ave 28.0 2.575 0.177 Std Dev 5.7 0.966 0.069 97 APPENDIX E Microcosm data from Experiment 1, November 17 to December 9,2002 Table E - l M i c r o c o s m p H data from Exper iment 1, N o v e m b e r 17 to December 9, 2002. No te : M i c r o c o s m variables (1. Con t ro l , 2. D I water, 3. O x i c and 4. M o l y b d a t e ions) Microcosm 18-Nov-02 20-Nov-02 2-Dec-02 9-Dec-02 5.73 6.44 5.60 6.54 5.38 6.02 4.03 6.44 5.80 5.32 4.80 5.73 5.73 6.68 6.48 6.70 Table E - 2 M i c r o c o s m conduct iv i ty data (uS/cm) data from Exper imen t 1, N o v e m b e r 17 to December 9, 2002. N o t e : M i c r o c o s m variables (1. Con t ro l , 2. D I water, 3. O x i c and 4. M o l y b d a t e ions) Mbrocc^m^^ 70 126 112 620 12 38 54 34.7 73 108 112 75.0 70 2675 2525 1385 /" Table E - 3 M i c r o c o s m disso lved oxygen data ( m g / L ) data f rom Exper iment 1, N o v e m b e r 17 to December 9, 2002. No te : M i c r o c o s m variables (1 . Cont ro l , 2. D I water, 3. O x i c and 4. M o l y b d a t e ions) McI9COsm_ 18-Nov-0*2 20-Nov-02 02^Dec-02 09-Dec-02 1 2.0 0.45 6.35 0.20 2 3.4 0.55 0.5 0.20 3 2.1 5.2 5.1 5.8 4 1.5 0.5 0.45 0.15 98 Table E - 4 M i c r o c o s m dissolved organic carbon data ( m g / L ) data f rom Exper iment 1, N o v e m b e r 17 to December 9, 2002. No te : M i c r o c o s m variables (1. Con t ro l , 2. D I water, 3. O x i c and 4. M o l y b d a t e ions) Microcosm 18-Nov-02 09-Dec-02 1 13 " 37 2 13 33 3 13 34 4 13 17 Table E - 5 M i c r o c o s m mercury data ( / /g/L) data f rom Exper imen t 1, N o v e m b e r 17 to December 9, 2002. Note : M i c r o c o s m variables (1. Con t ro l , 2. D I water, 3. O x i c and 4. M o l y b d a t e ions) Microcosm 18-Nov-02 25-Nov-02 1 0.104 0.47 2 0.300 0.204 3 0.173 0.081 4 0.173 0 02-Dec-02 09-Dec-02 09-Dec-02 Pis 1.3 2.092 1.953 0.88 1.631 1.400 0.758 0.570 0.524 0 0.201 0.450 Table E - 6 M i c r o c o s m Iron data (ppm) data from Exper imen t 1, N o v e m b e r 17 to December 9, 2002. Note : M i c r o c o s m variables (1. Con t ro l , 2. D I water, 3. O x i c and 4. M o l y b d a t e ions) Microcosm 18-NOV-02 25-NOV-02 02-Dec-02 09-Dec-02 09-Dec-02 Dis 1 0.108 0.213 0.128 " 224 0.084 2 0.624 0.464 0.129 0.804 0.176 3 0.448 0.476 0.184 0.714 0.327 4 1.654 1.353 0.263 1.784 1.092 Table E - 7 M e r c u r y concentrations o f B u m a b y lake sediment used i n M i c r o c o s m #1 analysis, N o v e m b e r 1, 2002 Description Concentration (wg/kg) % Solids Adjusted concentration (wg/kg) Microcosm Sediment 21 9.97 210.63 99 APPENDIX F Correlations for 1973-2003 stream sediment in the Brunette Watershed Table F - l Spearman's rho Correlat ions w i t h Bonfer roni Cor rec t ion- 1973 Stream Sediment i n the Brunette Watershed Fe Hg Mn Pb Cu Cr Ni Zn 1.000 35 .162 1.000 33 33 .347 .350 1.000 35 33 35 .188 .664(**) .127 1.000 35 33 35 35 .281 .821(**) .038 .850(**) 1.000 29 27 29 29 29 .288 .221 -.115 .312 .377 1.000 28 27 28 28 28 28 .483 .657(**) .212 .772(**) .815(**) .500 1.000 29 27 29 29 29 28 29 .362 774(**) .178 .843(**) .894C) .320 .820(") 1.000 29 27 29 29 29 28 29 29 .209 -.105 .069 -.087 -.042 -.168 -.088 -.041 33 32 33 33 28 28 28 28 OM% Fe Hg Mn Pb Cu Cr Ni Zn OM% Correlation Coefficient N Correlation Coefficient N Correlation Coefficient N Correlation Coefficient N Correlation Coefficient N Correlation Coefficient N Correlation Coefficient N Correlation Coefficient N Correlation Coefficient N 1.000 34 Correlation is significant at the 0.005 level (2-tailed). " Correlation is significant at the 0.001 level (2-tailed). 100 Table F - 2 Spearman's rho Correlat ions w i t h Bonfer roni Cor rec t ion- 1989 stream sediment data i n the Brunet te Watershed Fe Hg M n Pb Cu Cr Ni Zn Correlation Coefficient N Correlation Coefficient N Correlation Coefficient N Correlation Coefficient N Correlation Coefficient N Correlation Coefficient N Correlation Coefficient N Correlation Coefficient N Fe Hg Mn Pb Cu Cr 1.000 29 .190 1.000 29 29 .450 .216 1.000 29 29 29 .263 .901(**) .264 1.000 29 29 29 29 .150 .894(**) .133 .902(**) 1.000 29 29 29 29 29 •557(*) .654(**) .167 .630(**) .571(**) 1.000 29 29 29 29 29 29 .362 .750(") .262 .691 (**) .596(**) .725(**) 29 29 29 29 29 29 .490 .810(**) .380 825(**) .818(**) .541(**) 29 29 29 29 29 29 Ni Zn 1.000 29 .641(**) 29 1.000 29 Correlation is significant at the 0.005 level (2-tailed). ' Correlation is significant at the 0.001 level (2-tailed). 101 A p p e n d i x F-3 Table F - 3 Spearman's rho Correlat ions w i t h Bonfe r ron i Cor rec t ion- 1993 stream sediment i n the Brunette Watershed Fe Hg Mn Pb Cu Cr Ni Zn OM% Correlation Coefficient N Correlation Coefficient N Correlation Coefficient N Correlation Coefficient N Correlation Coefficient N Correlation Coefficient N Correlation Coefficient N Correlation Coefficient N Correlation Coefficient N Fe Hg Mn Pb Cu Cr Ni Zn 1.000 36 -.012 1.000 35 35 .427 -.080 1.000 36 35 36 .134 .640(**) .224 1.000 36 35 36 36 .288 .502 .052 .848(**) 1.000 30 29 30 30 31 .414(*) .445 -.027 .619(**) .706(**) 1.000 30 29 30 30 31 31 .496(*) .546(*) -.076 .531C) .565(**) .780(**) 1.000 30 29 30 30 31 31 31 .485 .345 .293 .701(**) .830(**) .631(**) .608(**) 1.000 30 29 30 30 31 31 31 31 .302 .285 .343 .299 .261 .147 .227 .291 36 35 36 36 30 30 30 30 OM% 1.000 36 " Correlation is significant at the 0.001 level (2-tailed). Correlation is significant at the 0.005 level (2-tailed). 102 A p p e n d i x F - 4 Table F - 4 Spearman's rho Correlat ions w i t h Bonferroni Cor rec t ion- 2003 Stream Sediment i n the Brunet te Watershed Fe Hg Mn Pb Cu Cr Ni Zn o% Fe Correlation 1.000 Coefficient N 36 Hg Correlation Coefficient N .041 36 1.000 36 Mn Correlation .398 36 .129 36 1.000 36 Coefficient N Pb Correlation Coefficient N .245 36 .304 36 .353 36 1.000 36 Cu Correlation Coefficient .555(") .200 .215 .930(") 1.000 N 30 30 30 30 30 Cr Correlation Coefficient .748(") .103 .167 .635(**) .800(") 1.000 N 30 30 30 30 30 30 Ni Correlation Coefficient .715(**) -.030 .189 .493(**) .667(**) .825(**) 1.000 N 30 30 30 30 30 30 30 Zn Correlation .712(") .135 Coefficient 5140 864(") .890(**) .685(**) .553(*) 1.000 N 30 30 30 30 30 30 30 30 Om Correlation Coefficient .332 .205 ,639(") 663(") .574(**) .307 .306 .703(") 1.000 N 36 36 36 36 30 30 30 30 36 * Correlation is significant at the 0.005 level (2-tailed). ** Correlation is significant at the 0.001 level (2-tailed). 103 APPENDIX G Correlations for Burnaby Lake composite core sediments Table G - l Spearman's rho Correlat ions w i t h Bonfer ron i Correc t ion- B u r n a b y L a k e composi te core sediments ( E n k o n 2002) Hg Mn Fe Pb TOC s Cu Ni Zn Hg Correlation 1.000 Coefficient N 15 Mn Correlation Coefficient N .533 15 1.000 15 Fe Correlation Coefficient N .454 15 ,832<**) 15 1.000 15 Pb Correlation Coefficient N .876(**) 15 .463 15 .461 15 1.000 15 TOC Correlation Coefficient .634 .197 .020 .448 1.000 N 15 15 15 15 15 s Correlation Coefficient .467 .027 .041 .229 .624 1.000 N 15 15 15 15 15 15 Cu Correlation Coefficient ,788(*») .668 .664 ,835(**) .159 .080 1.000 N 15 15 15 15 15 15 15 Nt Correlation Coefficient ,652(**) .576 .420 .571 .091 .163 .843(*») 1.000 N 15 15 15 15 15 15 15 15 Zn Correlation Coefficient 862(*») .496 .525 .976(**) .372 .181 .886(**) .626 1.000 N 15 15 15 15 15 15 15 15 15 * Correlation is significant at the 0.005 level (2-tailed). ** Correlation is significant at the 0.001 level (2-tailed). 104 APPENDIX H Correlations for Microcosm #1 data Table H - l Spearman's rho Correla t ions w i t h Bonfe r ron i Cor rec t ion for M i c r o c o s m #1 data 1 PH conductivity D.O. DOC Hg Fe pH Correlation 1.000 Coefficient Sig. (2-tailed) N 16 Conductivity Correlation Coefficient Sig. (2-tailed) N .346 .189 16 1.000 16 D.O. Correlation Coefficient Sig. (2-tailed) N -.649(*) .006 16 -.059 .828 16 1.000 16 DOC Correlation Coefficient Sig. (2-tailed) •754<*) .031 .345 .403 -.638 .089 1.000 N 8 8 8 8 Hg Correlation Coefficient -.500 -.265 .154 .651 1.000 Sig. (2-tailed) .049 .322 .570 .081 N 16 16 16 8 16 Fe Correlation Coefficient .539 .158 -.221 .533 .000 1.000 Sig. (2-tailed) .031 .560 .411 .174 1.000 N 16 16 16 8 16 16 ** Correlation is significant at the 0.008 level (2-tailed). * Correlation is significant at the 0.001 level (2-tailed). 105 APPENDIX I Correlations for the February 28, 1997 stormwater event in the Brunette Watershed Table 1-1 Spearman's rho Correlat ions w i t h Bonfe r ron i Correc t ion for the February 28, 1997 o n S t i l l C reek stormwater event (Sekela et al. 1998) C r C u H g F e M n N i P b Z n C r Correla t ion 1.000 Coefficient Sig . (2-tailed) C u Corre la t ion Coefficient S ig . (2-tailed) .257 .623 1.000 H g Corre la t ion Coeff icient Sig . (2-tailed) .600 .208 .771 .072 1.000 F e Corre la t ion Coefficient S ig . (2-tailed) .143 .787 .943(*) .005 .829 .042 1.000 M n Corre la t ion Coeff icient Sig . (2-tailed) .086 .872 -.714 .111 -.143 .787 -.543 .266 1.000 N i Corre la t ion Coeff icient .714 -.086 .371 -.143 .543 1.000 Sig . (2-tailed) .111 .872 .468 .787 .266 P b Corre la t ion Coefficient .086 .886 .543 .829 -.829 -.314 1.000 Sig . (2-tailed) .872 .019 .266 .042 .042 .544 Z n Corre la t ion Coefficient .029 .943(*) .600 .886 -.771 - .200 .943(*) 1.000 Sig . (2-tailed) .957 .005 .208 .019 .072 .704 .005 ** Cor re la t ion is significant at the 0.001 level (2-tailed). * Cor re la t ion is significant at the 0.006 level (2-tailed). 106 |Table 1-2 Spearman's rho Correlat ions w i t h Bonfe r ron i Cor rec t ion for the February 28, 1997 o n the Brunet te R i v e r stormwater event (Sekela et al. 1998) C r C u H g Fe M n N i P b Z n C r Corre la t ion 1.000 Coeff ic ient S ig . (2-tailed) C u Corre la t ion -.841 .036 1.000 Coeff icient S i g . (2-tailed) H g Corre la t ion Coeff ic ient S i g . (2-tailed) .464 .354 -.515 .296 1.000 F e Corre la t ion -.486 .329 .580 .228 -.725 .103 1.000 Coeff icient S i g . (2-tailed) M n Corre la t ion -.429 .397 .493 .321 -.870 .024 .943(*) .005 1.000 Coeff icient S i g . (2-tailed) N i Corre la t ion -.667 .647 -.250 -.116 -.029 Coeff ic ient 1.000 S i g . (2-tailed) .148 .165 .633 .827 .957 P b Corre la t ion -.429 .638 -.783 .943(*) Coeff ic ient .886 - .058 1.000 S ig . (2-tailed) .397 .173 .066 .005 .019 .913 Z n Corre la t ion .986(**) Coeff ic ient -.771 -.551 .600 .543 .638 .657 1.000 S i g . (2-tailed) .072 .000 .257 .208 .266 .173 .156 ** Cor re la t ion is significant at the 0.001 level (2-tailed). * Corre la t ion is significant at the 0.006 level (2-tailed). 107 APPENDIX J Quality control data for mercury in sediment Table J - l Q u a l i t y cont ro l data for mercury i n sediment, analyzed on a L u m e x A A . Resul ts i n ug/kg , dry wieght . Env i ronmen ta l Resource Associates : Reference Sample Ca ta log #540 L o t # D035-540 . Q C D a t a W e i g h t Cone . % (ppm) (mg) (ppm) R e c o v e r y era-24.6 18.6 26.0 105.8% era 24.6 35.2 21.9 89.0% era 24.6 31.6 20.5 83.5% era 24.6 20.9 25.2 102.3% era 24.6 33.3 23.9 97.2% era 24.6 4.7 29.6 120.3% era 24.6 31.0 23.0 93.5% Ave 23.5 95.6% std dev 3.0 conf@95% 1.86 check-30 100 26.3 87.7% check-30 100 28.3 94.3% check-30 100 24.6 82.0% check-50 100 57.4 114.8% check-50 100 45.7 91.4% check-50 100 52.6 105.2% Ave 95.9% Blank 1 -2.0 Blank 1 -1.3 Blank 1 -3.0 Blank 1 2.9 Blank 1 0.8 Blank 1 -0.2 Blank 1 -0.7 Ave -0.5 std dev 1.9 108 APPENDIX K Wilcoxon Paired Sample Signed Rank Test for mercury stream sediment data in the Brunette Watershed. Table K - l W i l c o x o n Pai red Sample S igned R a n k Test for 1973, 1989, 1996 and 2003 mercury stream sediment data in the Brunette Watershed N Mean Rank Sum of Ranks 1989-1973 Negative Ranks 0(a) .00 .00 Positive Ranks . 27(b) 14.00 378.00 Ties 0(c) Total 27 1993-1973 Negative Ranks 0(d) .00 .00 Positive Ranks 28(e) 14.50 406.00 Ties ' 0(f) Total 28 2003-1973 Negative Ranks 5(g) 10.80 54.00 Positive Ranks 23(h) 15.30 352.00 Ties 0(i) Total 28 1993-1989 Negative Ranks 12(1) 15.08 181.00 Positive Ranks 17(k) 14.94 254.00 Ties 0(l) Total 29 2003 -1989 Negative Ranks 22(m) 16.27 358.00 Positive Ranks 7(n) 11.00 77.00 Ties 0(o) Total 29 2003 - 1993 Negative Ranks 24(p) 16.71 401.00 Positive Ranks 6(q) 10.67 64.00 Ties 0(r) Total 30 a 1989 < 1973, b 1989 > 1973,c 1989 = 1973, d 1993 < 1973, e 1993 > 1973, f 1993 = 1973, g 2003 < 1973, h 2003 > 1973, i 2003 = 1973, j 1993 <1989, k 1993 >1989,1 1993 =1989, m 2003 < 1989, n 2003 > 1989, o 2003 = 1989, p 2003 < 1993, q 2003 > 1993, r 2003 = 1993 109 Table K - 2 Test Statistics for data from 1973-2003 1989-1973 1993- 1973 2003- 1973 1993-1989 2003 - 1989 2003 - 1993 z -4.541(a) -4.623(a) -3.393(a) -.789(a) -3.038(b) -3.466(b) Asymp. Sig. (2-tailed) .000 .000 .001 .430 .002 .001 a Based on negative ranks, b Based on positive ranks, c Wilcoxon Signed Ranks Test 110 APPENDIX L Mercury concentrations in stream sediment adjusted for a 66.8% loss caused by drying the sediment Table L - l M e r c u r y concentrations i n stream sediment adjusted for a 66.8% loss caused by d ry ing the sediment (Mg /kg, dry weight) . Stations 1973 Hg 1989 Hg 1993 Hg 2003 Hg (yg/kg) (ug/kg) (wg/kg) (ug/kg) 1 73 200* 220* 121 2 67 183* 220* 44 3 87 133 229* 109 4 18 75 85 34 6 18 . 133 95 172 7 32 133 142 131 8 23 58 85 99 9 33 75 192* 74 10 20 150 132 94 11 17 NA 172 97 13 45 67 75 18 14 50 58 83 55 15 15 67 25 95 16 22 83 25 132 17 23 42 100 143 19 30 158 102 169 20 37 175* 115 47 21 30 192* 158 55 24 88 584** 170 166 25 48 92 587* 41 26 25 108 107 104 27 37 117 113 81 29 122 150 257* 185* 30 168 267* 202* 86 31 100 150 249* 115 32 62 609** 152 77 33 57 692** 1451** 119 34 NA 334* 357* 30 35 NA 200* 229* 54 37 NA 292* NA 170 Mean 50 192* 211* 97 * indicates concentrations higher than Environment Canada Intenn Sediment Quality Guideline of 174 wg/kg ** indicates concentrations higher than Environment Canada Probable Effect Level of 486 wg/kg 111

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