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Pesticides in the aquatic environment. Hext, Herbert Daniel 1973

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I  PESTICIDES IN THE AQUATIC ENVIRONMENT  by  HERBERT DANIEL HEXT B.A.Sc, U n i v e r s i t y of B r i t i s h Columbia, 1970  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF APPLIED SCIENCE  i n the Department  of C i v i l Engineering  We accept t h i s thesis as conforming t o the required standard  THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 1973  In p r e s e n t i n g an  this thesis  in partial  advanced, d e g r e e a t t h e U n i v e r s i t y  the  Library  I further for  shall  agree  f u l f i l m e n t of the requirements f o r of British  make i t f r e e l y a v a i l a b l e  that  permission  Columbia,  f o rreference  I agree  that  and s t u d y .  f o r extensive copying o f t h i s  thesis  s c h o l a r l y p u r p o s e s may b e g r a n t e d b y t h e Head o f my D e p a r t m e n t o r  by  h i s representatives.  of  this thesis  written  f o r f i n a n c i a l gain  shall  permission.  Civil  Department o f  The U n i v e r s i t y o f B r i t i s h V a n c o u v e r 8, C a n a d a  Date  I t i s understood  A p r i l 13.  1933  Engineering  Columbia  that  copying or p u b l i c a t i o n  n o t be a l l o w e d w i t h o u t  my  A B S T R A C T  A comprehensive l i t e r a t u r e review i s presented  concerning  pesticides; i n p a r t i c u l a r the organochlorine i n s e c t i c i d e s , DDT and d i e l d r i n , and t h e i r r o l e i n the p o l l u t i o n of water resources. The r e s u l t s of a laboratory study on the removal of DDT and d i e l d r i n (HEOD) by adsorption onto a clay of the montmorillonite (bentonite) are presented.  type  For an i n i t i a l DDT concentration o f 100 ygm/1,  the addition of bentonite a t concentrations of 1.0 gm/l and 10.0 gm/l r e s u l t s i n the removal of about 60 and 72 per cent, r e s p e c t i v e l y , of the i n s e c t i c i d e . For an i n i t i a l HEOD concentration of 100 pgm/1, the a d d i t i o n o f bentonite at concentrations o f 1.0 gm/l and 10.0 gm/l brings about the removal of about 15 and 30 per cent, r e s p e c t i v e l y , of t h i s i n s e c t i c i d e . The r e s u l t s o f a laboratory study on the desorption of DDT and HEOD from the bentonite are presented.  Both i n s e c t i c i d e s are desorbed from  the clay, the HEOD being desorbed t o the greater extent and the DDT desorpt i o n being quite minimal. The r e s u l t s of a further laboratory study conducted t o ascertain the a b i l i t y of bentonite clay t o remove, by adsorption, i n s e c t i c i d e s from solution while s e t t l i n g through a quiescent water body are presented.  Bento-  nite a t concentrations of 1.0, 5.0, and 10.0 gm/l removes about 44, 48, and 54 per cent, r e s p e c t i v e l y , o f DDT from the quiescent water body  initially  containing 100 ygm/1 DDT. Bentonite at concentrations of 1.0, 5.0 and 10.0 gm/l removes about 14, 23, and 30 per cent, r e s p e c t i v e l y , of the HEOD from  *ii  iii  the quiescent water body i n i t i a l l y containing 100 ugm/1 HEOD. The r e s u l t s of an inorganic blanketing study indicates that the addition of a layer of sand over DDT and HEOD contaminated benthic deposits w i l l block, somewhat, the desorption o f these i n s e c t i c i d e s i n t o the overlying waters.  TABLE OF CONTENTS Page  LIST OF TABLES.  . . . . . viii  LIST OF FIGURES  i *  CHAPTER I.  INTRODUCTION. 1.1 1.2 1.3  1.4  1.5  II.  SCOPE AND AIM OF STUDY PESTICIDES . . USE OF PESTICIDES 1.3.1 Benefits 1.3.2 Hazards PESTICIDE FORMULATIONS . . 1.4.1 Powders 1.4.2 Wettable Powders 1.4.3 Granulated Preparations 1.4.4 Solutions of Pesticides i n Water and Organic Solvents 1.4.5 Emulsive Concentrates . . . 1.4.6 Aerosols SOURCES OF WATER-BORNE PESTICIDES. . . . . . 1.5.1 Manufacture . . . 1.5.2 A p p l i c a t i o n . . . . . . 1.5.3 Surface Drainage 1.5.4 Biota Transport . . 1.5.5 Atmospheric Deposition  . . . .  . . . .  . . .  . . . . . . . . . . . . . . . . . . . .  DDT AND DIELDRIN 11.1 INTRODUCTION 11.2 PROPERTIES OF DDT AND DIELDRIN 11.2.1 DDT 11.2.2 D i e l d r i n . . . . 11.2.3 A l d r i n 11.3 USE OF DDT AND DIELDRIN 11.3.1 Use o f DDT . 11.3.2 Use of D i e l d r i n 11.4 UBIQUITOUS NATURE OF DDT AND DIELDRIN. 11.5 LETHAL EFFECTS 11.5.1 On Man 11.5.2 On W i l d l i f e 11.6 SUB-LETHAL EFFECTS II.6.1 On Man  1 2 3 3 4 5 6 6 6 7 7 7 8 8 9 9 9 10  11 . . . . . . .  11 13 13 . . . . . . . 15 . . . . . 16 16 16 18 . . . . . . . 18 . . . . . . . 20 20 20 . . . . . . 24 24  CHAPTER  Page  II.6.2 On W i l d l i f e 11.7 PERSISTENCE IN THE ENVIRONMENT 11.8 BIOLOGICAL MAGNIFICATION 11.9 EUTROPHICATION  III.  . . . . . . .  24 26 28 31  INFLUENCE OF SEDIMENTS ON WATER QUALITY . . . .  33  111.1 111.2 111.3  33 35 38  ADSORPTION AND DESORPTION EFFECT OF SUSPENDED SOLIDS . . . . . . . EFFECT OF BOTTOM SEDIMENTS . . . . . . . . . . . .  IV. DETECTION OF DDT AND DIELDRIN IV. 1 IV. 2  IV.3  INTRODUCTION. GAS LIQUID CHROMATOGRAPHY IV.2.1 D e f i n i t i o n IV.2.2 Technique of Gas Liquid Chromatography . . IV. 2.3 C a r r i e r Gas IV.2.4 Sample Introduction. . . . . . IV.2.5 Column IV.2.6 S o l i d Support IV.2.7 Stationary Phase . IV. 2.8 Temperature IV.2.9 Detectors... THE ELECTRON CAPTURE DETECTOR USED WITH GAS LIQUID CHROMATOGRAPHY. . . . . . . . . . . . . IV.3.1 Introduction . . . . . . . . . ° IV.3.2 Operation: Mechanisms and P r i n c i p l e s of the Electron Capture Detector . . . . . IV.3.3 Electron Capture With A Nickel 63 Source . IV.3.4 P o t e n t i a l . . . . . . . . . . . IV.3.5 Standing Current IV.3.6 Peak Area TV.3.7 C a l i b r a t i o n Curve IV. 3.8 L i n e a r i t y IV.3.9 S e n s i t i v i t y IV.3.10 C a r r i e r Gas IV.3.11 C a r r i e r Gas Flow Rate IV.3.12 Detector Temperature . . . . IV.3.13 Pulse Interval  40 40 40 40 40 42 42 42 43 43 43 44 44 44 46 47 49 51 51 52 52 52 52 54 55 56  vi  CHAPTER  V.  METHODS OF ANALYSIS USING ELECTRON CAPTURE GAS CHROMATOGRAPHY V.l  V. 2  VI.  VII.  Page  GENERAL INFORMATION 58 V.l.l Sample Handling 58 V . l . 2 Glassware 58 V.l.3 Standards, Reagents and Solvents . 59 V. 1.4 Sample Transfer 60 V.l.5 Cleaning of Syringe 60 GAS LIQUID CHROMATOGRAPHY: RESEARCH APPLICATIONS . . . . 61 V.2.1 The Gas Chromatograph System 61 V.2.2 Columns 62 V. 2.3 Column E f f i c i e n c y 62 V.2.4 E x t r a c t i o n of Sample 64 V.2.5 Injection i n t o the Gas Chromatograph System,. . . 64 V.2.6 Q u a l i t a t i v e and Quantitative Analysis 65 V.2.7 Optimum Operating Conditions 66  DESCRIPTION OF STUDY METHODS  70  VI. 1 VI.2 VI. 3  70 71 72  ADSORPTION AND DESORPTION TESTS QUIESCENT REMOVAL TESTS SAND BLANKETING TESTS  RESULTS OF THE STUDY VII. l VII.2 VII.3 VII. 4  VIII.  58  ADSORPTION TEST RESULTS DESORPTION TEST RESULTS QUIESCENT REMOVAL TEST RESULTS SAND BLANKETING TEST RESULTS  . . . . .  73 73 . 79 79 85  CONCLUSIONS AND RECOMMENDATIONS  88  V I I I . 1 CONCLUSIONS VI11. 2 RECOMMENDATIONS  88 90  REFERENCES  92  APPENDICES  100  APPENDIX A: APPENDIX B: APPENDIX C:  COMPARATIVE CHROMATOGRAMS OF TWO HEXANES . . . . 102 THERMAL CLEANING RESULTS 104 EXAMPLES OF RECOVERY FROM SAMPLES CONTAINING KNOWN AMOUNTS OF INSECTICIDES 106  vii  Page  APPENDIX D: APPENDIX E: APPENDIX F:  EXAMPLES OP INJECTION TECHNIQUE PRECISION ANALYSIS TESTS ADSORPTION, DESORPTION, QUIESCENT REMOVAL AND SAND BLANKETING TEST RESULTS. . . . . . . . . . . SAMPLE CALCULATIONS . . . . . . .  108 Ill 166  LIST OF TABLES  Table  I.  Page  WORLDWIDE USAGE SURVEY FOR 1966  12  II.  EFFECTS OF PESTICIDES ON FISH AND WILDLIFE . . . . . .  21  III.  FISH KILLS, CALIFORNIA 1965-1969 . . . . . . . . . . .  23  \  IV.  APPROXIMATE RELATIVE AFFINITIES OF ELECTRON-CAPTURE DETECTOR FOR SOME ORGANIC COMPOUNDS  V. VI.  45  SAND BLANKETING TEST RESULTS FOR HEOD. . . . . . . . . 86 SAND BLANKETING TEST RESULTS FOR DDT . . . . . . . . .  viii  87  LIST OF FIGURES  Figure  Page  1.  Chemical Structure of DDT  13  2.  Chemical Structure o f HEOD  15  3.  Persistence o f Organochlorine  4.  B i o l o g i c a l Concentration o f DDT i n the Food Web  Insecticides  27  of a Long Island Estuary  30  5.  P e s t i c i d e Adsorption Isotherms  37  6.  Schematic Drawing of a Gas Chromatographic System. . . 41  7.  Schematic Drawing o f Two Electron A f f i n i t y C e l l s . . . 46  8.  Diagram of Electron Capture C e l l  47  9.  I l l u s t r a t i o n o f Pulsed EC C e l l Potential  50  10.  Six T y p i c a l L i n e a r i t y Plots  53  11.  Electron Concentration vs. Time Between Pulses . . . . 54  12.  E f f e c t o f C a r r i e r Gas Flow Rate on S e n s i t i v i t y . . . . 55  13.  L i n e a r i t y and S e n s i t i v i t y a t Various Pulse i n t e r v a l s . 57  14.  Column E f f i c i e n c y Parameters  63  15.  L i n e a r i t y Curve f o r DDT  67  16.  L i n e a r i t y Curve f o r HEOD  68  12..  HEOD Adsorption Curves:  1.0 gm/l Bentonite  74  18.  HEOD Adsorption Curves:  10.0 gm/l Bentonite  74  19.  HEOD Adsorption Curves: 0.01 Molar  1.0 gm/l Bentonite; Solution  HEOD Adsorption Curves: 0.01 Molar.  10.0 gm/l Bentonite; Solution  20.  76  76  ix  X  Figure  Page  21.  DDT Adsorption Curves:  1.0 gm/l Bentonite  77  22..  DDT Adsorption Curves:  10.0 gm/l Bentonite  77  23.  DDT Adsorption Curves: 0.01 Molar  1.0 gm/l Bentonite; Solution  DDT Adsorption Curves:  10.0 gm/l Bentonite; Solution  24.  78  0.01 Molar  78  25.  HEOD Desorption Curves:  1.0 gm/l Bentonite  80  26.  HEOD Desorption Curves:  10.0 gm/l Bentonite  80  27.  DDT Desorption Curves:  1.0 gm/l Bentonite. . . . . . . .  81  28.  DDT Desorption Curves:  10.0 gm/l Bentonite . . . . . . .  81  29.  HEOD Quiescent Removal Test Results  30.  DDT Quiescent Removal Test Results  82 . . . . . .  84  CHAPTER I  INTRODUCTION  1.1  SCOPE AND AIM OF STUDY There i s much p u b l i c concern about the widespread use of p e s t i -  cides i n North America.  This concern i s being expressed because p e s t i c i d e s ,  e s p e c i a l l y chlorinated hydrocarbon (organochlorine) i n s e c t i c i d e s , are highly toxic to w i l d l i f e and extremely p e r s i s t e n t i n the environment. This research i s directed towards f i n d i n g a solution t o a severe problem which i s occurring i n many natural water bodies today. The problem i s that o f the release of p e s t i c i d e s from lake bottom sediments i n t o overlying waters. 1  Certain clays, which are widespread constituents of bottom  sediments, have been shown t o adsorb p e s t i c i d e s and, under c e r t a i n condit i o n s , to permit desorption i n t o overlying waters.  This research i s directed  towards i d e n t i f y i n g the quantity of these i n s e c t i c i d e s adsorbed onto the clays, finding a method t o prevent the i n s e c t i c i d e s from being desorbed from the clay sediments, and i n using t h i s clay to remove the i n s e c t i c i d e s already present i n the water. This thesis project i s also designed to provide a review of the available l i t e r a t u r e concerning p e s t i c i d e s (in p a r t i c u l a r , the organochlorine i n s e c t i c i d e s , DDT and d i e l d r i n ) and t h e i r r o l e i n the p o l l u t i o n of water r e sources.  1  2  1.2  PESTICIDES Our society has gained tremendous benefits from the use of  pesticides.  Their use has helped to increase food and f i b r e production and  to prevent disease.  P e s t i c i d e s appear to be needed.  They were developed i n  response to p u b l i c needs and demands, and when used wisely and s k i l l f u l l y under responsible^leadership, have done much towards eradicating disease and improving  agriculture.  Improper care, however, through misuse or over-  use, has r e s u l t e d i n unnecessary damage, e s p e c i a l l y to w i l d l i f e and fishery resources. The environmental  widespread p u b l i c concern during the l a s t decade about the  damage caused by organic p e s t i c i d e s , stems largely from the  c i r c u l a t i o n of Rachel Carson's book, Silent  Spring  [1],  Her book dramati-  c a l l y i l l u s t r a t e d the broad range of damage caused by the improper use o f pesticides.  Several reports and publications written a f t e r the appearance  of Carson's book reinforced her p r i n c i p a l point:  that p e s t i c i d e s were  being used i n massive q u a n t i t i e s with l i t t l e or no regard t o undesirable side e f f e c t s .  The persistence, t o x i c i t y and pervasiveness, p a r t i c u l a r l y  of the organochlorine p e s t i c i d e s , as w e l l as the use o f increased quantit i e s and new p e s t i c i d e v a r i a n t s , further aroused p u b l i c concern.  In the  United States, i n 1969, synthetic organic p e s t i c i d e production was increasing  at an annual rate of 15 per cent with an estimated $3 b i l l i o n i n annual  sales by 1975 [2].  At the same time there were some 900 active p e s t i c i d a l  chemicals formulated i n t o over 60,000 preparations [2],  3  Benefits derived from pest control through p e s t i c i d e use are measured by t h e i r effectiveness i n reducing populations of pest species. Detrimental e f f e c t s are based on adverse e f f e c t s on l i f e forms other than the s p e c i f i e d pest.  There i s an abundance of recent evidence  indicating  the need to be concerned with the detrimental e f f e c t s of p e s t i c i d e s on non-target organisms.  The benefits of using p e s t i c i d e s must be weighed  against present and future  r i s k s of using p e s t i c i d e s .  The t o t a l problem  of p e s t i c i d e usage must be considered, not only i n the context of what i s known, but also i n the context of the many unknowns that w i l l probably come to l i g h t i n the near future. There i s a serious lack of information a v a i l a b l e on p e s t i c i d e use patterns, e s p e c i a l l y f o r non-agricultural uses [2].  There i s a  s i m i l a r lack of information concerning the fate of p e s t i c i d e s i n the aquatic environment.  The research of today must concentrate on the long-  range e f f e c t s of low-level doses and the p o s s i b l e s y n e r g i s t i c and  antagonis-  t i c e f f e c t s of p e s t i c i d e s .  1.3  USE OF PESTICIDES 1.3.1  B e n e f i t s . Increased control over the environment, i n c l u d i n g  the use of p e s t i c i d e s i n organized agriculture, has greatly r a i s e d our material standard of l i v i n g .  The domestication of food plants and large-  scale, single-crop farming has brought about a concentration and t i o n of crops and animals.  localiza-  This concentration and l o c a l i z a t i o n has  reduced  the amount of energy required to be expended by pests i n t h e i r search f o r i  food and has r e s u l t e d i n a s u b s t a n t i a l increase i n the pest problem.  Pest  4  control has thus become a v i t a l part of man's trend towards the concentrated monoculture system that he has adopted. A g r i c u l t u r a l needs have e n t a i l e d the l a r g e s t applications of p e s t i c i d e s i n developed nations and p r o d u c t i v i t y has increased to such an extent that famine i s an unknown experience i n such countries. Not only do p e s t i c i d e s reduce crop losses, but they also r e s u l t i n v i s u a l l y high q u a l i t y foodstuffs.  The  average shoppers of today, f o r ex-  ample, are accustomed to blemish-free  products at t h e i r supermarkets.  Besides enabling great increases i n a g r i c u l t u r a l production, p e s t i c i d e s have freed man precedented extent.  from several communicable diseases to an  Examples of diseases that have been l i m i t e d through  p e s t i c i d e use against t h e i r r e l a t e d i n s e c t vectors are malaria, and typhus. using DDT  un-  yellow  fever,  I t has been estimated that, from the s t a r t of  i n World War  II to 1953,  over 5 m i l l i o n deaths from malaria  have been prevented, and over 100 m i l l i o n r e l a t e d i l l n e s s e s prevented [3]. 1.3.2  Hazards.  Detailed examination of the hazards of p e s t i -  cide use i s beyond the scope of t h i s paper.  Subsequent chapters w i l l , how-  ever, give pertinent information on the environmental hazards associated with the use of DDT  and d i e l d r i n .  This section w i l l , therefore, only  b r i e f l y deal with general concepts. When p e s t i c i d e s were f i r s t introduced i t was time, that they were u s e f u l .  apparent, at that  However, armed with the knowledge we have  today, one would be hard-pressed to j u s t i f y t h e i r continued indiscriminate use.  large-scale,  I t can be e a s i l y argued that large-scale, single-crop  farming that needs an abundance of p e s t i c i d e s to work e f f i c i e n t l y may  not  be necessary. Perhaps i t would be wise to forsake some of t h i s material  5  e f f i c i e n c y f o r an e f f i c i e n c y more c l o s e l y related to the environment. After a l l , there i s no use i n being e f f i c i e n t i n producing foodstuffs i f the cost i s to slowly but s t e a d i l y k i l l ourselves through the poisoning of our environment. As mentioned i n the b e n e f i t s of using p e s t i c i d e s , we have high q u a l i t y foodstuffs as f a r as v i s u a l aspects are concerned, but there be a hidden low q u a l i t y inherent i n the product. of today may  may  For example, shoppers  i n f a c t be accustomed to blemish-free products a t t h e i r super-  markets, but i f given the choice, they may but p e s t i c i d e - f r e e foodstuffs. This may  opt f o r blemished, even wormy,  e s p e c i a l l y be so i f the a l t e r -  natives of both are properly presented to the shopper. As mentioned, western man has modified agriculture and livestock rearing to the extent that he needs p e s t i c i d e s .  The e f f i c i e n c y of t h i s sys-  tem i s such that i t has helped r a i s e h i s material standard of l i v i n g , but with hidden costs that are j u s t now  coming to l i g h t .  These hidden costs  are the environmental e f f e c t s of the large-scale use of p e s t i c i d e s and the consequences associated with t h i s .  I t i s time now to attempt to put  values on these hidden costs and i f not enough i s known about them, to ban the use of the related p e s t i c i d e , as has been done i n the case of certain organochlorine i n s e c t i c i d e s .  Perhaps western man  should s a c r i f i c e some  of h i s Gross National Product-related e f f i c i e n c y i n the production of foods t u f f s f o r more diverse, more complex and smaller-scale a g r i c u l t u r e that would not require the use of p e s t i c i d e s .  In other words, western man  should  seek to enhance the q u a l i t y of his l i f e , not j u s t the quantity. 1.4  PESTICIDE FORMULATIONS [4] The amount of p e s t i c i d e that gets i n t o n a t u r a l waters depends to  a large extent on the p e s t i c i d e formulations and methods of a p p l i c a t i o n .  6  Depending on the chemical properties of the p e s t i c i d e , i t s purpose, and the means of a p p l i c a t i o n , the formulation considered most e f f i c i e n t i s selected.  There are a tremendous number of d i f f e r e n t formulations manufactured  for use i n industry, a g r i c u l t u r e , and health p r o t e c t i o n .  In the United  States alone there are over 1200 formulations manufactured that are based on DDT only, and about 1500 based on other organochlorine i n s e c t i c i d e s The most important types of formulations are the following: 1.4.1 1.4.2 1.4.3 1.4.4 1.4.5 1.4.6  Powders (nusts). Wettable Powders. Granulated Preparations. Solutions i n Water and Organic Solvents. Emulsive Concentrates. Aerosols.  1.4.1  Powders.  The p e s t i c i d a l powders or dusts consist of a  mechanical mixture of the active ingredient and an i n e r t d i l u e n t .  The i n e r t  diluents are usually hydrophobic minerals of the t a l c and p y r o p h y l l i t e type, although i n dry climates h y d r o p h i l i c minerals of the kaolin and bentonite clay types are also used.  These powders are applied dry on the plants to  be protected. 1.4.2  Wettable Powders.  Wettable powders are powders that are  d i l u t e d with water to y i e l d stable suspensions.  These suspensions are  sprayed on plants and other surfaces and are gradually replacing the dusts, as they are usually more e f f e c t i v e .  The advantages of using wettable pow-  ders over dusts are that less p e s t i c i d e i s l o s t due to wind currents, being washed o f f by r a i n f a l l , or being applied on material that i s not to be treated. 1.4.3  Granulated Preparations.  Granulated formulations are  often used instead of dusts as they are frequently more convenient and  7  leave a smaller amount of undesirable formulations  contaminants on the p l a n t s .  These  are prepared by the granulation of powders on a s u i t a b l e  diluent, with subsequent screening.  Kaolin, bentonite, or s i m i l a r clays  are most often used as d i l u e n t s . 1.4.4  Solutions of Pesticides i n Water and Organic Solvents.  Only compounds that are rather soluble i n water can be used i n the form of aqueous s o l u t i o n s .  The main p e s t i c i d e s used i n aqueous solutions are  herbicides and some organophosphorus i n s e c t i c i d e s and fungicides. Various solutions of p e s t i c i d e s i n organic solvents are widely used for s o - c a l l e d  low-volume, finely-dispersed spraying of p l a n t s .  The  most frequently used solvents f o r the preparation of p e s t i c i d e solutions are the petroleum hydrocarbons:  dearomatized kerosene, white s p i r i t  (turpentine substitute),mineral o i l s and d i e s e l f u e l . 1.4.5  Emulsion Concentrates.  Emulsion concentrates  are formu-  l a t i o n s that upon d i l u t i o n with water give stable emulsions s u i t a b l e f o r spraying plants and surfaces.  These emulsions are usually more  concentrated,  than suspensions but otherwise are quite s i m i l a r to the pesticide-organic solvent s o l u t i o n s . 1.4.6  Aerosols.  Aerosols are a r e l a t i v e l y new  form of p e s t i -  cide a p p l i c a t i o n used mainly i n p u b l i c health and a g r i c u l t u r e . .'  The  simplest method of producing p e s t i c i d e aerosols i s by burn-  ing, i n s p e c i a l smoke pots, paper and other combustible products that have been impregnated with the p e s t i c i d e .  This method produces smoke and  clouds  poisonous to i n s e c t s , fungi or b a c t e r i a . Another method of producing p e s t i c i d e aerosols that i s recommended for control of f l i e s and other f l y i n g insects i n enclosed areas i s aerosols  8  i n spray  cans.  The  a e r o s o l s are o b t a i n e d by p l a c i n g s o l u t i o n s o f  i n s e c t i c i d e s i n v o l a t i l e s o l v e n t s , i n metal a e r o s o l c y l i n d e r s equipped w i t h an a t o m i z i n g by  device.  the i n t e r n a l p r e s s u r e  The  s o l u t i o n s are f o r c e d out o f the c y l i n d e r  c r e a t e d u s i n g carbon d i o x i d e o r a l o w - b o i l i n g  s o l v e n t such as F r e o n , o r methyl c h l o r i d e . As mentioned, the p e s t i c i d e f o r m u l a t i o n d e t e r m i n e s , t o a large extent, ment.  The  the amount o f p e s t i c i d e t h a t e n t e r s the a q u a t i c  environ-  l e s s s o l u b l e p e s t i c i d e s , such as the o r g a n o c h l o r i n e  c i d e s and the phenoxy h e r b i c i d e s , a r e f o r m u l a t e d  insecti-  w i t h emulsions o r  sur-  f a c t a n t s i n l i g h t o i l s o l u t i o n or i n o r g a n i c s o l v e n t s l i k e e t h a n o l acetone.  These p e s t i c i d e s , which a r e f o r m u l a t e d  come s u s p e n s i o n s i n water and a c t much l i k e s o l u t i o n s . spreading  i n water b o d i e s such a n a t u r e  [5].  solvents,  d i s p e r s e i n such f i n e p a r t i c l e s t h a t  Other f o r m u l a t i o n s  throughout the a q u a t i c environment.  granular formulations,  i n organic  or  have more d i f f i c u l t y W e t t a b l e powders  be-  they in  and  f o r example, t e n d t o s e t t l e t o the bottom S i n c e many o f the p e s t i c i d a l f o r m u l a t i o n s  are  t h a t t h e p e s t i c i d e can e n t e r and d i s p e r s e t h r o u g h o u t  a q u a t i c environment, an i m p o r t a n t  of the  c o n s i d e r a t i o n becomes the s o u r c e s  of  e n t r y o f these p e s t i c i d e s i n t o water b o d i e s .  1.5  SOURCES OF 1.5.1  WATER BORNE PESTICIDES  Manufacture.  The  manufacture of p e s t i c i d e s may  contribute a  s i g n i f i c a n t amount o f these p e s t i c i d e s t o the a q u a t i c environment. c i d e s may  Pesti-  e n t e r t h e water through the w a s t i n g o f c l e a n - u p w a t e r from p e s t i -  cide manufacturing or formulating p l a n t s .  P e s t i c i d e r e s i d u e s may  be  found  i n wastewater from t h e washing o f p r o t e c t i v e c l o t h i n g worn i n these p l a n t s .  The extent to which formulating plants may  contribute p e s t i -  cides to a stream i s i l l u s t r a t e d by a survey conducted j o i n t l y by the United States P u b l i c Health Service and the United States Department of A g r i c u l t u r e . Of the 57 lower M i s s i s s i p p i River drainage basin formulating plants inspected, every one carried out some operating procedure which could cause contamination 1.5.2  A p p l i c a t i o n . The majority of p e s t i c i d e s found i n the  aquatic environment trol.  of the surface water [6].  probably  r e s u l t from t h e i r a p p l i c a t i o n f o r pest con-  They may have been d i r e c t l y applied to the natural waters f o r con-  t r o l of filamentous algae, carp, or to k i l l mosquito larvae.  Wind cur-  rents during a e r i a l applications may have c a r r i e d them to an adjacent water body.  Occasional accidental s p i l l s into water courses during t r e a t -  ment of large forested areas i s a t h i r d p o s s i b i l i t y . 1.5.3  Surface Drainage.  A source of p e s t i c i d e residues i n  the aquatic environment not to be neglected would be due to surface drainage.  contamination  Surface drainage from treated crop lands  may  contain p e s t i c i d e s that have been desorbed from the s o i l i n concentrations ranging from picograms to micrograms per l i t r e of water [7].  R a i n f a l l of  a high i n t e n s i t y w i l l not only carry p e s t i c i d e s that have been desorbed from s o i l p a r t i c l e s , but w i l l also transport eroded, contaminated s o i l from the treated area [7, 8] . 1.5.4  Biota Transport.  t i o n , but one worth mentioning,  A minor route of p e s t i c i d e contamina-  i s through b i o t a transport.  L i v i n g organ-  isms may bring p e s t i c i d e s i n t o water bodies, e i t h e r i n the organisms themselves or adsorbed onto t h e i r surfaces [9] and through release of waste material or death, deposit the p e s t i c i d e s i n the aquatic environment.  10  A l t e r n a t i v e l y , the contaminated organism may  form a lower l i n k i n the  food chain and thus spread the p e s t i c i d e through the b i o t a . 1.5.5  Atmospheric Deposition.  Another minor route f o r p e s t i -  cide contamination of the aquatic environment i s through atmospheric deposition.  Evidence e x i s t s i n d i c a t i n g that p e s t i c i d e s can become airborne,  e i t h e r as a vapour or adsorbed onto dust p a r t i c l e s , and thus be translocated f a r from the treated area [10, 11, 12].  I t i s most l i k e l y that  some of the errant p e s t i c i d e would be deposited i n water courses.  CHAPTER II DDT AND DIELDRIN  II.1  INTRODUCTION A p e s t i c i d e i s a chemical used to k i l l non-human organisms  considered by man to be a pest; i . e . , h o s t i l e t o human i n t e r e s t s . Included as p e s t i c i d e s are:  i n s e c t i c i d e s , herbicides, fungicides and rodent-  icides. DDT and d i e l d r i n are two i n s e c t i c i d e s of the chlorinated hydrocarbon (organochlorine)  family.  Other members include:  a l d r i n , endrin,  toxaphene, lindane, methoxychlor, chlordane, and heptachlor. The United States Department of Agriculture has predicted that the domestic use o f i n s e c t i c i d e s w i l l more than double i n the period from 1969  t o 1975, and that foreign use of p e s t i c i d e s w i l l likewise continue  to increase.  Organochlorine and organophosphorus  i n s e c t i c i d e s w i l l con-  tinue t o represent a s i g n i f i c a n t part of the market [2]. the organochlorine  As late as 1967  i n s e c t i c i d e s made up approximately one-half of the  t o t a l United States production  of i n s e c t i c i d e s , o f which about 50 per cent  was DDT [2]. /  S h e l l International Chemical Company's Worldwide Usage Survey for 1966 (Table I) i l l u s t r a t e s the widespread usage o f i n s e c t i c i d e s , part i c u l a r l y the organochlorine  group, i n a g r i c u l t u r e .  Table I does not  include the large amounts o f i n s e c t i c i d e s used f o r reasons o f p u b l i c health. 11  12  TABLE I WORLDWIDE USAGE SURVEY FOR 1966  TOTAL INSECTICIDE USAGE (lbs.)  CROP  38 57 85 46 61 55 74 67 77 81 19 92  60,400 12,000 7,600 6,800 2,800 2,400 2,100 2,000 1,900 300 500 200  Cotton Rice A l l Other Cereals Vegetables Potatoes Sugar Beets Sugar Cane Tobacco Oilseeds Coffee Tea Sweet Potatoes  Source:  PER CENT CHLORINATED HYDROCARBON INSECTICIDES IN TOTAL  S h e l l International Chemical Company [2]  Since 1957 most of the p e r s i s t e n t i n s e c t i c i d e s have shown a decline i n use, with DDT use r a p i d l y d e c l i n i n g i n domestic pest control programs.  This s h i f t t o non-persistent i n s e c t i c i d e s w i l l probably con-  tinue a t an accelerated  rate.  However, there w i l l be a continued need  for the use of p e r s i s t e n t materials, i  such as DDT and d i e l d r i n , f o r the  control of selected pest problems. Although imaginative and e x c i t i n g research concerning noni n s e c t i c i d a l control techniques i s i n progress  (including research i n t o  b i o l o g i c a l methods ) i t i s not l i k e l y to have a s i g n i f i c a n t impact on the use of i n s e c t i c i d e s i n the foreseeable future. to be an increased  appreciation  There appears, however,  f o r the use o f integrated control u t i l i z i n g  less p e r s i s t e n t i n s e c t i c i d e s i n the management of pest problems [2].  t  13  II.2  PROPERTIES OF DDT AND DIELDRIN II.2.1  DDT.  DDT i s a chlorinated hydrocarbon  i n s e c t i c i d e ; or  more p r e c i s e l y , i t i s a diphehyl a l i p h a t i c chlorinated hydrocarbon.  Its  chemical name i s 1,1,1 - T r i c h l o r o - 2,2 - d i - (p-chlorophenyl) ethane and i t s chemical formula i s C, .H„Cl . 14 9 5 i n Figure 1. r  DDT s chemical structure i s shown 1  Figure 1 [13] Chemical Structure of DDT  14  Pure DDT has a melting point of between 108.5 C and 109 C. A l though the s o l u b i l i t y of DDT i n water i s only 0.001 mg/l (1 ppb),  evi-  dence e x i s t s i n d i c a t i n g that i t may occur at s i g n i f i c a n t l y higher concent r a t i o n s i n natural waters.  Wershaw et al.  [14] show that the addition  of sodium humate to d i s t i l l e d water (0.5% solution) increased the s o l u b i l i t y of DDT about 20 times. Bowman et al.  [15] showed that DDT may e x i s t  i n aqueous solutions as molecular aggregates at a concentration approximately 12 times greater than that i n a true s o l u t i o n . Acree et al. b i e n t temperatures.  [16] found that DDT c o d i s t i l l s with water at am-  This phenomenon, coupled with the DDT c a r r i e d by  wind currents from areas treated with a e r i a l spraying, may help explain the appearance of DDT i n regions where i t never has been used, such as the A n t a r c t i c . DDT penetrates through i n t a c t skin and exerts i t s t o x i c action when i t has entered i n t o the r e s p i r a t o r y t r a c t .  For t h i s reason, the  maximum permissible concentration i n the a i r i s only 1.0 mg/rn^ i n the 3 United States and 0.1 mg/m  i n the U.S.S.R.  The maximum permissible con-  centration i n seasonal foodstuffs i n the United States i s 1.0 mg/kg (ppm) [17]. In spite o f the many i n v e s t i g a t i o n s , the exact mechanisms o f DDT's action on l i v i n g organisms s t i l l has not been determined.  [4, 17,  18, 19], However, i t i s known that i n s o i l s and i n l i v i n g organisms, DDT i s broken down to residues of DDD [1, 1-bis  (4 - chlorophenyl) - 2 , 2 -  dichloroethane) and other compounds [17, 19, 20]. i  The p r i n c i p a l formulations o f DDT as i t i s applied are, as a 50 per cent wettable powder, as a 25 per cent emulsifiable concentrate, as a  15  f i v e per cent dust, and as a 10~per cent aerosol [21]. II.2.2  Dieldrin.  D i e l d r i n i s a white c y r s t a l l i n e substance  which i s highly toxic to both man and animals; i t s l e t h a l o r a l dose f o r a 50 per cent mortality  (LD^) f o r various animals being only 25 to 50 mg/kg  of body weight [17].  Its melting point, when pure, i s between 175°C and  176°C and i t has a s o l u b i l i t y i n water of 120 ppb at 20°C [22]. The technical grade product i s a l i g h t brown material containing not less than 85 per cent of the compound l,2,3,4,10,10-hexachloro-6,7epoxy-1,4,4a,5,6,7,8,8a-octahydro-l,4-endo,exo-5-8-dimethanonaphthalene, conveniently abbreviated as HEOD. ious impurities.  The other 15 per cent of d i e l d r i n i s var-  The chemical structure of HEOD i s shown i n Figure 2.  A n a l y t i c a l methods, p a r t i c u l a r l y those involving g a s - l i q u i d chromatography, determine HEOD, not d i e l d r i n [20].  Figure 2 [13] Chemical Structure of HEOD  16  As the t o x i c i t y of d i e l d r i n has been shown to be high, the maximum permissible concentration allowed i n the a i r i s 0.01 mg/kg (ppm) i n the United States and no residues are permitted on food or forage products.  The use of d i e l d r i n i s not permitted i n the U.S.S.R. [17]. The p r i n c i p a l formulations of d i e l d r i n as i t i s applied are,  as a 50 per cent wettable powder, as a 1.5 per cent dust, and as an emulsifiable concentrate containing 1.5 pounds per gallon [21]. II.2.3 without mentioning  Aldrin. aldrin.  No report about d i e l d r i n would be complete A l d r i n contains not less than 95 per cent  of the compound 1,2,3,4,10,10 - hexachloro - 1,4,4a,5,8,8a - hexahydro I, 4 - endo, exo - 5 - 8 - dimethanonaphthalene, commonly abbreviated as HHDN.  HHDN i s rapidly epoxidized i n animals and by s o i l microorganisms  to HEOD [18,23,24], or i n other words, a l d r i n i s r a p i d l y epoxidized to d i e l d r i n .  In subsequent chapters, discussion of d i e l d r i n w i l l apply  equally t o a l d r i n . A l d r i n i s used extensively i n t r e a t i n g corn acreage as i t k i l l s a wide variety o f corn pests.  Roughly one-half o f the t o t a l  United States corn acreage was treated with a l d r i n i n 1968.  This use  constituted over 81 per cent of the t o t a l a l d r i n and d i e l d r i n manufactured i n the United States f o r that year [ 2 1 .  In the U.S.S.R., the use  of a l d r i n i s not permitted [17].  II. 3  USE OF DDT AND DIELDRIN II.3.1  Use Of DDT. In Canada, the general use of DDT has been  i  banned by the Federal Government since January 1, 1970 [25].  t  Since  early i n 1971, DDT and DDT-like products have been c o l l e c t e d f o r disposal  17  at the Defense Research Establishment S u f f i e l d at Ralston, A l b e r t a . L i q u i d DDT products are to be. thermally destroyed with powdered  DDT  products from the Western Provinces to be stored there for use i n case of health emergencies.  There i s also an eastern storage s i t e for pow-  dered DDT products from Eastern Canada [26]. In the United States, the use of DDT  i n domestic pest con-  t r o l i s rapidly d e c l i n i n g , with the major need reported to be a s s o c i ated with cotton production i n the Southeastern  United States.  The  Secretary's Commission on Pesticides and Their Relationship to Environmental Health uses of DDT  [2, p. 8] recommended to "eliminate within two years a l l  and DDD  i n the United States excepting those uses e s s e n t i a l  to the preservation of human health and welfare and approved unanimously by the Secretaries of the Departments of Health, Education and  Welfare,  Agriculture and I n t e r i o r . " Production of DDT  i n the United States during 1967 was  m i l l i o n pounds of which 82 m i l l i o n pounds was of a l l DDT  exported.  103  Over one-half  exports were i n the form of wettable powders used p r i m a r i l y  for mosquito c o n t r o l by agencies of the World Health Organization  (WHO)  and the Food and Agriculture Organization (FAO) of the United Nations for malaria eradication [2]. an increasing amount of DDT  Although t o t a l production i s d e c l i n i n g ,  i s being purchased by these agencies f o r  t h e i r foreign malaria c o n t r o l programs [2]. WHO  and FAO use DDT  yellow fever and malaria.  for c o n t r o l of mosquitoes that spread  I t i s expected that this use of DDT  will  decrease s l i g h t l y as control programs become more sophisticated, but  18  DDT  f o r t h i s use i s s t i l l expected to amount to about 40 m i l l i o n pounds  per year [2].  The World Health Organization  states,  ". . . i t s (DDT) low cost makes i t i r r e p l a c e a b l e i n p u b l i c health at the present time. Limitations on i t s use would give r i s e to greater problems i n the majority of developing nations." [2, p. 50] II.3.2  Use of D i e l d r i n .  Due  to i t s high t o x i c i t y , d i e l d r i n  has never enjoyed the widespread use that DDT  has.  In Canada, the  of d i e l d r i n had declined from about 15,000 pounds per year i n 1962 about 6,000 pounds per year i n 1968  use to  [27].  In the United States d i e l d r i n i s used when a l o n g - l a s t i n g r e s i d u a l e f f e c t i s desired.  These r e s i d u a l uses of d i e l d r i n include i t s a p p l i -  cation f o r termite c o n t r o l , insect control on lawns and corn crops,  and  the permanent moth proofing of f a b r i c s [2]. D i e l d r i n i s used by WHO  and FAO  which transmit yellow fever and malaria.  for c o n t r o l l i n g mosquitoes I t i s also extensively used i n  A f r i c a to control sleeping sickness caused by the Tsetse f l y [2]. As previously mentioned, the use of d i e l d r i n i s not  permitted  i n the U.S.S.R. [17].  II.4  UBIQUITOUS NATURE OF DDT One  AND  DIELDRIN  of the major properties of the organochlorine i n s e c t i c i d e s  causing concern i s the ubiquitous nature of these chemicals.  In 1962 i n -  s e c t i c i d e s were d i s t r i b u t e d over nearly 90 m i l l i o n acres i n the States  United  (nearly one i n every 20 acres) and the annual sale of aerosol spray  cans of i n s e c t i c i d e s i n the same year exceeded more than one per household [18].  19  Weaver et al.  [28] divided the United States i n t o 15 major  drainage basins and sampled f o r p e s t i c i d e s .  D i e l d r i n , DDT  and DDE were  found i n a l l the major r i v e r basins, with d i e l d r i n being the most prevalent.  The United States Public Health Service has monitored major r i v e r  basins i n the United States f o r organochlorine p e s t i c i d a l compounds since 1957  [29].  Breidenbach  et al.  [30] have reported that DDT  and re-  lated compounds have been present through the entire period and again d i e l d r i n was  the most prevalent.  George and Frear [31] and Tatton and Ruzicka [32] found trace amounts of DDT  i n species taken i n the Antarctic and Cohen and Pinkerton  [10] found evidence of organochlorine compounds, including DDT, transported on dust p a r t i c l e s .  being  In England, Wheatleyand Hardman [11]  found organochlorine compounds i n r a i n water.  Schafer et al.  [29] found  d i e l d r i n i n over 40 per cent of the samples of finished drinking water taken i n the M i s s i s s i p p i and Missouri River basins.  More than 30 per cent  of these samples contained detectable endrin, p, p* - DDT,  and p, p' -  DDE.  DDT has been found i n the body f a t of residents, who had no occup a t i o n a l exposure, i n England, Germany, the United States and Canada with an average l e v e l of 12 ppm Germany [18].  i n the United States and two ppm  i n England  and  D i e l d r i n has been found i n the body f a t of residents of  England at an average of 0.2 ppm  and i s probably present i n the f a t of  North Americans as a r e s u l t of the extensive use of t h i s i n s e c t i c i d e  [18,  33]. The omnipresence of the p e r s i s t e n t organochlorine i n s e c t i c i d e s with regard to non-target f i s h i s i l l u s t r a t e d by the report that a l l 16  20  commercial  f i s h foods tested for use i n a Canadian f i s h hatchery contained  DDT and i t s metabolites.  Some of these commercial  foods caused 30 to 90  per cent mortality o f the f r y and f i n g e r l i n g s [2].  II.5  LETHAL EFFECTS II.5.1  On Man.  Each year approximately 150 deaths are a t t r i b u t e d  to the misuse of p e s t i c i d e s i n the United States, with over h a l f dealing with c h i l d r e n accidently exposed at home [18].  However, none of these  deaths were a t t r i b u t e d to e i t h e r DDT or d i e l d r i n . There have been numerous cases of acute poisoning due to DDT [17] but no mortality reported, as the t o x i c i t y of DDT t o man i s comp a r a t i v e l y small [2, 17].  While d i e l d r i n has caused many more cases of  serious poisoning [2], no instances of mortality have been found i n the l i t e r a t u r e reviewed. II.5.2  On W i l d l i f e .  The misuse and overuse of p e s t i c i d e s has  caused needless death to f i s h and w i l d l i f e , and numerous cases of l e t h a l e f f e c t s o f DDT and d i e l d r i n have been well documented. The more notable incidents of mortality are l i s t e d i n Table I I . Pesticides cause approximately twice as many f i s h t o be k i l l e d per incident than a l l other forms of p o l l u t i o n combined (Table III) and as indicated i n Table I I , d i e l d r i n and DDT and i t s metabolites account for most of the l e t h a l incidents. The data i n Table I I I r e f e r s only to f i s h k i l l s due to d i r e c t a c t i o n o f the p e s t i c i d e and not to subtle e f f e c t s on f i s h reproduction i  and behaviour.  21  TABLE II EFEECTS OF PESTICIDES ON FISH AND WILDLIFE  NO.  1.  CHEMICAL  EFFECT  Rice seed protection.  Widespread mortality of fulvous tree ducks.  Japanese beetle control.  Nearly complete eliminat i o n of many species of songbirds. Heavy mort a l i t y of gamebirds. Some mortality of mammals.  Clear Lake gnat.  Death of grebes and r e duction of breeding population.  DDT  Dutch elm disease control.  Heavy mortality of robins and songbirds.  DDT  Gypsy moth and b i t i n g fly.  Cessation of reproductive successes of trout due to death of f r y .  DDT  Forest protection.  Trout k i l l due to food depletion.  DDT  Agriculture drainage.  Death of many f i s h , some birds.  Spruce budworm and blackheaded budworm.  Salmon and trout populations reduced and production curtailed.  Rice pests.  Some deaths of mallards, pheasants and other birds.  Mosquito control  Deaths of f i s h , crabs, frogs, l i z a r d s and snakes.  DDD  DDT  2 lb/Acre  DDT  (A)  50 - 70 ppm i n water.  1/2 l b /A and 1 lb/A  DDT  10.  PURPOSE  Aldrin Aldrin  7.  RATE  0.2 - 1. lb / A  22  TABLE II (Continued)  NO.  CHEMICAL  RATE  11.  Dieldrin  12.  D i e l d r i n , DDT and others  13.  Dieldrin  14.  Endrin  15.  Heptachlor or D i e l d r i n  2 l b /A  16.  Heptachlor  17.  Cotton Insecticides  18.  Toxaphene  19.  Cotton Insecticides  Source:  2-3 lbs/A  1 l b /A 0.8 l b /A  PURPOSE  EFFECT  White fringed beetle, Japanese beetle.  Heavy mortality of songb i r d s , q u a i l , and waterb i r d s , rabbits and some other mammals.  Routine agricult u r a l applications .  Pheasant reduced.  Sandfly  Heavy f i s h mortality.  larvae.  production  Cutworm.  Heavy rabbit mortality.  Imported f i r e ant.  V i r t u a l elimination of b i r d s . Populations of q u a i l remained depressed for at l e a s t three years.  2 l b s /A  Japanese beetle.  Heavy songbird  D r i f t from treated fields.  Cotton insect control.  Death of some r a b b i t s , b i r d s , snakes, f i s h and frogs.  Crop protection.  Heavy mortality o f f i s h eating birds.each year 1960-1963.  Cotton insects.  Heavy f i s h k i l l s i n 15 streams.  Surface erosion from treated fields.  Reference [12].  mortality.  23  TABLE I I I FISH KILLS CALIFORNIA, 1965-1969  OTHER POLLUTANTS  PESTICIDES TOTAL INCIDENTS  48  NO. KILLED  NO. KILLED PER INCIDENT  408,457  Source:  8500  TOTAL INCIDENTS  180  NO. KILLED  612,985  NO. KILLED PER INCIDENT  4700  Reference [34]  D i e l d r i n and a l d r i n are many times more toxic to vertebrates than DDT [18].  Unlike most other i n s e c t i c i d e s , an average dosage of d i e l d r i n  (one t o three pounds per acre) produces high mortality of mammals i n the treated area [18]. An i n t e r e s t i n g case of f i s h mortality i s the example of number 5 i n Table I I .  In t h i s case, over the one month period when the small f r y  have almost completely absorbed t h e i r yolk sac, over 350,000 f r y died (close to 100 per cent m o r t a l i t y ) . fatty material i n t h e i r eggs.  This puzzling case was ultimately traced to The newly hatched f r y l i v e d on t h i s f a t t y  material from the egg and when they had absorbed approximately 2.9 ppm of the DDT, i t was enough to cause death.  This example i l l u s t r a t e s the i n d i r e c t  manner i n which organochlorine i n s e c t i c i d e s may cause death i n f i s h and wildlife. I  24  II.6  SUB-LETHAL EFFECTS II.6.1  On Man.  P r e c i s e l y because p e s t i c i d e chemicals are designed  to k i l l or metabolically upset some l i v i n g organism,  they are p o t e n t i a l l y  dangerous t o other l i v i n g non-target organisms, including man.  At the  present time there i s no evidence that the levels of pesticides i n the environment present  an acute t o x i c i t y hazard to man.  Not enough i s known,  however, about the e f f e c t s of long-term, low-level environmental exposures. Nor i s there enough known about the possible s y n e r g i s t i c e f f e c t s that two or more p e s t i c i d e s may have on  man.  In one study [18] people ingested 35 mgs of DDT per day. 18 month period these t e s t specimens showed no i l l e f f e c t s . and i t s metabolites averaged 270 ppm  Over an  However, DDT  i n t h e i r f a t t i s s u e s , more than 20  times the national average f o r that area. Many other studies conducted  [2]  show that DDT and i t s metabolites are stored i n the f a t tissues of people but an equilibrium l e v e l i s attained despite continuing exposure.  The pre-  c i s e concentration at which t h i s equilibrium l e v e l i s reached appears to be related to the l e v e l of exposure, but there are other determining factors such as the method of ingestion (orally, through the respiratory t r a c t or absorption through s k i n ) , the form the DDT i s i n ; and others. A two-year study group [2] on d i e l d r i n showed that no i l l  effects  were found i n the test subjects a t the highest l e v e l of ingestion of 0.22 5 mg/man/day.  Again, l i k e DDT,  blood to an equilibrium l e v e l .  i t d i d e x h i b i t a build-up i n body f a t and This equilibrium concentration was also r e -  lated to the l e v e l of exposure and declined when the exposure was discontinued, i  II.6.2  On W i l d l i f e .  The most noteworthy r e s u l t of the exposure of  w i l d l i f e to p e s t i c i d e s involve m o r t a l i t y .  In such s i t u a t i o n s the connection  25  between cause and e f f e c t i s e a s i l y seen because they are usually c l o s e l y r e lated i n time and space.  When these m o r t a l i t i e s occur, the course of action  to remedy the s i t u a t i o n i s quite apparent. These dramatic w i l d l i f e m o r t a l i t i e s are then highly p u b l i c i z e d and very often may  be wrongly considered  i c i d e s on f i s h and w i l d l i f e .  the most serious e f f e c t of the pest-  In actual f a c t , the long-term, low-level con-  centration of p e s t i c i d e s or the possible s y n e r g i s t i c e f f e c t s of p e s t i c i d e s may  have a greater and farther-reaching e f f e c t on the environment.  many i n d i r e c t e f f e c t s may harder to comprehend.  These  be much more serious and yet are usually much  Some of these i n d i r e c t e f f e c t s that have to be  studied  include e f f e c t s on the reproduction of non-target organisms, e f f e c t s on the metabolism of s o i l and aquatic micro-organisms, persistence i n the ment, b i o l o g i c a l magnification, and the e f f e c t s of population The e f f e c t s of DDT mented.  Risebrough et al.  suffered reproduction  environ-  suppression.  on the reproduction of b i r d s i s well docu-  [35] l i s t numerous studies that show b i r d s have  losses due to DDT.  S t i c k e l and Rhodes [36] show that  Coturnix q u a i l fed d i e t a r y dosages of p,p'-DDT produced fewer eggs and  their  eggs had thinner s h e l l s than the c o n t r o l population. DDT Some b i r d s may  has been found to be stored i n the f a t of b i r d s [37,38].  accumulate small amounts of DDT  i n t h e i r f a t tissues while eat-  ing and when u t i l i z i n g these f a t s during winter or migration,  these sub-lethal  amounts could become l e t h a l . It has been observed that d i e l d r i n , a f t e r 10 hours exposure at 1 ppm,  causes p h y s i o l o g i c a l i r r i a t i o n s i n osyters  [39].  Residues of only 4  i  ppm  i n the gonads of lake trout have been reported to have caused the death  of the developing f r y .  26  The e f f e c t s of pesticides on the metabolism of s o i l and aquatic micro-organisms  i s also well documented.  The presentation of t h i s abundance  of information i s , however, beyond the scope o f t h i s paper. The reader i s directed t o the work o f Ware and Roan [40] and others [41,42] who f u l l y r e view the studies done on the i n t e r a c t i o n s of i n s e c t i c i d e s with aquatic microorganisms and to the ample l i t e r a t u r e [43,44,45,46,47,48,49,50,51,52,53] concerning the actions o f various i n s e c t i c i d e s on s o i l  II.7  micro-organisms.  PERSISTENCE IN THE ENVIRONMENT An important c h a r a c t e r i s t i c of the organochlorine i n s e c t i c i d e s ,  p a r t i c u l a r l y DDT and d i e l d r i n , i s t h e i r persistence i n the natural environment i n toxic form.  The chemical half l i f e of these stable chlorinated hydro-  carbons i s measured, not i n weeks nor months, but i n years.  DDT, d i e l d r i n  and related compounds have persisted i n s o i l s from three to 15 years or longer  [23,52,53].  I t i s because o f t h i s s t a b i l i t y  that these organochlorine i n -  s e c t i c i d e s present such a major residue problem. Edwards [47] presents an excellent review o f the persistence of i n s e c t i c i d e residues i n s o i l s .  Lichtenstein and Schultz [54] recovered up  to 33 per cent of the DDT applied to a muck s o i l 3h years a f t e r the a p p l i c a t i o n . Wheatley et al. [55] indicate that the h a l f l i f e of d i e l d r i n -is approximately four years i n a mineral s o i l and f i v e to seven years i n an organic s o i l .  Lich-  tenstein et al. [56,57] found that a l d r i n was converted to d i e l d r i n i n the s o i l , and that eight to 10 per cent of the a l d r i n i n i t i a l l y applied was r e covered as d i e l d r i n four years l a t e r . Woodwell and Martin [58] report that the s o i l from sprayed f o r e s t stands i n New Brunswick and Maine contained DDT residues and these residues  27  increased between 1958 and 1961, although no new spray had been applied. This increase suggests that DDT residues may p e r s i s t f o r several years i n tree canopies, but are ultimately c a r r i e d t o the s o i l . Some of the chlorinated hydrocarbon i n s e c t i c i d e s are decomposed slowly i f a t a l l by s o i l organisms [52,59].  DDT and d i e l d r i n have  been found to be highly r e s i s t a n t to b i o l o g i c a l attack  [40], although some  micro-organisms have been i s o l a t e d that degrade a l d r i n to d i e l d r i n [60]. H i l l and McCarty [13] found that d i e l d r i n , although extremely r e s i s t a n t to microbial degradation,  was broken down i n an anaerobic b i o l o g i c a l system.  Figure 3 shows the r e l a t i v e persistence of several organochlorine i n s e c t i c i d e s . I t must be remembered that although a l d r i n breaks down f a i r l y r a p i d l y , a portion of i t i s converted to the highly stable dieldrin.  Figure 3 [47] Persistence of Organochlorine I n s e c t i c i d e s  28  II.8  BIOLOGICAL MAGNIFICATION The idea of b i o l o g i c a l magnification of i n s e c t i c i d e residues i n  the food chain r e f e r s to an accumulation of the i n s e c t i c i d e to a higher concentration than that i n the preceding trophic l e v e l . work, two basic processes must occur:  For t h i s concept to  b i o l o g i c a l magnification of the insec-  t i c i d e at one trophic l e v e l and then b i o l o g i c a l transfer of the i n s e c t i c i d e from that trophic l e v e l to the next highest. Several conditions [61] must be met by any i n s e c t i c i d e before i t w i l l be accumulated by an organism: 1. The i n s e c t i c i d e must p e r s i s t i n the p h y s i c a l environment long enough f o r a s s i m i l a t i o n by the organism to occur. 2. The i n s e c t i c i d e must p e r s i s t i n a form a v a i l able to the organism considered. A — : 3. Once assimilated by the organism, the i n s e c t i cide must be accumulated a t a rate greater than that at which i t i s metabolized and/or excreted. From previous discussions, i t i s evident that DDT  and d i e l d r i n are  p e r s i s t e n t and therefore condition (1) i s met. Condition DDT  (2) i s e a s i l y s a t i s f i e d by both DDT  and d i e l d r i n .  Both  and d i e l d r i n have been shown to be r e a d i l y assimilated into organisms be-  cause they are i n v a r i a b l y much more soluble i n the l i p i d part of any organism than i n water [40, 61]. and Lockwood [9].  One example of this i s the study conducted by Chacko  They found that over a 24-hour period, micro-organisms  accumulated 70 to 90 per cent of the d i e l d r i n and DDT ing 0.1 to 1.0 ppm  of these i n s e c t i c i d e s .  from solutions contain-  Since both dead and l i v e micro-  organisms accumulated nearly a l l the d i e l d r i n and DDT  from the medium, i t  appears that t h i s accumulation does not involve metabolism, but rather an  29  adsorption of the insecticide onto the surface of the micro-organism.  Whether  or not t h i s process i s adsorption or absorption, these phenomena make these insecticides  readily available  to higher trophic l e v e l s , as micro-organisms  are a lower.link i n the food chain of nearly a l l animals. of DDT  Many other examples  and d i e l d r i n e x i s t i n g i n forms e a s i l y assimilated are I l l u s t r a t e d by  the occurrence of these organochlorine i n s e c t i c i d e s  i n numerous organisms  [2, 18, 47]. Condition (3) i s s a t i s f i e d when considering the numerous examples of both DDT and d i e l d r i n being accumulated a t a rate greater than that a t which i t i s metabolized and/or excreted. property i n both man  DDT  and d i e l d r i n e x h i b i t  this  (p. 24 t h i s paper) and other organisms [38, 39, 45,  61,  62, 63] . Ko and Lockwood [45] added fungal and actinomycete containing d i e l d r i n , DDT  and pentachloronitrobenzene  mycelia to s o i l  (PCNB) and found that  these s o i l micro-organisms accumulated a l l the i n s e c t i c i d e s  to l e v e l s above  ambient concentrations. Woodwell [63] shows that DDT  and i t s residues have been b i o l o g i -  c a l l y magnified i n an estuary on the east coast of the United States. 4 shows the estuary f l o r a and fauna and the residual  concentrations of  Figure DDT  and i t s metabolites found i n them. In a study conducted by the United States Fish and W i l d l i f e Department [62], DDT was  found to be stored by oysters during a 40-day ex-  posure period i n amounts 70,000 times greater than the 0.1 ppb i n the water.  concentration  Earthworms, a major lower l i n k i n the food chain of many b i r d s ,  have been shown to concentrate a l d r i n and d i e l d r i n up to 10 times that of the surrounding s o i l  [50] and DDT  up to a thousandfold  [38].  30  NUMBERS INDICATE RESIDUES OF DDT AND ITS METABOLITES OBSERVED (IN MILLION, WET WEIGHT, WHOLE-BODY BASIS)  Figure 4 [63]  B i o l o g i c a l Concentration of DDT i n the Food Web of a Long Island Estuary  FARTS PER  31  Evidence also e x i s t s that aquatic plants take up these organochlorine, i n s e c t i c i d e s .  Wheeler et al.  [64] showed that DDT  and  dieldrin  can be sorbed through the root system of cereal crops and grasses.  These  i n s e c t i c i d e s are then d i s t r i b u t e d throughout the plant. I t i s obvious from the abundance of evidence presented that b i o l o g i c a l magnification does indeed occur.  In l i g h t of t h i s conclusion,  one should consider the p o s s i b l e increased e f f e c t s i n s e c t i c i d e s would have on humans due to t h i s process. Presently, the process of b i o l o g i c a l magnification appears to have a minimal impact on man  because human food i s produced by a two-  or  three-link food chain i n which the process, i f recognized, can be c o n t r o l l e d . For example, residues are permitted on feeds for domestic animals only i n amounts that w i l l not u l t i m a t e l y y i e l d or i n other animal products.  unacceptable  l e v e l s i n meat, i n milk,  Thus, excessive l e v e l s of p e s t i c i d e residues  i n a g r i c u l t u r a l products used f o r human consumption usually r e s u l t s only from accident or misuse. DDT  and d i e l d r i n  Of.course, by continuing to use such i n s e c t i c i d e s as  that can be b i o l o g i c a l l y magnified, man  cannot c o n t r o l the  concentration of these i n s e c t i c i d e s i n f i s h and w i l d l i f e , and i n the future, w i l l exert a diminishing amount of c o n t r o l on the l e v e l s which develop i n domestic animals.  II.9  EUTROPHICATION An important  action that the organochlorine  i n s e c t i c i d e s may  on aquatic organisms i s that of population suppression.  exert  This i n d i r e c t l e t h a l  e f f e c t i s caused by changes i n growth rates or changes i n s p e c i f i c  metabolic  32  processes,  such as photosynthesis  are e c o l o g i c a l l y very important. more organisms that may This may  and carbon f i x a t i o n .  These i n d i r e c t e f f e c t s  The i n s e c t i c i d e s exert stress on one or  permit previously suppressed competitors  to f l o u r i s h .  upset the environmental balance of the p a r t i c u l a r b i o l o g i c a l system. The d i v e r s i t y of species and the complexity  of t h e i r i n t e r a c t i o n s  i n the aquatic environment makes the evaluation of the e f f e c t s of i n s e c t i c i d e s on these populations extremely d i f f i c u l t .  Wurster [65] reports that concen-  t r a t i o n s of p,p'-DDT as low as a few parts per b i l l i o n reduced  photosynthesis  i n four species of coastal and oceanic phytoplankton representing four major classes of marine algae.  Ware and Roan [40] report that i n concentrations of  one part per m i l l i o n during four hours exposure, d i e l d r i n and DDT  caused a  reduction of carbon f i x a t i o n by estuarine phytoplankton of 85 and 77 per cent respectively.  I t was  on c e r t a i n a l g a e may  found by Bishop [53] that the s e l e c t i v e t o x i c i t y of a l t e r the species composition  DDT  of a natural phytoplankton  community. The f l o r a l imbalances caused by these actions of i n s e c t i c i d e s could e a s i l y favour species that would normally be suppressed by  others.  This s p e c i f i c i t y could produce population explosions and dominance of the community by one or a few species, since t h e i r natural suppressors have been k i l l e d by i n s e c t i c i d e s .  would  This process could aggravate the problems  of eutrophication caused by an excess of phosphates and n i t r a t e s i n natural water bodies.  Thus the a c t i o n of population suppression by i n s e c t i c i d e s may  play an important yet r a r e l y recognized r o l e i n  the eutrophication of lakes.  CHAPTER I I I  INFLUENCE OF SEDIMENTS ON WATER QUALITY  III.l  ADSORPTION AND DESORPTION The organochlorine i n s e c t i c i d e s are extremely hydrophobic and can  be e a s i l y concentrated on s o i l s , p a r t i c u l a r l y highly surface active Such adsorption often leads to a diminution o f the i n s e c t i c i d e  clays.  activity,  but i t must be r e a l i z e d that there may be grave r i s k s associated with the concept that what you do not see, w i l l not harm you.  I f the adsorption  i s i r r e v e r s i b l e then t h i s d e t o x i c i f i c a t i o n i s e s s e n t i a l l y permanent. However, i f t h i s adsorption i s not i r r e v e r s i b l e , then complications could arise. The s o i l , together with i t s adsorbed i n s e c t i c i d e , may be washed from treated areas into natural waters.  Epstein and Grant [7] showed that  runoff from treated plots contained s i g n i f i c a n t amounts of the applied i n s e c t i c i d e s , DDT, endosulfan, and endrin, with the concentration and amounts of DDT being higher than the other i n s e c t i c i d e s during almost a l l the season. When these s o i l - i n s e c t i c i d e combinations enter natural waters, there may be slow leakage of the i n s e c t i c i d e s back into the b i o l o g i c a l system. These concentrations may be too low t o be of significance  i n pest  control,  but possibly s t i l l be a t levels s u f f i c i e n t l y high t o be magnified i n successive steps i n the food chain.  Ultimately the i n s e c t i c i d e may reveal or ex-  press i t s e l f i n terms o f a harmful e f f e c t on some non-target organism. There have been several studies done on i n s e c t i c i d e adsorption onto, and desorption from, s o i l s .  H i l l and McCarty [13] showed that the adsorption 33  34  of  several organochlorine i n s e c t i c i d e s , i n c l u d i n g DDT and d i e l d r i n , onto  bentonite clay d i d occur, and that t h i s sorption was r e v e r s i b l e .  Eye [22]  found that d i e l d r i n was adsorbed from phosphate buffered water by various s o i l and c l a y - s o i l  mixtures.  Huang and Liao [66] found that DDT, d i e l d r i n , and heptachlor were e a s i l y adsorbed by i l l i t e , k a o l i n i t e , and montmorillonite, with DDT being adsorbed i n the largest quantity, heptachlor next, and d i e l d r i n adsorbed the least.  They found that a t an i n i t i a l concentration o f lOOngm/1 of i n s e c t i -  cide, from 75 to 95 per cent was adsorbed onto the clay, depending upon the s p e c i f i c i n s e c t i c i d e - c l a y combination  used, and the amount of clay added.  They also determined that the degree of desorption depended upon the mechanisms through which adsorption i s attained.  I f adsorption i s attained by  some weak forces of a t t r a c t i o n , then a c e r t a i n degree of desorption w i l l occur. Huang [67] found the adsorption of d i e l d r i n onto montmorillon i t e was not s i g n i f i c a n t l y a f f e c t e d by water temperature changes i n the range of  10°C to 30°C, and that the water pH only s l i g h t l y affected the adsorption.  He determined that several representative organic p o l l u t a n t s exerted no e f f e c t at  a l l on the adsorption of d i e l d r i n , heptachlor, and DDT by montmorillonite  or i l l i t e .  He also found that d i e l d r i n adsorption by montmorillonite was not  influenced by the soluble organic matter contained i n a f i l t e r e d domestic wastewater. There are several c o n f l i c t i n g theories and reports concerning the mechanisms of adsorption. reviews on the subject.  Bailey and White [68,69] have presented two good In one of these reviews  [69], the theory i s postu-  l a t e d that the expanding clay minerals, such as montmorillonite and v e r m i c u l i t e , have a high adsorptive capacity due t o t h e i r high cation exchange capacity and  35  large s p e c i f i c surface area. The non-expanding clay minerals, such as  illite,  kaolinte, and c h l o r i t e , because of t h e i r low c a t i o n exchange capacity, and small s p e c i f i c surface area, do not have as large an adsorptive capacity. Eye  [22], however, gives evidence  i n d i c a t i n g that the adsorp-  t i v e capacity of s o i l s i s more c l o s e l y r e l a t e d to organic content than the s p e c i f i c surface area or the cation or base exchange c a p a c i t i e s . He found that less d i e l d r i n was  adsorbed onto montmorillonite, a high cation exchange  capacity and large s p e c i f i c surface area clay, than onto several other clays and c l a y - s o i l mixtures.  S i m i l a r l y , Huang and Liao [66] found that the adsorp-  t i v e c a p a c i t i e s of the clay used i n t h e i r study; montmorillonite, and i l l i t e ,  kaolinite,  d i d not correlate to t h e i r ion exchange c a p a c i t i e s nor to t h e i r  s p e c i f i c surface areas. The nature of the i n s e c t i c i d e  formulation may  have an e f f e c t on  the r e l a t i v e adsorption, desorption-, and a v a i l a b i l i t y of the i n s e c t i c i d e . It has been reported that montmorillonite factants to some degree.  [70] and k a o l i n i t e [71] adsorb sur-  Since surfactants are present i n most organochlorine  i n s e c t i c i d e formulations, these may  r e s u l t i n competition for adsorption  s i t e s and thus would a f f e c t the adsorption and desorption of the i n s e c t i c i d e . Whatever the mechanism, adsorption onto and desorption from s o i l s does occur and therefore the role of suspended s o i l s becomes very  important  in water q u a l i t y analysis with respect to the movement and b i o a c t i v i t y of insecticides.  III.2  EFFECT OF SUSPENDED SOLIDS Suspended s o l i d s , washed from treated areas, may  i n s e c t i c i d e s f a r from t h e i r point of a p p l i c a t i o n .  carry adsorbed  Freeden et al.  [72] found  36  that DDT was adsorbed onto the suspended s o l i d s i n the Saskatchewan These suspended solids contained from 0.24  River.  to 2.26 ygms. of DDT per gram of  solids as f a r as 68 miles downstream from t h e i r point of a p p l i c a t i o n .  This  event started with an i n i t i a l rate of a p p l i c a t i o n to the r i v e r of 0.09  ppm  DDT,  f o r 16 minutes, as a 10 per cent s o l u t i o n i n methylated naphthalene and  kerosene .  The suspended s o l i d s i n t h i s case consisted mainly of clay and  f i n e s i l t , and during the tests the suspended s o l i d s content of the r i v e r ranged as high as 551  ppm.  As mentioned previously, Epstein and Grant [7] found that runoff from treated p l o t s contained s i g n i f i c a n t amounts of the applied i n s e c t i c i d e . They showed that the t o t a l amount, the i n t e n s i t y , and the freguency of r a i n f a l l or i r r i g a t i o n water received, not only affected the movement of the i n s e c t i c i d e from the treated p l o t s , but also affected the removal of the s o l i d s onto which these i n s e c t i c i d e s had been adsorbed. Adsorption isotherms, such as the one constructed by McCarty and Hill  [13] and reproduced i n Figure 5, can be used to estimate the p o t e n t i a l  p o l l u t i o n a l load of p e s t i c i d e s i n r i v e r waters.  If the types and r e l a t i v e  amounts of the material contained i n the suspended s o l i d s i s known, then the amount of p o t e n t i a l p o l l u t i o n by the adsorbed i n s e c t i c i d e can be estimated. McCarty and H i l l Figure 5.  [13] give an example of t h i s estimate  based on  I f a turbid water contained 0.1 ugm/litre of DDT i n s o l u t i o n and  carried a suspended s o l i d load of 100 ygm/ml bentonite clay, there would be more DDT associated with the clay, than there would be i n s o l u t i o n .  Similar  observations can be made f o r other i n s e c t i c i d e s and other clays or s o i l s . Evidence e x i s t s which indicates that DDT i s not as prevalent i n natural waters as one might expect from the preceding discussion.  Breiden-  0.01 I 0.01  :  1  0.1  1  1  1  10  I  1  100  CONCENTRATION OF PESTICIDE IN WATER  1000  (PPB)  Figure 5 [13] Pesticide Adsorption bach and Lichtenberg  Isotherms  [73], i n studies of the major r i v e r basins of the United  States, found d i e l d r i n to be more prevalent than DDT. study was  The sampling i n t h e i r  done by concentrating the pesticides from several thousand gallons  of water by adsorption onto carbon.  As Walker [74, p. 161] points out,  however, ". . .when taking large samples using the adsorpt i v e capacity of activated carbon, i t i s almost always necessary to remove the suspended s o l i d s with a sand f i l t e r f i r s t to avoid clogging the carbon c a r t r i d g e , " No mention of p r e - f i l t r a t i o n was made i n the above study, but with t u r b i d r i v e r waters, p r e - f i l t r a t i o n would seem l i k e l y .  I f p r e - f i l t r a t i o n did take  place, the r e s u l t s of this study would be low and misleading.  This f a c t i s  38  of p a r t i c u l a r importance as i t i l l u s t r a t e s the lack of knowledge concerning the ultimate fate of i n s e c t i c i d e s i n the aqueous environment.  These adsorbed  i n s e c t i c i d e s could possibly be desorbed and thus maintain small concentrations of these materials i n the water bodies.  III.3  EFFECT OF BOTTOM SEDIMENTS Some of the suspended s o l i d s of natural waters eventually s e t t l e  under quiescent conditions and become an i n t e g r a l part o f the bottom s e d i ments.  Thus the bottom sediments w i l l contain clays and s o i l s that may have  i n s e c t i c i d e s , e s p e c i a l l y the organochlorine ones, adsorbed onto them.  Under  c e r t a i n conditions, part o f the adsorbed i n s e c t i c i d e s may be desorbed and released onto overlying waters, where equilibrium system.  they would be maintained by a dynamic  As Woodwell [63, p. 30] states,  ". . .DDT has only a low s o l u b i l i t y i n water, but as algae and other organisms i n the water absorb the substance i n f a t s , where i t i s highly soluble, they make room f o r more DDT to be dissolved into the water. Accordi n g l y , water that never contains more than a trace of DDT can continuously transfer i t from deposits on the bottom to organisms." I t can be expected that the other organochlorine i n s e c t i c i d e s would behave i n a s i m i l a r manner. The concept of the bottom sediments providing a continuous supply of toxic material to the water, and thus t o aquatic organisms, i s reinforced by several studies [75,76,77,78,79] i n d i c a t i n g higher concentrations of organochlorine i n s e c t i c i d e s i n the mud than i n the overlying waters. Bailey and Hannum [75] found that the p e s t i c i d e concentrations i n C a l i f o r nia r i v e r sediments exceeded those i n water 20 to 100 times, with the concent r a t i o n s being proportionallyhigher as the sediments became f i n e r .  Bridges et  1  39  al.  [77] found DDT  and i t s metabolites were i n s i g n i f i c a n t l y higher concen-  t r a t i o n s i n the mud bottom of a farm pond than i n the water. Hickey et al. [78] found that the sediments obtained from Lake Michigan contained s i g n i f i c a n t amounts of DDT  and i t s metabolites.  These samples were from r e l a t i v e l y deep  sections of the lake (33 to 96 feet) and i l l u s t r a t e the prevalent nature of DDT  i n lake  sediments. Methods may be available to c u r t a i l t h i s release of t o x i c  chemicals from the bottom sediments to the overlying waters. Seabloom [80] who  Sylvester and  found that the q u a l i t y of the bottom s o i l had a detrimental  e f f e c t on the o v e r l y i n g water's q u a l i t y , determined  that a well-placed mineral  s o i l covering of about two inches i n thickness e f f e c t i v e l y reduced the leaching and exchange of solutes from the bottom s o i l .  Tenney and Echelberger  [81]  used f l y ash to develop a p h y s i c a l b a r r i e r at the mud-water interface which impaired the release of bottom pollutants into overlying waters. a blanket of f l y ash or mineral s o i l over bottom sediments may  Similarly,  effectively  stop the release of organochlorine i n s e c t i c i d e s into the overlying waters.  I  CHAPTER IV  DETECTION OF DDT AND DIELDRIN  IV.1  INTRODUCTION The  detection and measurement o f the organochlorine  insecticides  i s quite d i f f i c u l t due to t h e i r extremely low concentrations i n the natural environment.and i n b i o l o g i c a l t i s s u e s . electron  Gas l i q u i d chromatography with the  capture detector, because of i t s extreme s e n s i t i v i t y with respect  to electron  capturing compounds such as the organochlorine i n s e c t i c i d e s ,  overcomes the d i f f i c u l t y of these low concentrations and has proven t o be an i d e a l instrument for t h i s  5LV.2  analysis.  GAS LIQUID CHROMATOGRAPHY [82] IV.2.1  Definition.  The basis for gas chromatographic separation i s  the d i s t r i b u t i o n of a sample between two phases.  In gas l i q u i d chromato-  graphy (G.L.C.), one phase i s a l i q u i d stationary  bed spread as a t h i n f i l m  over an i n e r t s o l i d and the other phase i s a gas which percolates through t h i s stationary  bed.  The basis for separation i s the p a r t i t i o n i n g of the  sample i n and out of t h i s l i q u i d f i l m . IV.2.2  Technique of Gas L i q u i d Chromatography.  In gas l i q u i d chromato-  graphy the components t o be separated are carried through the column by an i n e r t gas (Carrier Gas)  as shown i n Figure 6.  between the c a r r i e r gas and a non-volatile  The sample mixture i s p a r t i t i o n e d  solvent (Stationary Phase) supported  on an i n e r t size-graded s o l i d (Solid Support).  The solvent s e l e c t i v e l y retards  the sample components, according to t h e i r d i s t r i b u t i o n c o e f f i c i e n t s  40  [the r a t i o  41  of the concentration of the solute (sample component) i n solvent one  (the  c a r r i e r gas) to that i n solvent two  (the l i q u i d phase)], u n t i l they form  separate bonds i n the c a r r i e r gas.  These component bands leave the column  i n the gas stream and are recorded  as a function of time.  Figure 6  [82]  Schematic Drawing of a Gas Chromatographic System  42  IV.2.3  C a r r i e r Gas.  source of c a r r i e r gas.  A high pressure gas c y l i n d e r serves as the  A pressure regulator i s used to assure a uniform pres-  sure to the column i n l e t , and thereby a constant rate of gas flow.  At a  given column temperature, t h i s constant rate w i l l elute components at a charact e r i s t i c time (the retention time) and thus q u a l i t a t i v e l y i d e n t i f y the components of the sample.  The choice of c a r r i e r gas depends p r i m a r i l y on the detec-  t o r used. A purge flow may be introduced to the column e f f l u e n t just a f t e r i t e x i t s from the column.  The purge gas i s added to increase the l i n e a r v e l o c i t y  of the gas flow and thus decrease the residence time of the components as they are swept into the detector.  This purge flow eliminates or minimizes band  broadening due to the increase i n the volume of the gas column.  a f t e r e x i t i n g the  At high flow rates (over 50 mls/min), band broadening i s not a fac-  tor and thus purge flow i s not necessary. IV.2.4  Sample Introduction.  The sample should be introduced  instantaneously as a "plug" onto the column so as to have subsequent narrow chromatogram peaks and good separation of components.  A standard technique  for the introduction of gases and l i q u i d s i s t o i n j e c t measured columns with a syringe, through a s e l f - s e a l i n g septum located i n the i n j e c t i o n port  (Figure  6) . IV.2.5  Column.  The column tubing may be made of copper, s t a i n -  less s t e e l , aluminum, or glass, i n a s t r a i g h t , bent, or c o i l e d form.  The  choice of column material i s dependent upon whether or not i t may adsorb or react with sample components. Straight columns are more e f f i c i e n t , but at longer lengths may not f i t into the column oven and thus may have to be bent or c o i l e d .  If coiled,  43  the s p i r a l diameter  should be at l e a s t 10 times the column diameter to mini-  mize d i f f u s i o n and racetrack e f f e c t s (the c a r r i e r gas finding a shorter route along the inside diameter of the column). IV.2.6  S o l i d Support.  The purpose of tehe'solid support i s to pro-  vide a large,uniform, i n e r t surface area for d i s t r i b u t i n g the l i q u i d phase. The s o l i d support should be of regular s i z e . available  There are several s o l i d supports  commercially. IV.2.7  Stationary Phase.  solvent i s an important task.  The correct choice of the p a r t i t i o n i n g  Ideally the solvent should have the following  characteristics: (a) sample components must exhibit d i f f e r e n t d i s t r i bution c o e f f i c i e n t s ; (b) sample components should have a reasonable i n the solvent;  solubility  (c) the solvent should have a n e g l i g i b l e vapour pressure at the operating temperatures. The v e r s a t i l i t y and s e l e c t i v i t y of gas l i q u i d chromatography i s l a r g e l y due to the wide choice of solvents a v a i l a b l e .  For the novice operator, the  choice of solvents i s best made a f t e r studying a v a i l a b l e l i t e r a t u r e concerning related work. IV.2.8  Temperature.  Three d i f f e r e n t temperature controls, a sep-  arate one each f o r the i n j e c t i o n chamber, the column oven, and the detector, are needed on the gas chromatograph. component parts serve trolled  The temperature of a l l three of these  d i f f e r e n t functions and thus must be able to be con-  independently. (a) Injection Port Temperature.  The i n j e c t i o n port must  be hot enough to completely and r a p i d l y vapourize the sample so that no loss of e f f i c i e n c y r e s u l t s from the i n j e c t i o n technique.  I t must also be low  44  enough so that there i s  no thermal decomposition of the components i n the  sample. (b) Column Temperature.  For most components the lower the  column operating temperature, the higher the r a t i o of p a r t i t i o n c o e f f i c i e n t s i n the stationary phase. t i o n times.  This r e s u l t s i n better separation and longer reten-  The column temperature should be optimized so that i t i s high  enough f o r analyses to be accomplished i n a reasonable  length of time, and  low enough so t h a t the desired separation i s obtained. (c) Detector Temperature.  The influence of temperature de-  pends considerably on the type of detector employed.  As a general r u l e , how-  ever, the detector, and the connections  from the column e x i t to the detector,  must be hot enough so that condensation  of the sample does not occur.  IV.2.9  Detectors.  The detector indicates the presence and mea-  sures the amounts of components i n the column e f f l u e n t .  Desirable  charac-  t e r i s t i c s of a detector are high s e n s i t i v i t y , low noise l e v e l , a wide l i n e a r i t y of response, response to a l l types of  compounds, ruggedness, and insen-  s i t i v i t y to flow and temperature changes. There i s no i d e a l detector? however, the thermal conductivity c e l l and the flame i o n i z a t i o n detector come close to s a t i s f y i n g the above c r i t e r i a .  In addition, s p e c i f i c detec-  tors such as the e l e c t r o n capture and the phosphorus detectors have the advantage of s e l e c t i v e l y measuring only c e r t a i n types of compounds.  This makes them  extremely useful f o r trace and q u a l i t a t i v e a n a l y s i s . IV.3  THE ELECTRON CAPTURE DETECTOR USED WITH GAS IV.3.1  Introduction.  LIQUID CHROMATOGRAPHY  Lovelock and Lipsky [83] were the f i r s t to sug-  gest the p o t e n t i a l f o r electron capture use i n gas l i q u i d chromatography.  45  They noted that such a detector would excel i n i t s a b i l i t y to s e l e c t i v e l y measure c e r t a i n compounds that show an a f f i n i t y f o r free electrons. The electron capture detector i s extremely sensitive to electron absorbing compounds such as organo-halides, conjugated carbonyls, n i t r i t e s , n i t r a t e s and organometallies.  I t i s v i r t u a l l y i n s e n s i t i v e to unsubstituted-hydrocarbons,  amines, alcohols, and ketones.  This s e l e c t i v e s e n s i t i v i t y to chlorine contain-  ing compounds makes the electron capture detector p a r t i c u l a r l y valuable f o r the determination of organochlorine i n s e c t i c i d e s .  I t i s capable of detecting  -12 picogram  (10  grams) quantities of many organochlorine i n s e c t i c i d e s i n a  more concentrated matrix of a non-responding  compound  such as hexane (see  Table IV). TABLE IV APPROXIMATE RELATIVE AFFINITIES OF ELECTRON-CAPTURE DETECTOR FOR SOME ORGANIC COMPOUNDSa DISC INTEGRATOR UNITS PER ygm. OF SAMPLE^  COMPOUND Hexane Chlorobenzene Atrazine 2,4-D Malathion DDT Heptachlor Dieldrin Lindane Carbon Tetrachloride  0.9 55.0 3,000 125,000 250,000 2,000,000 4,800,000 8,000,000 11,000,000 400,000,000  Marian-Aerograph Co., Walnut Creek, C a l i f o r n i a . Disc Integrator Units are based on peak area measurement of chromatograms with a Disc Integrator. Source:  Reference [84]  46  IV.3.2  Operation:  Capture Detector. nal  Mechanisms and P r i n c i p l e s of the Electron  In 1961 Lovelock [85] modified the geometry of h i s origi^-  diode i o n detector to that of two p a r a l l e l plates (Figure 7).  In this  new design the e f f l u e n t from the G.L.C. column enters through the anode. The radioactive beta-source was t r i t i u m or n i c k e l 63. When there i s only a non-electron absorbing gas i n the c e l l , the high energy 3 - p a r t i c l e s (18 kev f o r t r i t i u m and 67 kev f o r nickel)  produce p o s i -  t i v e ions'and about a t e n - f o l d increase of low-energy electrons due to the c o l l i s i o n s of the 3 - p a r t i c l e s with the molecules of the c a r r i e r gas. By applying a p o t e n t i a l to the electrodes these electrons w i l l migrate to the anode and thus e s t a b l i s h a current.  When a substance which can absorb these  electrons enters the c e l l , part of the electrons w i l l be removed i n the form of negative molecular a corresponding  ions.  This decrease i n the number  of electrons causes  decrease i n the current which i s amplified and displayed on a  s t r i p chart recorder.  A - ANODE AND GAS ENTRANCE C - CATHODE R - RADIOACTIVE p-SOURCE I  c  PARALLEL PLATE DETECTOR  s-r-i —  h  CONCENTRIC TUBE  Figure 7 [86] Schematic Drawing o f Two Electron A f f i n i t y C e l l s  47  TV.3.3  Electron Capture With A Nickel 63 Source [82,87].  One  of  the more, common detectors i n use today, and thus worthy of discussion i n more d e t a i l , i s the Nickel 63 p a r a l l e l plate detector.  This p a r a l l e l plate  electron capture detector i s based on and quite s i m i l a r to Lovelock's o r i g i n a l design  (Figure 8).  Nickel 63 i s used as the radioactive source be-  cause i t can be operated at higher temperatures (360°C maximum) than can tritium  (225°C maximum).  This higher  operating temperature o f f e r s greater  s e l e c t i v i t y i n operating parameters of the gas chromatograph. The n i c k e l 63 detector operates i n much the same manner as Lovelock's p a r a l l e l p l a t e detector; the radioactive source produces a current by emitting electrons (beta-radiations) which flow between an anode and a cathode.  A-NICKEL FOIL B-GAUZE C - A N O D E (INLET) D-CATHODE (OUTLET) E-PLASMA  2—o  Figure 8  [87]  Diagram of Electron Capture C e l l  48  With only purge gas i n the c e l l , an average current of 10 10  -9  amps flows across the c e l l from A to B.  to  This current i s produced  by electrons i n the c e l l , which are derived from two  sources:  (a) primary electrons or b e t a - p a r t i c l e s which are emitted by the n i c k e l f o i l  (A):  (b) secondary electrons which are formed by the c o l l i s i o n between primary electrons and molecules of the c a r r i e r gas.  The  of these secondary electrons occurs mainly i n the plasma (E).  production  P o s i t i v e ions  are also formed i n the plasma by these c o l l i s i o n s . When an electron capturing component i s introduced into the  cell  at C, i t moves into the plasma (E) where an abundance of free electrons e x i s t . The eluted components capture electrons by several reactions, for example: AB + e  -*• AB  ± energy  AB+e  -* A + B~ ± energy  AB + e  -+• AB  ± energy •* A + B  ± energy  The net r e s u l t of t h i s capturing i s the removal of electrons from the system and s u b s t i t u t i o n of negative ions having a f a r greater mass.  These ions w i l l  combine with p o s i t i v e ions a v a i l a b l e i n the plasma and be purged from  the  cell  as a neutral complex. The i o n i z a t i o n e f f i c i e n c y of c e r t a i n compounds may  approach 100  per  cent, and the ionized molecules of these compounds that have a high e l e c t r o n a f f i n i t y may  i n f a c t capture more than one electron.  These two factors  account, i n part, f o r the extremely high s e n s i t i v i t y of the detector with respect to t h i s type o f compound.  49  When a p o t e n t i a l i s applied t o the c e l l , e s s e n t i a l l y a l l the free electrons  are c o l l e c t e d a t the anode (A, Figure 8).  However, a t l e a s t one  electron has been captured f o r every molecule of electron capturing substance present. This loss o f electrons r e s u l t s i n a corresponding decrease i n c e l l current which, a f t e r a m p l i f i c a t i o n , i s presented on a recorder. IV.3.4  P o t e n t i a l . The p o t e n t i a l across the c e l l can be applied  e i t h e r as a continuous p o s i t i v e charge on one electrode (DC operation) or the charge may be applied p e r i o d i c a l l y as i n "pulsed" operation.  The pulsed  mode has an advantage over the DC operation i n that with the DC operation large ions d r i f t , under the influence of a constant e l e c t r i c a l p o t e n t i a l , toward the electrode of the opposite p o l a r i t y .  As a consequence, the current measured  i s a combination of both electrons and ion components with the r e s u l t i n g detector s i g n a l representing both electron capture and ion migration.  With  the pulsed mode t h i s ion migration i s n e g l i g i b l e . During the pulsed operation, the applied voltage lasts only f o r 0.75 micro-seconds, as indicated i n Figure 9.  The e l e c t r o n concentration v a r i e s  i n a saw-tooth fashion. When the pulse i s applied, the electrons are c o l l e c t e d a t the anode and t h e i r concentration drops r a p i d l y to zero (point A, Figure 9).  During  the i n t e r v a l between pulses, the concentration gradually builds up as beta.'  p a r t i c l e s are emitted from the Nickel 63 source (point B) .  The magnitude of  electron concentration then depends on the pulse i n t e r v a l (X).  Decreased-  detector s e n s i t i v i t y usually r e s u l t s from decreased pulse i n t e r v a l s . The c o l l e c t i o n of electrons a t each pulse constitutes a current flow.  Because of t h e i r small mass, the electrons accelerate, r a p i d l y reaching  the anode before the pulse terminates.  The large ions formed hardly begin to  50  move during the 0.75 microsecond pulse and consequently t h e i r contribution to c e l l current i s n e g l i g i b l e .  Thus, as previously mentioned, the e f f e c t  of ion migration i s n e g l i g i b l e when using the pulsed mode.  D-APPLIED POTENTIAL • TIME ( 3/4 U SEC.) X r PULSE INTERVAL (5,15,50,150 U SECj  A  TIME  (MICROSECONDS)  I l l u s t r a t i o n o f Pulsed EC C e l l P o t e n t i a l Figure 9 [87] The average or "standing" current noted i n Figure 9 i s amplified i n the electrometer and i s zeroed out to the recorder e l e c t r i c a l zero.  The cap-  ture of electrons by a sample component reduces the standing current and, as  51  mentioned, t h i s reduction i s measured, amplified, and recorded. TV.3.5  Standing Current.  The standing current of the e l e c t r o n  capture detector i s r e l a t e d t o : (a) detector c l e a n l i n e s s ; (b) contamination, e i t h e r from column or system bleed, or moisture or oxygen i n the c a r r i e r or purge gas; (c) detector temperature; (d) gas flow rate; (e) pulse rate. With a r e l a t i v e l y new and clean source, a standing current of about 4 - 6 x 10 ^° amps should be observed under the following conditionss (a) c a r r i e r gas flow rate: (b) c a r r i e r gas: (c) purge flow:  5% methane i n argon; none;  (d) detector temperature: (e) pulse i n t e r v a l : A value of less than 2.0 x 10 ^ preceding  60 ± 5 mis./min.;  245 - 255°C,;  50 u.secs.  amps f o r the standing current under the  conditions u s u a l l y means that either the detector needs cleaning  or there i s some contaminating material entering the detector. IV.3.6  Peak Area.  The peak formed on the s t r i p - c h a r t recorder  by the elution o f an electron capturing component of a sample not only q u a l i t a t i v e l y i d e n t i f i e s the component by retention time, but also q u a n t i t a t i v e l y measures the sample weight by e i t h e r peak height or peak area. The peak area may be measured by several methods, such as using a disc integrator, by t r i a n g u l a t i o n using a r u l e r , or by a planimeter.  52  IV.3.7  C a l i b r a t i o n Curve.  A c a l i b r a t i o n curve f o r the p e s t i c i d e  being analyzed should be prepared by making a series of solutions of p e s t i cide and pure (nanograde)  hexane of varying concentrations and subjecting  these solutions to gas chromatographic  analysis.  The most convenient curve constructed i s a p l o t of sample s i z e versus d i s c integrator u n i t s on log-log paper.  The curve should l i e on a  precise 45 degree l i n e and be l i n e a r over a weight range of about two log cycles. IV.3.8  Linearity.  The electron capture detector i s inherently a  non-linear device; however, as previously mentioned a p l o t of sample s i z e versus peak area i s l i n e a r over a weight range of about 100 times.  It i s  therefore e s s e n t i a l that p l o t s , such as those shown i n Figure 10, be constructed i n order t o ensure one i s working i n the l i n e a r range of the detector.  S i g n i f i c a n t errors may  a r i s e i n analysis, even though standards are  frequently run, i f sampling occurs i n the non-linear range. IV.3.9  Sensitivity.  Under proper operating conditions ( a clean  detector and no column or septum bleed, and no oxygen or water i n the c a r r i e r gas) the electron capture detector has an extremely high s e n s i t i v i t y . s e n s i t i v i t y i s i l l u s t r a t e d by the p l o t s i n Figure 10. smallest amount of a l d r i n that could be detected was  This  For example, the 0.01  ngs which, i n a  one m i c r o l i t r e s o l u t i o n of water, amounts to 0.01 parts per m i l l i o n or 10 parts per b i l l i o n . IV.3.10  C a r r i e r Gas.  The pulsed detector requires a flow of  argon/methane as e i t h e r a c a r r i e r gas or a purge gas, or as both. a purge gas, the detector becomes overloaded i n j e c t i o n of approximately 10 ^ grams.  Without  (non-linear response) at an  Adding purge gas flow w i l l extend  53  FIGURE 10-SIX TYPICAL  LINEARITY PLOTS  [84]  54  l i n e a r i t y up to ten-fold  (10  gram).  As previously mentioned, however, at  flow rates above about 50 mls/min., purge flow i s not needed i n order to optimize detector s e n s i t i v i t y , and thus i t s i n c l u s i o n i s not necessary. When used as a c a r r i e r gas, a composition of f i v e per cent methane and 95 per cent argon i s the optimum, as shown i n Figure 11.  co  TIME  (USEC)  Figure 11  [88]  Electron Concentration vs. Time Between Pulses  It i s e s s e n t i a l that both the c a r r i e r gas and the purge flow, i f any, be dry and contain no oxygen.  These two contaminants have a d e t r i -  mental e f f e c t on the standing current as both w i l l absorb electrons. IV.3.11  C a r r i e r Gas Flow Rate.  The electron capture detector i s  somewhat s i m i l a r to the thermal conductivity detector with regard to c a r r i e r gas flow rate i n that the s i g n a l increases as the flow rate i s decreased.  55  However, as shown i n Figure 12, t h i s i s not a l i n e a r  CARRIER  relationship.  20 40 GAS FLOW RATE (MLS/MIN)  Figure 12 [88] E f f e c t of C a r r i e r Gas Flow Rate on S e n s i t i v i t y  I t was found by Clark [89] that the pulsed mode detector i s i n s e n s i t i v e t o flow rate changes over the range of 40 to 200 mis. per minute. fore, i f the detector i s operated within t h i s range, t e s t s to optimize  Theresensi-  t i v i t y due to flow-rate changes need not be undertaken. IV.3."12  Detector Temperature.  an i n c r e d i b l e e f f e c t on s e n s i t i v i t y .  The detector temperature may have  The peak area may increase, decrease,  or remain r e l a t i v e l y constant as the detector temperature i s changed [87].  56  The detector operating temperature should be selected, i n conjunction with other operating parameters, with the view to optimizing the s e n s i t i v i t y of the gas chromatograph system.  This s e l e c t i o n may  encompass a wide range of  detector temperatures with the only l i m i t a t i o n being that t h i s temperature be kept a few degrees above that of the column to prevent condensation  of  sample components i n the detector. IV.3.13  Pulse I n t e r v a l .  The research gas chromatograph used i n  t h i s study o f f e r s a range of pulse i n t e r v a l s of 5, 15, 50 or 150 microseconds. The settings o f f e r a c o n t r o l on s e n s i t i v i t y and l i n e a r i t y as shown i n Figure 13. The longer the pulse i n t e r v a l , the greater the electron concent r a t i o n grows, and thus s e n s i t i v i t y increases.  However, other factors, such  as detector, oven, and i n j e c t i o n port temperatures and column bleed, alsoplay a part. intervals.  Optimum s e n s i t i v i t y may  therefore occur at shorter pulse  57  LINEARITY  SAMPLE SIZE (GRAMS)  Figure 13 [88] !  L i n e a r i t y and S e n s i t i v i t y a t Various Pulse Intervals  I  CHAPTER V  METHODS OF ANALYSIS USING ELECTRON CAPTURE GAS CHROMATOGRAPHY  V.l  GENERAL INFORMATION The methods described i n t h i s section were chosen a f t e r an exten-  sive review and analysis o f a l l available l i t e r a t u r e exhausted the p o s s i b i l i t y of any further refinements.  This section i s therefore l i m i t e d to a  discussion of the techniques used.  Comprehensive treatment o f a n a l y t i c a l  techniques are contained i n references [90, 91, 92 and 93]. V.l.l.  Sample Handling.  Samples taken f o r analysis were immedi-  ately centrifuged and then subjected t o extraction with nanograde hexane. Extracted samples were then analyzed by gas chromatography.  Due t o the  possible i n s t a b i l i t y of DDT or d i e l d r i n i n water, the samples were not stored at a l l . V.l.2  Glassware.  In order t o avoid contamination i t i s of p a r t i c -  ular importance that glassware used i n p e s t i c i d e analysis be scrupulously clean during use. the case.  Great care was therefore taken to ensure that t h i s was  Glassware was cleaned as soon as possible a f t e r use, using a  method recommended by Bevenue et al.  [94] with several minor changes.  Volumetric glassware was f i r s t washed with a strong soap s o l u t i o n and rinsed with tap water followed by a r i n s i n g with a sodium dichromates u l f u r i c acid solution.  The glassware was then r i n s e d with tap water, d i s -  t i l l e d water, f i n a l l y with nanograde hexane and allowed to a i r - d r y . Nonvolumetric glassware was subject to the same thorough washing and r i n s i n g  58  59  procedure, but a f t e r a i r drying i t was also heated  overnight at 200°C.  The  glassware was stored immediately a f t e r cleaning to prevent accumulation of dust or other contaminants.  I f possible, the glassware was stored inverted.  Several tests were undertaken to ensure that the glassware was thoroughly cleaned.  At f a i r l y  regular i n t e r v a l s during testing a sample  blank was run which contained no i n s e c t i c i d e .  The r e s u l t i n g extract was  subjected to gas chromatographic analysis and the chromatogram obtained studied f o r traces of i n s e c t i c i d e s .  The r e s u l t s showed that the cleaning  procedure employed was e f f e c t i v e i n removing possible adsorbed  insecticides  and any other i n t e r f e r i n g compounds. IV.1.3  Standards, Reagents and Solvents.  Stock solutions were  prepared by d i s s o l v i n g 100 mgs. of the i n s e c t i c i d e i n one l i t r e of p e s t i c i d e grade acetone.  Acetone i s not recommended f o r p e s t i c i d e use [92] as the  p e s t i c i d e may degrade upon standing i n t h i s solvent.  However t h i s i n f o r -  mation was not a v a i l a b l e a t the s t a r t of the t e s t and over the three month t e s t period, neither DDT nor d i e l d r i n showed any detectable degradation. The stock s o l u t i o n was transferred to one l i t r e ,  ground-glass  stoppered, volumetric f l a s k s and working standards prepared from these. The working standards were checked often f o r degradation and concentration and were renewed  several times over the course of the study.  A l l standards  were stored i n t i g h t l y stoppered f l a s k s i n a r e f r i g e r a t e d incubator i n order to minimize evaporation losses.  The standards were allowed to come  to room temperature before opening. The solvent (hexane) used f o r extraction was of nanograde q u a l i t y and was checked before use f o r degradation and/or interferences, by i n j e c t i o n into the gas chromatograph.  Other solvents and reagents used were also of  60  nanograde or p e s t i c i d e grade q u a l i t y .  Solvents were stored i n a cool dark  place according to the manufacturer's i n s t r u c t i o n s . Considerable  d i f f i c u l t y was met  i n obtaining nanograde hexane of  suitable q u a l i t y for p e s t i c i d e residue a n a l y s i s . f i r s t supplier was  Hexane supplied by the  found to contain considerable quantities of i n t e r f e r i n g  substances which were evidenced by poor chromatograms.  Because i t was  i n i t i a l l y thought that these poor chromatograms were due to machine or operator error, considerable time was wasted i n attempting  to determine the  cause of the problem. I t was poor q u a l i t y .  eventually found that the several gallons supplied were Of  Subsequently a second manufacturer was  able to supply high q u a l i t y nanograde hexane. of the two hexanes are shown i n Appendix A.  contacted who  was  Comparative chromatograms  The solvents used during  the  research undertaken i n t h i s thesis project were F i s h e r p e s t i c i d e grade acetone (C H 0) and Mallinckrodt nanograde hexanes (C_H,.). 3 6 V.1.4  o 14 Sample Transfer.  Extracted solutions of hexane were trans-  ferred very c a r e f u l l y i n order to reduce the possible occurrence of inaccurat results.  The i n t e r n a l wall of the t r a n s f e r r i n g vessel was  rinsed twice with  hexane and the funnels used for t r a n s f e r r i n g were also rinsed with hexane. Due to possible adsorption of the i n s e c t i c i d e onto the ground glass sections of the volumetric f l a s k s used [94], a l l transfers from such containers were made with clean, disposable glass p i p e t t e s . V.l.5  Cleaning of the Syringe.  The syringe used i n analysis was  scrupulously cleaned a f t e r each sample i n j e c t i o n . several solvent (nanograde hexane) r i n s e s .  This was  accomplished by  The plunger was., then removed  and further cleaned by p l a c i n g solvent on a t i s s u e and c a r e f u l l y wiping the  t  61  plunger, r i n s i n g the plunger with d i s t i l l e d water and then wiping dry with a clean,' dry, l i n t - f r e e t i s s u e .  The b a r r e l was cleaned with copious amounts  of solvents and then rinsed by drawing d i s t i l l e d water through the b a r r e l with the a i d of a low vacuum source.  The b a r r e l was dried  a i r from a clean compressed a i r source through i t .  then by f o r c i n g  The syringe was checked  p e r i o d i c a l l y during a test f o r c l e a n l i n e s s . The syringe used during t h i s study was a Unimetrics, 10 y l . syringe' with a replaceable needle.  V.2  GAS LIQUID CHROMATOGRAPHY V.2.1  The Gas Chromatograph System.  The gas chromatograph used i n t h i s  study was a Hewlett-Packard research gas chromatograph with a Nickel electron capture detector  63  (pulsed mode) and a model 7127A s t r i p chart recorder.  The c a r r i e r gas used was a mixture of 95 per cent argon and f i v e per cent methane supplied by Matheson o f Canada, and guaranteed suitable f o r electron capture detector a n a l y s i s .  No purge flow was maintained.  A molecular  sieve  g a s - f i l t e r d r i e r was used t o remove any p o s s i b l e moisture i n the c a r r i e r gas. The standing current t e s t was used as a check of detector c l e a n l i ness and contamination.  As mentioned previously a standing current of about  -10 4 - 6 xlO  amps should be observed under s p e c i f i e d conditions with a r e l a -  t i v e l y new and clean detector.  A value o f less than 2.0 x 10 ^  amps  indi-  cated the necessity for troubleshooting. Only once during the study period d i d the standing current f a l l below 3.5 x 10 ^  amps and t h i s was due to detector uncleanliness.  The de-,  tector was thermally cleaned by operating i t at 50°C above i t s normal operating temperature of 265°C, with normal operating flow for 48 hours.  The r e s u l t of  62  t h i s thermal cleaning i s shown i n Appendix B. V.2.2  Columns.  Since p e s t i c i d e s have been known to decompose upon  contact with hot metals [84, 89], a b o r o s i l i c a t e glass column was chosen f o r t h i s study.  The column was four feet long, with an inside diameter of four  millimeters and packed with f i v e per cent DOW-11 on 80/100 mesh high performance Chromosorb W. The column was packed to a uniform density.  Care was taken to  avoid loose packing and consequent excessive v o i d volumes and too dense packing which would create excessive back pressure.  The column tubing was rinsed  with solvent and d r i e d i n the gas chromatograph oven before packing.  The  column was f i l l e d through a funnel connected by f l e x i b l e tubing to one end. The other end of the column was plugged with s i l a n i z e d glass wool and a s l i g h t vacuum was applied.  The column was f i l l e d with the  aid  of an applied v i b r a t i o n and the applied vacuum.  end  was also plugged with s i l a n i z e d glass wool. The column was conditioned  (made hydrophobic)  When f i l l e d , the open  (prepared f o r use through removal of  i n t e r f e r i n g materials) i n the gas chromatograph oven, near i t s recommended maximum operating temperature f o r the l i q u i d phase, f o r 48 hours, under no flow conditions and not connected to the detector. V.2.3  Column E f f i c i e n c y .  The e f f i c i e n c y of the column and i n s t r u -  ment systems i s indicated by the narrowness of the eluted  peaks and i s c a l -  culated i n terms of the number of t h e o r e t i c a l plates (N).  High e f f i c i e n c y  w i l l make a difference between good and poor quantitative r e s u l t s .  A good  column, operated under optimum conditions, should have an e f f i c i e n c y of a t least 400 plates per foot [82].  63  The expression f o r c a l c u l a t i n g the number of t h e o r e t i c a l plates, as recommended by European and American Gas Chromatography Symposiums i s as follows  [82, 87]:  N = 16 (|)  2  where the distances X and Y are measured as shown i n Figure 14.  Figure 14 [87] Column E f f i c i e n c y Parameters  The e f f i c i e n c y of the column used i n t h i s study was about 1900 per foot f o r HEOD and about 1200 plates per foot for DDT.  plates  64  V.2.4  Extraction of Sample.. Two extraction techniques were em-  ployed i n t h i s study. from the sample.  Both techniques used hexane to extract the i n s e c t i c i d e  In both cases, 25 m i l l i l i t r e s of sample  (clay-insecticide  solution) was withdrawn a t the appropriate time, transferred to 50 ml. c e n t r i fuge tubes, and centrifuged f o r 20 minutes a t 2000 revolutions per minute. Ten mis. o f the centratewas then extracted with hexane i n a 50 ml, a l l - g l a s s , separatory funnel. The f i r s t method consisted of making three separate 5 ml. extractions, c o l l e c t i n g the extract  i n 25 ml. volumetric flasks and making the f i n a l  sample up t o exactly 25 mis.  The e f f i c i e n c y of extraction from samples with  known amounts of i n s e c t i c i d e f o r t h i s extraction technique ranged from 83 to 95 per cent f o r HEOD and 62 t o 92 per cent f o r DDT. The second method o f extraction involved making one extraction using 5 mis. of hexane and a second extraction using 2 mis. of hexane. The extract volume was made up t o 10 mis. i n volumetric f l a s k s and the e f f i c i e n c y of extraction for t h i s technique ranged from 88 t o 93 per cent f o r HEOD and 72 t o 84 per cent f o r DDT. The r e s u l t s of these recovery tests are shown i n Appendix C. V.2.5  Injection Into The Gas Chromatographic  System.  The 10 micro-  l i t r e syringe used i n t h i s study contained about 0.7 m i c r o l i t r e of sample i n the needle a f t e r i n j e c t i o n .  Depending on the v o l a t i l i t y of the sample and  the length of time the needle i s l e f t i n the i n j e c t i o n port, part of t h i s needle volume w i l l "bleed" into the i n j e c t i o n port.  Thus, t o t a l sample volumes  injected may range from 10 t o 10.7 m i c r o l i t r e s , depending upon the operator's i n j e c t i o n technique.  Slower v o l a t i l i z a t i o n from the needle w i l l also r e s u l t  65  i n a broader i n j e c t i o n plug and a consequent broadening of peaks.  However,  i f the i n j e c t i o n technique i s well r e f i n e d and the quickness of i n j e c t i o n i s good, this v o l a t i l i z a t i o n w i l l be minimized, Warnick and  i f not stopped altogether.  Gaufin [95] recommend that the operator p r a c t i c e i n j e c t i o n tech-  nique u n t i l he can make repeated i n j e c t i o n s with less than two per cent error.  Extensive p r a c t i c e during t h i s research enabled i n j e c t i o n to be  made with about one per cent error (Appendix D).  The expertise developed  resulted i n very l i t t l e , i f any, of the needle volume being v o l a t i l i z e d i n the i n j e c t i o n port. To avoid bleed o f f that may have caused background interferences, the i n j e c t i o n port septa were conditioned before use.  This was  accomplished  by placing a new low-bleed septum i n the unused i n j e c t i o n port a day ahead of time and, with a low gas flow, allow t h i s system t o condition overnight.  The  two septa were r a p i d l y interchanged the next morning r e s u l t i n g i n a short system s t a b i l i z a t i o n time. As mentioned previously, p e s t i c i d e s have been known to decompose upon contact with hot metals and thus some p e s t i c i d e may be l o s t i n the i n j e c t i o n port.  To make sure that t h i s was not the case, on-column i n j e c t i o n s  were c a r r i e d out.  In an on-column i n j e c t i o n , the sample i s injected d i r e c t l y  into the glass column and does not make contact with the hot metal of the i n jection port. V.2.6  Qualitative and Quantitative A n a l y s i s .  Qualitative identi-  f i c a t i o n of an unknown component i s made by matching the retention time of the unknown with that of a standard obtained under i d e n t i c a l conditions. i  Usually t h i s single gas chromatographic  determination does not provide un-  66  equivocal i d e n t i f i c a t i o n of the unknown component. since the i n s e c t i c i d e was  However, i n t h i s study,  the only chemical added that could have been ex-  tracted, i t i s not a c t u a l l y an unknown, and thus the comparison of retention time with that of a standard would constitute p o s i t i v e identification,. The area of the eluted peak i s proportional to the quantity of the i n s e c t i c i d e i n j e c t e d . This  area was  part of the s t r i p chart recorder. units.  measured by a d i s c integrator, which i s The units of measurement are termed d i s c  To improve p r e c i s i o n , three i n j e c t i o n s of each sample were made and  the areas calculated from each i n j e c t i o n were averaged. Standards were run f o r each s e r i e s of tests and c a l i b r a t i o n curves s i m i l a r to those shown i n Figures 15 and 16 were p l o t t e d .  I t was  necessary  to run these standards because neither detector s e n s i t i v i t y nor column v a r i ables, such as the amount of l i q u i d phase or temperature, may  remain con-  stant between t e s t s . The concentration of i n s e c t i c i d e s i n the sample i s calculated as follows:  A x _ . Concentration  .micrograms. (—, . ? ) = litre  t ________ V. x V 1 s  where  A = sample size i n nanograms as found from chromatograms; V. = volume of extract i n j e c t e d (uls); 1  V  t  V s V.2.7  = volume of t o t a l extract  (uls);  = volume of water extracted Optimum Operating Conditions.  (mis). The optimum operating  condi-  tions, combining a r e l a t i v e l y short retention time, good peak geometry, and no column packing breakdown, were as follows:  67  -10,000  ipoo z o CO Q < ID  rr <  <  ID CL  10.0  1.0  SAMPLE  SIZE  FIGURE 15 - LINEARITY  (NANOGRAMS) CURVE  FOR  DDT  68  10,000  jo ipoo o w Q  < UJ  cc <  < LO  100  0.1  1.0  SAMPLE  SIZE  FIGURE 16 - LINEARITY  10.0  (NANOGRAMS) CURVE  FOR  HEOD  1  69  Detector temperature:  225°C.  Injection port temperature:  230°C.  Column temperature:  230°C.  C a r r i e r gas flow rate:  90 mis./min.  Purge gas flow rate:  none  Rotameter s e t t i n g :  4.0  C a r r i e r gas i n l e t pressure:  40 p s i .  Pulse i n t e r v a l :  150 usees,  Range:  10  Attenuation:  variable  Temperature program:  isothermal  Chart speed:  0.25 inches/min.  Once these optimum operating conditions were determined, they were maintained throughout the study period.  CHAPTER VI  DESCRIPTION OF STUDY METHODS  VI.1  ADSORPTION AND DESORPTION TESTS Adsorption and desorption t e s t s were conducted i n a series of 2  l i t r e Pyrex b o t t l e s .  The t e s t solutions were agitated with glass-covered  s t i r r i n g bars which were operated by magnetic s t i r r e r s .  Glass-coated  r i n g bars were used instead o f t e f l o n as the teflon-coated have adsorbed some o f the i n s e c t i c i d e [93] .  stir-  s t i r r i n g bars may  During each t e s t the b o t t l e s  were t i g h t l y sealed with f o i l - c o v e r e d rubber stoppers. For each adsorption t e s t , a 1.5 l i t r e , 100 yg/1 aqueous i n s e c t i c i d a l s o l u t i o n was placed i n each of the 2 l i t r e b o t t l e s .  (Because of the low  s o l u b i l i t y of these i n s e c t i c i d e s , i n a l l tests one ml. of pesticide-grade acetone per l i t r e o f solution was used as a c a r r i e r solvent).  An accurate-  ly weighed quantity of clay was then added to each b o t t l e and allowed to be mixed with the s o l u t i o n .  The i n s e c t i c i d e remaining i n the water was deter-  mined at frequent i n t e r v a l s , beginning from when the clay was added, u n t i l equilibrium was reached. For the desorption t e s t s a suitable method of separating maining clay from the water had t o be found. l y repeating  the r e -  This was accomplished by exact-  the above adsorption tests except that a l l solutions were made  0.01 molar with respect  to C a C l  2  by the addition o f C a C l  2  • 2H 0. 2  The addi-  t i o n of t h i s s a l t had the desired e f f e c t o f causing the clay to f l o c c u l a t e i  and  settle.  The addition of enough C a C l 70  2  to make the solution 0.01 molar  71  was undertaken as t h i s procedure was shown to not a f f e c t the adsorption o f another chlorinated  hydrocarbon (Lindane) onto f i n e clays  [96]. At the end  of t h i s second series of adsorption t e s t s , the clay was allowed to s e t t l e overnight and the overlying water decanted and replaced with new d i s t i l l e d water.  The test solutions were then mixed continuously for the remainder  of the t e s t and the i n s e c t i c i d e concentration i n the water was determined a t frequent time i n t e r v a l s s t a r t i n g with the i n i t i a l replacement of the d i s t i l l e d water. Repeating the adsorption tests had the added advantage of determining whether or not the addition o f C a C l  • 2H 0 affected the adsorption  2  2  of the i n s e c t i c i d e s onto the clay p a r t i c l e s .  VI.2  QUIESCENT REMOVAL TESTS Quiescent removal tests were conducted i n two l i t r e Pyrex beakers.  The  t e s t solutions were well-mixed 1.5 l i t r e aqueous i n s e c t i c i d a l solutions  which had an i n i t i a l i n s e c t i c i d e concentration of 100 ugms/litre. again were made 0.01 molar with respect to C a C l . 2  amount of clay was l i g h t l y sprinkled  An accurately weighed  on top of the t e s t solutions  to s e t t l e into and through the solutions.  These  and allowed  The i n s e c t i c i d e concentration i n  the solution was determined a t regular time i n t e r v a l s s t a r t i n g immediately following  the addition of the clay.  The t e s t solutions were not agitated  i n any way during t h i s t e s t except f o r the i n i t i a l preparation of. the i n s e c t i c i d e - d i s t i l l e d water - CaCl^ * 2H 0 s o l u t i o n . 2  i  72  VI.3  SAND BLANKETING TESTS Sand blanketing tests were conducted immediately following the  quiescent removal t e s t s . further s e t t l e overnight.  The clay i n the test solutions was allowed to In one t e s t solution the s e t t l e d clay was covered  with approximately 1/4 inch of sand while the s e t t l e d clay of an i d e n t i c a l t e s t s o l u t i o n was l e f t uncovered.  The water i n the test solutions was then  replaced, attempting not to disturb the s e t t l e d clay or the sand layer. After 12 hours the water d i r e c t l y above the sand layer and d i r e c t l y above the s e t t l e d clay was sampled f o r i n s e c t i c i d e analysis.  The water was again  replaced and a f t e r a further 24 hours sampled and analyzed i n the same manner.  CHAPTER VII  RESULTS OF THE STUDY  VII.l  ADSORPTION TEST RESULTS The r e s u l t s of the adsorption study i n d i c a t e that s i g n i f i c a n t  amounts of the experimental  i n s e c t i c i d e s were adsorbed onto the bentonite.  Of the two i n s e c t i c i d e s , DDT i s adsorbed easier and i n greater quantities than HEOD.  The tabulated r e s u l t s of a l l the t e s t s are presented  i n Appendix  E. The spread i n i n d i v i d u a l tests as i l l u s t r a t e d by tests 1, 2, and 3 i n Figure 17 when compared to tests 4, 5 and 6 i n Figure 18, i s due to several f a c t o r s .  The l a t t e r t e s t s were more precise due to operator exper-  t i s e gained, i n operating the gas chromatograph, e x t r a c t i n g the samples, and other research procedures,  as the t e s t program progressed.  This spread was  evident i n the several t e s t s conducted during the i n i t i a l stages of the research.  Also, a c e r t a i n amount of the impreciseness  noted i n a l l t e s t s  conducted  was due t o the d i f f i c u l t y i n maintaining exact operating condi-  tions of the gas chromatograph throughout the t e s t period. Figures 17 and 18 show that HEOD i s adsorbed onto bentonite with the degree of adsorption depending upon the clay concentration.  With a  c l a y concentration o f 1.0 gm/l about 15 per cent of the HEOD i s adsorbed while with a clay concentration o f 10.0 gm/l about 30 per cent of the HEOD i s adsorbed. These f i g u r e s also show that the adsorption of HECD onto bentoi  n i t e i s e s s e n t i a l l y instantaneous with the maximum adsorption occurring 73  74  2  FIGURE  3 TIME (HOURS)  4  5  1 7 - H E O D ADSORPTION C U R V E S ' 1.0 G M / L BENTONITE  TEST NO. 5,6,7 BENTONITE CONC/IO.O GM/L HEOD CONC.: 100 pGM/L  CONTF OL-  .  / -  •  <  >  >  1  )  TIME  FIGURE  (HOURS)  1 8 - H E O D ADSORPTION CURVES' 10.0 G M / L BENTONITE  1  75  during the f i r s t 1/2 to 1 1/2 hours.  Thereafter, a gradual desorption takes  place u n t i l the equilibrium adsorption l e v e l i s attained about two hours a f t e r the s t a r t of the t e s t . Figures 19 and 20 confirm that the addition o f C a C l  2  • 2H 0, 2  enough to make the s o l u t i o n 0.01 molar, does not s e r i o u s l y a l t e r the f i n a l equilibrium adsorption l e v e l of the HEOD onto the bentonite. i n i t i a l adsorption l e v e l s are affected by the C a C l  2  However, the  * 2H 0 addition and i n 2  the t e s t s containing the higher c l a y concentrations the time required to reach the f i n a l equilibrium l e v e l i s increased. Figures 21 and 22 i n d i c a t e that DDT i s adsorbed onto bentonite to a much greater degree than HEOD.  With a clay concentration of 1.0 gm/l  about 60 per cent of the DDT i s adsorbed while with a clay concentration of 10.0 gm/l the adsorption i s increased to about 72 per cent.  These f i g -  ures also show that the rate of adsorption of DDT onto bentonite i s dependent upon the clay concentration.  The solutions containing 1.0 gm/l clay take  nearly four hours t o reach equilibrium compared to about two hours f o r the 10.0 gm/l. clay solutions.  This d i f f e r e n c e i n the rate of adsorption i s l i k e -  ly due to the DDT having easier access t o the adsorption s i t e s located on the clay p a r t i c l e s when there i s a higher clay concentration. As shown i n Figures 23 and 24, the addition of enough C a C l  2  • 2H 0 2  to make the s o l u t i o n 0.01 molar does not s e r i o u s l y a l t e r the f i n a l equilibrium adsorption of DDT. DDT adsorption.  However, the addition of t h i s s a l t does slow the rate of  I t appears that the C a  + +  ion i s , i n a l l p r o b a b i l i t y , changing  the structure of the layers of the c l a y molecule such that i t a f f e c t s the rate of DDT adsorption.  76  40L-  2 TIME  3 (HOURS)  4  FIGURE 1 9 - H E O D ADSORPTION CURVES 1.0 G M / L BENTONITE; SOLUTION 0.01 MOLAR h  T E S T NO. 10, 11,12 B E N T O N I T E CONC. 10.0 GM/L HEOD CONC. 100 U G M / L WT. CaCI 2 < 2 H 0 = 2.205 GMS. 2  )  &  ____________ <I  —  —  -< ' —•  <\  ;  MM TIME  (HOURS)  FIGURE 2 0 - H E O D ADSORPTION C U R V E S ' 10.0 G M / L BENTONITE; SOLUTION 0.01 MOLAR  77  40 CO Y T R 0 L  EQUILIB RWM CC >NC.= 7 3 U G M /  T E S T NO. 13, 14,15 BENTONITE C O N C - 1.0 6 M / L DDT CONC. • 100 U G M / L  o  5  30  or  UJ o z 5  i 20  3  ui  _  \  <•  )  /  (  •-(js) —  < IE 10 rZ Ul  i >•  1  • S  o z o o  2  3 TIME (HOURS)  4  FIGURE 21- DDT ADS0RTI0N CURVES. 1.0 G M / L BENTONITE 40  cor T R 0 L  E QUILIBF IUM CO MC.= 81  JGM/L  TEST  NO. 16, 17, 18  BENTONITE  V  DDT.  CONC/10.0 G M / L  CONC.: 100 p G M / L  2  5  30  ui  I a  z z  20  < S  ui  rr z o  Si  10  »-  *  8  cc  Z Ul  r-  o z o o  TIME  (HOURS)  FIGURE 2 2 - D D T ADSORPTION CURVES 10.0 G M / L BENTONITE  1  p  45  5 I 0  1 1  1  1  1  1  1  2  1  1  3 TIME  1  1  4  1  U  5  6  (HOURS)  FIGURE 2 3 - DDT ADSORPTION CURVES 1.0 G M / L BENTONITE,- SOLUTION 0.01 MOLAR  tj  3  T E S T NO. 2 2 , 2 3 . 2 4 BENTONITE C O N C . 10.0 G M / L D D T CONC. 100 U G M / L WT. C a C I a - 2 H z O 2 . 2 0 5 GMS  5  ;  s O  30  —,  ,  rr  0  1  0  1  1  1  I  1  1  1  2  1  3 TIME  1  ,  4  1  L  6  (HOURS)  FIGURE 2 4 - DDT ADSORPTION CURVES 10.0 G M / L BENTONITE i SOLUTION 0.01 MOLAR  ,  ,  79  VII.2  DESORPTION TEST RESULTS The overlying water that was decanted during the adsorption tests  was quite c l e a r , with an average of 1.61 mg/l clay was  total solids.  Thus very  little  removed with the decanted water. As a l l the overlying water could not be removed without d i s t u r b i n g  and/or removing some of the clay, the water was l e v e l f o r each clay concentration. mis. of clay-water s o l u t i o n was  only decanted to a s p e c i f i e d  For the 1.0 gm/l  clay, a maximum of 53  l e f t i n the b o t t l e s , and f o r the 10.0  clay concentration, a maximum of 310 mis of clay-water s o l u t i o n was  gm/l  left.  Therefore a c e r t a i n p o r t i o n of the i n s e c t i c i d e measured during the desorption tests would come from the t h i n layer of water overlying the clay which was not decanted.  This concentration however can be calculated from the  tion test results. does i n f a c t occur.  adsorp-  I t can therefore be c a l c u l a t e d whether or not desorption Such c a l c u l a t i o n s are presented i n Appendix F.  Results of the adsorption t e s t s i l l u s t r a t e d i n Figures 25 and  26  show that the desorption of HEOD from bentonite does occur, with an e q u i l i brium value of about 10 ygm/1 and 10.0  reached f o r both clay concentrations, 1.0  gm/l  gm/l. Figures 27 and 28 i n d i c a t e that DDT  desorption from bentonite  does occur; with a desorption concentration of 3 ygm/1  and 1 ycrm/1 f o r c l a y  concentrations of 1.0 gm/l and 10.0 gm/l, r e s p e c t i v e l y .  VII.3  QUIESCENT REMOVAL TEST RESULTS The r e s u l t s of the quiescent removal t e s t s for HEOD are presented  I i n Figure 29. solved HEOD.  The curves confirm that bentonite can be used to remove d i s The clay, added t o the s o l u t i o n under quiescent conditions,  80 ;i T E S T NO. 25, 26,27 B E N T O N I T E CONC. 1.0 G M / L INITIAL HEOD CONC. .100 U G M / L  s ca-  i' — — —  /  rr ui  _—  1> i >. < rr  ST*  —  1  /  _ • ——  C»  L -  •  / /  ,  (  1  — ky  *.  3  1  /  \ s  ui o z o u  o  MAXIHrfUM POJ5SIBLE CONCENTf NATION C U E TO CILUTION  TIME  FIGURE  JT  25-HEOD 1.0 G M / L  o  (HOURS)  DESORPTION BENTONITE  CURVES'  1  T E S T NO. 2 8 , 2 9 , 3 0 BENTONITE CONC. 10.0 G M / L IN1TIALHE0D CONC. 100 P G M / L 1  -© 2'  o  i) ii  .  n. rr. ui < r<  -  ~f. f  '-/.  / •v.  i.  2 o  P 0 SSIBLE  ClONCENT RATION DUE TO DILUTION 1  i  Ul  .{  {  MAXI MUM  < rr iz  <  o  o z o o  TIME  FIGURE  (HOURS)  2 6 - H E O D DESORPTION CURVES' 10.0 G M / L B E N T O N I T E  r  81  T E S T NO. 31, 32,33 BENTONITE CONC. I.O G M / L INITIAL DDT CONC. 100 p G M / L  _l  JS —  I  MAX MUM 1  PC3SSI8LE CONCEIT T R A T I O ^ 1  t 1  t  2  3 TIME  FIGURE  I  1  (HOURS)  D U E •0 -  1i  —  n . IO  i  i  DILU" ION  4  2 7 - D D T DESORPTION I.O G M / L BENTONITE  I  7  CURVES'  T E S T NO. 3 4 , 3 5 , 3 6 BENTONITE CONC. I0.0 G M / L INITIAL DDT CONC. I00 U G M / L  M WIMUM POSSIBL E  1  <i  I  9^4-  C)  A  TIME  FIGURE  JS)  CONC ENTRATi ON DUE. TO DIL UTION  m  S i IS n .  f  /  (HOURS)  2 8 - DDT DESORPTION CURVES'! 10.0 G M / L BENTONITE  /  *  7  CONCENTRATION  38  REMAINING IN WATER  (UGM LITRE)  83  s e t t l e d through the solution, and while s e t t l i n g adsorbed HEOD from i t . The amount o f HEOD removed from the water i s dependent upon the amount of clay used as an adsorbing agent. Figure 30 i l l u s t r a t e s the r e s u l t s of the tests using bentonite to remove DDT from quiescent water bodies.  As i n the case f o r .HEOD, the  bentonite removed DDT from the solution while s e t t l i n g through i t , and the amount removed i s dependent upon the amount o f clay used as an adsorbing agent. The results o f the quiescent removal t e s t s f o r HEOD indicate that the same o r s l i g h t l y more HEOD was adsorbed during these tests while under quiescent conditions, than was adsorbed during the adsorption t e s t s , while under constant mixing conditions.  A possible explanation of t h i s phe-  nomenon i s that the weak HEOD-clay bond was broken i n some cases, due t o the r a p i d mixing that was undertaken during the adsorption t e s t s , and thus just s l i g h t l y less HEOD was adsorbed during such t e s t s than during the quiescent removal t e s t s . In the case o f the adsorption tests f o r DDT, the stronger DDT-clay bond  was not affected by the rapid mixing and thus the r e s u l t s f o r the adsorp-  t i o n t e s t s (mixing) and the quiescent removal t e s t s (no mixing) compare quite closely.  1  85  VII.4  SAND BLANKETING TEST RESULTS . The sand blanketing tests were undertaken to see i f t h i s method  would stop the desorption of adsorbed i n s e c t i c i d e s from benthic clay deposits into overlying waters.  The r e s u l t s o f these tests are presented i n  Tables V and VI f o r HEOD and DDT, respectively. In these t e s t s , water samples were taken just p r i o r to the addit i o n o f the Ottawa sand and sample number one (time: 0 hours) was taken just a f t e r the sand addition.  I t was found by comparing the results from these  samples that the sand i t s e l f d i d not adsorb any i n s e c t i c i d e s . As can be seen i n Tables V and VI, the sand layer does i n f a c t help prevent the desorption of the i n s e c t i c i d e s into the overlying  water.  Some of the i n s e c t i c i d e present i n the water i s due to d i l u t i o n (as i n the desorption t e s t s , not a l l the water could be removed) but both test  solutions,  the solution with the sand blanket and the one without, were l e f t with essent i a l l y the same amount of water. Thus the differences  i n i n s e c t i c i d a l concentration between the  samples with a sand blanket and those without, as shown i n Tables V and VI, cannot be attributed t o d i l u t i o n e f f e c t s , but must be caused by desorption. Therefore, i t i s apparent that the sand blanket used was a t l e a s t somewhat e f f e c t i v e i n reducing desorption o f the i n s e c t i c i d e s from the clay. The effectiveness  of the sand blanket was due to the fact that i t  acts as a physical block to the desorption of the i n s e c t i c i d e into the overl y i n g waters.  TABLE V SAND BLANKETING TESTS FOR HEOD  1  TEST NUMBER  2  3  1  2  3  1.0  1.0  1.0  1.0  1.0  0  12  36  0  12  36  l  13  -  1  13  -  Sample Number  :i  B e n t o n i t e C o n c e n t r a t i o n (mg/l)  1.0  Time sample t a k e n (hrs)  Time when o v e r l y i n g water r e p l a c e d (hrs)  Cone, o f HEOD i n o v e r l y i n g water f o r sample w i t h o u t sand b l a n k e t (ygm/1)  Cone, o f HEOD i n o v e r l y i n g water f o r sample w i t h sand b l a n k e t (vigm/1)  60.0  9.1  55.0  8.43  4  3  2  1  10.0  2  3  1 .  10.0  2  3  10.0  10.0  10.0  10.0  0  12  36  0  12  36  1  13  -  1  13  -  2.4  62.0  8.7  3.1  50.5  6.3  Trace  57.0  8.3  Trace  52.5  4.14  .  2.5  51.0  4.3  Trace  49.0  2.21  1.7  Trace  CO  TABLE VI SAND BLANKETING TESTS FOR DDT  1  TEST NUMBER  Sample number  2  3  1  2  3  1  2  3  1.0  1.0  1.0  1.0  1.0  1.0  Time sample taken (hrs)  0  12  36  0  12  36  Time when o v e r l y i n g water r e p l a c e d (hrs)  1  13  -  1  13  B e n t o n i t e C o n c e n t r a t i o n (mg/l)  Cone, o f DDT i n o v e r l y i n g water f o r sample w i t h o u t sand b l a n k e t (ygm/1)  19.0  Cone, o f DDT i n o v e r l y i n g water f o r sample w i t h sand b l a n k e t (ygm/1)  15.0  4.0  1  10.0  2  4  3  10.0  10.0  0  12  3.6  -  1  13  1  10.0  2  3  10.0  10.0  0  12  36  -  1  13  ••  2.64  16.2  3.7  2.8  9.4  3.4  2.6  9.5  3.2  2.5  2.0  14.1  3.6  2.1  9.0  2.1  Trace  9.3  2.2  Trace  CHAPTER VIII  CONCLUSIONS AND RECOMMENDATIONS  VIII.1  CONCLUSIONS 1.  DDT and d i e l d r i n are p e r s i s t e n t i n the environment,  can be b i o l o g i c a l l y magnified, and may e x i s t i n the natural h a b i t a t of man and animals, exerting t h e i r l e t h a l and sub-lethal e f f e c t s , f o r a long period o f time. 2.  The adsorption of DDT and HEOD onto bentonite does occur  (Figures 17 to 24) with DDT being adsorbed to a greater extent.  The rate  of adsorption, and the f i n a l adsorption equilibrium l e v e l attained f o r both i n s e c t i c i d e s , are related t o the c l a y concentration of the s o l u t i o n , with the higher clay concentration adsorbing more i n s e c t i c i d e , and reaching i t s f i n a l adsorption equilibrium l e v e l f a s t e r . With a DDT concentration of 100 ygm/1 (ppb) i n s o l u t i o n the addit i o n of bentonite at a concentration of 1.0 gm/l w i l l cause the removal of about 60 per cent o f t h i s i n s e c t i c i d e , while the addition of bentonite at a concentration of 10.0 gm/l w i l l r e s u l t i n removal o f about 72 per cent. With a HEOD concentration o f 100 ygm/1 i n solution, the addition /  of s i m i l a r bentonite concentrations of 1.0 gm/l and 10.0 gm/l w i l l b r i n g about the removal of about 15 and 30 per cent o f the HEOD, r e s p e c t i v e l y . The addition of a s a l t  (CaCl  2  • 2H 0) has r e l a t i v e l y l i t t l e or 2  no e f f e c t on the f i n a l i n s e c t i c i d e adsorption l e v e l attained. However, due to the s a l t ' s i n i t i a l competition with the i n s e c t i c i d e f o r the adsorp88  89  t i o n s i t e s on the clay p a r t i c l e s , the time required t o reach the f i n a l adsorption l e v e l i s increased. 3.  The desorption of DDT and HEOD from bentonite does occur  (Figures 25 t o 28), with HEOD being desorbed t o the greater degree and DDT desorption being quite minimal.  The DDT appears t o be much more t i g h t l y  bound t o the bentonite than the HEOD. The desorption equilibrium l e v e l attained for HEOD appears to be unrelated t o the c l a y concentration, and thus t o the amount of HEOD adsorbed, as e s s e n t i a l l y the same amount of HEOD was desorbed for both clay concentrations  (1.0 gm/l and 10.0 gm/l).  In the case of DDT, the r e s u l t s  were inconclusive, except t o say that some desorption does occur. 4.  The i n s e c t i c i d a l removal during quiescent removal tests was  r e l a t e d t o the amount o f bentonite that was s e t t l e d through the water. As expected from the adsorption t e s t s , DDT was removed t o a greater extent than HEOD (Figures 29 and 30). The r e s u l t s i n d i c a t e that bentonite a t concentrations of 1.0, 5.0, and 10.0 gm/l, w i l l remove about 44, 48, and 54 per cent, r e s p e c t i v e l y , o f the DDT while s e t t l i n g through a quiescent water body that i n i t i a l l y  con-  tained DDT at a concentration of 100 ygm/1. Bentonite at s i m i l a r concentrations of 1.0, 5,0, and 10.0 gm/l w i l l remove about 14, 23, and 30 per cent, r e s p e c t i v e l y of the HEOD while s e t t l i n g through a quiescent water body that had an i n i t i a l HEOD concentrat i o n of 100 ygm/1. 5.  The a d d i t i o n of a layer o f sand blocks  of DDT and HEOD from benthic clays.  the desorption  The sand blanket i s somewhat e f f e c t i v e  90  because i t acts as a p h y s i c a l block to the desorption of the i n s e c t i c i d e . Suspended materials, onto which i n s e c t i c i d e s may be adsorbed, when s e t t l e d make up an i n t e g r a l part of bottom sediments.  Under c e r t a i n condi-  tions part of the adsorbed i n s e c t i c i d e s may be desorbed from these benthic deposits and released i n t o the overlying waters where they would be maintained by a dynamic equilibrium system.  A sand layer over these benthic  deposits, a c t i n g as a p h y s i c a l b a r r i e r , would m a t e r i a l l y reduce t h i s desorption into the overlying waters.  This sand layer would also reduce  the p o t e n t i a l f o r further contamination due to the transportation of these p o l l u t e d bottom sediments to uncontaminated areas.  VIII.2  RECOMMENDATIONS P e s t i c i d e s , e s p e c i a l l y the organochlorine  i n s e c t i c i d e s DDT and^ d i e l -  d r i n , are highly t o x i c to w i l d l i f e and extremely p e r s i s t e n t i n the natural environment.  Due to the many instances of overuse and misuse, i t i s strong-  l y recommended that research i n t o the contamination o f the aquatic ment by the organochlorine  i n s e c t i c i d e s be continued.  environ-  I t i s of particular  importance to examine the ultimate fate o f these i n s e c t i c i d e s once they have entered  the marine ecosystem.  This research should be d i r e c t e d towards  evaluating the long-range e f f e c t s of low-level doses and the possible synerg i s t i c and antagonistic e f f e c t s of p e s t i c i d e s i n the aquatic environment.  The p o l l u t i o n o f natural water bodies by contaminated benthic dep o s i t s i s becoming an i n c r e a s i n g l y common occurrence. This contamination may be due to i n s e c t i c i d e s or other pollutants such as mercury, nutrients, radioactive isotopes, vention.  and others, and w i l l require further research i n t o i t s pre-  The concept of using a blanket of inorganic material t o act as a  p h y s i c a l b a r r i e r to any r e - s o l u t i o n i s worthy of much more research.  In  the case of such research, the type of inorganic material to be used as the blanket should be studied, as should the optimum thickness of the blanket.  The a p p l i c a t i o n of d i f f e r e n t types and thicknesses of inorganic  materials should be studied for d i f f e r e n t contaminants. D i f f e r e n t materials to be used as adsorbants pollutants should also be researched.  for various soluble  The research should eventually be  undertaken with a dynamic system i n order to duplicate as closely as possible the conditions i n nature.  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"Reactions of Surfactants With Montmorillonite: Adsorption Mechanisms," Proceedings, S o i l Science Society of America, V o l . 30 (1966), p. 321. Barbaro, R. D. and J . V. Hunter. "Surfactural Adsorption on Several Homoionic Forms of Kaolin," Water Research, V o l . 1, p. 157 (1967), as c i t e d i n "Factors Influencing the Adsorption, Desorption and Movement of P e s t i c i d e s i n S o i l , " Residue Reviews, V o l . 32 (1970), p. 29.  98  [72]  Fredeen, F. J . , A. P. Arnason.and B. Berck. "Adsorption of DDT on Suspended Solids i n River Water and I t s Role i n Black F l y Cont r o l , " Nature, V o l . 171 (1953), p.,700.  [73]  Breidenbach, A. W. and J . J . Lichtenberg. " I d e n t i f i c a t i o n of DDT and D i e l d r i n i n Rivers.'A Report of the National Water Quali t y Network," Science, V o l . 141 (1963), p. 899.  [74]  Walker, K. C. 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(1966), p. 141.  [79]  Anonymous. Evaluation of the Extent and Nature of Pesticides and Detergent Involvement in Surface Waters of a Selected Watershed, Research Report No. 10, Part I, Syracuse U n i v e r s i t y Research Corporation (1963).  [80]  Sylvester, R. o. and R. W. Seabloom. Quality of Impounded Water as Influenced by Site Preparation, College of Engineering, Univers i t y of Washington, Seattle, Washington (December, 1964).  [81]  Tenny, M. W. and W. F. "Echelberger,Jr. " F l y Ash U t i l i z a t i o n i n the Treatment o f Polluted Waters," Bureau of Mines Information Circular 8488, Ash U t i l i z a t i o n Proceedings, p. 237 (1970).  [82]  McNair, H. M. and E. J . B o n e l l i . Basic Gas Chromatography. Aerograph, Walnut Creek, C a l i f o r n i a (1969).  [83]  Lovelock, J . E. and S. R. Lipsky. "Electron A f f i n i t y Spectroscopy — A New Method f o r I d e n t i f i c a t i o n of Functional Groups i n Chemic a l Compounds Separated by Gas Chromatography," Journal American Chemical Society, V o l . 82 (1960), p. 431.  Con-  Varian  99  Dimick, K. P. and H. Hartmann. "Gas Chromatography For the Analys i s of Pesticides Using Aerograph Electron Capture Detector," Residue Reviews, V o l . 4 (1963), p. 150. Lovelock, J . E. and S. R. Lipsky. "Ionization f o r the Analysis of Gases and Vapors," Analytical Chemistry, V o l . 33 (1961), p. 162. Gaston, L. K. "Gas Chromatography Using an Electron Absorption Detector," Residue Reviews, V o l . 5 (1964), p. 21. Anonymous. Operating and Service Manual for the Series 57SOB Research Gas Chromatograph, Hewlett-Packard A n a l y t i c a l Instruments, Avondale, Pennsylvania (1966). Anonymous. 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Official Methods of Analysis of the Association of Official Agricultural Chemists, Association of O f f i c i a l A g r i c u l t u r a l Chemists, Washington, D. C. (1965). Bevenue, A., T. W. K e l l y and J . W. H y l i n . "Problems i n Water Analysis f o r Pesticide Residues," Journal of Chromatography, Vol. 54 (1971), p. 71. Warnick, S. L. and A. R. Gaufin. "Determination of Pesticides by Electron Capture Gas Chromatography," Journal American Water Works Association, V o l . 57, No. 8 (1965), p. 1023. Lots, E. G., D. A. Graetz, G. Chesters, G. B. Lee and L. W. Newland. "Lindane Adsorption by Lake Sediments," Environmental Science and Technology, V o l . 2, No. 5 (1965), p. 353.  A P P E N D I C E S  APPENDIX A  COMPARATIVE CHROMATOGRAMS OF TWO ..HEXANES  3 ••  2 ••  I --  BOTH INJECTIONS ARE T H E SAME SIZE, WITH T H E S A M E OPERATING CONDITIONS. T H E CHROMATOGRAM ON L E F T (FROM SUPPLIER'A') SHOWS I N T E R F E R E N C E S WHILE T H E ONE ON T H E RIGHT SHOWS NONE.  APPENDIX B  THERMAL CLEANING RESULTS  i  MEASUREMENT OF THE STANDING CURRENT [94]  1. Balance the electrometer to true recorder zero which should coincide to the chart 0 per cent. 2.  Set the following range and attenuation: Nickel . . . .  10 x 6 4  3.  Disconnect the electrometer cable a t the detector.  4.  Zero the pen t o 100 per cent using the electrometer zeroing  5.  Reconnect the cable and note the recorder reading (R).  6.  Calculate the Standing Current  controls.  S.C. = [electrometer s e n s i t i v i t y  A.  Standing Current *  B.  Standing Current = ( l x l O  (S.C.)  —12 100—R (1x10 amps)] X Range X Attenuation X ^  (lxl0~ )(10)(64)( ° Q ) 1 2  1 0  2  0  - 1 2  ) (10) (64)  104  = 1.79 x 1 0 ~  (i~zH) = 4 . 3 5 i o " x  1 0  10  amps.  amps.  105  STANDING  CURRENT T E S T  1  A". STANDING CURRENT BEFORE THERMAL CLEANING = 1.79 x I0 amps. _l0  B in  z  LJ CC CC 13 O  o z  STANDING CURRENT AFTER THERMAL CLEANING OVER WEEKEND = 4.35 x I0"'°amps.  APPENDIX C  EXAMPLES OF RECOVERY FROM SAMPLES CONTAINING KNOWN AMOUNTS OF INSECTICIDE  A.  EXAMPLES FOR HEOD RECOVERY FROM SAMPLE CONTAINING 100 ugm/litre WITH NO CLAY ADDED  3-5 ml. extractions Sample No.  *  1-5 ml., 12 ml. extraction  1  2  1  2_  Volume Water Ext. (mis) 10 Volume Extract (mis) 25 Volume Inject (yls) 5 271 Disc Area (D.U.*s) 0.167 Sample Size (ngs) Concentration (u. g/1) 83.5 Recovery E f f . (%) 83.5  10 25 5 273 0.169 84.5 84.5  10 10 3 455 0.286 95.3 95.3  10 10 3 421 0.267 89.0 89.0  * B.  EXAMPLES FOR DDT RECOVERY FROM SAMPLES CONTAINING 100 u gm/litre WITH NO CLAY ADDED  3-5 ml. extractions  1-5 ml., 12 ml. extr  1  2:  1_  Volume Water Ext. (mis) 10 Volume Extract (mis) 25 Volume Inject (uls) 5 Disc. Area (D.U.'s) 176 0.143 Sample Size (ngs) 71.5 Concentration (yg/1) Recovery E f f . (%) 71.5  10 25 5 152 0.125 62.5 62.5  10 10 3 329 0.278 92.6 92.6  Sample No.  2_ 10 10 3 267 0.221 73.6 73.6  * In a l l recovery e f f i c i e n c y t e s t s from spiked samples, the samples were extracted i n the same manner as the actual t e s t samples. Therefore, recovery e f f i c i e n c y includes loss of i n s e c t i c i d e on c e n t r i fuge tubes and walls of other vessels, as well as the e f f i c i e n c y of the extraction process. I t appears that the loss on vessels walls i s a major factor i n l o s s o f i n s e c t i c i d e , as the samples that were extracted the l e a s t , but also handled the l e a s t , had the highest recovery e f f i c i e n c i e s .  107  APPENDIX D  EXAMPLES OF INJECTION TECHNIQUE PRECISION ANALYSIS TESTS  PEAK AREA REPRODUCIBILITY TESTS  Operating Conditions: Pulse Interval - 5 0  u  sees.  Attenuation - 64 Range - 10 Oven Temperature - 230°C. Detector Temperature - 265°C. Injection Port Temperature - 230°C. I n l e t Pressure - 40 p s i . C a r r i e r Gas Flow Rate - 90 mls/min.  EXAMPLE 1  INJECTION NO.  PEAK AREA (X)  1 2 3 4 5 6 7 8 9 10  762 747 739 758 763 751 758 764 753 763  X-X  (X-X)  6.2 -8.8 -16.8 2.2 7.2 -4.8 2.2 8.2 -2.8 -7.2  2  38.44 77.44 283.00 4.84 51.84 23.04 4.84 67.24 7.14 51.83  T o t a l = 610.36  755.8  X s = 3.22  s  2  =  , , 4  ( % >  =  (  .5.54 755.8  ;  3 6  = 67,  . X = 755.8 ± 8.2  error = (0.6745)(8.2) = 5.54 error  6 1 0  ) 1 0  °  = 0.73%.  EXAMPLE 2  INJECTION NO.  PEAK AREA (X)  444 450 458 428 438 452 451 447 444 439  1 2 3 4 5 6 7 8 9 10  X-X  (X-X)  -1.2 4.8 12.8 -17.2 7.2 6.8 5.8 1.8 -1.2 -6.2  1.44 23.04 163.84 295.84 51.84 46.24 33.64 3.24 1.44 38.44  T o t a l = 659.00  X = 445.2 s s  2  659.0 = —  _ = 73.22 0  = 8.55  .*. X = 445.2 ± 8.55 Probable error = (0.6745)(8.55) = 5.77 Probable error (%)  -  (  f  ^  j  )  1  0  0  = 1.29%.  \  APPENDIX E  ADSORPTION, DESORPTION, AND QUIESCENT REMOVAL TESTS  ADSORPTION TEST NO. 1  .  HEOD CONC.  DDT CONC.  (ugm/1)  (ugm/1)  100  VOLUME OF DISTILLED WATER (mis)  BENTONITE CONC.  (mg/l)  —  1.0  -  CaCl, • 2 H 0 ADDED (gms) 2  —  1500  Sample Number  1  2  3  4  5  6  Time (hours)  0  h  1  2  4  6  10  10  10  10  10  10  25  10  25  25  25  25  5  5  5  5  5  5  Peak Area (Disc Units)  166  195  164  182  179  181  Sample Size (ngs)  0.131  0.155  0.128  0.145  0.141  .0.151  65.5  62.0  64.0  72.0  70.5  75.5  Volume  o f Water Extracted (mis)  Extract Volume (mis)  Volume Injected (uls)  Concentration i n Water (ugm/1)  ADSORPTION TEST NO. 2  HEOD CONC.  DDT CONC.  (ygm/1)  (ygm/1)  100  (mg/l)  VOLUME OF DISTILLED WATER (mis)  1.0  1500  BENTONITE CONC.  —  CaCl- • 2 H 0 ADDED (gms) 2  —  Sample Number  1  2  3  4  5  6  Time (hours)  0  h  1  2  4  6  10  10  10  10  10  10  25  25  25  25  25  25  Volume Injected (yls)  5  5  5  5  5  5  Peak Area (Disc Units)  198  204  200  211  223  225  0.17  0.172  85.0  86.0  Volume  o f Water Extracted (mis)  Extract Volume (mis)  Sample Size (ngs)  0.15  0.155  0.i52  Concentration i n Water (ygm/1)  75.0  77.5  76.0  0.16  80.0  ADSORPTION TEST NO. 3  HEOD CONC.  DDT CONC.  (ygm/1)  (ygm/1)  100  —  VOLUME OF DISTILLED WATER (mis)  BENTONITE CONC.  (mg/l)  1.0  CaCl- • 2 H 0 ADDED (gms) 2  1500  —  Sample Number  1  2  3  4  5  6  Time (hours)  0  h  1  2  4  6  Volume  o f Water Extracted (mis)  10  10  10  10  10  10  10  10  10  10  10  10  Volume Injected (yls)  5  5  5  5  5  5  Peak Area (Disc Units)  227  203  229  236  259  Extract Volume (mis)  272  Sample Size (ngs)  0.38  0.34  0.385  0.40  0.438  0.462  Concentration i n Water (ygm/1)  76.0  68.0  77.0  80.0  87.6  92.4  ADSORPTION TEST NO.  HEOD CONC.  DDT CONC.  (ugm/1)  (ygm/1)  100  4  (mg/l)  VOLUME OF DISTILLED WATER (mis)  10.0  1500  BENTONITE CONC.  —  CaCl- • 2 H 0 ADDED (gms) 2  —  Sample Number  1  2  3  4  5  6  Time (hours)  0  h  1  2  4  6  Volume  o f Water Extracted (mis)  10  10  10  10  10  10  25  25  25  25  25  25  Volume Injected (yls)  5  5  5  5  5  5  Peak Area (Disc Units)  160  169  177  161  180  163  0.116  0.130  0.118  58.0  65.0  59.0  Extract Volume (mis)  Sample Size (ngs)  Concentration i n Water (ygm/1)  0.115  0.122  57.5  61.0  0.129 64.5  ADSORPTION TEST NO. 5  HEOD CONC.  DDT CONC.  (ygm/1)  (ygm/1)  100  VOLUME OF DISTILLED WATER (mis)  BENTONITE CONC.  (mg/l)  10.0  —  CaCl- • 2 H 0 ADDED (gms) 2  1500  —  Sample Number  1  2  3  4  5  6  Time (hours)  0  h  1  2  4  6  10  10  10  10  10  10  25  25  25  25  25  25  5  5  5  5  5  5  146  159  153  169  167  180  0.106  0.117  0.113  0.125  0.124  53.0  58.5  56.5  62.5  62.0  Volume  o f Water Extracted (mis)  Extract Volume (mis)  Volume Injected .(yls)  Peak Area (Disc Units)  Sample Size (ngs)  Concentration i n Water (ygm/1)  0.13  65.0  ADSORPTION TEST NO. 6  DDT CONC.  HEOD CONC.  (ygm/1)  (ygm/1)  100  (mg/l)  VOLUME OF DISTILLED WATER (mis)  10.0  1500  BENTONITE CONC.  —  CaCl- • 2 H 0 ADDED (gms) 2  —  Sample Number  1  2  3  4  5  6  Time (hours)  0  h  1  2  4  6  Volume  o f Water Extracted (mis)  10  10  10  10  10  10  25  25  25  25  25  25  Volume Injected (yls)  5  5  5  5  5  5  Peak Area (Disc Units)  170  175  186  180  190  186  Sample Size (ngs)  0.11  0.113  0.12  0.117  0.122  0.12  Concentration i n Water (ygm/1)  55.0  56.5  60.0  58.0  61.0  60.0  Extract Volume (mis)  1  -  ,  ADSORPTION TEST NO. 7  HEOD CONC.  DDT CONC.  (ugm/1)  (Ugm/1)  100  VOLUME OF DISTILLED WATER (mis)  BENTONITE CONC.  (mg/l)  1.0  —  CaCl, • 2 H 0 ADDED (gms) 2  1500  2.205  Sample Number  1  2  3  4  5  6  Time (hours)  0  h  1  2  4  6  Volume  o f Water Extracted (mis)  10  10  10  10  10  10  25  25  25  25  25  25  Volume Injected (yls)  5  5  5  5  5  5  Peak Area (Disc Units)  201  218  219  221  227  223  Sample Size (ngs)  0.138  0.148  0.149  0.151  0.156  0.153  Concentration i n Water (ygm/1)  69.0  74.0  74.5  75.5  78.0  76.5  Extract Volume (mis)  ADSORPTION TEST NO. 8  HEOD CONC.  DDT CONC.  (ygm/1)  (ygm/1)  100  VOLUME OF DISTILLED WATER (mis)  BENTONITE CONC.  (mg/l)  1.0  —  CaCl  • 2 H0 ADDED (gms) 2  1500  2  2.205  Sample Number  1  2  3  4  5  6  Time (hours)  0  h  1  2  4  6  10  10  10  10  10  10  25  25  25  25  25  25  5  5  5  5  5  5  340  195  180  185  193  182  0.29 .  0.156  0.142  0.147  0.155  0.143  73.0  71.0  73.5  77.5  71.5  Volume  o f Water Extracted (mis)  Extract Volume (mis)  Volume Injected (yls)  Peak Area (Disc Units)  Sample Size (ngs)  Concentration i n Water (ygm/1)  145  ADSORPTION TEST NO. 9  HEOD CONC.  DDT CONC.  (ygm/1)  (ygm/1)  100  —  VOLUME OF DISTILLED WATER (mis)  BENTONITE CONC.  (mg/l)  CaCl, • 2 H 0 ADDED (gms) 2  1500  1.0  2.2Q5  Sample Number  1  2  3  4  5  6  Time (hours)  0  h  1  2  4  6  10  10  10  10  10  10  25  25  25  25  25  25  5  5  5  5  5  5  185  200  196  200  Sample Size (ngs)  0.152  0.164  0.16  0.164  0.168  0.16  Concentration i n Water (ygm/1)  76.0  82.0  84.0  80.0  Volume  o f Water Extracted (mis)  Extract Volume (mis)  Volume Injected (yls)  Peak Area (Disc Units)  82.0  80.0  212  196  ADSORPTION TEST NO. 10  HEOD CONC.  DDT CONC.  (ygm/1)  (ygm/1)  100  VOLUME OF DISTILLED WATER (mis)  BENTONITE CONC.  (mg/l)  2  1500  10.0  —  CaCl- • 2 H 0 ADDED (gms)  2.205  Sample Number  1  2  3  4  5  6  Time (hours)  0  h  1  2  4  6  Volume  o f Water Extracted (mis)  10  10  10  10  10  10  25  25  25  25  25  25  Volume Injected (yls)  5  5  5  5  5  ' 5  Peak Area (Disc Units)  222  231  203  207  210  211  Extract Volume (mis)  Sample Size (ngs)  0.129  0.131  0.115  0.119  0.12  0.12  Concentration i n Water (ygm/1)  64.5  65.5  57.5  59.5  60.0  60.0  ADSORPTION TEST NO. 11  HEOD CONC.  DDT CONC.  (ugm/1)  (ygm/1)  100  —  VOLUME OF DISTILLED WATER (mis)  BENTONITE CONC.  (mg/l)  CaCl  • 2 H0 ADDED (gms) 2  1500  10.0  2  2.205  Sample Number  1  2  3  4  5  6  Time (hours)  0  h  1  2  4  6  10  10  10  10  10  10  25  25  25  25  25  25  5  5  5  5  5  5  Peak Area (Disc Units)  138  136  115  136  142  150  Sample Size (ngs)  0.115  0.113  0^096  0.113  0.119  0.124  Concentration i n Water (ygm/1)  57.5  56.5  48.0  56.5  59.5  62.0  Volume  o f Water Extracted (mis)  Extract Volume (mis)  Volume Injected (yls)  ADSORPTION TEST NO. 12  HEOD CONC.  DDT CONC.  (ugm/1)  (ugm/1)  100  —  VOLUME OF DISTILLED WATER (mis)  BENTONITE CONC.  (mg/l)  CaCl- • 2 H 0 ADDED (gms) 2  1500  10.0  2.205  Sample Number  1  2  3  4  5  6  Time (hours)  0  h  1  2  4  6  10  10  10  10  10  10  25  25  25  25  25  25  Volume Injected (uls)  5  5  5  5  5  5  Peak Area (Disc Units)  209  210  209  215  217  217  Sample Size (ngs)  0.12  0.1205  0.12  0.123  Concentration i n Water (ugm/1)  60.0  62.25  60.0  61.5  Volume  o f Water Extracted (mis)  Extract Volume (mis)  Q.124  62.0  0.124  62.0  ADSORPTION TEST NO. 13  HEOD CONC.  DDT CONC.  (ygm/1)  (ygm/1)  100  —  VOLUME OF DISTILLED WATER (mis)  BENTONITE CONC.  (mg/l)  CaCl- • 2 H 0 ADDED (gms) 2  1500  1.0  —  Sample Number  1  2  3  4  5  6  Time (hours)  0  h  1  2  4  6  10  10  10  10  10  10  25  25  25  25  25  25  5  5  5  5  5  5  Peak Area (Disc Units)  45  27  23  23  32  25  Sample Size (ngs)  0.04  0.0238  0.02  0.02  0.02E  0.023!  Concentration i n Water (ygm/1)  20.0  11.9  10.0  10.0  10.0  8.4  Volume  o f Water Extracted (mis)  Extract Volume (mis)  Volume Injected (yls)  ADSORPTION TEST NO. 14  HEOD CONC.  (ygm/1)  (mg/l)  VOLUME OF DISTILLED WATER (mis)  100  1.0  1500  DDT CONC.  (ugm/1)  —  BENTONITE CONC.  CaCl  • 2 H0 ADDED (gms) 2  2  —  Sample Number  1  2  3  4  5  6  Time (hours)  6  h  1  2  4  6  10  10  10  10  10  10  10  10  10  10  10  10  5  5  5  5  5  5  158  150  144  120  91  67  0.129  0.115  0.111  0.092  0.084  0.052  25.8  23.0  22.2  18.4  16.8  10.4  Volume  o f Water Extracted (mis)  Extract Volume (mis)  Volume Injected (yls)  Peak Area (Disc Units)  Sample Size (ngs)  Concentration i n Water (ygm/1)  ADSORPTION TEST NO.  HEOD CONC.  DDT CONC.  (ygm/1)  5  VOLUME OF DISTILLED WATER (mis)  BENTONITE CONC.  (ygm/1)  (mg/l)  100  1.0  —  1  CaCl, • 2 H 0 ADDED (gms) 2  1500  —  Sample Number  1  2  3  4  5  6  Time (hours)  0  h  1  2  4  6  10  10  10  10  10  10  25  25  25  25  25  25  5  5  5  5  5  5  51  42  42  40  32  31  Volume  o f Water Extracted (mis)  Extract Volume (mis)  Volume Injected (yls)  Peak Area (Disc Units)  Sample Size (ngs)  Concentration i n Water (ygm/1)  0.04  20.0  0.0336  0.0336  16.8  16.8  0.316 15.8  0.024E  0.024  12.4  10.2  ADSORPTION TEST NO.  HEOD CONC.  DDT CONC.  (ygm/1)  (ygm/1)  VOLUME OF DISTILLED WATER (mis)  BENTONITE CONC.  (mg/l)  100  —  16  CaCl- • 2 H 0 ADDED (gms) 2  1500  10.0  —  Sample Number  1  2  3  4  5  6  Time (hours)  0  h  1  2  4  6  Volume  o f Water Extracted (mis)  10  10  10  10  10  10  10  10  10  10  10  10  5  5  5  5  5  5  Peak Area (Disc Units)  82  77  75  69  62  48  Sample Size (ngs)  0.063  0.059.  0.0575  0.0525  0.047  Concentration i n Water (ygm/1)  12.6  11.8  11.5  10.5  9.4  Extract Volume (mis)  Volume Injected (yls)  0.0365  7.3  ADSORPTION TEST NO. 17  HEOD CONC.  DDT CONC.  (ygm/1)  (ygm/1)  (mg/l)  CaCI- • 2 H 0 ADDED (gms) 2  1500  10.0  100  —  VOLUME OF DISTILLED WATER (mis)  BENTONITE CONC.  —  Sample Number  1  2  3  4  5  6  Time (hours)  0  h  1  2  4  6  10  10  10  10  10  10  25  25  25  25  25  25  5  5  5  5  5  5  33  27  28  23  26  25  0.0205  0.020E 0.0169  10.25  10.4  Volume  o f Water Extracted (mis)  Extract Volume (mis)  Volume Injected (yls)  Peak Area (Disc Units)  Sample Size (ngs)  Concentration i n Water (ygm/1)  0.025  12.5  8.45  0.018E 0.0184  9.25  9.2  ADSORPTION TEST NO.  HEOD CONC.  DDT CONC.  (Ugm/1)  (ygm/1)  VOLUME OF DISTILLED WATER (mis)  BENTONITE CONC.  (mg/l)  100  —  18  10.0  CaCl, • 2 H 0 ADDED (gms) 2  1500  —  Sample Number  1  2  3  4  5  6  Time (hours)  0  h  1  2  4  6  10  10  10  10  10  10  10  10  10  10  10  10  5  5  5  5  5  5  68  74  70  66  59  58  Volume  o f Water Extracted (mis)  Extract Volume (mis)  Volume Injected (yls)  Peak Area (Disc Units)  Sample Size (ngs)  Concentration i n Water (ygm/1)  0.055  0.059  0.056  0.053  0.047  11.0  11.8  11.2  10.6  9.4  0.0465  9.3  ADSORPTION TEST NO. 19  HEOD CONC.  DDT CONC.  (ygm/1)  (ygm/1)  (mg/l)  VOLUME OF DISTILLED WATER (mis)  1.0  1500  BENTONITE CONC.  100  —  CaCl- • 2 H 0 ADDED (gms) 2  2.205  Sample Number  1  2  3  4  5  6  Time (hours)  0  h  1  2  4  6  10  10  ' 10  10  10  10  10  10  10  10  10  10  Volume Injected (yls)  5  5  5  5  5  5  Peak Area (Disc Units)  163  142  100  114  61  51  Sample Size (ngs)  0.15  0.13  0.09  Concentration i n Water (ygm/1)  30.0  Volume  o f Water Extracted (mis)  Extract Volume (mis)  26.0  18.0  0.105  21.0  0.056!  0.047  11.3  9.4  ADSORPTION TEST NO. 20  HEOD CONC.  DDT CONC.  (ugm/1)  (ygm/1)  (mg/l)  100  1.0  —  VOLUME OF DISTILLED WATER (mis)  BENTONITE CONC.  CaCl  • 2 H0 ADDED (gms) 2  1500  2  2.205  Sample Number  1  2  3  4  5  6  Time (hours)  0  h  1  2  4  6  10  10  10  10  10  10  Extract Volume (mis)  25  25  25  25  25  25  Volume Injected (yls)  5  5  5  5  5  5  93  45  43  53  36  35  0.036  0.045  0.029  0.028  18.0  22.5  14.5  14.0  Volume  o f Water Extracted (mis)  Peak Area (Disc Units)  Sample Size (ngs)  Concentration i n Water (ygm/1)  0.079  39.5  0.038  19.0  ADSORPTION TEST NO. 21  HEOD CONC.  (ygm/1)  (mg/l)  VOLUME OF DISTILLED WATER (mis)  100  1.0  1500  DDT CONC.  (ygm/1)  —  BENTONITE CONC.  CaCl. • 2 H-0 ADDED (gms)  2.205  Sample Number  1  2  3  4  5  6  Time (hours)  0  h  1  2  4  6  10  10  10  10  10  10  Extract Volume (mis)  25  25  25  25  25  25  Volume Injected (yls)  5  5  5  5  5  5  79  48  47  39  28  Volume  o f Water Extracted (mis)  Peak Area (Disc Units)  Sample Size (ngs)  Concentration i n Water (ygm/1)  105 0.084  42.0  0.063  31.5  0.0385  0.0375  0.031  0.0215  19.25  18.75  15.5  12.75  ADSORPTION TEST NO. 22  HEOD CONC.  DDT CONC.  (pgm/1)  (ugm/1)  --  VOLUME OF DISTILLED WATER (mis)  BENTONITE CONC.  (mg/l)  10.0  100  CaCl- • 2 H 0 ADDED (gms) 2  1500  2.205  Sample Number  1  2  3  4  5  6  Time (hours)  0  h  1  2  4  6  10  10  10  10  10  10  25  25  25  25  25  25  5  5  5  5  5  5  46  43  34  25  25  22  0.024  0.024  12.0  12.0  Volume  o f Water Extracted (mis)  Extract Volume (mis)  Volume Injected (uls)  Peak Area (Disc Units)  Sample Size (ngs)  Concentration i n Water (ugm/1)  0.042  0.0395  21.0  19.75  0.0315  15.75  0.0195  9.75  ADSORPTION TEST NO. 23  HEOD CONC.  (ygm/1)  (mg/l)  VOLUME OF DISTILLED WATER (mis)  100  10.0  1500  DDT CONC.  (ygm/1)  —  BENTONITE CONC.  CaCl- • 2 H 0 ADDED (gms) 2  2.205  Sample Number  1  2  3  4  5  6  Time (hours)  0  h  1  2  4  6  Volume  o f Water Extracted (mis)  Extract Volume (mis)  Volume Injected (yls)  Peak Area (Disc Units)  Sample Size (ngs)  Concentration i n Water (ygm/1)  10  10  10  10  10  10  25  25  25  25  25  25  7  7  7  7  7  7  30  23  31  34  30  24  0.025  0.019  8.93  6.78  0.0262  9.36  0.0285  10.2  0.025  0.02  8.93  7.15  ADSORPTION TEST NO. 24  HEOD CONC.  DDT CONC.  (mg/l)  VOLUME OF DISTILLED WATER (mis)  10.0  1500  BENTONITE CONC. r  (ugm/1)  (ygm/1) 100  —  CaCl  • 2 H0 ADDED (gms) 2  2  2.205  Sample Number  1  2  3  4  5  6  Time (hours)  0  h  1  2  4  6  Volume  10  10  10  10  10  10  10  10  10  10  10  10  5  5  5  5  5  5  125  92  77  67  73  65  o f Water Extracted (mis)  Extract Volume (mis)  Volume Injected (yls)  Peak Area (Disc Units)  Sample Size (ngs)  Concentration i n Water (ygm/1)  0.101  0.073  0.062  0.053  0.058  0.052  20.2  14.6  12.4  10.6  11.6  10.4  DESORPTION TEST NO.  INITIAL  1  INITIAL  HEOD CONC.  DDT CONC.  (ygm/1)  (ygm/1)  100  INITIAL BENTONITE CONC. (mg/l)  1.0  —  Sample Number  1  2  3  4  5  6  Time (hours)  0  k  h  1  2  4  Volume o f Water Extracted (mis)  10  10  10  10  10  10  Extract Volume (mis)  10  10  10  10  10  10  5  5  5  5  5  5  94  102  101  118  106  103  0.053  0.057  0.057  0.067  0.061  0.058  11.4  11.4  13.4  12.2  11.6  Volume Injected (yls)  Peak Area (Disc Units)  Sample Size (ngs)  Concentration i n Water (ygm/1)  10.6  DESORPTION TEST NO. 2  INITIAL  INITIAL  INITIAL  HEOD CONC.  DDT CONC.  (ygm/1)  (ygm/1)  100  BENTONITE CONC. (mg/l)  1.0  —  Sample Number  1  2  3  4  5  6  Time (hours)  0  h  h  1  2  4  Volume o f Water Extracted (mis)  10  10  10  10  10  10  Extract Volume (mis)  10  10  10  10  10  10  5  5  5  5  5  5  115  116  120  124  122  0.073  '0.073  0.077  14.6  14.6  15.4  Volume Injected (yls)  Peak Area (Disc Units)  Sample Size (ngs)  Concentration i n Water (ygm/1)  0.08  16.0  0.078  15.6  124 . 0.08  16.0  DESORPTION TEST NO. 3  INITIAL  INITIAL  HEOD CONC.  DDT CONC.  (ugm/1)  (ugm/1)  100  —  INITIAL BENTONITE CONC. (mg/l)  1.0  Sample Number  1  2  3  4  5  6  Time (hours)  0  k  h  1  2  4  Volume of Water Extracted (mis)  10  10  10  10  10  10  Extract Volume (mis)  10  10  10  10  10  10  5  5  5  5  5  84  86  86  91  90  Volume Injected (yls)  Peak Area (Disc Units)  Sample Size  (ngs).  Concentration i n Water (ugm/1)  0.057  11.4  0.059  11.8  0.059  11.8  0.062  12.4  5  94  0.062  0.084  12.4  12.8  DESORPTION TEST NO. 4  INITIAL  INITIAL  HEOD CONC.  DDT CONC.  (ygm/1)  (ygm/1)  100  —  INITIAL BENTONITE CONC. (mg/l)  10.0  Sample Number  1  2  3  4  5  6  Time (hours)  0  h  h  1  2  4  Volume o f Water Extracted (mis)  10  10  10  10  10  10  Extract Volume (mis)  10  10  10  10  10  10  5  5  5  5  5  5  Peak Area (Disc Units)  146  163  159  167  169  175  Sample Size (ngs)  0.098'  0.112  0.108  0.114  0.115  0.12  Concentration i n Water (ygm/1)  19.8  22.4  21.6  22*3  23,0  Volume Injected (yls)  _  -  - - -.  -  -  24.0  I 1  DESORPTION TEST NO. 5  INITIAL  INITIAL  HEOD CONC.  DDT CONC.  (ygm/1)  (Ugm/1)  100  INITIAL BENTONITE CONC. (mg/l)  10.0  —  Sample Number  1  2  3  4  5  6  Time (hours)  0  h  h  1  2  4  Volume of Water Extracted (mis)  10  10  10  10  10  10  Extract Volume (mis)  10  10  10  10  10  10  5  5  5  5  5  5  65  154  150  165  171  165  0.038  0.102  0.098  0.11  0.115  0.11  20.4  19.6  22.0  23.0  22.0  Volume Injected (uls)  Peak Area (Disc Units)  Sample Size (ngs)  Concentration i n Water (ugm/1)  7.6  DESORPTION TEST NO. &  INITIAL  INITIAL  HEOD CONC.  DDT CONC.  (ygm/1)  (ygm/1)  100  INITIAL BENTONITE CONC. (mg/l)  10.0  —  Sample Number  1  2  3  4  5  6  Time (hours)  0  h  h  1  2  4  Volume o f Water Extracted (mis)  10  10  10  10  10  10  Extract Volume (mis)  10  10  10  10  10  10  5  5  5  5  5  5  120  176  193  205  199  196  0.102  0.111  0.117  0.114  0.113  20.4  22.2  23.4  22.8  22.6  Volume Injected (yls)  Peak Area (Disc Units)  Sample Size (ngs)  Concentration i n Water (ygm/1)  0.068  12.6  DESORPTION TEST NO. 7  INITIAL  INITIAL  HEOD CONC.  DDT CONC.  (ygm/1)  (ygm/1)  INITIAL BENTONITE CONC. (mg/l)  100  —  1.0  Sample Number  1  2  3  4  5  6  Time.(hours)  0  k  h  1  2  4  Volume o f Water Extracted (mis)  10  10  10  10  10  10  Extract Volume (mis)  10  10  10  10  10  10  Volume Injected (yls)  7  7  7  7  7  7  33  34  35  35  35  36  Peak Area (Disc Units)  Sample Size (ngs),  Concentration i n Water (ygm/1)  0.026  3.71  0.027  0.0275  0.0275  0.0275  0.0285  3.85  3.93  3.93  3.93  4.07  DESORPTION TEST NO. 8  INITIAL  INITIAL  HEOD CONC.  DDT CONC.  (Ugm/1)  (Ugm/1)  INITIAL BENTONITE CONC. (mg/l)  1.0  100  —  Sample Number  1  2  3  4  5  6  Time (hours)  0  h  h  1  2  4  Volume o f Water Extracted (mis)  10  10  10  10  10  10  Extract Volume (mis)  10  10  10  10  10  10  7  7  7  7  7  7  33  32  33  30  33  30 0.0232  Volume Injected (uls)  Peak Area (Disc Units)  Sample Size (ngs)  Concentration i n Water (ugm/1)  0.026  0.025  0.026  0.232  0.026  3.71  3.57  3.71  3.31  3.71  3.31  DESORPTION TEST NO. 9  INITIAL  INITIAL  INITIAL  HEOD CONC.  DDT CONC.  (ygm/1)  (ygm/1)  (mg/l)  100  1.0  —  BENTONITE CONC.  Sample Number  1  2  3  4  5  6  Time (hours)  0  h  h  1  2  4  Volume o f Water Extracted (mis)  10  10  10  10  10  10  Extract Volume (mis)  10  10  10  10  10  10  7  7  7  7  7  7  32  34  30  33  35  36  Volume Injected (yls)  Peak Area (Disc Units)  Sample Size (ngs)  0.025  0.027  0.0232  0.026  0.0275  0.0282  Concentration i n Water (ygm/1)  3.57  3.85  3.31  3.71  3.93  4.03  DESORPTION TEST NO. 10  INITIAL  INITIAL  HEOD CONC.  DDT CONC.  (ygm/1)  (ygm/1)  —  100  INITIAL BENTONITE CONC. (mg/l)  10.0  Sample Number  1  2  3  4  5  6  Time (hours)  0  \  h  1  2  4  Volume o f Water Extracted (mis)  10  10  10  10  10  10  Extract Volume (mis)  10  10  10  10  10  10  7  7  7  7  7  7  21  25  27  27  29  28  Volume Injected (yls)  Peak Area (Disc Units)  Sample Size (ngs)  o.oi6:  0.0195  0.021  0.021  Concentration i n Water (ygm/1)  2.71  2.78  3.0  3.0  0.0225  3.21  0.022  3.1  DESORPTION TEST NO. 11  INITIAL  INITIAL HEOD CONC.  DDT CONC.  (ygm/1)  (ygm/1)  INITIAL BENTONITE CONC. (mg/l)  10.0  100  —  Sample Number  1  2  3  4  5  6  Time (hours)  0  h  h  1  2  4  Volume of Water Extracted (mis)  10  10  10  10  10  10  Extract Volume (mis)  10  10  10  10  10  10  Volume Injected (yls)  7  7  7  7  7  7  25  28  23  22  20  Peak Area (Disc Units)  23 ; I  Sample Size (ngs)  0.017<  0.0195  0.0215  0.0179  0.017  0.0155  Concentration i n Water (ygm/1)  2.55  2.78  3.13  2.55  2.43  2.21  DESORPTION TEST NO. 12  INITIAL  INITIAL  HEOD CONC.  DDT CONC.  (ygm/1)  (ygm/1)  INITIAL BENTONITE CONC. (mg/l)  10.0  100  —  Sample Number  1  2  3  4  5  6  Time (hours)  0  h  h  1  2  4  Volume o f Water Extracted (mis)  10  10  10  10  10  10  Extract Volume (mis)  10  10  10  10  10  10  7  7  7  7  7  7  21  24  28  27  29  28  Volume Injected (yls)  Peak Area (Disc Units)  Sample Size (ngs)  Concentration i n Water (ygm/1)  0.0164  2.34  0.0187  0.022  0.021  0.0227  0.022  2.67  3.1  3.0  3.18  3.1  QUIESCENT REMOVAL TEST NO. 1  HEOD CONC. (ygm/1)  100  BENTONITE CONC.  DDT CONC. (ygm/1)  —  VOLUME OF DISTILLED WATER  (mg/l)  (ml)  1.0  1500  WEIGHT OF C a C l • 2H 0 ADDED 2  2  (gms)  2.205  Sample Number  1  2  3  4  5  6  7  8  Time (hours)  0  h  h  1  2  4  6  8  Volume of Water Extracted (mis)  10  10  10  10  10  10  10  10  Extracted Volume (mis)  25  25  25  25  25  25  10  10  5  5  5  5  5  5  5  5  Peak Area (Disc. Units)  253  262  253  250  248  261  368  360  Sample Size (ngs)  0.147  0.152  0.147  0.145  0.143  0.151  0.215  0.21  Concentration i n Water (ygm/1)  73,5  76.0  73.5  72.5  71.5  75.5  71.7  70.0  Volume Injected (yls)  QUIESCENT REMOVAL TEST NO. 2  HEOD CONC. (ugm/1)  100  BENTONITE CONC.  DDT CONC. (ygm/1)  VOLUME OF DISTILLED WATER  (mg/l)  (ml)  1.0  1500  —  WEIGHT OF C a C l • 2H 0 ADDED 2  2  (gms)  2.205  Sample Number  1  2  3  4  5  6  7  8  Time (hours)  0  h  h  1  2  4  6  8  Volume of Water Extracted (mis)  10  10  10  10  10  10  10  10  Extracted Volume (mis)  25  25  25  25  25  25  25  25  5  5  5  5  5  5  5  5  245  246  249  256  252  250  258  256  0.148  0.146  0.145  0.149  0.148  74.0  73.0  72.5  74.5  74.0  Volume Injected (yls)  Peak Area (Disc. Units)  Sample Size (ngs)  0.141  0.142,  0.144  Concentration i n Water (ygm/1)  70.5  71.0  72.0  QUIESCENT REMOVAL TEST NO. 3  HEOD CONC. (ygm/1)  100  BENTONITE CONC.  DDT CONC.  VOLUME OF DISTILLED WATER  2  (gms)  1500  1.0  —  2  (ml)  (mg/l)  (ygm/1)  WEIGHT OF C a C l • 2H 0 ADDED  2.205  Sample Number  1  2  3  4  5  6  7  8  Time (hours)  0  h  h  1  2  4  6  8  Volume of Water Extracted (mis)  10  10  10  10  10  10  10  10  Extracted Volume (mis)  25  25  25  25  25  25  25  25  5  5  5  5  5  5  5  5  255  260  258  262  251  251  248  250  0.1485  0.15  0.149  0.151  0.146  0.146  0.144  0.145  74.25  75.0  74.5  75.5  73.0  73.0  72.0  72.5  Volume Injected (yls)  Peak Area (Disc. Units)  Sample Size (ngs)  Concentration i n Water (ygm/1)  QUIESCENT REMOVAL TEST NO. 4  HEOD CONC. (ugm/1)  100  BENTONITE CONC.  DDT CONC.  WEIGHT OF C a C l • 2H 0 ADDED  VOLUME OF DISTILLED WATER  (ygm/1)  (mg/l)  (ml)  —  5.0  1500  2  2  (gms)  2.205  Sample Number  1  2  3  4  5  6  7  8  Time (hours)  0  h  h  1  2  4  6  8  Volume of Water Extracted (mis)  10  10  10  10  10  10  10  10  Extracted Volume (mis)  25  25  25  25  25  25  25  25  5  5  5  5  5  5  5  5  Peak Area (Disc. Units)  258  240  240  236  234  232  220  212  Sample Size (ngs)  0.149  0.138  0.138  0.136  0.134  0.132  0.126  0.122  Concentration i n Water (ygm/1)  74.5  69.0  69.0  68.0  67.0  66.0  63.0  61.0  Volume Injected (yls)  QUIESCENT REMOVAL TEST NO.  HEOD CONC. (ygm/1)  BENTONITE CONC.  DDT CONC. (ygm/1)  100  VOLUME OF DISTILLED WATER  2  (ml)  (mg/l)  2  (gms)  1500  5.0  —  WEIGHT OF C a C l • 2H 0 ADDED  2.205  Sample Number  1  2  3  4  5  6  7  8  Time (hours)  0  h  h  1  2  4  6  8  Volume of Water Extracted (mis)  10  10  10  10  10  10  10  10  Extracted Volume (mis)  25  25  25  25  25  25  25  25  5  5  5  5  5  5  5  5  238  238  239  238  236  224  218  210  0.137  0.137  0.138  0.137  0.136  0.125  0.121  68.5  68.5  69.0  68.5  68.0  62.5  60.5  Volume Injected (yls)  Peak Area (Disc. Units)  Sample Size (ngs)  Concentration i n Water (ygm/1)  0.13  65.0  QUIESCENT REMOVAL TEST NO. 6  HEOD CONC. (ygm/1)  BENTONITE CONC.  DDT CONC. (ygm/1)  VOLUME OF DISTILLED WATER  WEIGHT OF C a C l • 2H 0 ADDED 2  (ml)  (mg/l)  (gms)  1500 100  2  2.205  5.0  —  Sample Number  1  2  3  4  5  6  7  8  Time (hours)  0  h  h  1  2  4  6  8  Volume of Water Extracted (mis)  10  10  10  10  10  10  10  10  Extracted Volume (mis)  25  25  25  25  25  25  25  25  5  5  5  5  5  5  5  5  230  238  235  230  232  225  220  214  0.132  0.137  0.135  0.132  0.133  66.0  68.5  67.5  66.0  66.5  Volume Injected (yls)  Peak Area (Disc. Units)  Sample Size (ngs)  Concentration i n Water (ygm/1)  0.13  65.0  0.126  63.0  0.122  61.0  QUIESCENT REMOVAL TEST NO. 7  HEOD CONC. (ugm/1)  100  BENTONITE CONC.  DDT CONC. (ygm/1)  VOLUME OF DISTILLED WATER  (mg/l)  2  (ml)  2  (gms)  1500  10.0  —  WEIGHT OF C a C l • 2H 0 ADDED  2.205  Sample Number  1  2  3  4  5  6  7  8  Time (hours)  0  h  h  1  2  4  6  8  Volume of Water Extracted (mis)  10  10  10  10  10  10  10  10  Extracted Volume (mis)  25  25  25  25  25  25  25  25  4  4  4  4  4  4  4  4  186  183  193  180  169  171  168  170  0.106  0.098  0.104  0.095  0.09  0.098  0.096  0.098  66.3  61.2  65.0  59.4  49.0  48.0  49.0  Volume Injected (yls)  Peak Area (Disc. Units)  Sample Size (ngs)  Concentration i n Water (ygm/1)  56.3  QUIESCENT REMOVAL' TEST NO. 8  HEOD CONC. (ugm/1)  BENTONITE CONC.  DDT CONC. (ygm/1)  VOLUME OF DISTILLED WATER  WEIGHT OF C a C l • 2H 0 ADDED 2  (ml)  (mg/l)  (gms)  1500 100  2  2.205  10.0  —  Sample Number  1  2  3  4  5  6  7  8  Time (hours)  0  h  h  1  2  4  6  8  Volume of Water Extracted (mis)  10  10  10  10  10  10  10  10  Extracted Volume (mis)  25  25  25  25  25  25  25  25  4  4  5  5  5  5  5  5  252  172  184  190  186  184  180  177  0.145  0.098  0.105  0.109  0.106  0.105  0.103  0.101  90.5  61.2  52.5  54.5  53.0  52.5  51.5  50.5  Volume Injected (yls)  Peak Area (Disc. Units)  Sample Size (ngs)  Concentration i n Water (ygm/1)  QUIESCENT REMOVAL TEST NO.  HEOD CONC. (ygm/1)  9  BENTONITE CONC.  DDT CONC. (ygm/1)  VOLUME OF DISTILLED WATER  WEIGHT OF C a C l • 2H 0 ADDED 2  (ml)  (mg/l)  (gms)  1500 100  2  2.205  10.0  —  Sample Number  1  2  3  4  5  6  7  8  Time (hours)  0  k  h  1  2  4  6  8  Volume of Water Extracted (mis)  10  10  10  10  10  10  10  10  Extracted Volume (mis)  25  25  25  25  25  25  25  25  5  5  5  5  5  5  5  5  236  153  148  144  135  124  126  122  0.11  0.10  0.101  0.098  50.5  49.0  Volume Injected (yls)  Peak Area (Disc. Units)  Sample Size (ngs)  Concentration i n Water (ygm/1)  0.136  0.1245  68.0  62.25  0.12  60.0  0.117  58.5  55.0  50.0  QUIESCENT REMOVAL  T  HEOD CONC. (ygm/1)  —  E  S  T  N 0  «  1  0  BENTONITE CONC.  DDT CONC. (ygm/1)  VOLUME OF DISTILLED WATER  2  (ml)  (mg/l)  2  (gms)  1500  1.0  100  WEIGHT OF C a C l • 2H 0 ADDED  2.205  Sample Number  1  2  3  4  5  6  7  8  Time (hours)  0  h  h  1  2  4  6  8  Volume of Water Extracted (mis)  10  10  10  10  10  10  10  10  Extracted Volume (mis)  25  25  25  25  25  10  10  10  5  5  5  5  5  5  5  5  96  70  54  58  52  146  123  114  0.0535  0.048  0.132  0.113  0.105  26.75  24.0  26.4  22.6  21.0  Volume Injected (yls)  Peak Area (Disc. Units)  Sample Size (ngs)  Concentration i n Water (ygm/1)  0.086  0.064  43.0  32.0  0.05  25.0  QUIESCENT REMOVAL TEST NO. 11  HEOD CONC. (ygm/1)  BENTONITE CONC.  DDT CONC. (ygm/1)  VOLUME OF DISTILLED WATER  WEIGHT OF C a C l • 2H 0 ADDED 2  (ml)  (mg/l)  (gms)  1500 —  2  2.205  1.0  100  Sample Number  1  2  3  4  5  6  7  8  Time (hours)  0  h  h  1  2  4  6  8  Volume of Water Extracted (mis)  10  10  10  10  10  10  10  10  Extracted Volume (mis)  25  25  25  25  25  10  10  10  5  5  5  5  5  5  5  5  72  63  57  57  49  127  114  94  Volume Injected (yls)  Peak Area (Disc. Units)  Sample Size (ngs)  Concentration i n Water (ygm/1)  0.067  0.058  0.053  0.053  0.045  0.116  0.105  0.086  38.5  29.0  26.5  26.5  22.0  23.2  21.0  17.2  QUIESCENT REMOVAL TEST NO. 12  HEOD CONC. (ugm/1)  —  BENTONITE CONC.  DDT CONC. (ygm/1)  (mg/l)  100  1.0  VOLUME OF DISTILLED WATER  WEIGHT OF C a C l • 2H 0 ADDED 2  (ml)  2  (gms)  1500  2.205  Sample Number  1  2  3  4  5  6  7  8  Time (hours)  0  h  h  1  2  4  6  8  Volume of Water Extracted (mis)  10  10  10  10  10  10  10  10  Extracted Volume (mis)  25  25  25  25  25  25  25  25  5  5  5  5  5  5  5  5  85  72  65  60  57  50  54  0.04  0.043  Volume Injected (yls)  Peak Area (Disc. Units)  112  Sample Size (ngs)  0.091  Concentration i n Water (ygm/1)  45.5  0.068  0.057  0.052  0.048  0.045  34.0  28.5  26.0  24.0  22.5  20.0  21.5  QUIESCENT REMOVAL TEST NO. 13  HEOD CONC. (ygm/1)  BENTONITE CONC.  DDT CONC. (ygm/1)  VOLUME OF DISTILLED WATER  WEIGHT OF C a C l • 2H 0 ADDED 2  (ml)  (mg/l)  (gms)  1500 —  2  2.205  5.0  100  Sample Number  1  2  3  4  5  6  7  8  Time (hours)  0  k  h  1  2  4  6  8  Volume of Water Extracted (mis)  10  10  10  10  10  10  10  10  Extracted Volume (mis)  10  10  10  10  10  10  10  10  5  5  5  5  5  5  5  5  120  111  117  108  93  91  89  0.101  0.107  0.098  0.084  0.083  0.082  0.095  20.2  21.4  19.6  16.8  16.6  16.4  19.0  Volume Injected (yls)  Peak Area (Disc. Units)  Sample Size (ngs)  Concentration i n Water (ygm/1)  0.11  22.0  -  105  QUIESCENT REMOVAL TEST NO.  HEOD CONC. (ugm/1)  —  14  BENTONITE CONC.  DDT CONC. (Ugm/1)  VOLUME OF DISTILLED WATER  2  2.205  1500  5.0  2  (gms)  (ml)  (mg/l)  100  WEIGHT OF C a C l • 2H 0 ADDED  Sample Number  1  2  3  4  5  6  7  8  Time (hours)  0  h  h  1  2  4  6  8  Volume of Water Extracted (mis)  10  10  10  10  10  10  10  10  Extracted Volume (mis)  10  10  10  10  10  10  10  10  5  5  5  5  5  5  5  5  Peak Area (Disc. Units)  111  110  114  106  109  99  93  89  Sample Size (ngs)  0.101  0.10'  0.105  0.096  0.10  0.91  0.084  0.082  Concentration i n Water (ugm/1)  20.2  20.0  21.0  19.2  20.0  18.2  16.8  16.4  Volume Injected (yls)  QUIESCENT REMOVAL TEST NO. 15  HEOD CONC. (ygm/1)  BENTONITE CONC.  DDT CONC. (ygm/1)  (mg/l)  100  5.0  VOLUME OF DISTILLED WATER  WEIGHT OF C a C l • 2H 0 ADDED 2  (gms)  (ml)  2.205  1500 —  2  Sample Number  1  2  3  4  5  6  7  8  Time (hours)  0  h  h  1  2  4  6  8  Volume of Water Extracted (mis)  10  10  10  10  10  10  10  10  Extracted Volume (mis)  10  10  10  10  10  10  10  10  5  5  5  5  5  5  5  5  Peak Area (Disc. Units)  156  125  130  122  113  111  110  105  Sample Size (ngs)  0.128  0.101  0.104  0.099  0.092  0.088  0.086  Concentration i n Water (ygm/1)  25.6  20.2  20.8  19.8  18.4  Volume Injected (yls)  0.09  18.0  17.6  17.2  QUIESCENT REMOVAL TEST NO. 16  HEOD CONC. (ygm/1)  BENTONITE CONC.  DDT CONC. (ygm/1)  VOLUME OF DISTILLED WATER  WEIGHT OF C a C l • 2H 0 ADDED 2  (ml)  (mg/l)  (gms)  1500 —  2  2.205  10.0  100  Sample Number  1  2  3  4  5  6  7  8  Time (hours)  0  h  h  1  2  4  6  8  Volume of Water Extracted (mis)  10  10  10  10  10  10  10  10  Extracted Volume (mis)  25  25  25  25  25  10  10  10  5  5  5  5  5  5  5  5  31  25  28  28  23  56  57  59  0.0285  0.023  0.026  0.026  0.0215  14.25  11.5  13.0  13.0  10.75  Volume Injected (yls)  Peak Area (Disc. Units)  Sample Size (ngs)  Concentration i n Water (ygm/1)  0.0515  10.3  0.053  0.0521  10.6  10.42  QUIESCENT REMOVAL TEST NO.  HEOD CONC. (ygm/1)  DDT CONC. (ygm/1)  VOLUME OF DISTILLED WATER  WEIGHT OF C a C l • 2H 0 ADDED 2  (ml)  (mg/l)  (gms)  1500  10.0  2  2.205  Sample Number  1  2  3  4  5  6  7  8  Time (hours)  0  k  h  1  2  4  6  8  Volume of Water Extracted (mis)  10  10  10  10  10  10  10  10  Extracted Volume (mis)  25  25  25  25  25  25  25  25  5  5  5  5  5  5  5  5  42  41  40  36  35  32  29  31  Volume Injected (yls)  Peak Area (Disc. Units)  Sample Size (ngs)  |  BENTONITE CONC.  100  —  17  Concentration  i n Water (ygm/1)  0.0335  0.023  0.031  0.0285  0.028  16.75  16.5  15.5  14.25  14.0  0.0245\  12.25  0.023  0.024  11.5  12.0  QUIESCENT REMOVAL TEST NO. 18  HEOD CONC. (ugm/1)  —  BENTONITE CONC.  DDT CONC.  VOLUME OF DISTILLED WATER  (ugm/1)  (mg/l)  (ml)  100  10.0  1500  WEIGHT OF C a C l • 2H 0 ADDED 2  2  (gms)  2.205  Sample Number  1  2  3  4  5  6  7  8  Time (hours)  0  k  h  1  2  4  6  8  Volume of Water Extracted (mis)  10  10  10  10  10  10  10  10  Extracted Volume (mis)  25  25  25  25  10  10  10  10  5  5  5  5  5  5  5  5  35  32  28  30  75  68  60  57  Volume Injected (yls)  Peak Area (Disc. Units)  Sample Size (ngs)  0.0315  0.029  0.026  0.0275  Concentration i n Water (ygm/1)  15.75  14.5  13.0  12.75  0.068  13.6  0.063  0.055  0.053  12.6  11.0  10.6  APPENDIX F  SAMPLE CALCULATIONS  t  167  (a) Concentration of Insecticide i n Water A xV Cone. = - — i s v  (ygms/litre)  where A = sample s i z e i n nanograms; V  = volume of t o t a l extract ( y l s ) ;  V\ = volume of extract injected V  s  (yls);  = volume of water extracted (mis)  For Test #1, Sample No. 1 A = 0.131 ngs = 25,000 y l s  V V V  ±  s  = 5 yls = 10  (0.131) (25,000) c _ _ ._ Cone. = .—(5) (jo) = 65.5 ygm/1 l t r e  (b) C a l c u l a t i o n of I n s e c t i c i d e L e f t i n Solution A f t e r Removal of Water; Desorption Tests (i) For 1.0 gm/l Clay Concentration, f o r HEOD t e s t s 25, 26, 27: Amount of water l e f t = 53 mis Maximum concentration i n t h i s water (from adsorption tests)  = 80 ygms/litre  168  Amount of water i n Desorption tests = 1350 mis  maximum possible concentration due to d i l u t i o n =  . .. . i , c » =3.14 ygm/litre  ( i i ) For 10 gm/l Clay Concentration, f o r HEOD tests 28, 29, 30:  Amount o f water l e f t = 310 mis. Maximum concentration i n t h i s water (from desorption tests)  = 62 ygm/litre  Amount of water i n desorption t e s t (added a f t e r decanting)  = 1350 mis.  . . Maximum p o s s i b l e concentration due to d i l u t i o n =  .  . .  —1350  =  1  3  ,  8  Vqm/Htre  ( i i i ) For 1.0 gm/l Clay Concentration, f o r DDT tests 31, 32, 33: Amount of water l e f t = 53 mis. Maximum concentration i n t h i s water = 14 ygm/litre Amount of water i n desorption t e s t .*. Maximum possible concentration due to d i l u t i o n =  = 1350 mis (53)(14) 1  3  5  Q  = 0.55 ygms/litre  169  (iv) For 10.0 gm/l Clay Concentration, f o r DDT tests 34, 35, 36s  Amount o f water l e f t =310 mis Maximum concentration i n t h i s water = 10.5 ugm/litre Amount of water i n desorption t e s t  = 1350 mis  .*. Maximum possible concentration due -• - .. to d i l u t i o n =  (c) C a l c u l a t i o n of Amount o f CaCl,,  \ ———- • c  loll); tlU.S; lODU  .  ., .  =2.4 ygms/litre  Added  Gram Molecular Weight of C a C l  2  • 2H 0 = 147 gms 2  . Add 1.47 gms and b r i n g solution up t o one l i t r e by adding d i s t i l l e d water t o make s o l u t i o n 0.01 molar.  .". Add (1.47)(1.5) = 2.205 gms of C a C l • 2H 0 and bring s o l u t i o n up to 1.5 l i t r e s to make s o l u t i o n 0.01 Molar. 2  2  

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