Treatment and Disposal of Pesticide Wastes 9780841208582, 9780841210875, 0-8412-0858-1

Table of contents :
Title Page ......Page 1
Half Title Page ......Page 3
Copyright ......Page 4
ACS Symposium Series......Page 5
FOREWORD......Page 6
PREFACE......Page 7
INTRODUCTION......Page 9
Literature Cited......Page 10
PdftkEmptyString......Page 0
History of Disposal Regulation......Page 11
Current Disposal Practices......Page 13
EPA Guidance on Disposal......Page 14
RCRA/FIFRA......Page 16
FIFRA Regulatory Requirements......Page 17
Registration Guidelines......Page 18
Disposal Technologies and Data Requirements......Page 20
Literature Cited......Page 22
Background......Page 24
Generation/Transportation......Page 25
Management......Page 26
Current Activities......Page 27
Pesticide Use......Page 31
Nature and Handling of Wastes......Page 32
A System for Safe Disposal of Pesticide Wastes......Page 33
Summary and Current Status......Page 36
Acknowledgments......Page 38
Literature Cited......Page 40
4 Degradation of Pesticides in Controlled Water-Soil Systems......Page 41
Alachlor......Page 42
2,4-D Ester......Page 43
Description of System......Page 44
Extraction Procedures......Page 45
Soil and Liquid Analyses......Page 47
Degradation Summary......Page 60
Water Loss, pH and Temperature......Page 65
CONCLUSIONS......Page 68
LITERATURE CITED......Page 69
5 Pesticide Disposal Sites: Sampling and Analyses......Page 72
Description of Disposal Pits......Page 73
Extraction Procedures......Page 75
Separation and Detection Procedures......Page 77
Segregation......Page 78
Horticulture Pit......Page 81
Agronomy Pit......Page 90
Evidence of Degradation......Page 96
ACKNOWLEDGMENTS......Page 97
LITERATURE CITED......Page 98
6 Disposal of Pesticide Wastes in Lined Evaporation Beds......Page 99
Evaporation Bed Experimental Design......Page 100
Methods......Page 101
Results and Discussion......Page 104
Literature Cited......Page 118
7 On-Site Pesticide Disposal at Chemical Control Centers......Page 119
Sampling and Analysis......Page 121
Literature Cited......Page 125
Background......Page 127
Materials and Methods......Page 129
Results and Discussion......Page 136
Conclusions......Page 149
Literature Cited......Page 153
9 Treating Pesticide-Contaminated Wastewater Development and Evaluation of a System......Page 154
Literature Cited......Page 161
10 Long-Term Degradation Studies Massive Quantities of Phenoxy Herbicides in Test Grids, Field Plots, and Herbicide Storage Sites......Page 162
Herbicide Spray Equipment Test Grids......Page 163
Soil Incorporation/Biodegradation Plots......Page 166
Studies of Herbicide Storage Sites......Page 173
Discussion and Conclusions......Page 178
Literature Cited......Page 179
11 Incineration of Pesticide Wastes......Page 181
Pesticide Incineration......Page 182
RCRA Regulations......Page 185
Hazardous Waste Incineration......Page 186
Summary......Page 189
Literature Cited......Page 190
12 A Large Scale UV-Ozonation Degradation Unit Field Trials on Soil Pesticide Waste Disposal......Page 192
Methods and Materials......Page 193
Results and Discussion......Page 197
Literature Cited......Page 206
13 Reaction of Sodium Perborate with Organophosphorus Esters......Page 207
Results......Page 210
Discussion......Page 214
Literature Cited......Page 215
14 Abiotic Hydrolysis of Sorbed Pesticides......Page 216
Preliminary Considerations......Page 217
Experimental Considerations......Page 221
Results and Discussion......Page 223
Summary and Conclusions......Page 237
Literature Cited......Page 238
15 Investigation of Degradation Rates of Carbamate Pesticides Exploring a New Detoxification Method......Page 240
Experimental......Page 242
Results and Discussion......Page 244
Conclusion......Page 251
Literature Cited......Page 254
16 Pesticide Availability Influence of Sediment in a Simulated Aquatic Environment......Page 255
Methods and Materials......Page 256
Results and Discussion......Page 259
Literature Cited......Page 271
17 Organophosphorus Pesticide Volatilization Model Soil Pits and Evaporation Ponds......Page 272
Laboratory Model......Page 273
Two-Film Model for Volatilization of Organics from Water......Page 276
Experimental and Predicted Volatilization Kate Constants......Page 278
Volatilization from Water, Soil-Water, and Soil Systems......Page 280
Use of EXAMS with Model Disposal Systems......Page 283
Emulsifier Effect on Volatilization of Pesticides from Water......Page 285
Conclusions......Page 286
Literature Cited......Page 287
18 Potential Pesticide Contamination of Groundwater from Agricultural Uses......Page 289
Chemical Characteristics & Monitoring Data......Page 290
Mathematical Modeling......Page 301
Discussion......Page 304
Conclusions......Page 309
Field Conditions......Page 310
Legend of chemical names and abbreviations......Page 311
Literature Cited......Page 312
19 Transfer of Degradative Capabilities Bacillus megaterium to Bacillus subtilis by Plasmid Transfer Techniques......Page 318
Materials and Methods......Page 323
Results......Page 325
Discussion......Page 327
Acknowledgments......Page 330
Literature Cited......Page 331
20 Degradation of High Concentrations of a Phosphorothioic Ester by Hydrolase......Page 333
METHODS......Page 334
Stability of Parathion Hydrolase......Page 337
Degradation of Diazinon in Greenhouse Soil by Parathion Hydrolase......Page 340
CONCLUSIONS AND SUMMARY......Page 341
Literature Cited......Page 342
Author Index......Page 343
A......Page 344
B ......Page 345
C ......Page 346
D ......Page 347
E ......Page 348
H ......Page 349
L ......Page 350
N ......Page 351
P ......Page 352
Q ......Page 353
S ......Page 354
T ......Page 355
W ......Page 356
Z ......Page 357

Citation preview

Treatment and Disposal of Pesticide Wastes

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

ACS SYMPOSIUM SERIES 259

Treatment and Disposal of Pesticide Wastes Raymond F. Krueger, EDITOR Environmental Protection Agency

James N. Seiber, EDITOR University of California, Davis

Based on a symposium sponsored by the Division of Pesticide Chemistry at the 186th Meeting of the American Chemical Society, Washington, D.C., August 28-September 2, 1983

American Chemical Society, Washington, D.C. 1984

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

Library of Congress Cataloging in Publication Data

Treatment and disposal of pesticide wastes. (ACS symposium series, ISSN 0097-6156; 259) Includes bibliographies and indexes. 1. Pesticides industry—Waste disposal—Congresses. I. Krueger, Raymond F. II. Seiber, James N., 1940.III. American Chemica Pesticide Chemistry. TD899.P37T74 1984 ISBN 0-8412-0858-1

668'.65

84-12327

Copyright © 1984 American Chemical Society All Rights Reserved. The appearance of the code at the bottom of the first page of each chapter in this volume indicates the copyright owner's consent that reprographic copies of the chapter may be made for personal or internal use or for the personal or internal use of specific clients. This consent is given on the condition, however, that the copier pay the stated per copy fee through the Copyright Clearance Center, Inc., 21 Congress Street, Salem, MA 01970, for copying beyond that permitted by Sections 107 or 108 of the U.S. Copyright Law. This consent does not extend to copying or transmission by any means—graphic or electronic—for any other purpose, such as for general distribution, for advertising or promotional purposes, for creating a new collective work, for resale, or for information storage and retrieval systems. The copying fee for each chapter is indicated in the code at the bottom of thefirstpage of the chapter. The citation of trade names and/or names of manufacturers in this publication is not to be construed as an endorsement or as approval by ACS of the commercial products or services referenced herein; nor should the mere reference herein to any drawing, specification, chemical process, or other data be regarded as a license or as a conveyance of any right or permission, to the holder, reader, or any other person or corporation, to manufacture, reproduce, use, or sell any patented invention or copyrighted work that may in any way be related thereto. Registered names, trademarks, etc., used in this publication, even without specific indication thereof, are not to be considered unprotected by law. PRINTED IN THE UNITED STATES OF AMERICA

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

ACS Symposium Series M. Joan Comstock, Series Editor Advisory Robert Baker U.S. Geological Survey

Geoffrey D. Parfitt Carnegie-Mellon University

Martin L . Gorbaty Exxon Research and Engineering Co.

Theodore Provder Glidden Coatings and Resins

Herbert D. Kaesz University of California— Los Angeles

James C . Randall Phillips Petroleum Company

Rudolph J. Marcus Office of Naval Research

Charles N. Satterfield Massachusetts Institute of Technology

Marvin Margoshes Technicon Instruments Corporation

Dennis Schuetzle Ford Motor Company Research Laboratory

Donald E . Moreland U S D A , Agricultural Research Service W. H . Norton J. T. Baker Chemical Company Robert Ory U S D A , Southern Regional Research Center

Davis L . Temple, Jr. Mead Johnson Charles S. Tuesday General Motors Research Laboratory C. Grant Willson I B M Research Department

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

FOREWORD The ACS SYMPOSIUM SERIES was founded in 1974 to provide

a medium for publishing symposia quickly in book form. The format of the Series parallels that of the continuing ADVANCES IN CHEMISTRY SERIE papers are not typese mitted by the authors in camera-ready form. Papers are reviewed under the supervision of the Editors with the assistance of the Series Advisory Board and are selected to maintain the integrity of the symposia; however, verbatim reproductions of previously published papers are not accepted. Both reviews and reports of research are acceptable since symposia may embrace both types of presentation.

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

PREFACE IMPROPER HANDLING A N D DISPOSAL of chemical wastes represents a serious problem in the United States and in other parts of the world. Although the recent spotlight has been on the management of hazardous industrial wastes and the paucity of properly designed facilities for their treatment, storage, or disposal, a keen interest also exists in developing better disposal strategies for pesticide containing wastes. Continuing emphasis on greater crop production and the resulting need to control pests, often generally accomplished by the use of pesticide chemicals in large quantities, has created a problem o areas affected, and potentia for the development of improved waste disposal practices. Several studies have been conducted during the last five or six years that bear directly on pesticide waste disposal, but many have yet to be published in the open literature. Some of these studies were just being initiated when ACS SYMPOSIUM SERIES N O . 73 was published. In addition, federal requirements for pesticide disposal under the Resource Conservation and Recovery Act (RCRA) and the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) as amended have recently been modified and/or clarified to provide more explicit rules and guidance to those with waste disposal needs. For these reasons, a symposium was held by the American Chemical Society that brought together papers on the chemical, biological, and physical methods of disposal; the basic principles underlying each of these methods; the analytical and modeling approaches applicable to waste disposal conditions; and the EPA regulatory viewpoint on safe disposal. This symposium was the basis for this volume. Special thanks go to the co-organizers of the symposium, D. Kaufmann, J . Plimmer, and D. Severn; to P. Roberts, who, through the ACS Division of Environmental Chemistry, cosponsored the symposium; and to the ACS Division of Pesticide Chemistry, which sponsored the symposium, arranged the scheduling, and provided some funding. R A Y M O N D F. K R U E G E R

Environmental Protection Agency—Washington J A M E S N. SEIBER

University of California, Davis May

3,

1984 ix

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

INTRODUCTION AT SEVERAL STAGES in the lifetime of a given pesticide, wastes are generated that need attention. These stages include manufacturing; testing; formulation; transport; field mixing and application; the recall of cancelled, suspended, or outdated products; and the enormous numbers of empty containers left after use of the chemicals. Although none of these stages commonly generate large quantities of waste (except for the empty containers) the total amount of wast generated th pesticide' useful lifetim can be substantial. The pesticide wastewaters generated by commercial aerial applicators is just one example of the magnitude of the disposal problem. Commercial aerial applicators account for roughly half of all pesticide applications in the United States. Every day, each sprayplane can generate 30 gallons of aqueous rinsate, principally from washing residual material from the hoppers, containing approximately 500 ppm of residue (1,2)—the simple act of washing the exterior of the aircraft makes a contribution. By combining these figures with the number of aircraft involved in commercial spraying (6,000) one may calculate a potential volume of 60 million gallons containing 120,000 kg of chemical residue each year from this single source. Although often these solutions are legally used as spray diluent, a substantial proportion may be considered as waste in need of disposal. The disposal of these pesticide-containing wastewaters varies considerably in terms of legal compliance and safety. In California, for example, more than 100 haphazard wastewater dumpsites are believed to exist in the Central Valley; a few of these sites have been highlighted by recent adverse publicity. Wells at applicators' facilities have been found to be contaminated as a result of the mismanagement of these wastes. On the other hand, the University of California has maintained soil pit disposal beds at its field stations just for handling pesticide wastewater, with generally favorable results. Comparable results have been experienced by others using similar facilities. According to a recent survey of commercial aerial applicators across the U.S., a large number wanted to improve their wastewater systems, if acceptable methods were made known to them (5). This one area—disposal of wastewater by commercial applicators— demonstrates the need that exists not only for better disposal strategies, but

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In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

also for the more effective dissemination of information relating to them. The chapters in this book provide a source of information to attain these goals.

Literature Cited 1. "Disposal of Dilute Pesticide Solutions," SCS Engineers, 1979, NTIS Report PB-297 985. 2. Whittaker, Κ. F.; Nye, J. C.; Wukash, R. F.; Squires, R. G.; York, N. C.; and Kazimier, H. A. "Collection and Treatment of Wastewater Generated by Pesticide Applicators." Unpublished report, Purdue University, West Lafayette, Indiana, 1979. 3. Craigmill, A. C.; and Seiber, J. N. Unpublished data.

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In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

1 Regulation of Pesticide Disposal RAYMOND F. KRUEGER and DAVID J. SEVERN Office of Pesticide Programs, Environmental Protection Agency, Washington,DC20460

One result of the annual use of millions of pounds of pesticide chemicals each year is the production of numerous empty containers and other pesticide wastes. When th tics of the man used are taken into consideration, the possibility of injury to man and the environment due to improper disposal can be considerable. Information on improved disposal technologies has been published to provide better management of pesticide wastes but f a l l short in that they do not cover all wastes or disposal methods. Regulations that are intended to control improper disposal have been promulgated under FIFRA and RCRA which, in general, are intended to control disposal methods in common use today such as land disposal, incineration, open burning, certain physical/chemical methods, and some systems that u t i l i z e biological degradation. The RCRA regulations also provide standards for construction and operation of certain disposal f a c i l i t i e s . The regulations do not provide specific information to the pesticide user as to how to dispose of his wastes. One way to make such information readily available is to put it on the label of each pesticide product. Guidelines that establish data requirements to register certain pesticides have been published. Similar guidelines for disposal statements are being prepared the Environmental Protection Agency. H i s t o r y of D i s p o s a l Regulation In the l a t e 1960's, the seriousness of the hazard to human h e a l t h and the environment r e s u l t i n g from mismanagement of p e s t i c i d e wastes i n p a r t i c u l a r and hazardous wastes i n general became inThis chapter not subject to U.S. copyright. Published 1984, American Chemical Society

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

4

T R E A T M E N T A N D D I S P O S A L OF PESTICIDE WASTES

créasingly c l e a r . As a part of t h i s general awareness, and as the use of p e s t i c i d e s continued to grow, r e s u l t i n g i n more and more empty containers and other wastes to be disposed of, the problem of p e s t i c i d e waste d i s p o s a l became a point of major concern. This focus of i n t e r e s t was heightened by an increase i n documented cases of p e s t i c i d e d i s p o s a l mismanagement such as i n j u r i e s to c h i l d r e n p l a y i n g with empty p e s t i c i d e containers or f i s h k i l l s r e s u l t i n g from s o - c a l l e d empty containers being c a r e l e s s l y dumped i n t o streams or ponds In 1972 Congress enacted the Federal Environmental P e s t i c i d e C o n t r o l Act (FEPCA) which amended the Federal I n s e c t i c i d e , Fungicide and Rodenticide Act (FIFRA) to i n c l u d e , among other a d d i t i o n s , a t t e n t i o n to the p e s t i c i d e d i s p o s a l problem. Specifi c a l l y , Section 19 was added which says, "The Administrator s h a l l . . . e s t a b l i s h procedures and r e g u l a t i o n s f o r the d i s p o s a l or storage of packages and or storage of excess amount convenient l o c a t i o n s f o r safe d i s p o s a l a p e s t i c i d e the r e g i s t r a t i o n of which i s cancelled under s e c t i o n 6(c) i f requested by the owner of the p e s t i c i d e . " Section 19 was f u r t h e r modified i n 1978 to r e q u i r e information on d i s p o s a l to accompany a l l c a n c e l l a t i o n orders· On May 1, 1974, i n response to the mandate f o r procedures and r e g u l a t i o n s , the Agency published i n the Federal R e g i s t e r , " P e s t i c i d e s and P e s t i c i d e Containers, Regulations f o r the Acceptance and Recommended Procedures f o r Disposal and Storage of P e s t i c i d e s and P e s t i c i d e Containers" (40 CFR 165) (2). The Regulatory p o r t i o n makes up a r e l a t i v e l y small part of the t o t a l package, p r e s c r i b i n g the process owners of p e s t i c i d e s the r e g i s t r a t i o n s of which have been suspended and c a n c e l l e d , must f o l l o w i n order f o r the EPA to accept the products that q u a l i f y f o r d i s p o s a l . The remaining parts of the May 1, 1974, p u b l i c a t i o n provide general guidance on d i s p o s a l of p e s t i c i d e s and of empty containers. These are recommendations only and have no f o r c e or e f f e c t of law. The basic o b j e c t i v e s of the p u b l i c a t i o n were to meet the requirements of the law, to provide agency p o l i c y on p e s t i c i d e d i s p o s a l and to give guidance to the s t a t e s where none had e x i s t e d before. Another piece of l e g i s l a t i o n having impact on the hazardous waste problem i s the Resource Conservation and Recovery Act (RCRA). Passage of t h i s act i n 1976 was stimulated by s e v e r a l episodes of severe mismanagement of hazardous wastes that received c o n s i d e r able a t t e n t i o n i n the news media. RCRA i s intended to provide c o n t r o l over management of hazardous wastes from point of generat i o n , through transport and to f i n a l treatment, storage or d i s posal. This "cradle-to-grave" coverage has had an impact on pesticide disposal a c t i v i t i e s . However, as w i l l be explained l a t e r , the r e g u l a t i o n s promulgated under RCRA do not cover a l l pesticides.

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

1.

KRUEGER AND

Current

SEVERN

Disposal

Regulation of Pesticide Disposal

5

Practices

P e s t i c i d e s have been used i n large q u a n t i t i e s f o r many years and during that time the wastes that have been generated were d i s posed of i n various ways. Past p r a c t i c e s have not n e c e s s a r i l y been s a t i s f a c t o r y , as p r e v i o u s l y noted; however, i t i s a l s o true that some of the d i s p o s a l methods that were used f i f t y years ago are s t i l l i n use today. According to a USDA survey done i n 1972 ( 3 ) , i n i t i a l d i s p o s i t i o n of empty p e s t i c i d e containers was done as f o l l o w s : Returned to dealer Burned Buried P r i v a t e Dump Comme r c i a Left i n f i e l L e f t where sprayer f i l l e d Retained Other

3.1% 49.2% 5.8% 18.9%

8.4% 11.0% 1.6% 100.0%

The method of container d i s p o s a l given does not mean f i n a l " r e s t ing p l a c e " i n the environment of any o f the r e s i d u a l m a t e r i a l s t i l l i n the c o n t a i n e r . I t only i n d i c a t e s what farmers d i d with the container i n i t i a l l y . F i e l d surveys conducted as a part of an economic a n a l y s i s of p e s t i c i d e d i s p o s a l i n C a l i f o r n i a , Iowa, New York and M i s s i s s i p p i (4) showed a f a i r l y c o n s i s t e n t p a t t e r n . In C a l i f o r n i a , combustible c o n t a i n e r s , paper, p l a s t i c , e t c . , were g e n e r a l l y burned o n - s i t e . Metal and glass containers were disposed of i n sanitary l a n d f i l l s . Rinsing of empty c o n t a i n e r s , which i s required under some circumstances, was found to be a common p r a c t i c e . A s i m i l a r p a t t e r n was found i n Iowa and New York. M i s s i s s i p p i d i f f e r e d only i n that the s t a t e operates a r u r a l c o l l e c t i o n system. Trash c o l l e c t i o n containers are p o s i t i o n e d a t s t r a t e g i c l o c a t i o n s to accept empty c o n t a i n e r s . The contents a r e p e r i o d i c a l l y c o l l e c t e d and d e l i v e r e d to s a n i t a r y l a n d f i l l s that have been s p e c i a l l y designated by the State Health Department. Farmers a r e urged to r i n s e a l l containers p r i o r to p u t t i n g them i n t o the c o l l e c t i o n system f o r d i s p o s a l . The study a l s o noted that p e s t i c i d e s are handled i n bulk or i n 55 g a l l o n drums more f r e q u e n t l y i n the South than i n other parts of the country. The empty 55 g a l l o n drums a r e g e n e r a l l y made a v a i l a b l e to a drum r e c o n d i t i o n e r who c o l l e c t s them a t regular i n t e r v a l s . As a p r a c t i c a l matter, d i s p o s a l i s t i e d c l o s e l y with economics. For example, empty 55 g a l l o n drums have value to drum r e c o n d i t i o n e r s who f r e q u e n t l y seek them out to r e c o n d i t i o n f o r reuse. A l s o , during the mid-1970's when the p r i c e of scrap s t e e l

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

T R E A T M E N T A N D D I S P O S A L OF PESTICIDE WASTES

6

soared to unusual heights, empty f i v e g a l l o n cans were c o l l e c t e d and s o l d f o r scrap. When the p r i c e of scrap s t e e l dropped, the p r a c t i c e ended. In one case, about a quarter of a m i l l i o n cans that had been c o l l e c t e d f o r scrap were abandoned. The p i l e stood f o r s e v e r a l years as a monument to the volume of p e s t i c i d e s used i n that area. Although "high-tech" s o l u t i o n s to d i s p o s a l are r e a d i l y a v a i l a b l e they are not put to use because of the cost f a c t o r . The more common d i s p o s a l methods are those that have been with us for some time. EPA

Guidance on

Disposal

EPA i s looked to f o r guidance i n the f i e l d of p e s t i c i d e d i s p o s a l ; however, i n the past a low p r i o r i t y was g e n e r a l l y assigned to development of waste managemen resources were a l l o c a t e technologies. To be required to spend money to throw something away i s not an acceptable s i t u a t i o n . Thus users of p e s t i c i d e s are i n c l i n e d to look f o r inexpensive ways of g e t t i n g r i d of p e s t i c i d e wastes. Strategies f o r waste management do e x i s t , but are often too expensive to be r e a d i l y accepted. Simple, inexpens i v e d i s p o s a l systems are not g e n e r a l l y a v a i l a b l e , l a r g e l y because there i s no one method that can be s a f e l y employed i n every situation. The complexity of choosing a d i s p o s a l method or providing safe guidance f o r the d i s p o s a l of a p a r t i c u l a r product becomes apparent when some of the f a c t o r s that must be considered i n evaluating a d i s p o s a l a c t i o n are l i s t e d : -Chemical, p h y s i c a l , b i o l o g i c a l and t o x i c o l o g i c a l c h a r a c t e r i s t i c s of the formulated products ; -Composition, c o n c e n t r a t i o n and q u a n t i t y of the waste; - S i z e , composition and numbers of waste c o n t a i n e r s ; -Geographic l o c a t i o n of the wastes; - A v a i l a b i l i t y , u t i l i t y and r e l a t i v e costs of d i s p o s a l methods and f a c i l i t i e s ; -Technical and economic f e a s i b i l i t y of r e c y c l i n g the wastes; - A t t i t u d e of the p e s t i c i d e i n d u s t r y , u s e r , and the general p u b l i c concerning waste d i s p o s a l ; -State r e g u l a t o r y requirements that a f f e c t the proposed d i s posal a c t i o n , such as d e p o s i t / r e t u r n laws. Given t h i s complex maze of information needs, the EPA i s expected to provide guidance on d i s p o s a l of p e s t i c i d e wastes i n a l l parts of the c o n t i n e n t a l United States as well as i n other parts of the world. This has created a serious challenge.

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

1.

KRUEGER A N D SEVERN

Regulation of Pesticide Disposal

1

D i f f e r e n t options f o r g e t t i n g d i s p o s a l information to the p e s t i c i d e user have been t r i e d . For example, a number of manuals were published to provide advice on s p e c i f i c d i s p o s a l problems. These were intended to provide "how-to" information to the people i n the f i e l d who advise and r e g u l a t e p e s t i c i d e users. Each made a d e f i n i t e c o n t r i b u t i o n , but information gaps remained. "Guidelines f o r the D i s p o s a l of Small Quantities of Unused P e s t i c i d e s " (5), published i n 1975, was and EPA sponsored study by Midwest Research I n s t i t u t e . Most of the p e s t i c i d e s that were i n common use at the time were reviewed and grouped by chemical c l a s s . The report gave d i s p o s a l technologies that were described i n the l i t e r a t u r e . Although the report brought together a wealth of i n f o r m a t i o n on chemical c h a r a c t e r i s t i c s such as t o x i c i t y , s o l u b i l i t y , and v o l a t i l i t y a c t u a l d i s p o s a l advice was l i m i t e d Another p u b l i c a t i o n Common Chemical Methods This report evaluated 20 common p e s t i c i d e s and concluded that only 7 could be disposed of by a l k a l i and/or acid h y d r o l y s i s . A d e t a i l e d procedure f o r d i s p o s a l by h y d r o l y s i s of the s p e c i f i c p e s t i c i d e s was a l s o given. However, again, the information was of l i m i t e d u t i l i t y . A follow-up report covered another f o r t y pesticides (7)· An EPA r e p o r t "Disposal of D i l u t e P e s t i c i d e S o l u t i o n s " (8) summarized technologies used i n d i s p o s a l of such wastes. Another study e n t i t l e d "Economic A n a l y s i s of P e s t i c i d e Disposal Methods" (4) evaluated commonly used d i s p o s a l systems i n terms of c o s t . L o c a l , r e g i o n a l and statewide c o l l e c t i o n and d i s p o s a l s t r a t e g i e s were a l s o considered. Although each of these reports c o n t a i n v a l u a b l e information, they f a l l short of the target of p r o v i d i n g adequate information to p e s t i c i d e r e g u l a t o r s and users to draw upon i n day-today o p e r a t i o n s . Another approach to developing information was to study s p e c i f i c technologies with an eye toward development of s e l e c t e d d i s p o s a l methods. Some of the systems that were studied or are being s t u d i e d i n c l u d e i n c i n e r a t i o n , a c a t a l y t i c d e c h l o r i n a t i o n system u t i l i z i n g n i c k e l boride, ozone/UV r a d i a t i o n , and microwave plasma d e s t r u c t i o n . A summary of the research being done at the time was published i n August 1978 under the t i t l e "State of the Art Report: P e s t i c i d e Disposal Research" ( 9 ) . While much of t h i s work has produced needed research information, the problem of making p r a c t i c a l information a v a i l a b l e to the user remains. At the same time, an i n c r e a s i n g p u b l i c awareness of the problem was f o r c i n g a d e c i s i o n as to how the r e s p o n s i b i l i t y f o r p r o v i d i n g d i s p o s a l information would be handled.

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

8

T R E A T M E N T A N D DISPOSAL O F PESTICIDE WASTES

RCRA/FIFRA Although r e g u l a t i o n s covering broad areas of hazardous waste treatment, storage and d i s p o s a l have been promulgated, the d i s posal of p e s t i c i d e wastes i s not t o t a l l y under RCRA c o n t r o l . There are s e v e r a l reasons f o r t h i s . Under RCRA, p e s t i c i d e wastes are treated as any another waste and many f a i l to q u a l i f y as hazardous under the standards s e t f o r t h i n the r e g u l a t i o n s . This could be due to a combination of s m a l l amounts and low t o x i c i t y . For example, 2,4-D or DDT wastes i n q u a n t i t i e s of l e s s that 1,000 kilograms per month would not be regulated under RCRA. P e s t i c i d e products r e g i s t e r e d f o r household use are simply not addressed by RCRA and are t h e r e f o r e not r e g u l a t e d . Empty c o n t a i n e r s a r e not regulated as hazardous wastes" under RCRA; however, f o r c e r t a i n h i g h l y t o x i c wastes, i n c l u d i n g some p e s t i c i d e s , the c o n t a i n e r must be t r i p l e r i n s e d ( o i t i s considered "empty t i o n s (40 CFR 261.7). A l s o , i n order to reduce the enormous r e g u l a t o r y workload promised by the burden of e n f o r c i n g the r e g u l a t i o n s , a s p e c i a l exemption f o r farmers was w r i t t e n i n t o the r e g u l a t i o n s (40 CFR 262.51). This exemption provides that a farmer who t r i p l e r i n s e s h i s empty containers and disposes of them on h i s own property w i l l be exempt from the requirements of RCRA. Commercial a p p l i c a t o r s do not enjoy such an exemption. lf

Given the complexity of the problem of s e l e c t i n g a s a f e , e f f e c t i v e waste d i s p o s a l s t r a t e g y from the r e l a t i v e l y s o p h i s t i cated array o f d i s p o s a l systems that a r e a v a i l a b l e , and g i v e n the RCRA farmer's exemption, there needs to be a way of providing d i s p o s a l i n f o r m a t i o n d i r e c t l y to the p e s t i c i d e user. One such method would be to put i t on the l a b e l . Why put i t on the l a b e l ? One reason i s that i t would make compliance with the requirements of the d i s p o s a l statement mandat o r y . Section 12 ( a ) ( 2 ) (G) o f FIFRA says i t i s unlawful to use any p e s t i c i d e i n a manner i n c o n s i s t e n t with i t s l a b e l i n g , and d i s p o s a l has been determined to be part of the use process. This means that the a l a b e l d i s p o s a l statement would be, i n e f f e c t , a r e g u l a t i o n . Another reason i s that the d i s p o s a l d i r e c t i o n s can be t a i l o r e d to f i t the e n t i r e package, the c o n t a i n e r , the chemic a l i t contains, and the s i t e and mode of use. An appropriate d i s p o s a l statement can be extremely important as one p e s t i c i d e manufacturer ( r e g i s t r a n t ) found out. There i s a s t o r y c i r c u l a t e d i n EPA concerning the r e g i s t r a n t who submitted a s p e c i a l l a b e l f o r a p p r o v a l . The comments contained i n the response from EPA g r a n t i n g approval advised the r e g i s t r a n t to i n c l u d e a statement on the l a b e l to provide guidance f o r d i s p o s a l of the empty cont a i n e r which read: "Crush and bury, do not re-use". The r e g i s t r a n t was heard to complain that he had intended to use the l a b e l on a r a i l r o a d tank c a r .

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

1.

KRUEGER A N D SEVERN

The Label Statement and

Regulation of Pesticide Disposal

9

Labeling

Placing the d i s p o s a l statement on the l a b e l means that development of the l a b e l statement becomes the r e s p o n s i b i l i t y of the r e g i s t r a n t who created the product i n the f i r s t place. Given h i s knowledge of the c h a r a c t e r i s t i c s of the chemical formulation, he i s i n the best p o s i t i o n to provide an environmentally s a f e d i s posal method. Indeed, he i s o f f e r e d the opportunity to use a broad range of s o p h i s t i c a t e d technologies rather than the f a m i l i a r "Crush and Bury, Do Not Reuse". This could assume c o n s i d e r able importance i n the f u t u r e given changing container economics and d i s p o s a l c o s t s . Since the l a b e l accompanies the product, necessary and s p e c i f i c information i s placed d i r e c t l y i n the hands of the user. This i s p a r t i c u l a r l y important f o r farmers i f they wish to a v a i l themselves of the exemption provided by RCRA to avoid the extensive r e s p o n s i b i l i t i e "generator" of hazardou In the foregoing d i s c u s s i o n as w e l l as what f o l l o w s , the term " l a b e l " i s not l i m i t e d to the p r i n t e d matter attached to the c o n t a i n e r . More c o r r e c t l y , the term " l a b e l i n g " should be used which r e f e r s to the p r i n t e d information on the container as w e l l as any i n f o r m a t i o n that may accompany o r r e f e r to the product such as pamphlets, books, or other p r i n t e d m a t e r i a l even though i t may not be p h y s i c a l l y attached to the c o n t a i n e r or i n c l o s e proximity. It i s p o s s i b l e that r e l a t i v e l y l o n g , d e t a i l e d d i s p o s a l i n s t r u c t ions could be developed and included i n the l a b e l i n g , but as a p r a c t i c a l matter, o n l y guidance on d i s p o s a l of the empty container w i l l appear on the package. Information on d i s p o s a l of l e f t - o v e r tank mixes, d i l u t e s o l u t i o n s or unwanted product would be s u p p l i e d i n the l a b e l i n g or accompanying l i t e r a t u r e . In t h i s way r e l a t i v e l y complex d i s p o s a l procedures, complete with s a f e t y i n s t r u c t i o n s , can be provided to the user of the p e s t i c i d e . FIFRA Regulatory

Requirements

The r e g u l a t i o n s f o r l a b e l i n g p e s t i c i d e s are found i n 40 CFR 162.10. These r u l e s r e q u i r e that d i s p o s a l information be a part of any proposed statement. The c u r r e n t i n s t r u c t i o n s to r e g i s trants on d i s p o s a l statements are contained i n PR Notice 83-3 ( P e s t i c i d e R e g i s t r a t i o n Notice 83-3). This n o t i c e advises r e g i s trants that the l a b e l s of a l l products must contain updated d i s p o s a l statements. The s p e c i f i c statements that are provided cover most types of products such as home and garden or a g r i c u l t u r a l and most of the c o n t a i n e r s , metal, p l a s t i c or paper. A t y p i c a l recommended statement, such as one f o r metal c o n t a i n e r s , reads as f o l l o w s : " T r i p l e r i n s e (or e q u i v a l e n t ) . Then o f f e r f o r r e c y c l i n g or r e c o n d i t i o n i n g , or puncture and dispose of i n a s a n i t a r y l a n d f i l l , or by other procedures approved by s t a t e and local authorities".

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

T R E A T M E N T A N D D I S P O S A L OF PESTICIDE WASTES

10

The O f f i c e of P e s t i c i d e Programs recognizes that the d i s posal statements i n t h i s n o t i c e may not be appropriate f o r every p e s t i c i d e . Registrants have the o p t i o n of proposing a l t e r n a t i v e language for p e s t i c i d e d i s p o s a l statements. Registrants proposing a l t e r n a t e language must submit proposals to EPA and r e c e i v e approval before using any a l t e r n a t i v e language. Under FIFRA r e g u l a t i o n s r e g i s t e r e d products must have a d i s p o s a l statement that i s s e t apart and c l e a r l y d i s t i n g u i s h a b l e from other d i r e c t i o n s f o r use. The r e g u l a t i o n s also r e q u i r e that the d i s p o s a l i n s t r u c t i o n s be grouped together and p r i n t e d i n a s p e c i f i e d type s i z e , depending on the s i z e of the l a b e l f r o n t panel. PR n o t i c e 83-3 i s an attempt to improve and standardize the l a b e l statements on d i s p o s a l . Although the statements provided meet the r e g u l a t o r y need, they c l e a r l y f a l l short of p r o v i d ing the t e c h n i c a l d i r e c t i o n to the user that i s required to assure a high degree o minimal guidance i s provide advantage of the RCRA exemption and dispose on h i s own p r o p e r l y . Although FIFRA r e g u l a t i o n s r e q u i r e data to support proposed l a b e l statements on d i s p o s a l , the statements are now provided by EPA and such data i s not r e q u i r e d . C l e a r l y , before a data r e q u i r e ment could be imposed, the r e g i s t r a n t must be thoroughly advised as to what data he must submit. This i s the o b j e c t i v e of the Regis t r a t i o n Guidelines· Registration

Guidelines

A considerable h i s t o r y i s attached to r e g u l a t i o n of the present r e g i s t r a t i o n process as regards p e s t i c i d e d i s p o s a l statements. On July 3, 1975, the Agency promulgated f i n a l r e g u l a t i o n s , 40 CFR part 163, Subpart A (10). These r e g u l a t i o n s e s t a b l i s h e d the b a s i c requirements f o r r e g i s t r a t i o n of p e s t i c i d e products. During the period extending from 1975 to 1981, EPA i s s u e d or made a v a i l a b l e s e v e r a l subparts of the g u i d e l i n e s f o r r e g i s t e r i n g p e s t i c i d e s i n the United States which described, with more s p e c i f i c i t y , the kinds of data that must be submitted to s a t i s f y the requirements of the r e g i s t r a t i o n r e g u l a t i o n s . These guidel i n e s included s e c t i o n s d e t a i l i n g what data are required and when, the standards f o r conducting acceptable t e s t s , guidance on the e v a l u a t i o n and r e p o r t i n g of data, and examples of acceptable protocols· In October of 1981, EPA decided to reorganize the guidel i n e s and l i m i t the r e g u l a t i o n to a concise presentation of the data requirements and when they are r e q u i r e d . Therefore, data requirements f o r p e s t i c i d e r e g i s t r a t i o n p e r t a i n i n g to a l l former subparts of the g u i d e l i n e s are now s p e c i f i e d i n part 158 (40 FR 53192 November 24, 1982) which s p e c i f i e s the kinds of data and

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

1.

KRUEGER A N D SEVERN

Regulation of Pesticide Disposal

information that must be submitted to EPA t o support the r e g i s ­ t r a t i o n of each p e s t i c i d e under t h e FIFRA. The standards f o r conducting acceptable t e s t s , guidance on e v a l u a t i o n and r e p o r t i n g of data, f u r t h e r guidance on when data are r e q u i r e d and examples of protocols are not s p e c i f i e d i n part 158. This information c o n s t i t u t e s the g u i d e l i n e s and i s a v a i l a b l e as a d v i s o r y document­ a t i o n through the National Technical Information Service (NTIS). Guidelines were published i n 1982 under such t i t l e s a s : Sub­ d i v i s i o n D Chemistry Requirements: Product Chemistry; S u b d i v i s i o n F Hazard E v a l u a t i o n : Humans and Domestic Animals; Subpart G Product Performance; S u b d i v i s i o n Ν Chemistry Requirements: Environmental Fate, among others. S u b d i v i s i o n P: Disposal Data Requirements was reserved f o r future p u b l i c a t i o n . The b a s i c purpose of each of these g u i d e l i n e s i s to provide EPA with data to evaluate: 1. D i r e c t hazard t 2. D i r e c t hazard t 3. P o t e n t i a l f o r contaminating ground water; 4. P o t e n t i a l f o r m a g n i f i c a t i o n i n the food chain; 5. P o t e n t i a l uptake by r o t a t i o n a l crops. S p e c i f i c data requirements are based on use patterns and are l i s t e d i n Section 158. For example, i n S u b d i v i s i o n N: E n v i r ­ onmental Fate, use patterns f a l l i n t o the categories of t e r r e s ­ t r i a l uses, aquatic and aquatic impact uses. T e r r e s t r i a l uses i n c l u d e domestic outdoor, green house, non-crop, orchard crop, e t c . , and data required v a r i e s with the use s i t e . Depending on the s i t e of use, s t u d i e s on degradation, metabolism, m o b i l i t y , d i s s i p a t i o n , and accumulation might be r e q u i r e d . The general g u i d e l i n e format i s as follows : a. b. c.

d. e.

Purpose When r e q u i r e d Test standards (1.) t e s t substances (2.) t e s t procedures Reporting and e v a l u a t i o n References

The Subpart N, Environmental Fate Guidelines (11) w i l l probably provide much of what i s needed to support many of the d i s p o s a l statements that would probably be proposed. However, many of the studies would have to be conducted a t " d i s p o s a l r a t e s " , that i s hundreds of pounds o r p o s s i b l y tons per acre as opposed to "use r a t e s " of ounces or a few pounds per a c r e .

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

12 Disposal

TREATMENT AND Technologies and

DISPOSAL OF PESTICIDE WASTES

Data Requirements

Based on use patterns and s i t e - o f - u s e , s p e c i f i c data are r e q u i r e d by the Section 158 r e g u l a t i o n s f o r each product r e g i s t e r e d . Depending on the d i s p o s a l technology s e l e c t e d , the information needed to support the l a b e l d i s p o s a l statement may w e l l be a d d i t i o n a l to that required by Section 158. The f o l l o w i n g d i s c u s s i o n covers a few of the many d i s p o s a l systems that might be candidates for l a b e l statements and some of the kinds of data that might be required. Land d i s p o s a l . Land d i s p o s a l i s the most widely used, l e a s t expensive, most often a v a i l a b l e d i s p o s a l system at the present time. The term land d i s p o s a l includes s a n i t a r y l a n d f i l l s , s u r face impoundments, evaporation ponds and land farming. Land disposal i n a sanitary l a n d f i l l such wastes, can be expecte majority of the l a b e l statements proposed. Empty c o n t a i n e r s , waste p e s t i c i d e s and other wastes are commonly disposed of i n a s a n i t a r y l a n d f i l l or buried at the s i t e of use. The s o i l i s a complex and h i g h l y v a r i a b l e mixture of components, c o n t a i n i n g many types of l i v i n g organisms b a c t e r i a , f u n g i , algae, i n v e r t e b r a t e animals - and supporting the l i f e of h i g h e r p l a n t s , i n v e r t e b r a t e and v e r t e b r a t e animals. The a d d i t i o n of a p e s t i c i d e to a s o i l may therefore have e f f e c t s on many l i v i n g organisms, and may i n turn be a f f e c t e d by them. The p e s t i c i d e i s also a f f e c t e d by the nature of the s o i l and by the climate v a r i a b l e s that a f f e c t the s o i l . Data on these f a c t o r s and t h e i r i n t e r r e l a t i o n s h i p s must be developed before any land d i s p o s a l method that may impact those functions can be f u l l y evaluated. An example of the kinds of data required f o r land d i s p o s a l options would be information on s o i l / p e s t i c i d e i n t e r a c t i o n s to determine the e f f e c t of the p e s t i c i d e on the s o i l and s o i l on the p e s t i c i d e . The p h y s i c a l composition of the s o i l and the p h y s i c a l properties of the p e s t i c i d e and i t s formulation w i l l determine the adsorption, l e a c h i n g , water d i s p e r s a l , and v o l a t i l i z a t i o n of the p e s t i c i d e which, i n t u r n , determine the m o b i l i t y of the p e s t i c i d e i n s o i l . Even p e s t i c i d e s of c l o s e l y r e l a t e d s t r u c t u r e s may have very d i f f e r e n t s o i l r e t e n t i o n p r o p e r t i e s . Much of t h i s data w i l l be a v a i l a b l e from that developed to meet other r e g i s t r a t i o n data requirements with the exception that d i s p o s a l rates are o f t e n orders of magnitude h i g h e r than normal a p p l i c a t i o n rates and the d i f f e r e n c e must be considered. Other considerations would i n c l u d e ; data on adsorption and leaching or other movement of the p e s t i c i d e i n the s o i l ; the e f f e c t s of the p e s t i c i d e on microorganisms i n the s o i l under aerobic and anaerobic conditions ; e f f e c t s of microorganisms on the p e s t i c i d e ; e f f e c t s of the p e s t i c i d e on higher plants and

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

1.

Regulation of Pesticide Disposal

KRUEGER AND SEVERN

13

animals; e f f e c t s on d i s p o s a l f a c i l i t i e s , such as l i n e r s or other s t r u c t u r a l m a t e r i a l ; and such other c o n s i d e r a t i o n s that may be needed to determine i f the proposed p e s t i c i d e can be s a f e l y and e f f e c t i v e l y disposed of by land d i s p o s a l means (12)(13). If the p e s t i c i d e to be disposed of i s s p e c i f i c a l l y c o n t r o l l e d under RCRA, then a very s p e c i f i c s e t of r e g u l a t i o n s i s i n f o r c e (40 CFR 261 to 270) that r e q u i r e s management i n a permitted f a c i l i t y . I n c i n e r a t i o n . A " p e s t i c i d e i n c i n e r a t o r " i s defined as "any i n s t a l l a t i o n capable of the c o n t r o l l e d combustion of p e s t i c i d e s , a t a temperature of 1000 C (1832 F) f o r two seconds dwell time i n the combustion zone, or lower temperatures and r e l a t e d dwell times that w i l l assure complete conversion of the s p e c i f i c p e s t i cide to i n o r g a n i c gases and s o l i d ash r e s i d u e s " ( 2 ) . In a d d i t i o n , an i n c i n e r a t o r must meet the performance standards promulgated under RCRA (40 CFR 264 Subpar RCRA are to be burned. Thi capable of d e s t r o y i n g or removing 99.99% of the p e s t i c i d e put i n t o i t . Test burns that are f u l l y monitored are normally r e q u i red to determine whether t h i s performance standard i s achieved. A r e g i s t r a n t planning to suggest i n c i n e r a t i o n on a d i s p o s a l statement would need to observe these requirements. I n c i n e r a t i o n of p e s t i c i d e s and/or containers r e q u i r e s s p e c i a l equipment that i s not widely a v a i l a b l e . Due to the h i g h l y s p e c i a l i z e d nature of an i n c i n e r a t o r that can meet the s p e c i f i c a t i o n s necessary to d e s t r o y complex p e s t i c i d e formulat i o n s , plus the energy requirements, the process can be very expensive and not g e n e r a l l y the method of choice f o r s m a l l quanti t i e s that may be generated by a farmer, f o r example. On the other hand, i t can be a h i g h l y e f f e c t i v e means of d i s p o s i n g of unwanted m a t e r i a l (14). x

X

Open burning. "Open burning" i s d e f i n e d as combustion of a pesticide or p e s t i c i d e c o n t a i n e r i n any f a s h i o n other than i n c i n e r a t i o n (2^). Open burning i s u s u a l l y done by the simple act of p i l i n g up empty paper bags or p l a s t i c jugs and s e t t i n g them on f i r e and i s commonly used to dispose of combustible empty c o n t a i n ers where l o c a l r e g u l a t i o n s permit the p r a c t i c e . I t i s sometimes p r o h i b i t e d by Regional A i r Q u a l i t y r e g u l a t i o n s . Where i t i s permitted open burning represents an inexpensive and convenient way of d i s p o s i n g of the combustible containers that are commonly used to package p e s t i c i d e s . The p r a c t i c e can, however, present hazards to worker h e a l t h and to other persons, and to p l a n t s and animals that may be i n the v i c i n i t y . The impact upon the environment i s mainly through d i s p e r s a l of combustion gases, smoke and fumes i n t o the atmosphere and through contamination of s o i l s and waters by ashes and p a r t i a l l y burned containers h o l d i n g t o x i c r e s i d u e s . Data would be r e q u i r e d to address these i s s u e s .

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

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TREATMENT AND DISPOSAL OF PESTICIDE WASTES

Thermal degradation s t u d i e s might be required to determine the decomposition c h a r a c t e r i s t i c s of of the s u b j e c t p e s t i c i d e when heated alone o r i n the presence of o x i d i z e r s and/or binders i n both closed and open systems and a t various temperatures. Data required could cover the amounts and kinds of r e s i d u a l s that might be found i n the off-gases or remain i n the ash. The i g n i t i o n c h a r a c t e r i s t i c s of c o n t a i n e r m a t e r i a l s and t h e i r maximum burning temperatures must be t e s t e d under c o n d i t i o n s s i m u l a t i n g the a c t u a l open burning c o n d i t i o n s seen i n the f i e l d . Data on the r e s u l t s of burning s m a l l q u a n t i t i e s of a s u b j e c t p e s t i c i d e i n a sample of the packaging m a t e r i a l might also be r e q u i r e d . Such s t u d i e s could be designed to show the composition of the endproduct gases produced by combustion a t temperatures normally achieved by burning wood, paper, cardboard, or p l a s t i c s . Informa t i o n on any s p e c i a l procedures that might be required or recommended would a l s o be u s e f u subject product would b P h y s i c a l / c h e m i c a l methods. Chemical d e a c t i v a t i o n / d e t o x i f i c a t i o n provides the opportunity to reduce a t o x i c chemical to a non-toxic state. I t i s a procedure that i s not c u r r e n t l y used to any s i g n i f i c a n t degree i n common d i s p o s a l systems even though there are many chemicals that can be s u c c e s s f u l l y degraded when mixed with an a l k a l i or a c i d s o l u t i o n or i n some cases a s p e c i a l l y prepared enzyme. The p r i n c i p a l use would be i n r i n s i n g containers i n s i t u a t i o n s where the r i n s a t e cannot be added to the mix. Data requirements here would be d i c t a t e d by the chemical involved and the s i t e of use as i s the case i n many other r e g i s t r a t i o n s i t u a tions . Developing l a b e l statements on d i s p o s a l that are informat i v e and f u l l y supported by sound data w i l l take time but the e f f o r t i s expected to be w e l l worth while. P r e p a r a t i o n of g u i d e l i n e s i s underway by EPA and input from any and a l l i n t e r ested p a r t i e s w i l l be most welcome.

Literature Cited 1. 2.

3.

Report of the Secretary's Commission on Pesticides and Their Relationship to Environmental Health, U.S. Department of Health Education and Welfare. December 1969. U.S. Environmental Protection Agency. Pesticides and Pesticide Containers, Regulation for Acceptance and Recommended Procedures for Disposal and Storage. Federal Register, 39(85):15236-15241, May 1, 1974. Fox, A.S. and A.W. Delvo, 1972. "Pesticide Containers Associated With Crop Production," Proceedings of the National Conference on Pesticide Containers, New Orleans, November 28, 1972, Published by the Federal Working Group on Pest Management, Washington, D.C.

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

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KRUEGER AND SEVERN

Regulation of Pesticide Disposal

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4.

Arthur D. Little, Inc. Economic Analysis of Pesticide Disposal Methods. Cambridge Massachusetts, Strategic Studies Unit, March 1977. EPA/540/9-77/018, 181 p. 5. Lawless, E.W., T.L. Ferguson, and A.F. Meiners. Guidelines for the Disposal of Small Quantities of Unused Pesticides. Midwest Research Institute, Kansas City, Missouri, June 1975. EPA/670/2-75/057, 342 p. (Available from the National Technical Information Service as PB-244 557) 6. Shih, C.C. and D.F. Dal Porto. Handbook of Pesticide Disposal by Common Chemical Methods. TRW Systems, Inc., Redondo Beach, California, December 1975. EPA/530/SW-112c, 109 p. (Available from the National Technical Information Service as PB-242 864) 7. Lande, S.S. Identification and Description of Chemical Deactivation/Detoxification Methods for the Safe Disposal of Selected Pesticides mental Protection Agency 8. Day, H.R. Disposal of Dilute Pesticide Solutions. U.S. Environmental Protection Agency, Washington, D.C., Office of Solid Waste Management Programs, 1976. EPA/530/SW519, Day, 18 p. (Available from the National Technical Information Service as PB-261 160). 9. Wilkinson, R. R., E.W. Lawless, A.F. Meiners, T.L. Ferguson, G.L.Kelso and F.C. Hopkins. State of the Art Report on Pesticide Disposal Research. Midwest Research Institute, Kansas City, Missouri, September 1978. EPA/600/2-78-183, 225 p. 10. U.S. Environmental Protection Agency, Pesticide Registration: Proposed Data Requirements, Federal Register, Vol 47, No. 227, November 24, 1982. 11. U.S. Environmental Protection Agency, Pesticide Assessment Guidelines, Subdivision N, Chemistry, Environmental Fate, October 1982. EPA-540/9-82-021, 12. Sanborn, J.R., B.M. Francis, and R.L. Metcalf. The Degradation of Selected Pesticides in Soil: A Review of the Published Literature. Municipal Environmental Research Laboratory, Cincinnati, Ohio, EPA/600/9-77/022, 635 p. 1977 (Available from the National Technical Information Service as PB-272 353) 13. Ghassemi, M. and S. Quinlivan. A Study of Selected Landfills Designed As Pesticide Disposal Sites. EPA Publication No. SW-114c, 1975. 14. Ferguson, T.L., F.J. Berman, G.R. Cooper, R.T. L i , and F.I. Honea. Determination of Incinerator Operating Conditions Necessary for Safe Disposal of Pesticides. Midwest Research Institute, Kansas City, Missouri, December 1975. EPA/600/275 /041, 415 p. (Available from the National Technical Information Service as PB-251 131) RECEIVED

April 26,

1984

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

2 The Resource Conservation and Recovery Act DAVID FRIEDMAN Office of Solid Waste, Environmental Protection Agency, Washington, DC 20460 Background RCRA mandates the EPA to i d e n t i f y those residuals which, if improperly managed, pose a hazard to either human health or the environment. In implementing the Act, EPA has promulgate through 270 of T i t l e 40 of the Code of Federal Regulations. Parts 260 and 261 e s t a b l i s h the conditions under which a material becomes a waste and i d e n t i f y those wastes which are "hazardous wastes" and must be managed according to the management standards of Parts 262 through 270. Pesticide-containing materials may be c l a s s i f i e d as wastes subject to RCRA if they have served t h e i r intended use and are sometimes discarded, i r r e s p e c t i v e of whether they are being disposed of or are destined for r e c y c l i n g . A waste i s a "hazardous waste" if i t exhibits any of the c h a r a c t e r i s t i c s of a hazardous waste, or i s l i s t e d i n sections 261.31, .32, or .33. Pesticide wastes that are hazardous by reason of the c h a r a c t e r i s t i c s are those which are e i t h e r : solvent based and have a flash point AND LOGS IN EXISTING PART Β FACILITY

PREPARATION ' OF DRAFT PERMIT

-ψ COMPLETENESS CHECK

TECHNICAL EVALUATION

PUBLIC NOTICE OF DRAFT J PERMIT, COMMENT PERIOD, AND HEARING

STATEMENT OF | ^ADMINISTRATIVE \ BASIS OR RECORD FACT SHEET

NEW STATEMEN

H

PUBLIC HEARING

ADMINISTRATIVE L RECORD *H 1

H

PUBLIC NOTICE OF HEARING; EXTENSION OF COMMENT PERIOD

PANEL HEARING

Figure 1. EPA's permitting process f o r e x i s t i n g land disposal facilities.

Figure 2. Q u a n t i t i e s of hazardous waste disposed i n 1981 (preliminary data).

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

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T R E A T M E N T A N D DISPOSAL O F PESTICIDE WASTES

i o n a s p a r t o f t h e RCRA r e a u t h o r i z a t i o n p r o c e s s l e g i s l a t e a lowering o f t h e exemption t h r e s h o l d p e c t i v e o f Agency a c t i o n .

a n d may irres-

P r e s e n t hazardous waste i d e n t i f i c a t i o n characteri s t i c s g e n e r a l l y do n o t i n c l u d e a means o f i d e n t i f y i n g t h o s e w a s t e s w h i c h p o s e a p r o b l e m due t o t h e p r e s e n c e of organic t o x i c a n t s . The E x t r a c t i o n P r o c e d u r e T o x i c i t y c h a r a c t e r i s t i c only includes thresholds f o r s i x organic compounds. To c o r r e c t t h i s d e f i c i e n c y , t h e Agency i s working t o include a d d i t i o n a l t o x i c organic chemicals. The e x p a n s i o n may t a k e t h e f o r m t h a t a n y w a s t e c o n t a i n i n g any o f t h e l i s t e d compounds a t o r above a c e r t a i n t h r e s h o l d i s a hazardous waste. The t h r e s h o l d s would be a c o m p o u n d s p e c i f i c a n d b a s e d o n s u c h f a c t o r s a s NOAELs (No O b s e r v e d (Acceptable D a i l y Intak w i l l l i k e l y i n c l u d e a number o f p e s t i c i d a l c o m p o u n d s . T h r e e o t h e r a c t i o n s a r e b e i n g s t u d i e d t h a t may have a s i g n i f i c a n t , i f n o t s u b s t a n t i a l b e a r i n g on p e s t i c i d e w a s t e d i s p o s a l u n d e r RCRA. T h e s e a r e (1) expansion o f the l i s t i n g o f commercial chemical products t h a t a r e h a z a r d o u s w a s t e when d i s p o s e d o f , (2) e x p a n s i o n of the discarded commercial chemical product l i s t i n g to i n c l u d e products which a r e mixtures o f a c t i v e i n g r e d i e n t s , a n d (3) e s t a b l i s h m e n t of concentration limits f o r t h e compounds o n t h e l i s t . While t h e f i r s t and second o f these a c t i o n s would a c t t o b r i n g a l a r g e number o f c o m m e r c i a l p e s t i c i d e p r o d u c t s u n d e r RCRA control, the t h i r d (establishment of threshold levels) w o u l d a c t t o e x e m p t many, i f n o t m o s t , a p p l i c a t i o n s t r e n g t h s o l u t i o n s f r o m RCRA c o n t r o l . Once t h e s e t h r e s h o l d s have been e s t a b l i s h e d , p r o d u c t s o r s o l u t i o n s containing the toxic chemicals at concentrations below t h e t h r e s h o l d w o u l d a u t o m a t i c a l l y be e x c l u d e d from r e g u l a t i o n as a hazardous waste. The f i n a l r e g u l a t o r y c h a n g e b e i n g contemplated t o be d i s c u s s e d i s t h e l a n d d i s p o s a l b a n . Both C o n g r e s s and t h e A g e n c y a r e c o n c e r n e d t h a t f o r c e r t a i n w a s t e s l a n d d i s p o s a l may n o t b e p r o t e c t i v e o f human h e a l t h a n d the environment f o r as l o n g as t h e waste remains h a z a r dous, t a k i n g i n t o a c c o u n t t h e u n c e r t a i n t i e s a s s o c i a t e d with land disposal. In order t o e l i m i n a t e such p r a c t i c e s , changes a r e being formulated t o b o t h t h e RCRA i t s e l f and t h e hazardous waste r e g u l a t i o n s which w i l l prevent the land d i s p o s a l o f c e r t a i n wastes. It i s c o n c e i v a b l e t h a t some p e s t i c i d a l w a s t e s , e s p e c i a l l y t h o s e t h a t a r e p e r s i s t e n t , t h a t have a p o t e n t i a l t o

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

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b i o a c c u m u l a t e , and a r e p o t e n t i a l l y l e a c h a b l e i f p l a c e d i n a n o n - s e c u r e l a n d f i l l w o u l d b e among t h o s e b a n n e d u n l e s s t h e y have been t r e a t e d by such methods as stabilization, neutralization, or destruction of toxic species. I n a d d i t i o n , t h e House a n d S e n a t e a r e c o n s i d e r i n g enactment o f bans on d i s p o s a l o f b o t h c o n t a i n e r i z e d and b u l k l i q u i d s i n l a n d f i l l s and a ban on underground i n j e c t i o n o f hazardous waste i n C l a s s IV we11s. I n c o n c l u s i o n , t h e h a z a r d o u s w a s t e management r e g u l a t o r y s y s t e m u n d e r RCRA i s b o t h d y n a m i c a n d complex. P e s t i c i d e s , by t h e i r v e r y n a t u r e , pose unique d i s p o s a l problems. I t i s t h u s incumbent upon p e r s o n s managing such m a t e r i a l s t o keep a b r e a s t o f c u r r e n t s t a n d a r d s and r e g u l a t i o n s free "hotline" f o r number i s 8 0 0 - 4 2 4 - 9 3 4 6 o r i f i n W a s h i n g t o n , D.C., 382-3000.

RECEIVED February 13, 1984

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

3 Pesticide Waste Disposal in Agriculture CHARLES V. HALL Department of Horticulture, Iowa State University, Ames, IA 50011 Chemical compounds c l a s s i f i e d as pesticides (fungicides, herbicides and insecticides) t o t a l over 500. Others used as rodenticides, desiccants, defoliants, e t c . , increase that number. Agricult u r a l uses includ all d livestock farms, plus thos greenhouses, parks, golf courses, nurseries and lawns i n urban areas. Chemicals are applied by farmers, industry, or i n s t i t u t i o n a l employees, commercial applicators and individual c i t i z e n s . With proper planning the most common form of waste to be disposed of i s dilute rinse water. Occasionally discontinued or non-usable concentrate pesticides must and can be disposed of safely. Greatest dangers of improper disposal are to water supplies, food or feeds, recreation areas, animal habitats, and other waste disposal facilities. Three years research conducted j o i n t l y by 6 departments at Iowa State University and sponsored by the U.S. Environmental Protection Agency has demonstrated that wastes from over 45 pesticides were safely disposed of by containment i n a concrete p i t allowing evaporation of the l i q u i d component, and biodegradation, and other forms of pesticide decay. P l a s t i c lined p i t s were less satisfactory. A small disposal p i t suitable for individual farmers and small applicators has been developed. Pesticide Use A prominent publisher (1) lists 678 compounds which are classed as pesticides and used i n the broad field of agriculture. Included are insecticides, fungicides, herbicides, rodenticides, growth regulators, etc. These compounds are often used to adjust the b i o l o g i c a l balance i n favor of the desired plant or animal 0097-6156/ 84/0259-0027$06.00/0 © 1984 American Chemical Society

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population being grown or the products being s t o r e d . They a l s o are used to completely e l i m i n a t e the unwanted competitor. Many are used to p r o t e c t human h e a l t h . The number o f p e s t i c i d e s used on a l a r g e s c a l e i n a g r i c u l t u r e probably does not exceed 100 and o f t e n they are very s p e c i f i c . A l s o , many are marketed i n d i f f e r e n t f o r m u l a t i o n s . The r e l a t i v e volume of waste to be disposed o f i s not p r o p o r t i o n a l to the volume o f p e s t i c i d e s used. For example, the volume of h e r b i c i d e s used on corn, soybeans, etc., i s very l a r g e , but l i t t l e waste i s generated. Container r i n s a t e i s r e c y c l e d by t r i p l e r i n s i n g back i n t o the sprayer tank. Commercial a p p l i c a t o r s use r i n s a t e s where the same chemical i s being used and only r i n s e the sprayer when a d i f f e r e n t p e s t i c i d e i s being used or when d i s c o n t i n u i n g the o p e r a t i o n . Nature and Handling of Wastes Often p e s t i c i d e wastes f a c i l i t i e s , are i n a d i l u t e form and r e s u l t from r i n s a t e s from c o n t a i n e r s , spray tanks, and equipment wash water. These may o r i g i n a t e from the small a p p l i c a t o r or l a r g e commercial operator. Such wastes should be sprayed on an area f o r which they are approved or placed i n a safe d i s p o s a l f a c i l i t y . O c c a s i o n a l l y , f a i r l y l a r g e volumes of recommended c o n c e n t r a t i o n d i l u t e mixtures r e s u l t i n g from l i v e s t o c k d i p p i n g operations, overestimating the amount needed f o r a spray o p e r a t i o n , e t c . , must be d i s c a r d e d . For such operations, safe f a c i l i t i e s or procedures are e s s e n t i a l to p r o t e c t human h e a l t h and environmental s a f e t y . I f a hazardous chemical, such as toxaphene i s used, which r e q u i r e s many years to degrade, the waste should be p r o p e r l y contained. However, most organo-phosphates are r e a d i l y biodegradable and can be spread on land i n accordance with l a b e l recommendations. In a l l cases, d i s p o s a l must be i n accordance with the F e d e r a l Resource Conservation and Recovery Act, and s t a t e and l o c a l r e g u l a t i o n s . P e s t i c i d e wastes can and should be minimized by c a r e f u l l y c a l c u l a t i n g the p r e c i s e amount o f p e s t i c i d e needed and then a p p l y i n g that e n t i r e amount on the area of intended use. A l l l i q u i d c o n t a i n e r s should be t r i p l e r i n s e d , punctured, and disposed of i n an authorized solid-waste f a c i l i t y or p r o p e r l y r e c y c l e d . Paper bags, p l a s t i c c o n t a i n e r s , e t c . , should be p r o p e r l y i n c i n e r a t e d or taken to an authorized solid-waste f a c i l i t y where s t a t e and l o c a l r e g u l a t i o n s permit. In cases where p e s t i c i d e s are d i s c o n t i n u e d , banned, flooded, out of date, contaminated or f i r e damaged, i t i s necessary to dispose o f concentrated or formulated compounds. These are abnormal s i t u a t i o n s and the s t a t e departments of environmental q u a l i t y and the U.S. Environmental P r o t e c t i o n Agency o f f i c i a l s provide a s s i s t a n c e i n such emergencies. They should be n o t i f i e d immediately as r e q u i r e d by f e d e r a l and s t a t e law. In many such cases d i s p o s a l can be accomplished over a period of time by d i l u t i o n , containment, biodégradation and evaporation.

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

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Pesticide Waste Disposal in Agriculture

29

Combustion may be the most s a t i s f a c t o r y method f o r nonbiodegradable m a t e r i a l s . The problem o f d i s p o s a l o f long term r e s i d u a l m a t e r i a l s i s o f a l e s s e r magnitude than 10 years ago due to discontinued use, b e t t e r planning, higher cost o f chemicals, and use o f more r a p i d l y biodegradable p e s t i c i d e s . In f a c t , some p e s t i c i d e s c u r r e n t l y i n use biodegrade so r e a d i l y that they are l i m i t e d i n e f f e c t i v e n e s s as i n s e c t i c i d e s , h e r b i c i d e s , e t c . (3)· However, i t i s important that non-biodegradable chemicals be p r o p e r l y contained i n accordance with f e d e r a l r e g u l a t i o n u n t i l approved d i s p o s a l can be accomplished. A System f o r Safe D i s p o s a l o f P e s t i c i d e Wastes The d i s p o s a l p i t (Figures 1 and 2 ) , used a t the H o r t i c u l t u r e S t a t i o n since 1970, was designed to c o n t a i n surplus d i l u t e d insecticides, fungicides from spraying operation t u r f g r a s s research p l a n t i n g s . The farm c o n s i s t s o f 229 acres with d i v e r s i f i e d p l a n t i n g s . Therefore, the operation i s t y p i c a l of many a g r i c u l t u r a l research and development centers l o c a t e d throughout the U.S. i n that a wide v a r i e t y o f d i f f e r e n t p e s t i c i d e s are used which r e s u l t i n the generation o f small q u a n t i t i e s o f concentrate and l a r g e r amounts o f d i l u t e d p e s t i c i d e mixtures. The system described i n Table I was constructed to provide a safe and s a t i s f a c t o r y s o l u t i o n to the d i s p o s a l o f such wastes. Waste from over 45 p e s t i c i d e s were disposed o f i n the concrete p i t between 1970-76 (Table I I ) . Research was conducted at Iowa State U n i v e r s i t y by f a c u l t y i n the Departments o f Agronomy, A g r i c u l t u r a l Engineering, Energy and M i n e r a l Resource I n s t i t u t e , Entomology, M i c r o b i o l o g y , and H o r t i c u l t u r e . I t was sponsored by the U.S. Environmental P r o t e c t i o n Agency over a three year p e r i o d to evaluate the e f f e c t i v e n e s s o f current d i s p o s a l methods and develop new systems. In a d d i t i o n , evaporation o f d i l u t e p e s t i c i d e mixtures from a h o l d i n g p i t was compared with water evaporation from a standard weather evaporation pan and c o r r e l a t e d with temperature, r e l a t i v e humidity, sky c o n d i t i o n s , wind d i r e c t i o n , and v e l o c i t y . Evaporation models were developed f o r p r e d i c t i n g evaporative d i s p o s a l needs f o r other geographic r e g i o n s . A l s o , checks were made f o r leakage and a i r p o l l u t i o n . A l l methods and models are described f u l l y i n the f i n a l published r e p o r t ( 2 ) . A new l a r g e p i t was constructed a t the Agronomy-Agricultural Engineering Research Center with two thicknesses o f 6-mil black polyethylene p l a s t i c f i l m as a l i n e r . More i n t e n s i v e research was conducted i n 56 p l a s t i c m i n i p i t s to evaluate chemical i n t e r a c t i o n s , degradation, and b i o l o g i c a l a c t i v i t y ( 2 ) . Research r e s u l t s revealed that the concrete p i t a t the H o r t i c u l t u r e S t a t i o n was s a f e from leakage, d i d not present a hazard o f a i r p o l l u t i o n , and allowed chemical and m i c r o b i a l degradation o f the deposited m a t e r i a l s ( 2 ) . The concrete p i t , 12

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

30

T R E A T M E N T A N D DISPOSAL OF PESTICIDE WASTES

Table I .

C h a r a c t e r i s t i c s o f t h e D i s p o s a l P i t shown i n F i g u r e 1.

Dimensions

—

12 f t by 30 f t by 4 f t deep

Construction —

8 i n c h r e i n f o r c e d c o n c r e t e w a l l s and b o t t o m w i t h g r o o v e d c o n n e c t i o n and f l e x i b l e t i e s . (See ( 2 ) f o r d e t a i l s ) . An a u t o m a t e d m o b i l e c o v e r t o a l l o w f o r f u l l sun and w i n d e x p o s u r e . Has d r a i n t i l e i n s t a l l e d a r o u n d base w i t h a c c e s s i b l e r i s e r f o r sampling f o r leakage. C o n n e c t e d t o t h e m i x i n g room i n a d j a c e n t b u i l d i n g by a p i p e f r o m t h e sump t o p e r m i t transfe

Orientation —

on t h e w e s t end o f t h e p e s t i c i d e and s p r a y equipment s t o r a g e b u i l d i n g w i t h f u l l s o u t h and west e x p o s u r e t o sun and w i n d w h i c h maximizes e v a p o r a t i o n . R a i s e d above ground l e v e l t o p r e v e n t f l o o d i n g by s u r f a c e w a t e r f r o m heavy r a i n s .

Contents —

two one f t l a y e r s o f c o a r s e (3/4 i n ) washed r i v e r g r a v e l w i t h a one of f i e l d s o i l c o n t a i n i n g i n excess p e r c e n t o r g a n i c m a t t e r i n between soil-gravel) .

1 1/2 f t layer of three (gravel-

f t by 30 f t by 4 f t deep, f i l l e d w i t h a l a y e r o f g r a v e l , one f t o f s o i l , and a n o t h e r l a y e r o f g r a v e l , was e f f e c t i v e f o r e v a p o r a t i o n o f a p p r o x i m a t e l y 6000 g a l l o n s o f l i q u i d w a s t e s a n n u a l l y between A p r . 1 and O c t . 15 ( F i g u r e s 1 and 2 ) . The s o i l l a y e r w i t h i n the p i t c o n t a i n e d r e l a t i v e l y normal a e r o b i c b a c t e r i a l a c t i v i t y d u r i n g t h e s e months ( J O . The two p r i m a r y b a c t e r i a l g r o u p s were B a c i l l u s and Pseudomonas s p p . No c h e m i c a l p o l l u t i o n was d e t e c t e d i n t h e s a m p l i n g t i l e l o c a t e d b e n e a t h t h e p i t , i n t h e s t a t i o n w e l l 50 y a r d s away, o r i n t h e s t a t i o n l a k e 1000 y a r d s down g r a d e f r o m t h e d i s p o s a l s i t e . The s y s t e m i s e f f e c t i v e a t p r e s e n t a f t e r 13 s e a s o n s o f u s e . P e s t i c i d e c o n t a i n e r s were t r i p l e r i n s e d , c r u s h e d and d i s p o s e d o f as s o l i d waste ( F i g u r e 3 ) . Containment o f l i q u i d w a s t e s by t h e n e w l y c o n s t r u c t e d p l a s t i c l i n e d p i t was q u e s t i o n a b l e a f t e r one y e a r . T h e r e a p p e a r e d t o be some l e a k a g e or f l u c t u a t i o n o f t h e l i q u i d l e v e l . There i s c o n t i n u a l danger o f r u p t u r e o f s u c h l i n e r s by m e c h a n i c a l i n j u r y , c h e m i c a l i n t e r a c t i o n , rodents, e t c . , which could r e s u l t i n contamination

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

HALL

Pesticide Waste Disposal in Agriculture

Figure 1. The concrete disposal p i t with automated mobile cover and adjacent p e s t i c i d e storage f a c i l i t y .

Figure 2.

Same as Figure 1 with cover c l o s e d .

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

T R E A T M E N T A N D DISPOSAL O F PESTICIDE WASTES

32

Table I I .

P e s t i c i d e s used at the H o r t i c u l t u r e S t a t i o n 1970-76. Small amounts of l e f t o v e r d i l u t e d m a t e r i a l s were deposited.

Compound

Compound

Alachlor Atrazine Azinphos methyl Benomyl Bensulide Butralin Captan Carbaryl Chlorothaloni Chloroxuron Citcop 2,4-D 2,4-DB DCPA (Dacthal) Diathane M-22, M-45, and Dicamba Dichlobenil Diphenamid Endosulfan I and I I EPTC (Eptam) Ethylparation Folpet Glyphosate

Guthion Heptachlor Hexachlorobenzene Kelthane Lannate Malathion Mancozeb

Z-78

Methomy1 Methoxychlor Metribuzin Naptalam Omite Paraquat d i c h l o r i d e Penoxalin Phosmet Polyram Propachlor Simazine Sulphur Trifluralin

of subsurface water where the water t a b l e i s high (5). C e r t a i n l y , two 6 m i l p o l y e t h y l e n e l a y e r s would be inadequate f o r long term containment, e s p e c i a l l y i f equipment i s to be d r i v e n over the f i l l s u r f a c e . In more a r i d regions the problem would be of l e s s e r magnitude f o r most commonly used a g r i c u l t u r a l p e s t i c i d e s and e s p e c i a l l y where the water t a b l e i s 200-300 f e e t deep and there i s a deep c l a y s u b s o i l l a y e r between. However, l o c a l r e g u l a t i o n s must be considered i n each case to ensure environmental s a f e t y . Summary and Current Status Based on research sponsored by the U.S. Environmental P r o t e c t i o n Agency and long term experience at Iowa State U n i v e r s i t y some e s s e n t i a l components o f safe d i s p o s a l o f a g r i c u l t u r a l p e s t i c i d e wastes were: 1) d i l u t i o n , 2) containment i n a s t r u c t u r e that w i l l

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

3.

HALL

Pesticide Waste Disposal in Agriculture

Figure 3. H y d r a u l i c a l l y operated can crusher with f i v e cans before and a f t e r c r u s h i n g .

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

33

gallon

T R E A T M E N T A N D DISPOSAL O F PESTICIDE WASTES

34

not leak, overflow, f l o o d or otherwise p o l l u t e the environment, 3) evaporation of the water, and 4) b i o d e g r a t i o n of most compounds. The system i n use i s too l a r g e and elaborate f o r most farm, greenhouse, nursery, g o l f course, or small park o p e r a t i o n s , A new precast concrete m i c r o p i t was i n s t a l l e d at the Iowa State U n i v e r s i t y H o r t i c u l t u r e S t a t i o n i n 1983 which may serve as a model f o r such i n d i v i d u a l operators (Figures 4 and 5). The same f u n c t i o n a l components used i n the macropit were i n c o r p o r a t e d to provide maximum evaporation, b i o d e g r a t i o n , and environmental s a f e t y . Previous attempts to use p l a s t i c , f i b e r g l a s s and other containers were u n s u c c e s s f u l because o f f r e e z i n g , thawing, and r u p t u r i n g problems i n winter. T h i s s t r u c t u r e should withstand those c o n d i t i o n s and i n c o r p o r a t e s the g r a v e l - s o i l - g r a v e l system p r e v i o u s l y used. The cover i s s i m i l a r to that suggested f o r m o d i f i c a t i o n of the l a r g sampling f o r leakage. M u l t i p l depending on evaporative needs and l o c a l evaporation r a t e s . The same precautions should be used to avoid f l o o d i n g and to maximize evaporation. A l s o , s i m i l a r u n i t s should be a v a i l a b l e from l o c a l concrete products companies throughout the country. The s t r u c t u r e (12 f t by 30 f t by 4 f t deep) has been i n use at the H o r t i c u l t u r a l S t a t i o n s i n c e 1970 and during the three years i n t e n s i v e research, was used to dispose of over 6000 g a l l o n s of l i q u i d each year or the equivalent of approximately 35 surface inches per year. No contamination o f surrounding s o i l , water, or a i r was detected. Therefore, the system was found to be environmentally s a f e , however, some m o d i f i c a t i o n s could be made which would improve o v e r a l l e f f i c i e n c y of use and r e t a i n e f f e c t i v e n e s s (Table I I I ) .

Acknovle dgment s Funding f o r research conducted and reported (2) was provided under U.S. Environmental P r o t e c t i o n Agency Grant No. R804533, C i n c i n n a t i , Ohio. Other f a c u l t y a c t i v e l y i n v o l v e d i n the research were: James B a k e r - A g r i c u l t u r a l Engineering, Paul Dahm-Entomology, Loras F r e i b u r g e r - H o r t i c u l t u r e , Layne Johnson-Microbiology, Gregor JunkEnergy and M i n e r a l Resources I n s t i t u t e , Fred W i l l i a m s Microbiology and Charles J . Rogers-U.S.E.P.A. as P r o j e c t O f f i c e r . O r i g i n a l macropit design was by Thamon Hazen and r e v i s i o n s by Dennis J o n e s - A g r i c u l t u r a l Engineers. Journal Paper No. J-11207 of the Iowa A g r i c u l t u r e and Home Economics Experiment S t a t i o n , Ames, Iowa. P r o j e c t No. 2216.

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

3.

HALL

Pesticide Waste Disposal in Agriculture

35

Threaded Inserts

IT

ι ί 6" Mesh Reinforcement Wire

4 8 " I.D. RCP

5" Wall

#4 Rod on 12 " Center Each Way 6" Base

Figure 4. S t r u c t u r a l s p e c i f i c a t i o n s f o r a modified precast manhole s t r u c t u r e as r e v i s e d and redrawn from Iowa Concrete Products Co. SK-83-61.

Figure 5. The above concrete u n i t as i n s t a l l e d a t the I . S . U . H o r t i c u l t u r e S t a t i o n as a small q u a n t i t y d i s p o s a l u n i t .

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

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T R E A T M E N T AND D I S P O S A L O F P E S T I C I D E W A S T E S

Table III.

Suggested Modifications for the Concrete Macropit.

1.

Install a raised fixed cover of opaque corregated fiberglass in hinged sections which slope to prevailing sun and with sufficient overhang to prevent rain from entering. The cover should be designed to withstand maximum wind velocities for region where located.

2.

Enclose the disposal pit with 1/2 in mesh hail screen attached to cover support posts, to keep children and animals from entering and debris from collecting on the pit surface.

3.

Install an enclosed wash rack for equipment in an adjacent structure with drai installed) for disposa equipment. Wash rack must have a cleanout trap for removal of soil and other debris from equipment. Install a recirculating pump with a mist system for enhancement of evaporation in more humid climates.

4. 5.

Design capacity to needs based on environmental conditions of the region and state, and local regulations.

6.

Provide adequate sampling tubes, or tiles, to conform to federal and state monitoring regulations.

Literature Cited 1. 2. 3. 4. 5.

Farm Chemicals Handbook 82. Meister Pub. Co. p. C 3-318. Hall, Charles V. et a l . "Safe Disposal Methods for Agricultural Pesticide Wastes". National Technical Information Service. May 1981. PB-81-197 584. Fox, Jeffery L. Soil Microbes Pose Problems for Pesticides. Science. Vol. 221, No. 4615, pp. 1029-30. Sept. 9, 1983. Johnson, Layne M. and Paul A. Hartman. Microbiology of a Pesticide Disposal Pit. Bull. of Environm. Contom. Toxical. 25, 448-455 (1980). Haxo, H. E . , Jr. Interaction of Selected Lining Materials with Various Hazardous Wastes. II. Proceedings of the Sixth Annual Research Suymposium. U.S.E.P.A. pp. 160-180. March 1980.

RECEIVED March 6, 1984

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

4 Degradation of Pesticides in Controlled Water-Soil Systems G. A. JUNK, J. J. RICHARD, and P. A. DAHM1 Ames Laboratory, Iowa State University, Ames, IA 50011

Atrazine, alachlor, 2,4-D ester, trifluralin, carbaryl, and parathio mixtures to 60 L 110 L plastic garbage containers that were buried partially in open ground. Degradations from initial pesticide concentrations of 0.4 and 0.02 weight percent were investigated. Additional variables of aeration at 1 L/min and peptone nutrients at 0.1 weight percent, as possible aids to degradation, were also studied. Aliquots from 56 buried containers were taken for chemical analyses at regular intervals during a 68 week period. These samples were analyzed for the added pesticides and their hydrolysis products. Conclusions based on analytical results for the field experiment and supplementary laboratory experiments are: 1) soil and water in an inexpensive container provide for satisfactory containment of common pesticides so that chemical and biological degradations can occur; 2) soil is essential for containment and is a satisfactory source of microorganisms; 3) aeration and addition of buffers, nutrients and inoculants are of questionable value; 4) the half-life concept for degradation is not applicable; 5) sampling of disposal sites, even small controlled ones, is a problem; 6) degradations vary from rapid for hydrolysis of 2,4-D ester and carbaryl to unobservable for atrazine. Current address: Department of Entomology, Iowa State University, Ames, IA 50011

1

0097-6156/84/0259-0037$08.75/0 © 1984 American Chemical Society

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

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T R E A T M E N T A N D DISPOSAL OF PESTICIDE WASTES

Studies were i n i t i a t e d at Iowa State U n i v e r s i t y i n 1977 to d e t e r mine i f p e s t i c i d e s would be contained and degraded when deposited i n w a t e r / s o i l systems. Although the a d d i t i o n of known amounts of the s e l e c t e d p e s t i c i d e s was c o n t r o l l e d , the p h y s i c a l environment was not; temperature, humidity, wind speed, e t c . were normal for the climate of Central Iowa. Four h e r b i c i d e s and two i n s e c t i c i d e s were chosen on the basis of three f a c t o r s . F i r s t l y , they represented s i x d i f f e r e n t f a m i l i e s of p e s t i c i d e s . The four h e r b i c i d e s , a l a c h l o r , a t r a z i n e , t r i f l u r a l i n , and 2,4-D e s t e r , represent the a c e t a n i l i d e s , t r i a z i n e s , d i n i t r o a n i l i n e s , and phenoxy acid h e r b i c i d e s , r e s p e c t i v e l y . The two i n s e c t i c i d e s , c a r b a r y l and parat h i o n , represent the carbamate and organophosphorus i n s e c t i c i d e s , respectively. Secondly, the p e s t i c i d e s were chosen on the b a s i s of current and projected use i n Iowa (1) and the Midwest. T h i r d l y , the chosen p e s t i c i d e s were ones for which a n a l y t i c a l methodology was a v a i l a b l e . Considerable informatio degradation of these p e s t i c i d e s . A b r i e f summary of t h e i r degrada t i o n pathways and t h e i r expected persistence i n the environment i s presented here. Atrazine The major degradation of a t r a z i n e i n s o i l was i t s conversion to hydroxyatrazine by loss of the c h l o r i n e atom (2-5). Dealkylation also occurred with d e e t h y l a t i o n predominating over d e i s o p r o p y l a t i o n (5,6). Only small amounts of the r a d i o a c t i v i t y of the r i n g labeled a t r a z i n e was converted to COz by s o i l (6,8-10). G e l l e r (11) found that the percentages of C 0 evolved from C-labeled side chains were s i m i l a r for b i o l o g i c a l and n o n b i o l o g i c a l dealkyl a t i o n . No d i s t i n c t i o n could be made between the two processes so degradation was assumed to be i n i t i a t e d by a b i o t i c environmental f a c t o r s , such as low pH, mineral s a l t s , organic matter and photolysis. The ^ - t r i a z i n e s are one of the most r e c a l c i t r a n t groups of h e r b i c i d e s and p e r s i s t e n c e of over one year i n the s o i l was observed when a t r a z i n e was applied at the recommended rates (12). lk

llf

ilf

2

Alachlor Most a c e t a n i l i d e s are biodegraded r a p i d l y i n s o i l , but a l a c h l o r appears to be degraded by a mechanism d i f f e r e n t from that for other members of t h i s group of h e r b i c i d e s . The presence of e i t h e r the 2' , 6 ^ - d i a l k y l s u b s t i t u e n t s , the N-alkoxylmethyl s u b s t i t u e n t , or both, may preclude enzymatic h y d r o l y s i s of the carbonyl or

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

4.

J U N K ET A L .

Controlled Water-Soil Systems

39

amide linkages of a l a c h l o r (13). Hargrove and Merkle (14) r e p o r t ed that 2 - c h l o r o - 2 , 6 ' - d i e t h y l a n i l i d e was formed i n a l a c h l o r t r e a t e d , a i r - d r i e d s o i l incubated at 46°C. This degradation product was shown to r e s u l t from acid catalyzed h y d r o l y s i s on mineral s u r f a c e s . Beestman and Deming (15) found a h a l f - l i f e of 7.8 days for a l a c h l o r i n u n s t e r i l i z e d s o i l . The average p e r s i s t e n c e for recommended rates of a p p l i c a t i o n was 6-10 weeks ( 1 2 ) . Trifluralin Both aerobic and anaerobic degradation pathways have been proposed for t r i f l u r a l i n (16) . D e a l k y l a t i o n i s the i n i t i a l aerobic degradation followed by sequential removal of the second a l k y l group to give the d e a l k y l a t e d product. Reduction of the two n i t r o groups e v e n t u a l l y leads to the formation of the 3,4,5-triamino-a,a,at r i f l u o r o t o l u e n e . Unde reduced f i r s t , followed same 3 , 4 , 5 - t r i a m i n o - a , a , a - t r i f l u o r o t o l u e n e product. Degradation of t r i f l u r a l i n was more r a p i d and extensive i n substrate-amended s o i l under anaerobic conditions compared with well-aerated systems. The r e l a t i v e rates followed the order, moist anaerobic > flooded anaerobic > moist aerobic (17) . Degradation i n these environments a f t e r 20 days was 99, 45 and 15%, r e s p e c t i v e l y . Under f i e l d c o n d i t i o n s t r i f l u r a l i n has been p r e d i c t e d to degrade to nonphytotoxic l e v e l s w i t h i n a growing season when s o i l c o n d i t i o n s are moist and warm ( 1 2 ) . A f t e r three years, less than 1.5% of C - t r i f l u r a l i n was detected i n test p l o t s maintained under n a t u r a l c o n d i t i o n s (18). 1 I +

2,4-D

Ester

Evidence for the m i c r o b i o l o g i c a l degradation of 2,4-D ester i n s o i l s was based on the s t i m u l a t i o n by warm, moist conditions and organic matter (19); a c o r r e l a t i o n between degradation rate and the numbers of aerobic s o i l b a c t e r i a ( 2 0 ) ; and i n h i b i t i o n when the s o i l s were a i r - d r i e d and autoclaved ( 1 9 7 . L i t t l e information i s a v a i l a b l e , however, on the nature of the degradation products. The r e s u l t s of many studies of the degradation of phenoxyalkanoates using pure c u l t u r e s of microorganisms have been reported. The use of Arthrobacter i s o l a t e d by Loos (21) has been studied e s p e c i a l l y well . This organism was i s o l a t e d from s i l t loam and i t r a p i d l y o x i d i z e d 2,4-D. The f i r s t intermediate was 2 , 4 - d i c h l o rophenol. E v e n t u a l l y the aromatic r i n g of the 2,4-D was cleaved with a l l the bound c h l o r i n e converted to free c h l o r i n e .

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

40

T R E A T M E N T A N D DISPOSAL OF PESTICIDE WASTES

The r e s u l t s of Smith (22) suggested that the i s o p r o p y l and nb u t y l esters of 2,4-D are subject to rapid chemical h y d r o l y s i s i n soils; however the i s o o c t y l ester was more stable and p o s s i b l y undergoes some b i o l o g i c a l h y d r o l y s i s . B a i l e y et a l . (23) reported that the h y d r o l y s i s of the propylene g l y c o l b u t y l ester i n pond water was 90% complete i n 16-24 hours and 99% complete in 33-49 hours. Zepp et a l . (24) reported that the h a l f - l i f e for h y d r o l y s i s of various 2,4-D esters v a r i e d from 0.6 hour for the 2-butoxye t h y l ester to 37 hours for the 2-octyl e s t e r . Persistence of the e s t e r i n the s o i l environment was estimated to be less than one week. The degradation of the 2,4-D a c i d was also rapid (12) but slower than the h y d r o l y s i s of the e s t e r . Parathion Degradation of parathio phenol and d i e t h y l t h i o p h o s p h o r i thion (25,26). Chemical o x i d a t i o n of parathion i n s o i l s and waters was not prevalent, although o x i d a t i o n of the phosphoruss u l f u r bond has been shown to occur under u l t r a v i o l e t l i g h t and i n o x i d i z i n g environments (26). At ordinary l e v e l s of a p p l i c a t i o n to s o i l , parathion was degraded w i t h i n weeks i f m i c r o b i a l a c t i v i t y was a v a i l a b l e (27) . Accumulations even a f t e r repeated a p p l i c a tions were u n l i k e l y (28). When higher concentrations were a p p l i e d to s o i l , p e r s i s t e n c e increased. Simulated s p i l l s of concentrated parathion r e s u l t e d i n a 15% residue a f t e r f i v e years (29) and 0.1% a f t e r 16 years (30). Carbaryl Carbaryl degradation was p r i m a r i l y m i c r o b i o l o g i c a l as reported by a number of i n v e s t i g a t o r s (31-36). S o i l organisms transformed c a r b a r y l to many metabolites, i n c l u d i n g 1-naphthol, 1-naphthyl Nhydroxy methyl carbamate, 1-naphthyl carbamate, and 4 and 5hydroxy-1-naphthyl methyl carbamate. The degradation of 1-napht h o l also occurred m i c r o b i o l o g i c a l l y (32,35) by a pathway s i m i l a r to h y d r o x y l a t i o n with subsequent r i n g cleavage of naphthalene (37). Predicted p e r s i s t e n c e of c a r b a r y l i n the environment v a r i e d from one to s e v e r a l weeks (38). The degradation of 1-naphthol was p r e d i c t e d to be f a s t e r (34,35) than degradation of c a r b a r y l . EXPERIMENTAL D e s c r i p t i o n of System A t r a z i n e (Aatrex; 80W), a l a c h l o r (Lasso; E.C.) 2,4-D ester (Weedone LV4; E . C ) , t r i f l u r a l i n ( T r e f l a n ; E.C.), c a r b a r y l (Sevin; 50W) and parathion ( S e c u r i t y ; 15W) were blended, i n d i v i d u a l l y and as mixtures, with 60 L of water and 15 kg of sandy loam s o i l i n 110 L

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

4.

J U N K ET A L .

41

Controlled Water-Soil Systems

p l a s t i c garbage containers buried p a r t i a l l y i n the ground. A c r o s s - s e c t i o n a l view of one of these buried containers i s shown i n Figure 1. The i n d i v i d u a l p e s t i c i d e s were studied i n separate containers at the high and low concentrations of 0.4 and 0.02 weight percent a c t i v e i n g r e d i e n t . The mixtures were studied with a l l s i x p e s t i c i d e s each present at high and low concentrations i n separate c o n t a i n e r s . A d d i t i o n a l v a r i a b l e s of a e r a t i o n at 1 L/min and peptone n u t r i e n t s at 0.1% by weight r e s u l t e d i n a f a c t o r i a l experiment of 56 c o n t a i n e r s . The layout of these containers i n a 7x8 matrix, with dots showing the l o c a t i o n s , i s shown i n Figure 2. The high and low concentrations are i n d i c a t e d by IX and 0.05X, r e s p e c t i v e l y . Those systems under a e r a t i o n and with n u t r i e n t s are also i d e n t i f i e d . A l l 56 c o n t a i n e r s , for studying the degradations of these s i x p e s t i c i d e s , and the associated equipment were l a i d out i n a fenced area covering only 60 M 2

Sampling A 100 g sample of the s o i l and l i q u i d contents of each container was taken for analyses at 1, 3, 4, 8, 12, 16, 20, 24, 28, 52 and 68 weeks a f t e r a d d i t i o n . The samples were obtained by slowly lowering and r a i s i n g a 100 mL b o t t l e , capped with a two-hole rubber stopper, through the s w i r l formed by vigorous mixing of the contents of the c o n t a i n e r . The mixing was accomplished using a p r o p e l l e r blade attached to a shaft d r i v e n by a v a r i a b l e speed drill. The amount of water necessary to adjust the volume to the o r i g i n a l 60 L was recorded before mixing and sample c o l l e c t i o n . E x t r a c t i o n Procedures The c o l l e c t e d sediment and water samples were c e n t r i f u g e d f o r 0.5 hour at 200 rpm. The water was decanted and the volume measured p r i o r to t r a n s f e r to a 250 mL separatory funnel where i t was ext r a c t e d four times with four 50 mL volumes of d i e t h y l ether for the high concentration samples and with 50 mL followed by two 25 mL volumes for the low concentration samples. The 2,4-D samples only were a c i d i f i e d to a pH of ~2 with H S0 to a i d i n the s o l v e n t extraction. For the four h e r b i c i d e s , the s o i l f r a c t i o n i n the sample b o t t l e was extracted by adding 50 mL of d i e t h y l ether followed by a g i t a t i o n for 15 minutes on a w r i s t - a c t i o n shaker. The d i e t h y l ether was decanted and the high concentration samples were ext r a c t e d three more times with 50 mL of d i e t h y l ether by hand shaking the capped b o t t l e s for 2 to 3 minutes. The low c o n c e n t r a t i o n samples were extracted two a d d i t i o n a l times with 25 mL of d i e t h y l ether. For the two i n s e c t i c i d e s , the s o i l was extracted with 75, 50 and 50 mL of an acetone :benzene:methanol (1:2:1 by v o l . ) mixture. The sample b o t t l e s were capped and a g i t a t e d for 60 minutes on a w r i s t - a c t i o n shaker for each e x t r a c t i o n . The contents of the bot2

1+

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

42

T R E A T M E N T A N D DISPOSAL O F PESTICIDE WASTES

Figure 1. C r o s s - s e c t i o n a l view o f a buried garbage can. A,D Tygon tube and d i f f u s e r used f o r a e r a t i o n ; B~ground l e v e l ; C—110L p l a s t i c garbage c o n t a i n e r . North

t J

^ ixvi .05x

2

lx

3

IÎ

.05x

4

T"

lx

5

·

Q|—shed

V) C

.92

P'P

e

Ό5χ

6

lx

7

.05χ

8

4

Figure 2. Layout of the 7 χ 8 or 56 matrix of garbage cans containing 6 p e s t i c i d e s at two d i f f e r e n t concentrations and mixtures with and without a e r a t i o n and n u t r i e n t s .

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

4.

J U N K ET A L .

Controlled Water-Soil Systems

43

t i e s were then c e n t r i f u g e a for 15 minutes and the supernatant l i q u i d was decanted. The combined l i q u i d from the three e x t r a c ­ t i o n s was reduced to about 25 mL under p a r t i a l vacuum. The l i q u i d was e x t r a c t e d i n a separatory funnel with three 50 mL p o r t i o n s of d i e t h y l ether. The combined d i e t h y l ether e x t r a c t s were f i l t e r e d through anhydrous Ν 3 8 0 ^ and the f i l t r a t e reduced to 50 mL under p a r t i a l vacuum. 2

Separation and

Analyses

A t r a z i n e , a l a c h l o r and t r i f l u r a l i n were determined i n the e x t r a c t s of the samples by gas chromatography using a N-P d e t e c t o r . An EC detector was used for the determination of parathion, 2,4-D e s t e r and the 2,4-D acid a f t e r e s t e r i f i c a t i o n with diazomethane. Carb a r y l and 1-naphthol were determined c o l o r i m e t r i c a l l y by the pro­ cedure of McDermott and Recoveries f o r s o i with the s i x commercial formulations at the 0.4 and 0.02% l e v e l s were 96 and 97%, r e s p e c t i v e l y . Comparable recovery e f f i c i e n c i e s were obtained for mixures of the p e s t i c i d e s . In a d d i t i o n , the a b i l i t y to account for a l l the deposited p e s t i c i d e s i n the analyses of the samples taken from the containers p r i o r to any degradations was v a l i d a t i o n for the e f f e c t i v e n e s s of the e x t r a c t i o n procedures. RESULTS AND

DISCUSSION

S o i l and L i q u i d

Analyses

The a n a l y t i c a l data for the added p e s t i c i d e s and two of the h y d r o l y s i s products, 2,4-D acid and 1-naphthol, were used to formulate the degradation graphs shown i n Figures 3-14. Atrazine underwent no degradation e i t h e r alone or i n mixtures and a l a c h l o r and t r i f l u r a l i n underwent no degradation i n mixtures, so the graphs for these p e s t i c i d e s under these c o n d i t i o n s are not shown. For the sake of c l a r i t y , some of the a n a l y t i c a l data from 1, 3, and 4 weeks have been averaged and p l o t t e d as a s i n g l e r e s u l t at the four week i n t e r v a l . These graphs i n d i c a t e v i v i d l y which p e s t i c i d e s degrade and what f a c t o r s such as c o n c e n t r a t i o n , aera­ t i o n , mixtures, and n u t r i e n t s a f f e c t the rate of degradation. The graphs also i n d i c a t e the i n e v i t a b l e u n c e r t a i n t y i n the a n a l y t i c a l r e s u l t s , due to e r r o r s i n c o l l e c t i n g samples from a heterogeneous medium. The placement of the graphs show the e f f e c t of c o n c e n t r a t i o n , where s e v e r a l p e s t i c i d e s decay r e a d i l y at low l e v e l s but do not show measurable degradation when present at high c o n c e n t r a t i o n . The rate of degradation for an i n d i v i d u a l p e s t i c i d e when i t i s alone or i n mixtures can be compared by i n s p e c t i n g successive figures. For example, F i g u r e 3 shows the p l o t s f o r 2,4-D e s t e r when i t i s present alone at two d i f f e r e n t concentrations and under

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

T R E A T M E N T A N D DISPOSAL O F PESTICIDE WASTES

NO

AERATION

NO NUTRIENTS

NO

OTHER

PESTICIDES

3 0 0

200

100

DRY Α ^ Α Ϊ Ι Ο Ν -lJ/MIN.

N O NIJTRIENTS

NCTOVHA^PESTICIDES

ο UJ

e>

UJ >

NO

AERATION

0.1% P E P T O N E

NO OTHER

PESTICIDES

300

200

100

-

AERATION^TJ/MIN.

0.1%PEPTONE

NO

OTHER

300

PESTICIDES RESPIKE

Ψ

200 100

15

30

45

15

3 0

WEEKS

45

66

68 WEEKS

Figure 3. 2,4-D e s t e r degradation with time. s o i l and water; o , amount i n water.

· , amount i n

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

4.

J U N K ET A L .

45

Controlled Water-Soil Systems

NO

AERATION

WEEKS

NO

NUTRIENTS

FIVE

OTHER

PESTICIDES

WEEKS

Figure 4. 2,4-D e s t e r degradation with time in presence of f i v e other formulated p e s t i c i d e s . · , amount i n s o i l ; o , amount in water.

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

T R E A T M E N T A N D DISPOSAL O F PESTICIDE WASTES

NO AERATION

NO NUTRIENTS

AERATION-li/MIN.

AERATION~H/MIN.

NO NUTRIENTS

0.1% PEPTONE

NO OTHER

PESTICIDES

NO OTHER

PESTICIDES

NO OTHER

PESTICIDES

68

68

WEEKS Figure

5.

Degradation

of

hydrolysis

decomposition

and w a t e r ;

o,

amount

in

WEEKS 2,4-D product

ester with

plus time.

the ·,

2,4-D amount

acid in

water.

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

soil

4.

JUNK ET AL.

NO

AERATION

NO N U T R I E N T S

300 200 100

-·

•

·

ο

LU >

OTHER

PESTICIDES

FIVE

OTHER

PESTICIDES

FIVE

OTHER

PESTICIDES

FIVE

OTHER

PESTICIDES

1510

ο

AERATION-lf/MIN.

ο

FIVE

5

oo o ° ο

LU

47

Controlled Water-Soil Systems

NO NUTRIENTS

300 200 100 Q ° Q O O ° NO AERATION 0

«1

300

τ

• ··

CO




CD r-l 1·° co Η

α ^ ο •Η 6 CO ^ ί-ι CD CD Γ Β Ο •Η Η G

CD © o o o o o m m m o Η Η Ν η η 99%) l i b e r a t i o n of _p-nitrophenolate (PNP). Water f o r k i n e t i c experiments was obtained from a M i l l i - Q reverse-osmosis/ion exchange system and was g l a s s - d i s t i l l e d before use. We s y n t h e s i z e d EPMP, by the method of Fukuto and Metcalf (6) by r e a c t i n g d i e t h y l methylphosphonate with phosphorus pentac h l o r i d e , f o l l o w e d by r e a c t i o n with sodium _p-nitrophenolate. EPMP was p u r i f i e d by d i s t i l l a t i o n at reduced pressure. A n a l y s i s f o r C H n N 0 P . C a l c u l a t e d : % C, 44.1; % H, 4.93; % N, 5.71. Found: % C, 43.9; % H, 4.77: % N, 4.59. [Caution! EPMP i s a VERY TOXIC NERVE POISON; the subcutaneous l e t h a l dose (LD50) i n mice i s 350 μg/kg (R. Howd, R. Kenley, unpublished), and the m a t e r i a l should be handled w i t h extreme care at a l l times.] PDEP, was synthesized by r e a c t i n g t e t r a e t h y l biphosphine d i s u l f i d e with S0C1 by the method of P a r s h a l l , (7_) y i e l d i n g ( C H ^ ) P ( 0 ) C 1 . Subsequent r e a c t i o n of the phosphinochloridate w i t h jv-nitrophenol f o l l o w i n g the general method of Douglas and Williams (8) y i e l d e d the d e s i r e d product, which was p u r i f i e d by vacuum d i s t i l l a t i o n . Analysis for C^QH^NO^P. C a l c u l a t e d : % C, 49.28; % H, 5.74; % Ν, 5.74. Found: % C, 49.08; % H, 5.83; % N, 5.59. 2

2

9

2

2

5

2

2

2

Safety P r e c a u t i o n s . Because the phosphorus e s t e r s used i n our s t u d i e s e x h i b i t v a r y i n g (and sometimes unknown) degrees of acute t o x i c i t y , we recommend observing s t r i c t l a b o r a t o r y s a f e t y precautions when handling these m a t e r i a l s .

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

13.

LEE ET AL.

NaBOi Reaction with Organophosphorus Esters

213

Apparatus. Spectrophotometry determination of PNP production was performed with a Perkin-Elmer Model 554 u v - v i s i b l e spectrophoto­ meter equipped with a thermostatted 5 x 5 p o s i t i o n c e l l holder and c e l l programmer. The c e l l programmer a u t o m a t i c a l l y c y c l e s between cuvette p o s i t i o n s and permits the unattended o p e r a t i o n of the instrument. Temperature c o n t r o l was maintained a t 27.5 ± 0.2°C with a Forma S c i e n t i f i c c i r c u l a t i n g constant-temperature bath. Reaction temperatures were determined i n the cuvettes with a N a t i o n a l Bureau of Standards c a l i b r a t e d thermometer. Quartz 1-cm pathlength cuvettes were used throughout. pH readings and adjustments were made using a p o t e n t i o m e t r i c Metrohm Model E526 automatic t i t r a t e r / p H meter. Methods. A l l experiments were conducted i n aqueous s o l u t i o n with PB i n at l e a s t 10-fold molar excess over the other r e a c t a n t . Under these c o n d i t i o n s k i n e t i c production of PN contained the f o l l o w i n g : 0.1 χ 10" mol dm" disodium ethylene diamminetetraacetate, 0.1 mol dm" b u f f e r (sodium borate unless otherwise s p e c i f i e d ) , and NaClO^ added t o b r i n g the s o l u t i o n t o i o n i c strength - 0.50 mol dm" . T y p i c a l l y , PB was added to the a p p r o p r i a t e b u f f e r medium and used immediately to minimize any p o s s i b l e l o s s of peroxygen content. OP reagents were t r a n s f e r r e d v i a m i c r o l i t e r s y r i n g e t o a second b u f f e r s o l u t i o n ; as f o r PB, s o l u t i o n s were used immediately a f t e r p r e p a r a t i o n . The r e a c t i o n s were i n i t i a t e d by t r a n s f e r r i n g an appropriate volume of PB s o l u t i o n ( v i a Ρipetman automatic p i p e t t o r ) to a cuvette and then s i m i l a r l y adding OP e s t e r s o l u t i o n to b r i n g the t o t a l r e a c t i o n volume to 3.00 cm . PNP production was monitored a t 402 nm and q u a n t i t a t e d u s i n g e x t i n c t i o n c o e f f i c i e n t s determined experimentally f o r each r e a c t i o n medium. The f r a c t i o n of r e a c t a n t conversion to product was given by the r a t i o ( A - Α )/(Α - A ) where the s u b s c r i p t s t , o, and » r e f e r , r e s p e c t i v e l y , to absorDance values taken at time t , i n i t i a l l y , and a t long r e a c t i o n times when PNP l i b e r a t i o n c l e a r l y stopped. Rate constants were determined by l i n e a r least-squares r e g r e s s i o n a n a l y s i s , and e r r o r l i m i t s are reported as standard d e v i a t i o n s (S.D.). The r e a c t i o n mechanism between PB and OP compounds i s complex (see equations (2) through (7) below) and leads to very cumbersome a l g e b r a i c expressions; we chose an a l t e r n a t e technique to c a l c u l a t e a, the d i s s o c i a t i o n f r a c t i o n of PB, needed i n our k i n e t i c a n a l y s i s below. The r e a c t i o n s e t was n u m e r i c a l l y modeled using the computer program CHEMK (9) w r i t t e n by G. Z. Whitten and J . P. Meyer and modified by A. Baldwin of SRI t o run on a MINC l a b o r a t o r y computer. CHEMK n u m e r i c a l l y i n t e g r a t e s a defined set of chemical r a t e equations t o reproduce chemical c o n c e n t r a t i o n as a f u n c t i o n of time. E q u i l i b r i a can be modeled by i n c l u d i n g forward and reverse r e a c t i o n s t e p s . Forward and reverse r e a c t i o n r a t e 3

3

3

3

3

t

0

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

214

TREATMENT AND DISPOSAL OF PESTICIDE WASTES

constants were chosen i n r a t i o s to g i v e the f o l l o w i n g e q u i l i b r i a constants based on l i t e r a t u r e values (4,5,10) extrapolated to 27.5°C: K

4

= 1.2xl0~ ,

2

K3 = 2 . 5 x l 0 ~ , 12

K

11

= β.βχΙΟ" .

4

The

c a l c u l a t i o n s were p r e c i s e because concentrations obeyed both mass balance equations and mass a c t i o n expressions f o r equations (2) through (4) (see below). The constant α was c a l c u l a t e d from the expression α = ( [ P B ] - [ P B ] ) / [ P B ] . Q

Q

Results Table 1 shows r e a c t a n t concentrations ( [ P B ] , [PDEP]), f r a c t i o n a l product conversion ( [PNP]^/[PDEP] ), observed h a l f - t i m e ( t ^ o ) , and p s e u d o - f i r s t - o r d e r r a t e constant ( k b ) values f o r r e a c t i o n of PDEP i n pH 8 b u f f e r with and without added PB. Q

Q

s

Table I . Experimental Data f o r Reaction of Sodium Perborate with PDEP at pH 8 (Run 4953-22)

Cuvette 1

Cuvette 2

Cuvette 3

Cuvette 4

Cuvette 5

0

0.500

1.00

2.50

5.00

10 [PDEP] (mol dm" )

5.08

4.98

4.88

4.57

4.07

[PNP] /[PDEP]

1.08

1.08

1.08

1.09

1.07

2.50

1.47

0.852

0.540

0.336

4.72

8.12

3

3

1 0 [ P B ] ( m o l dm" ) Q

6

3

Q

œ

4

10" t

a

1 / 2

c

^obs

a

The k b Q

Q

(s)

l

s

c

u

l

a

t

e


10, the r e a c t i o n conversions were q u a n t i t a t i v e , and that PB concentrations of 0.5 to 5 mM s i g n i f i c a n t l y a c c e l e r a t e d the l i b e r a t i o n of PNP from PDEP. These data are t y p i c a l of a l l experiments performed to date, so d e t a i l s f o r other r e a c t i o n s are not reported here. F i g u r e 1 i s a p l o t of k i n e t i c data according to equation (1) for r e a c t i o n of EPMP with various concentrations of PB at pH = 8. Figure 1 i s t y p i c a l f o r a l l other experiments performed and

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

13.

L E E ET AL.

215

NaBÛ3 Reaction with Organophosphorus Esters

0

480

960

1440

1920

TIME (s)

Figure 1. P s e u d o - f i r s t - o r d e r k i n e t i c p l o t of - n ( A - A ) / ( A - A ) versus time f o r production o f p-nitrophenolate from r e a c t i o n o f sodium perborate at various concentrations with EPMP at 27.5 o c , pH = 8. t

0

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

0

216

T R E A T M E N T A N D DISPOSAL O F PESTICIDE WASTES

shows that the data adhere to equation (1) at l e a s t to 90% conversion. F i n a l l y , F i g u r e 2 shows k p l o t t e d as a f u n c t i o n of [ P B ] f o r paraoxon s o l u t i o n s , repeated at three pH's. These data are again r e p r e s e n t a t i v e , showing that k i s l i n e a r l y r e l a t e d to Q b s

Q

Q b s

For the simultaneous r e a c t i o n of added OP e s t e r with base, water, and perhydroxyl, we must consider the f o l l o w i n g minimum reaction set: PB


PNP + products

(6)

+ OP

2

k S

OP

p

From t h i s scheme we can o b t a i n equation ( 7 ) : -d[0P]/dt = [ 0 P ] ( k

+ ^

g p

0 0

[Η0 "])

(7)

2

i n which k i s the p s e u d o - f i r s t - o r d e r r a t e constant f o r OP h y d r o l y s i s i n the absence of PB. With PB i n great excess, i n buffered s o l u t i o n , k and [Η0 ~] are constant. Then pseudof i r s t - o r d e r k i n e t i c s r e s u l t and we get equation ( 8 ) , 2

-An([0P] /[0P] ) t

= k

o

o b s

*t

(8)

=

i f we d e f i n e k b s ^sp ^H00^^2 ^ * T h i s i s equivalent to equation (1) used i n our spectrophotometric assay. At any pH, [H0 ~] w i l l depend on the f r a c t i o n of PB d i s s o c i a t e d (a) and the f r a c t i o n of the t o t a l peroxide content e x i s t i n g as Η 0 ~ · T h i s l a t t e r number i s g i v e n by Κ^/ζΚ^ + H ) . Combining these r e s u l t s g i v e s : Q

2

+

2

[H0 ~] = ( a ) [ P B ] K / ( K 2

Q

3

From our d e f i n i t i o n of k

k

k

+

obs - sp

k

a

P B

+

3

+ [H ])

we f i n a l l y get by s u b s t i t u t i o n of

o b g

K

K

H0 < t ]o 3/< 3 2

(9)

+

l

H +

10

]»

( >

Equation (10) p r e d i c t s the dependence of k on [ P B ] , i l l u s t r a t e d i n F i g u r e ( 1 ) , and r e q u i r e s that the slope be equal to k ( a K / ( K + [ H ] ) ) and that the i n t e r c e p t be k . Since α can be c a l c u l a t e d , and K 3 and [H ] are known, we can determine k ^ Q from the slope of a l i n e a r r e g r e s s i o n of k^QQ as a Q b s

Q

+

R 0 0

3

3

+

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

13.

L E E ET AL.

NaBC>3 Reaction with Organophosphorus Esters

1

0

4

I

8 10

3

I

I

I

I

12

16

20

24

217

Γ

28

32

36

[ P E R B O R A T E ] (mol dm" ) 3

Figure 2. K i n e t i c p l o t o f p s e u d o - f i r s t - o r d e r r a t e constant f o r r e a c t i o n of paraoxon (k . ) versus concentration o f added sodium perborate at 27.5 oc a t various pH i n 0.1 mol dm" borate b u f f e r . 3

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

218

TREATMENT AND DISPOSAL OF PESTICIDE WASTES

f u n c t i o n o f [ P B ] . T h i s was done f o r f i v e compounds a t pH 8. The r e s u l t s are d i s p l a y e d i n Table 2 along with l i t e r a t u r e values f o r Q

k

H00*

Table II· Comparison of Experimental and L i t e r a t u r e Values f o r k^QQ

Compounds

Slope ( m o l "

Paraoxon

1

(2.2 ± 0.1)

EPMP

(1.0 ± 0.1)

PDEP

(3.2 ± 0.2)

b

(5.9 ± 0.1)

PMP

PNPA

a

(5.6

X

ΙΟ"

X

ίο-*

(K

X

10° 10"

5.1

X

10

2.0 2.6

X

IO" 10"

2.9 3.7

X

X

X

10 10

1

t h i s work

t h i s work 12 t h i s work 13

3

By our

At pH 8.00,

3

3

= 4.0 χ 1 0 . 2

3

3

3

3

l

3

+

t h i s work 11

1

Q

pH 12.00, 0.10 mol dm"" Na HP0 3

X

1

s"" ) Reference

as a f u n c t i o n of [ P B ] .

Q b s

3

+ [H ])/K

3

dm

= (slope) (K3 + [H ] )/YL )(a)~ .

R 0 0

α = 0.78 and (K3 + [ H ] ) / K In

1

1.1 8.4

+

+

b

1

From a l i n e a r r e g r e s s i o n of k analysis k

HOP (mol*"

2

10"

IO"

a

4

X

X

1.1)

l

s~ )

3

dm

4

b u f f e r , a = 1.0 and

=1.4.

Discussion Aqueous PB s o l u t i o n s a r e well-behaved k i n e t i c a l l y with the f i v e OP's s t u d i e s , as evidenced by e x c e l l e n t p s e u d o - f i r s t - o r d e r k i n e t i c s and mass balance between OP and PNP a t the r e a c t i o n termination. Our k i n e t i c a n a l y s i s confirms that r e a c t i o n s (2) through (6) adequately d e s c r i b e PB r e a c t i v i t y , judged by the good agreement of c a l c u l a t e d k^QQ values with l i t e r a t u r e v a l u e s . Equation (10), upon which our a n a l y s i s i s based, i m p l i c i t l y assumes that α i s constant, independent of [ P B ] . This c o n d i t i o n must be t r u e as demonstrated by the l i n e a r r e l a t i o n s h i p between obs l lo' °deling e f f o r t s (not shown) confirm t h i s result. I t i s a consequence of performing r e a c t i o n s i n excess borate b u f f e r , which r e s u l t s i n a b u f f e r i n g of [PB]. In agreement with others, (13) we f i n d H0 ~~ to be 5 0 - f o l d more r e a c t i v e than "~0H as a n u c l e o p h i l e toward e l e c t r o p h i l i c phosQ

k

a

n

d

P B

0

u

r

m

2

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

13.

L E E ET A L .

NaBO Reaction with Organophosphorus Esters 3

219

phorus, and, t h e r e f o r e , sodium perborate i s a p o s s i b l e reagent f o r chemical d e t o x i f i c a t i o n of p e s t i c i d e wastes because i t s u p p l i e s s i g n i f i c a n t concentrations of H0 ~ i n the pH range 8 to 12. 2

Conclusions Sodium perborate, d i s p e r s e d i n water, enhances the degradation rate of phosphorus e s t e r s . I t owes i t s r e a c t i v i t y to hydroperoxyl anion, a powerful n u c l e o p h i l e , which i s produced by d i s s o c i a t i o n of PB i n aqueous s o l u t i o n . Because of i t s s t a b i l i t y , commercial a v a i l a b i l i t y , and great r e a c t i v i t y we recommend PB as a detoxicant for hazardous OP wastes. Acknowledgements T h i s research was supporte Research and Developmen 0003. Approved f o r p u b l i c r e l e a s e ; d i s t r i b u t i o n u n l i m i t e d .

Literature Cited 1. Kirk-Othmer Encyclopedia of Chemical Technology, 2nd ed., Vol. 14, (Wiley Interscience, 1967), pp. 758-760. 2. Edwards, J. O.; Pearson, R. G . ; J. Amer. Chem. Soc. 1962, 8, 16. 3. Edwards, J. O.; Proceedings of Symposium on Non Biological Transport and Transformation of Pollutants on land and Water, National Bureau of Standards, 1976. 4. Edwards, J. O.; J. Amer. Chem. Soc. 1953, 75, 6154. 5. Evans, M. G . ; U r i , N . ; Trans. Faraday Soc. 1949, 45, 224. 6. Fukuto, T. R.; Metcalf, R. L.; J. Amer. Chem. Soc. 1959, 81, 372. 7. Parshall, G. W.; Org. Syn. 1965, 45, 102. 8. Douglas, K. T . ; Williams, Α . ; J. Chem. Soc. Perkin II, 1976, 515. 9. CHEMK, A Computer Modeling Scheme for Chemical Kinetics (undated). G. Z. Whitten and J. P. Meyer. Systems Applications, Inc., 950 Northgate Drive, San Rafael, CA 94903. 10. (a) Determination of pH. Theory and Practice, R. G. Bates (Wiley Interscience, 1973), p 125. (b) Quantitative Chemistry. J. Waser (W. A. Benjamin, 1964), p. 400. 11. Epstein, J.; Demek, M. M.; Rosenblatt, D. H.; J. Org. Chem. 1956, 21, 796. 12. Behrman, E . J.; Biallas, M. J.; Brass, H. J.; Edwards, J. O.; Isaks, M . ; J. Org. Chem. 1970, 35, 3069. 13. Fina, N. J.; Edwards, J. O.; Int. J. Chem. Kin. 1973, 5, 1. RECEIVED February 13, 1984

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

14 Abiotic Hydrolysis of Sorbed Pesticides D. L. MACALADY Department of Chemistry and Geochemistry, Colorado School of Mines, Golden,CO80401 N. L. WOLFE Environmental Research Laboratory, U.S. Environmental Protection Agency, Athens, GA 30613

The hydrolysis of pesticides which are sorbed to sterilized natura in aqueous system pH's. The results show that the rate constants of pH independent ("neutral") hydrolyses are the same within experimental uncertainties as the corresponding rate constants for dissolved aqueous phase pesticides. Base-catalyzed rates, on the other hand, are substantially retarded by sorption and acid-catalyzed rates are substantially enhanced. A large body of evidence w i l l be presented which substantiates these conclusions for a variety of pesticide types sorbed to several well-characterized sediments. The significance of our results for the evaluation of the effects of sorption on the degradation of pesticides in waste treatment systems and natural water bodies w i l l also be discussed.

Whether such d i s p o s a l i s i n t e n t i o n a l or i n c i d e n t a l , s i g n i f i c a n t q u a n t i t i e s of p e s t i c i d e s and p e s t i c i d e wastes end up i n n a t u r a l and a r t i f i c i a l aquatic systems. Thus, any c o n s i d e r a t i o n of the d i s p o s a l of t h i s broad category of anthropogenic chemicals must include an understanding of the r e a c t i o n mechanisms and p r i n c i p a l pathways f o r degradation of p e s t i c i d e s i n aquatic systems. Of the degradative pathways relevant to such systems, h y d r o l y s i s reactions are perhaps the most important type o f chemical decomposition process (Jj-7). Since many p e s t i c i d e s are compounds of low water s o l u b i l i t y , t h e i r form i n aquatic systems i s often dominated not by m a t e r i a l i n aqueous s o l u t i o n , but rather by m a t e r i a l sorbed to suspended or bottom sediments (8_-9). Thus, an understanding of the h y d r o l y t i c reactions of p e s t i c i d e s which are sorbed to 0097-6156/84/0259-0221$07.00/0 © 1984 American Chemical Society

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

222

T R E A T M E N T A N D DISPOSAL O F PESTICIDE WASTES

sediments i s c r u c i a l for an adequate representation of the dominant chemical dégradâtive pathways for these compounds i n aquatic systems. It i s the purpose of t h i s a r t i c l e to summarize the present status of our understanding of the f a c t o r s governing the rates of h y d r o l y s i s of p e s t i c i d e s which are sorbed to sediments. The work reported herein deals s p e c i f i c a l l y with a b i o t i c h y d r o l y s i s r e a c t i o n s , which for some p e s t i c i d e s , may be as important or more important than b i o l o g i c a l l y mediated h y d r o l y s i s r e a c t i o n s (7_, 10-13). U n t i l r e c e n t l y , no e f f o r t s to measure the rates of h y d r o l y t i c degradation of sorbed p e s t i c i d e s have been reported. Indeed, i t has been widely assumed that h y d r o l y t i c reactions are important only i n the aqueous phase and that h y d r o l y s i s of sorbed p e s t i c i d e s proceeds at an i n s i g n i f i c a n t rate (13). The only a v a i l a b l r e l a t e s , though i n d i r e c t l y , to h y d r o l y s i s of sorbed p e s t i c i d e s concerns p e s t i c i d e s i n s o i l systems (see for example 14, 15). Though the r e s u l t s of such studies are not d i r e c t l y a p p l i c a b l e to aquatic systems, they do, i n general, show that c e r t a i n p e s t i c i d e s undergo a b i o t i c r e a c t i o n s i n s o i l - s o r b e d s t a t e s . This review, then, reports r e s u l t s of experiments which provide information that can be used to test the hypothesis that h y d r o l y s i s r e a c t i o n s proceed at s u b s t a n t i a l l y reduced rates when the molecules undergoing h y d r o l y s i s are sorbed to sediments. Results are reported for a v a r i e t y of p e s t i c i d e s and for model compounds that are s i m i l a r i n s t r u c t u r a l features to pesticides. Included are n e u t r a l , base-catalyzed and, to a l i m i t e d extent, a c i d - c a t a l y z e d h y d r o l y s i s r e a c t i o n s . Preliminary

Considerations

Three general c l a s s e s of h y d r o l y t i c r e a c t i o n s in aqueous s o l u t i o n s have been c h a r a c t e r i z e d . In n e u t r a l , or pH independent h y d r o l y s i s , the rate of disappearance of a p e s t i c i d e , P, i s given by

where kj i s the f i r s t - o r d e r disappearance rate constant. For base-mediated h y d r o l y s i s , the corresponding expression i s 4?*-

= -k_[B][P]

=

-k

,

[P]

(2)

dt Β obs where Β represents a generalized base. For n a t u r a l waters and the experimental systems relevant to t h i s report, the only base of s i g n i f i c a n c e for such r e a c t i o n s i s the hydroxide ion, OH (16). In equation 2, k ^ represents a pseudo f i r s t - o r d e r rate constant, v a l i d at f i x e d pH (or [B]). Q

s

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

14.

MACALADY AND WOLFE

Abiotic Hydrolysis of Sorbed Pesticides

223

Recently reported r e s u l t s for the h y d r o l y s i s k i n e t i c s of c h l o r p y r i f o s (7) suggest that equation 2 may not be a v a l i d r e p r e s e n t a t i o n of a l k a l i n e h y d r o l y s i s k i n e t i c s for at l e a s t one c l a s s of p e s t i c i d e s (organophosphorothioates). In short, kg may be pH dependent. However, disappearance k i n e t i c s for such molecules are s t i l l adequately described at f i x e d pH by pseudo first-order kinetics. A c i d - c a t a l y z e d h y d r o l y s i s k i n e t i c s are described by the expression -

dt

"k

+

a

lH ][P]

- -k

. [P] obs

(3)

+

where [H ] represents the hydrogen ion a c t i v i t y , and k ^ the pseudo f i r s t - o r d p r disappearance rate constant at f i x e d pH. For a given p e s t i c i d e which undergoes h y d r o l y s i s any or a l l of these h y d r o l y t i pH's. Organophosphorothioates n e u t r a l and a l k a l i n e h y d r o l y s i s rate constants (7)· Esters of 2,4-dichlorophenoxyacetic a c i d (2,4-D), on the other hand, hydrolyze by acid and a l k a l i n e catalyzed r e a c t i o n s , but have extremely small n e u t r a l h y d r o l y s i s rate constants (17). Thus, any study of the h y d r o l y s i s of sorbed p e s t i c i d e s must be prefaced by an understanding of the h y d r o l y t i c behavior of i n d i v i d u a l p e s t i c i d e s i n aqueous s o l u t i o n . Another important c o n s i d e r a t i o n i n i n v e s t i g a t i o n of the r e a c t i o n of sorbed p e s t i c i d e s i s the nature of the s o r p t i o n process i t s e l f . Sorption/desorption k i n e t i c s and the physicochemical c h a r a c t e r i s t i c s of the p e s t i c i d e molecules i n the sediment-sorbed state can be expected to i n f l u e n c e the k i n e t i c observations made i n experimental systems. Sorption has been commonly described as an e q u i l i b r i u m process, in which the p e s t i c i d e molecules are r a p i d l y and r e a d i l y exchanged between the sediment and aqueous phases. In t h i s approach (8), the e q u i l i b r i u m water phase concentration, C (expressed r e l a t i v e to suspension volume) i s r e l a t e d to the sediment phase concentration, C (expressed r e l a t i v e to dry weight sediment), through 0

g

w

g

K

p

= C /C s

(4)

w

where Κ i s the e q u i l i b r i u m p a r t i t i o n c o e f f i c i e n t (L-g~*) f o r the p e s t i c i d e . C i s then r e l a t e d to the t o t a l concentration of p e s t i c i d e , C , by w

T

C

w

T 1+pK

Ρ where ρ i s the sediment-to-water r a t i o . K has been shown to be d i r e c t l y p r o p o r t i o n a l to the weight f r a c t i o n of organic carbon i n the sediments (O.C.) p

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

TREATMENT AND DISPOSAL OF PESTICIDE WASTES

224

the p e s t i c i d e (18). Several i n v e s t i g a t i o n s have, however, v e r i f i e d the inadequacy of t h i s r e p r e s e n t a t i o n of the s o r p t i o n process. V a r i a t i o n s of "K " with sediment concentration Cl_9,_20) have been reported. More importantly, the rate of the sorption process has been shown to be more complex than a simple rapid e q u i l i b r i u m between sediment and aqueous phases (9_ lOj 21). The fact that s o r p t i v e e q u i l i b r i u m can be approached quite slowly i s i l l u s t r a t e d d r a m a t i c a l l y by data for the system i n which c h l o r p y r i f o s i s sorbed to EPA-14, one of a group of sediments c o l l e c t e d and c h a r a c t e r i z e d for the U. S. Environmental P r o t e c t i o sediment/aqueous concentratio system. It i s c h a r a c t e r i z e d by a r a p i d s o r p t i o n process and a much slower s o r p t i o n process which does not reach e q u i l i b r i u m u n t i l about 10 days a f t e r i n i t i a l mixing of the sediment and chlorpyrifos solution. Though t h i s system i s perhaps an extreme example of slow s o r p t i o n k i n e t i c s , i t i l l u s t r a t e s that the assumption of r a p i d e q u i l i b r i u m between the sediment and aqueous phases i s questionable. The importance of such an observation to the i n v e s t i g a t i o n of h y d r o l y s i s k i n e t i c s i n sediment/water systems must be emphasized. C e r t a i n l y , any model of h y d r o l y s i s k i n e t i c s i n sediment/water systems must include e x p l i c i t expressions for the k i n e t i c s of the s o r p t i o n / d e s o r p t i o n process. Unfortunately, our present understanding of sorption k i n e t i c s i s inadequate to allow unambiguous representation of the s o r p t i o n - d e s o r p t i o n process. C l e a r l y the states of sorbed p e s t i c i d e s include f r a c t i o n s which vary i n t h e i r l a b i l i t y with respect to desorption (9, 10, 21). The f r a c t i o n of the sorbed molecules i n r e l a t i v e l y l a b i l e and n o n - l a b i l e states i s a f u n c t i o n of the nature of the p e s t i c i d e and sediment and the time of contact between the sediment and p e s t i c i d e s o l u t i o n . With these l i m i t a t i o n s i n mind, however, we have used the f o l l o w i n g model to represent the k i n e t i c s of the h y d r o l y s i s of p e s t i c i d e s i n sediment/water suspensions (10) 9

C, w

C

(7)

s k, s

*w Products

Here, k j represents a pseudo f i r s t - o r d e r rate constant ( l i n e a r in sediment concentration) for the s o r p t i o n process, k the Q

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

14.

MACALADY AND WOLFE

Abiotic Hydrolysis of Sorbed Pesticides

1 5

1

1

1

1

1

10

15

20

25

30

1 35

Time (K min) Figure 1. K i n e t i c s o f the s o r p t i o n of c h l o r p y r i f o s sediment, P = 0 . 2 0 , t = 25 ° C .

to EPA-14

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

225

TREATMENT A N D DISPOSAL OF PESTICIDE WASTES

226

f i r s t order rate constant f o r d e s o r p t i o n , k the f i r s t or pseudo f i r s t - o r d e r rate constant f o r h y d r o l y s i s of the aqueous ( d i s s o l v e d ) p e s t i c i d e and k the corresponding rate constant for h y d r o l y s i s of the sorbed p e s t i c i d e . T h i s model, i n l i g h t of the d i s c u s s i o n above, i s c l e a r l y not r e p r e s e n t a t i v e of a l l of the k i n e t i c processes which are o c c u r r i n g i n sediment/water systems c o n t a i n i n g hydrophobic pesticides. However, i t does include at l e a s t the more l a b i l e f r a c t i o n of the sorbed p e s t i c i d e i n the o v e r a l l k i n e t i c model. Complications due to the inadequacy of t h i s r e p r e s e n t a t i o n w i l l be i l l u s t r a t e d and discussed below. Based on t h i s model, the f o l l o w i n g rate equations r e l a t i n g the h y d r o l y t i c degradation of p e s t i c i d e s from sediment water suspensions can be w r i t t e n : dC ~Τ7Γ~ = ~( dt w w

g

dC -Jdt 1

= -(k +k )C s o s

+ k C I w T

(8)

14,000 minutes) the disappearance rate i s f i r s t order f o r both the water and sediment phases. A l s o , the aqueous disappearance rate constant c a l c u l a t e d from the slope of the l i n e a r p o r t i o n of the n a t u r a l log aqueous c o n c e n t r a t i o n versus time plot i s 0.5±0.2 χ 10" min" , which i s s i m i l a r to the values measured i n sediment-free EPA-14 supernatant (Table II). A plot summarizing two experiments using EPA-23 sediment i s shown i n Figure 4. The value of 1^ c a l c u l a t e d from the n a t u r a l log water c o n c e n t r a t i o n vs. time plot i n t h i s f i g u r e i s (1.9*0.2) χ 10" m i n " . Data from these studies were analyzed by a computer using equations 8 based on our simple k i n e t i c model for the sediment/water systems (eqn. 7). The computer program (23) uses concentrations of c h l o r p y r i f o s i n the water and sediment phases and product concentrations (obtained by d i f f e r e n c e ) as a 5

1

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

14.

Abiotic Hydrolysis of Sorbed Pesticides

MACALADY A N D WOLFE

231

8

11

•

Sediment Phase (moles/Kg

•

Water Phase (moles/l x

x

10 ) 6

10 ) 7

Time (K minutes)

Figure 3. C h l o r p y r i f o s disappearance from an EPA-14 sediment/ water system, P= 0 . 2 0 , t = 25 ° C .

io.h

8-

ο

76-

#

Log sediment phase concentration (moles/kg χ 1 0 ) 5

4H 3H

•

Log water phase concentration 7

(moles/1 χ 10 )

I

10

20

30

40

50

60

Time (K min) Figure 4. C h l o r p y r i f o s disappearance from EPA-23 sediment/ water systems, P= 0.016, t = 25 °C.

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

232

T R E A T M E N T A N D DISPOSAL O F PESTICIDE WASTES

f u n c t i o n of time to c a l c u l a t e values f o r any three of the rate constants k j , k , k and k . For the purposes of our c a l c u l a t i o n s , a "known" value of 1.0x10 min" f o r 1^ was used to enable c a l c u l a t i o n of k j , k and k . The r e s u l t s of these c a l c u l a t i o n s are shown i n Table I I I . A l s o shown i n Table I I I are values f o r k , the o v e r a l l c h l o r p y r i f o s disappearance r a t e constant, and a value c a l c u l a t e d f o r k using equation 10, which i s based on k^O, i . e . no h y d r o l y s i s of sorbed chlorpyrifos. Q

w

Q

g

o b

o b s

Table I I I .

Observed and C a l c u l a t e d Values of Rate Constants (min ) f o r C h l o r p y r i f o s i n Sediment/Water Systems at Non-adjusted p H s . f

sediment/ water (p) fraction sorbed sterile? k o b g

k (calc.) k k k (fixed) k PH (H 0 phase)

a

EPA 14

EP

0.20

0.016

0.016

0.94 yes l.OxlO"

0.87 no 1.7xl0~

0.87 yes 1.6xl0~"

5

5

5

Q b

b

x

Q

c

w

s

2

7

6.0xl0~ 6 ± 2)xl0~ (6 ± 2 ) x l 0 " l.OxlO' (6.9 ± 0.9)xl0""

6

3

6

- 3

4

4

5

6

7.2 ± 0.2

1.3xl0" (4 ± D x l O " (4 ± 2 ) x l 0 " l.OxlO" (1.2 ± O . D x l O " 3

4

5

4.1 ± 0.4

1.3xl0" (4 ± D x l O (9 ± 3 ) x l 0 " l.OxlO"" (1.8 ± O.DxlO

5

5

5

7.4 ± 0.4

j*(See text f o r Symbol D e f i n i t i o n s ) . Assuming sediment/water e q u i l i b r i u m , no h y d r o l y s i s i n the sorbed s t a t e , and k - 1.0x10 , k , = k /(1+pK ). C„ , , η , . ODS W Ρ For computer model c a l c u l a t i o n s . W

Several features of these c a l c u l a t i o n s are important. F i r s t , the computer c a l c u l a t e d u n c e r t a i n t i e s shown f o r the c a l c u l a t e d values of k , k and k are an i n d i c a t i o n that the 1 0 s . . model has considerable v a l i d i t y f o r d e s c r i b i n g the k i n e t i c s of the system, at l e a s t over one h a l f - l i f e i n the disappearance of chlorpyrifos. Second, the values of k and k^ are a l l s i m i l a r and t h e i r magnitude i n d i c a t e s that i n t h i s case the assumption of r a p i d s o r p t i o n / d e s o r p t i o n k i n e t i c s compared to h y d r o l y s i s i s valid. More importantly, the c a l c u l a t e d values of k are a l l s i m i l a r i n magnitude to 1^. Coupled with the fact that the T

Q

g

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

14.

Abiotic Hydrolysis of Sorbed Pesticides

MACALADY AND WOLFE

233

values c a l c u l a t e d for k ^ assuming no sediment phase h y d r o l y s i s are a l l c o n s i d e r a b l y lower than the actual values for k ^ > these k values i n d i c a t e that n e u t r a l h y d r o l y s i s of c h l o r p y r i f o s i n the sorbed state proceeds at a rate that i s the same as the disappearance rate i n the aqueous phase. 2. Diazinon and Ronnel. The c o n c l u s i o n that n e u t r a l h y d r o l y s i s of sorbed c h l o r p y r i f o s i s c h a r a c t e r i z e d by a f i r s t order rate constant s i m i l a r to the aqueous phase value i s strengthened and made more general by the r e s u l t s f o r d i a z i n o n , 0,0-diethyl 0-(2-iso-propyl-4-methyl-6-pyrimidyl) phosphorothioate, and Ronnel, 0,0-dimethyl 0-(2,4,5t r i c h l o r o p h e n y l ) phosphorothioate (10). The r e s u l t s f o r the pH independent h y d r o l y s i s at 35°C f o r these compounds i n an EPA-26 sediment/water system (p=0.040) are summarized i n Table IV. Because the aqueous ( d i s t i l l e d ) values of k f o r d i a z i n o n and Ronnel are s i m i l a r i n magnitud and because these value be slow compared to s o r p t i o n / d e s o r p t i o n k i n e t i c s , computer c a l c u l a t i o n s of k were not deemed necessary and were not made for these data. Q

s

Q

s

g

w

g

Table IV.

Experimental Values for Neutral H y d r o l y s i s Disappearance Rate Constants (min ) i n an EPA 26 Sediment/Water System for Diazinon and Ronnel at 35°C a

Diazinon 0.040 0.64 (3 ± D x l O " 1.3xl0~ (1.2 ± 0.2)xl0~^ (3.8 ± 0.6)xl0 (2.9 ± 0 . 5 ) x l 0 "

sediment/waterip) f r a c t i o n sorbed

5

k

obs , obs ( l l d) k^ U i s t i l l e d ) k^ (observed)

k

c a

c u

5

a t e

5

5

k

s

Ronnel 0.040 0.96 (2.7 ± 0 . 4 ) x l 0 " 2.3xl0"

5

6

(2.0 ± 0.2)xl0J (3.8 ± 1.8)xl0 I (2.6 ± 0 . 3 ) x l 0 "

5

Symbols Defined i n t e x t . ^Assuming sediment/water e q u i l i b r i u m , no h y d r o l y s i s i n the sorbed state and k = 3 χ k ( d i s t i l l e d ) - s e e d i s c u s s i o n . k b w

Q

s

~

Again the values of k , c a l c u l a t e d from the log C v s . time p l o t s , were s i m i l a r i n magnitude to the value of k calculated from the log C vs. time p l o t s . A l s o the values or k ^ c a l c u l a t e d from the k =0 assumption i m p l i c i t i n equation 10 were lower than the experimental k ^ v a l u e s . This l a t t e r e f f e c t i s less dramatic for d i a z i n o n since i t s lower Κ value r e s u l t s i n ρ an e q u i l i b r i u m f r a c t i o n sorbed of only 0.64. Note also that the g

w

Q

g

g

Q

s

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

234

T R E A T M E N T A N D DISPOSAL O F PESTICIDE WASTES

values f o r k are 2-3 times the d i s t i l l e d water values. This v observation i s also c o n s i s t e n t with the rate enhancements observed f o r c h l o r p y r i f o s i n n a t u r a l ( c f . d i s t i l l e d ) waters. Thus, for c h l o r p y r i f o s , d i a z i n o n , Ronnel (and by extension, other organophosphorothioate p e s t i c i d e s ) , n e u t r a l h y d r o l y s i s proceeds at s i m i l a r rates i n both the aqueous and sediment phases of sediment/water systems. 3. Experiments on the h y d r o l y s i s of 4-(p-chlorophenoxy) b u t y l bromide, (PCBB) which proceeds v i a an S 2 s u b s t i t u t i o n mechanism (11) were s i m i l a r i n design and data a n a l y s i s procedures to the c h l o r p y r i f o s experiments d e t a i l e d above. Results from a study at 35°C using EPA-12 sediment with 80% of the compound i n the sorbed state are i l l u s t r a t e d i n Figure 5. C a l c u l a t e d and observed values from t h i s study, using the d i s t i l l e d water value for 1^ of (7.9±0.5xl0~ ) min" as a "known value for compute N

5

1

11

kj » 5

1

k = 1.6 χ 10" min k = 5.1 χ 10 min" Again, the value of k i s s i m i l a r i n magnitude to the value of 1^. Other studies using EPA-12 (80-95% sorbed) at 25°C and EPA-10 (90% sorbed) at 35° also i n d i c a t e s i m i l a r values for k and k . Several features of the PCBB experiments are d i f f e r e n t than those f o r c h l o r p y r i f o s . The h y d r o l y s i s r e a c t i o n proceeds v i a a d i f f e r e n t mechanism. The rate enhancements observed for c h l o r p y r i f o s i n n a t u r a l waters and the aqueous phases of the sediment/water systems (as compared to s t e r i l e d i s t i l l e d water) are not observed f o r PCBB. The values of kj. and k c a l c u l a t e d for PCBB are slower than those for c h l o r p y r i f o s anS s i m i l a r i n magnitude to the h y d r o l y s i s r a t e s . In s p i t e of these d i f f e r e n c e s , n e u t r a l h y d r o l y s i s i s s t i l l c h a r a c t e r i z e d by s i m i l a r rate constants f o r both sediment-sorbed and aqueous PCBB. 4. Benzyl c h l o r i d e h y d r o l y s i s proceeds v i a a t h i r d mechanism (S*,l). Results of studies of benzyl c h l o r i d e h y d r o l y s i s ( Π ) i n d i s t i l l e d water and EPA-13 and EPA-2 sediment/water systems are summarized i n Table V. Results f o r t h i s compound include only o v e r a l l f i r s t - o r d e r disappearance rate constants, but the data c l e a r l y show that the h y d r o l y s i s rate i s independent of the f r a c t i o n sorbed to sediment. Thus, the c o n c l u s i o n i s again made that n e u t r a l h y d r o l y s i s proceeds v i a s i m i l a r rate constants i n both the aqueous and sedimentsorbed phases. 0

5

1

s

g

g

w

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

14.

MACALADY A N D WOLFE

Table V.

k

Abiotic Hydrolysis of Sorbed Pesticides

H y d r o l y s i s of Benzyl Chloride Systems at 25°C

obs, m i n ^ x l O

3

i n Sediment/Water

Fraction Sorbed

Sediment to Water R a t i o , p(Sed. *)

1.18 ± 0.05 1.33 ± 0.03 1.1 ± 0.1 1.4 ± 0.1 1.15 ± .05 1.10 ± .08

235

0 0 0.15 0.25 0.87 0.87

0 0 0.025 (EPA 13) 0.05 (EPA 13) 1.0 (EPA 2) 1.0 (EPA 2)

5. The h y d r o l y s i hexachlorocyclopentadien (HEX) represents a fourth h y d r o l y s i s mechanism (S^2*). Studies of the o v e r a l l disappearance k i n e t i c s of HEX from s t e r i l e d i s t i l l e d water and EPA-13 sediment/water systems (12) are summarized i n Table VI. Again, the rate constants are e s s e n t i a l l y independent of the sediment concentration and therefore independent of the f r a c t i o n of the HEX which i s sorbed to the sediment. This i n d i c a t e s that n e u t r a l h y d r o l y s i s of HEX i s also c h a r a c t e r i z e d by s i m i l a r rate constants for both the sediment-sorbed and aqueous phases.

Table VI.

H y d r o l y s i s of Hexachlorocyctopentadiene i n EPA-13 Sediment/Water Systems at 30°C

Sediment to Water Ratio, ρ

0 0.05 0.10 0.15 0.20 0.40 1.0 2.0

k

obs

m

n

i

9 21 26 27 22 16 20 13

± ± ± ± ± ± ± ±

x

^

3 2 2 4 2 1 2 2

In summary, n e u t r a l h y d r o l y s i s rate constants for s i x d i f f e r e n t compounds which hydrolyze by four d i f f e r e n t h y d r o l y s i s mechanisms were determined i n sediment/water systems using seven

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

236

TREATMENT AND

DISPOSAL OF PESTICIDE WASTES

d i f f e r e n t sediments. Sediment to water r a t i o s varying from 5x10 to 2.0 were used. Yet, i n each case, n e u t r a l h y d r o l y s i s of the sorbed compounds was shown to be c h a r a c t e r i z e d by rate constants which were very n e a r l y equal to the rate constants f o r h y d r o l y s i s i n the aqueous phase of these systems. The conclusion i s that n e u t r a l h y d r o l y s i s reactions are not quenched when the molecules undergoing h y d r o l y s i s are sorbed to sediments. In fact the rate of n e u t r a l h y d r o l y t i c r e a c t i o n s appears to be unaffected by s o r p t i o n .

A l k a l i n e H y d r o l y s i s Studies. A l k a l i n e catalyzed h y d r o l y s i s k i n e t i c s i n sediment/water systems have been i n v e s t i g a t e d for c h l o r p y r i f o s and the methyl and n - o c t y l esters of 2,4dichlorophenoxyacetic acid (2,4-D). 1. Chlorpyrifos h y d r o l y s i s s t u d i e s , th a l k a l i n e h y d r o l y s i s k i n e t i c s i n sediment/water systems have been conducted using c h l o r p y r i f o s (10). As can be seen from Figure 2, a l k a l i n e h y d r o l y s i s of c h l o r p y r i f o s i s not second-order, so the value s e l e c t e d for 1^ cannot be c a l c u l a t e d from the pH and a second-order rate constant. Nevertheless, since aqueous k i n e t i c s at a l k a l i n e pH's for c h l o r p y r i f o s was always pseudof i r s t order, c a r e f u l pH measurements and Figure 2 can be used to s e l e c t accurate values for 1^ at any pH. A p r e l i m i n a r y c o n s i d e r a t i o n for studies at a l k a l i n e pH's i s the e f f e c t of pH on Kp values and on sorption/desorption rate constants. Studies using c h l o r p y r i f o s and EPA-26 (p=0.0150) i n d i c a t e no measurable e f f e c t s on Κ over the pH range 5.5-10.8 (K -250±37 for f i v e determinations). K i n e t i c e f f e c t s are a l s o minor, as i l l u s t r a t e d by the s i m i l a r i t y in the c a l c u l a t e d values of k j and k for EPA-23 at pH's of 7.2 and 7.4 (Table III) and 10.67 (Table V I I ) . Two types of i n v e s t i g a t i o n s of the a l k a l i n e h y d r o l y s i s of c h l o r p y r i f o s i n sediment/water systems were made, a l l at pH's between 10.6 and 10.8. F i r s t , studies were conducted i n which the pH was adjusted (using a carbonate b u f f e r ) immediately upon mixing the sediments (EPA-23 and EPA-26) with the c h l o r p y r i f o s solution. Second, a study using EPA-26 was made i n which the a l k a l i n e b u f f e r was not added u n t i l three days a f t e r mixing the sediment with the c h l o r p y r i f o s s o l u t i o n . Three days represents a time which i s long with respect to the achievement of sediment-water e q u i l i b r i u m for t h i s system, yet short compared to the n e u t r a l h y d r o l y s i s h a l f l i f e (~50 days).

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

14.

MACALADY AND WOLFE

Table VII.

Abiotic Hydrolysis of Sorbed Pesticides

237

Experimental and C a l c u l a t e d Values of the Rate Constants f o r the A l k a l i n e H y d r o l y s i s of C h l o r p y r i f o s i n Sediment/Water Systems 3

EPA pH Ρ K

P

ave f r . sorbed

23

EPA

10.67 ± 0 04 0.019 ± 0 001 453 ± 59 0.90 (1.05 ± 0 l l ) x l 0 ~ 5.0xl0" 3 (1.3 ± 0 8)xl0 (1.8 ± 1 D x l O " 4.8xl0" (7. 8)xl 5

k^g(calculated)

b

4

k (fixed)

0

w

k

s

4

26

10.60 ± 0 ,04 0.031 ± 0 ,001 191 ± 4 0.85 (1.10 ± 0 04)xl0"" 6.2x10 (2.5 ± 0.9)xl0 -3 (4.4 ± 1.7)xl0 (4.

4

0.3)xl0

^Symbols defined i n the t e x t . No p r e - e q u i l i b r i u m between gediment and c h l o r p y r i f o s p r i o r to pH adjustment. Assuming sediment/water e q u i l i b r i u m , no h y d r o l y s i s i n the sorbed s t a t e , k ( c a l e . ) = k /(1+pK ). Q ops w ρ For computer c a l c u l a t i o n s . The value of i s the expected d i s t i l l e d water h y d r o l y s i s rate constant at t h i s pH. K

In the f i r s t type of study, pseudo f i r s t - o r d e r k i n e t i c s were observed i n both the sediment and aqueous phases from t=0 through two h a l f - l i v e s i n o v e r a l l c h l o r p y r i f o s disappearance ( t o t a l time -8 days). For these s t u d i e s , computer c a l c u l a t i o n s using the model i l l u s t r a t e d i n equations 7 were again used to c a l c u l a t e values for k j , k and k , assuming a value of k equal to the pseudo f i r s t - o r d e r rate constant i n d i s t i l l e d water buffered to the same pH. Values were also c a l c u l a t e d f o r k ^ assuming kg^O (equation 10) f o r comparison to the experimental k v a l u e s . The r e s u l t s of these c a l c u l a t i o n s are shown i n Table VII. The contrast between these a l k a l i n e h y d r o l y s i s r e s u l t s and the n e u t r a l h y d r o l y s i s r e s u l t s i s s t r i k i n g . The c a l c u l a t e d values of k are lower by f a c t o r s of 7-10 than the corresponding k v a l u e s . The values c a l c u l a t e d f o r k ^ g assuming k =0 are only 1.8-2.1 times smaller than the experimental k ^ values ( c f . c a l c u l a t e d values 12-17 times lower than observed f o r n e u t r a l h y d r o l y s i s at s i m i l a r f r a c t i o n s sorbed). These r e s u l t s , t h e r e f o r e , show that a l k a l i n e h y d r o l y s i s i s c o n s i d e r a b l y slowed when the c h l o r p y r i f o s i s sorbed to sediments. The r e s u l t s from the study f e a t u r i n g s e d i m e n t - c h l o r p y r i f o s e q u i l i b r a t i o n p r i o r to pH adjustment (Figure 6) are Q

g

w

s

g

w

g

Q

s

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

238

T R E A T M E N T A N D DISPOSAL O F PESTICIDE WASTES -4.8-1

-5.0-Τ

-5.2Η c

Φ

-5.4Η

υ c ο ο

σ> ο

Jj

-5.6Η

-5.8Η

•

Sediment layer (moles/Kg)

^

Water layer (moles/1) "Γ­

-6.0-

ιο

12

Time (K minutes) Figure 5. PCBB disappearance from 3 s t e r i l i z e d EPA-12 sediment/ water system, P= 0.050, t = 35 ° C .

c ο k.

c φ υ C

• Total Concentration -7.6-

A Sediment Concentration

Ο

σ> ο

-

1

• Water Concentration -7.8Η

-8.0Η -8.210

20

30

40

Time (K minutes)

"I 50

Figure 6. C h l o r p y r i f o s disappearance from an EPA-26 sediment/ water system e q u i l i b r a t e d f o r three days p r i o r to pH adjustment to 10.6; P= 0.031, t = 25 o c .

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

14.

MACALADY AND WOLFE

Abiotic Hydrolysis of Sorbed Pesticides

239

q u a l i t a t i v e l y d i f f e r e n t than those from the studies without preequilibration. Attempts to f i t these data to our simple k i n e t i c model gave a very poor f i t . The model i s c l e a r l y inadequate i n t h i s case. Though t h i s i s a very l i m i t e d data set, the k i n e t i c s appear to f o l l o w an i n i t i a l disappearance of c h l o r p y r i f o s dominated by a l k a l i n e h y d r o l y s i s of the aqueous phase m a t e r i a l and d e s o r p t i o n of a f r a c t i o n of the sorbed m a t e r i a l . Through approximately one h a l f - l i f e , k ^ i s 2xlO"~ min" , a value s i m i l a r to the k ^ measured f o r the EPA-26 study without pree q u i l i b r a t i o n (1x10 min ). Subsequently, however, k falls to 5x10 min , a number quite s i m i l a r to the k value c a l c u l a t e d f o r the p a r a l l e l study without p r e - e q u i l i b r a t i o n (4xl0~ min" ). These o b s e r v a t i o n s , though t e n t a t i v e , suggest the existence of a s u b s t a n t i a l f r a c t i o n of the sorbed m a t e r i a l which i s c o n s i d e r a b l y less l a b i l m a t e r i a l i n i t i a l l y sorbe these e f f e c t s i s c l e a r l y needed. 2. E s t e r s of 2,4-D. Studies of the a l k a l i n e h y d r o l y s i s of the methyl and n - o c t y l e s t e r s of 2,4-D i n sediment/water systems (24), though less d e t a i l e d than the c h l o r p y r i f o s s t u d i e s , show similar effects. Results from i n v e s t i g a t i o n s using EPA-13 at pH's near 10 f o r the methyl and o c t y l e s t e r s of 2,4-D are summarized i n Figure 7. Under the conditons i n these experiments, the f r a c t i o n s of the methyl and o c t y l e s t e r s which are sorbed to the sediment are 0.10 and 0.87, r e s p e c t i v e l y . The aqueous h y d r o l y s i s h a l f - l i v e s of the methyl and o c t y l esters at pH=10 are 3.6 and 27 minutes, r e s p e c t i v e l y . In the sediment/water system, the methyl e s t e r , which i s mainly i n the d i s s o l v e d phase, hydrolyzes at a rate s i m i l a r to that expected for the sediment-free system at the same pH. The o c t y l e s t e r , on the other hand, hydrolyses at a rate which i s c o n s i d e r a b l y retarded (and n o n - f i r s t - o r d e r ) when compared to the expected aqueous phase r a t e . Though the data are l e s s d e t a i l e d and do not permit c a l c u l a t i o n s s i m i l a r to those conducted f o r c h l o r p y r i f o s , i t i s c l e a r that the e f f e c t of s o r p t i o n i s to c o n s i d e r a b l y slow the a l k a l i n e h y d r o l y s i s r a t e . Studies of the disappearance of the o c t y l ester at pH 9.8 i n sediment/water systems aged 3 days p r i o r to pH adjustment are summarized i n Figure 8. For the systems with p=0.013 and 0.005 ( f r a c t i o n s sorbed = .978 and .945) the rate i s pseudo f i r s t order, but the rate constant i s 1 0 times smaller than the aqueous value (1.6x10 min ) at t h i s pH. As was suggested f o r chlorpyrifos, this k | value may be c h a r a c t e r i s t i c of the a c t u a l value of k . At p=0.001, ( f r a c t i o n sorbed = 0.78), the disappearance k i n e t i c s i s not f i r s t order, but shows r a p i d disappearance of the aqueous e s t e r , followed by disappearance of the sorbed e s t e r at a rate s i m i l a r to the studies with higher sediment to water r a t i o s . 4

Q

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Figure 7. A l k a l i n e h y d r o l y s i s o f the 2,4-D methyl e s t e r ÇpH 10.01) and 2,4-D n-octyl e s t e r (pH 10.12) from h e a t - s t e r i l ized EPA-13 sediment/water systems.

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

14.

M A CA L A D Y A N D W O L F E

Ο * •

Abiotic Hydrolysis of Sorbed Pesticides

2,4-DOE 2,4-DOE 2,4-DOE

ρ = 0.013 ρ = 0.005 ρ = 0.001

k

p

241

= 3500

Time, min Figure 8. A l k a l i n e h y d r o l y s i s o f the 2,4-D n-octyl e s t e r (pH 9.8) in EPA-13 sediment/water systems e q u i l i b r a t e d 3 days p r i o r to pH adjustment.

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Based on experiments f o r these three compounds, i t i s c l e a r that the a l k a l i n e h y d r o l y s i s of sorbed molecules i s s u b s t a n t i a l l y retarded with respect to the rate for d i s s o l v e d molecules. The extent of t h i s r e t a r d a t i o n cannot be q u a n t i t a t i v e l y discussed at t h i s time, however, due to lack of a s u f f i c i e n t l y broad set of d e t a i l e d experimental data. 3. Acid H y d r o l y s i s . Considering the observed r e s u l t s f o r n e u t r a l and a l k a l i n e h y d r o l y s i s , i t i s i n t e r e s t i n g to speculate as to the expected e f f e c t s of s o r p t i o n on a c i d - c a t a l y z e d hydrolysis. Since most sediments are of predominantly c l a y mineralogy, sediment grains e x h i b i t g e n e r a l l y negative surface changes at pH s common i n n a t u r a l waters (25). When t h i s i s the case, one would expect the concentration of negative ions such as OH to be lower near the sediment p a r t i c l e surface. In a d d i t i o n , the ( a c i d i c ) f u n c t i o n a l groups of the organic matter associated with the sediment charged at a l k a l i n e pH's to reduce the rate of a l k a l i n e h y d r o l y t i c processes occuring at these s u r f a c e s . A l s o , r e c a l l that a l k a l i n e h y d r o l y s i s of organophosphorothioates has been shown to involve a n e g a t i v e l y charged intermediate (v.s. and 7_). Such an intermediate would be expected to be less stable i n the n e g a t i v e l y charged environment of the sediment p a r t i c l e surface. On the other hand, the concentration of p o s i t i v e i o n s , i n c l u d i n g H^O , near sediment p a r t i c l e surfaces would be expected to be enhanced r e l a t i v e to the bulk s o l u t i o n concentrations. From t h i s c o n s i d e r a t i o n , we would p r e d i c t that a c i d - c a t a l y z e d h y d r o l y s i s r e a c t i o n s should occur at enhanced rates f o r sorbed molecules. Unfortunately, there i s p r e s e n t l y only a very t e n t a t i v e b i t of evidence a v a i l a b l e to substantiate t h i s p r e d i c t i o n . In one experiment at an a c i d pH, the o v e r a l l rate of h y d r o l y s i s of the n - o c t y l ester of 2,4-D was measured i n a sediment/water s l u r r y i n which a s u b s t a n t i a l f r a c t i o n of the ester was sorbed. The rate was observed to be s u b s t a n t i a l l y f a s t e r than the p r e d i c t e d aqueous phase r a t e . Though t h i s i s an i n d i c a t i o n that the above p r e d i c t i o n i s c o r r e c t , much more experimental work i s needed to s u b s t a n t i a t e and q u a n t i f y t h i s predicted rate enhancement. f

Summary and Conclusions The hypothesis that h y d r o l y s i s of sorbed molecules occurs at rates i n s i g n i f i c a n t with respect to aqueous phase h y d r o l y s i s has been demonstrated to be i n c o r r e c t for n e u t r a l (pH-independent) h y d r o l y s i s r e a c t i o n s . The rate-constants for sorbed s t a t e n e u t r a l h y d r o l y s i s are, on the contrary, s i m i l a r i n magnitude to those for h y d r o l y s i s i n the aqueous phase. The hypothesis has been shown to be more nearly correct f o r a l k a l i n e h y d r o l y s i s r e a c t i o n s , since s i g n i f i c a n t rate

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

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r e t a r d a t i o n s , corresponding to g r e a t l y reduced rate constants for sorbed molecules, occur when s u b s t a n t i a l f r a c t i o n s of the h y d r o l y z i n g molecules are sorbed to sediments. Inadequate understanding of the k i n e t i c s of the s o r p t i o n / d e s o r p t i o n process detracts from our a b i l i t y to completely understand the e f f e c t s of s o r p t i o n on h y d r o l y t i c r a t e s , and more research i s needed i n t h i s regard. Limited experimental evidence and t h e o r e t i c a l c o n s i d e r a t i o n s suggest that a c i d - c a t a l y z e d h y d r o l y s i s rates are s u b s a n t i a l l y enhanced f o r sorbed molecules. Much more experimental evidence i s necessary, however, to v e r i f y t h i s effect. These conclusions have several i m p l i c a t i o n s f o r p e s t i c i d e waste d i s p o s a l c o n s i d e r a t i o n s . For i n c i d e n t a l or a c c i d e n t a l d i s p o s a l of p e s t i c i d e s i n n a t u r a l aquatic systems, the r e s u l t s suggest that model c a l c u l a t i o n for a b i o t i c neutral hydrolysi without regard to s o r p t i o n to sediments. For a l k a l i n e h y d r o l y s i s , on the other hand, models must e x p l i c i t l y include s o r p t i o n phenomena and the corresponding rate reductions i n order to a c c u r a t e l y p r e d i c t h y d r o l y t i c degadation. The l i m i t e d a c i d - h y d r o l y s i s r e s u l t s , i f substantiated, have broader i m p l i c a t i o n s . They suggest that rapid h y d r o l y s i s of p e s t i c i d e wastes i n a c i d i f i e d a r t i f i c i a l sediment/water s l u r r i e s may be an a t t r a c t i v e method f o r the i n t e n t i o n a l d i s p o s a l and degradation of p e s t i c i d e wastes. Acknowledgments Most of the work reviewed i n t h i s a r t i c l e was performed at the U. S. Environmental Research Laboratory i n Athens, GA. Support f o r Donald Macalady's work at t h i s laboratory was provided by a Senior A s s o c i a t e s h i p award from the National Rsearch C o u n c i l . NOTE : Mention of trade names or commercial products does not c o n s t i t u t e endorsement or recommendation f o r use by the U. S. Environmental P r o t e c t i o n Agency.

Literature Cited 1. 2. 3. 4. 5. 6.

Wolfe, N.L.; Zepp, R.G.; Paris, D.F. Water Research, 1978, 12, 561. Wolfe, N.L.; Burns, L.A.; Steen, W.C. Chemosphere, 1980, 9, 393. Wolfe, N.L.; Zepp, R.G.; Doster, J.C.; H o l l i s , R.C. J. Agric. Food Chem., 1976, 24, 1041. Wolfe, N.L.; Zepp, R.G.; Paris, D.F. Water Reserch, 1978, 12, 565. Maquire, R.J.; Hale, E.J. J. Agric. Food Chem., 1980, 28, 372. Ou, L.T.; Gancarz, D.H.; Wheeler, W.B.; Rao, P.S.C.; Davidson, J.M. J. Environ. Quality, 1982, 11, 293.

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7. 8. 9.

10.

11.

12. 13. 14. 15. 16. 17. 18. 19. 20. 21.

22.

23. 24.

25.

Macalady, D.L.; Wolfe, N.L., J. Agric. Food Chem., 1983, 31, 1139. Karickhoff, S.W.; Brown, D.S.; Scott, T.A. Water Research, 1979, 13, 241. Karickhoff, S.W. In Contaminants and Sediments, Baker, R.A., Ed. Ann Arbor Science, Ann Arbor, MI, 1980; Vol. 2, Chapter II. Macalady, D.L.; Wolfe, N.L. "Effects of Sediment Sorption on Abiotic Hydrolyses: I. Organophosphorothioate Esters", submitted to Environ. S c i . Technol., 1983. Pierce, J.H.; Wolfe, N.L. "Effects of Sediment Sorption on Abiotic Hydrolyses: II. 4-(p-chlorophenoxy) butyl bromide and Benzyl Chloride", paper in preparation, 1984. Wolfe, N.L.; Zepp, R.G.; Schlotzhauer, P.; Sink, M. Chemosphere 1982, 11, 91. Wolfe, N.L.; Zepp H o l l i s , R.C. Environ Sethunan, N.; MacRae, I.C., J. Agric. Food Chem. 1969, 17, 221. Mingelgrin, U.; Saltzman, S.; Yaron, B. Soil Sci. Soc. Am. J. 1977, 41, 519. Perdue, E . M . ; Wolfe, N.L. Environ. Sci. Technol. 1983, 11, 635. Wolfe, N.L., U.S. Environmental Protection Agency, Athens, GA. Unpublished results, 1982. Karickhoff, S.W. Chemosphere, 1981, 10, 833. O'Connor, D.J.; Connolly, J.P. Water Research, 1980, 14, 1517. Voice, T.C.; Rice, C . P . ; Weber, W . J . , J r . Environ. Sci. Technol., 1983, 17, 513. M i l l e r , C.T.; Weber, W . J . , J r . 186th National Meeting of the American Chemical Society, Washington, D.C., August, 1983; Abstr. PEST 73. Hassett, J.J.; Means, J.C.; Banwort, W.L.; Wood, S.G. "Sorption Properties of Sediments and Energy Related Pollutants"; U.S. Environmental Protection Agency, Athens, Georgia. EPA-600/3-80-041, 1980. Knott, G.; Reece, D. "MLAB", Division of Computer Research and Technology, National Institute of Health, Bethesda, MD 20014, 7th ed., 1977. Wolfe, N.L. "Effects of Sediment Sorption on Abiotic Hydrolyses: III. Carboxylic Acid Esters", paper in preparation, 1984. Stumm, W.; Morgan, J.J. "Aquatic Chemistry", 2nd E d . , John Wiley & Sons, New York, 1981; Ch. 10.

RECEIVED April 16, 1984

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

15 Investigation of Degradation Rates of Carbamate Pesticides Exploring a New Detoxification Method A. T. LEMLEY and W. Z. ZHONG Department of Design and Environmental Analysis, Cornell University, Ithaca, NY 14853 G. E. JANAUER and R. ROSSI Department of Chemistry, State University of New York at Binghamton, Binghamton, NY 13901

Base hydrolysis kineti solutions of carbofuran,3-OH carbofuran, methomyl and oxamyl. The results are compared with those reported previously for aldicarb, aldicarb sulfoxide, and aldicarb sulfone. Second order reaction rate constants, k , have been calculated and range from 169 l i t e r min mole for oxamyl to 1.15 l i t e r min mole for aldicarb. The order for rate of base hydrolysis is as follows: oxamyl >3-hydroxycarbofuran >aldicarb sulfone ~ carbofuran >aldicarb sulfoxide > methomyl ~ aldicarb. The activation energy for the base hydrolysis of carbofuran was measured to be 15.1 + 0.1 kcal mole , and is similar to the value previously reported for aldicarb sulfone. Rapid detoxification of aldicarb, a representative oxime carbamate pesticide, by in s i t u hydrolysis on reactive ion exchange beds is reported. Nucleophilic cleavage, acid catalyzed hydrolysis, and oxidation of aldicarb in dilute solution were achieved in batch and/or column experiments using macroporous reactive ion exchange resins. As in solution, nucleophilic cleavage proceeds faster than acid catalyzed hydrolysis. The basis for pursuing study of the latter mechanism is discussed. r

-1

-1

-1

-1

-1

Chemical degradation has been i n v e s t i g a t e d by Shih and D a l Porto (1) and by Lande (2) under EPA auspices as an a l t e r n a t i v e approach ( t o l a n d f i l l d i s p o s a l ) f o r the removal of p e s t i c i d e r e s i d u e s . Among candidate r e a c t i o n s f o r the s a f e d e t o x i f i c a t i o n of p e s t i c i d e s , only a l k a l i n e h y d r o l y s i s was recommended. Several organophosphates and carbamates were i d e n t i f i e d as amenable to a degradation procedure using strong base/aqueous a l c o h o l . The 0097-6156/84/0259-0245S06.00/0 © 1984 American Chemical Society

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main c r i t e r i o n f o r a p p l i c a b i l i t y was the v i r t u a l absence of t o x i c (degradation/reaction) products, which was met by 18 compounds i n c l u d i n g major p e s t i c i d e s such as malathion, phorate, and a l d i c a r b . Although d e g r a d a t i o n / r e a c t i o n products and t h e i r t o x i c o l o g i c a l p r o p e r t i e s were i d e n t i f i e d wherever p o s s i b l e , there were many cases where such information was not a v a i l a b l e and chemical d i s p o s a l was not recommended. The p o t e n t i a l u t i l i t y of a l k a l i n e h y d r o l y s i s was e s t a b l i s h e d , other p o s s i b i l i t i e s such as a c i d h y d r o l y s i s explored, and a d d i t i o n a l research suggested by these authors (1,2) . Janauer et a l . (3} showed r e c e n t l y that r e a c t i v e i o n exchange (RIEX) methods, p r e v i o u s l y employed f o r the p r e c o n c e n t r a t i o n / i s o l a t i o n of i n o r g a n i c t r a c e s p e c i e s , can e f f e c t i v e l y degrade i n s i t u (on s u i t a b l e r e s i n s ) r e p r e s e n t a t i v e organophosphates which are subject to n u c l e o p h i l i c a t t a c k Thus, r a p i d decomposition/remova accomplished by passin r e s i n bed i n the f r e e 0H~ form. In one s e r i e s of experiments, s o l u t i o n s c o n t a i n i n g 1-25 ppm of the p e s t i c i d e s malathion, guthion, d i a z i n o n , f e n i t r o t h i o n , and parathion were passed through short columns (ID = 0.70 cm) packed with strong base anion exchange r e s i n s (0H~ form) at flow rates v a r y i n g from 2-5 ml/min which produced e f f l u e n t s c o n t a i n i n g l e s s than 0.1% of the s t a r t i n g m a t e r i a l (4)· A d d i t i o n a l column experiments with paraoxon e s s e n t i a l l y d u p l i c a t e d e a r l i e r r e s u l t s (5) so that the i n s i t u degradation of organophosphates on r e a c t i v e r e s i n s was shown to work with at l e a s t f i v e d i f f e r e n t i n s e c t i c i d e s . Janauer a l s o predicted that RIEX would be e f f e c t i v e i n d e t o x i f y i n g s o l u t i o n s containing carbamate p e s t i c i d e s . The discovery of the contamination of d r i n k i n g water on eastern Long Island by the p e s t i c i d e Temik, whose a c t i v e i n g r e d i e n t i s a l d i c a r b [2-methyl-2-(methylthio)propionaldehyde-O-(methylcarbamoyl)oxime], provided a case study f o r the a p p l i c a t i o n of strong base h y d r o l y s i s v i a RIEX to p e s t i c i d e contaminated d r i n k i n g water. The p o t e n t i a l use of s u b s t i t u t e crop protectants i n areas where contamination has been discovered and the general l a c k of information with respect to the l e a c h i n g p r o p e r t i e s and groundwater p e r s i s t e n c e of many carbamate and organophosphorus p e s t i c i d e s make i t imperative to i n v e s t i g a t e the degradation behavior of a broad range of these compounds· The c o l l a b o r a t i o n of two research groups on t h i s d r i n k i n g water p r o j e c t was brought about through the i n t e r v e n t i o n of C o r n e l l ' s Center f o r Environmental Research. The i n i t i a l seed money provided helped to l a y the groundwork f o r the more ambitious p r o j e c t now being supported by the United States Environmental P r o t e c t i o n Agency. Major research o b j e c t i v e s of the p r o j e c t i n c l u d e d : 1. Development of improved methodology f o r separation and q u a n t i t a t i o n of a l d i c a r b and s i m i l a r carbamate p e s t i c i d e s .

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

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L E M L E Y ET AL.

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2.

I n v e s t i g a t i o n of the k i n e t i c s of h y d r o l y s i s of a l d i c a r b and other carbamate p e s t i c i d e s under a v a r i e t y of c o n d i t i o n s i n s o l u t i o n , 3. Demonstration of the f e a s i b i l i t y and e f f i c i e n c y of r e a c t i v e i o n exchange procedures f o r the d e t o x i f i c a t i o n of carbamates· 4. Development and f i e l d t e s t i n g of an experimental D e t o x i f i c a t i o n / F i l t e r Unit by adapting a s u i t a b l e conventional i o n exchange device· The f i r s t o b j e c t i v e has been accomplished by the development of an HPLC procedure as reported by S p a l i k et a l . (5) and GC/NPD procedures developed by Lemley and Zhong (6)· The second and t h i r d o b j e c t i v e s are being accomplished by fundamental s o l u t i o n studies and r e a c t i v e i o n exchange experiments conducted i n p a r a l l e l . Lemley and Zhon k i n e t i c s data f o r base metabolites at ppm concentrations and f o r a c i d h y d r o l y s i s of a l d i c a r b s u l f o n e . They have s i n c e (6) reported s i m i l a r r e s u l t s f o r ppb s o l u t i o n s of a l d i c a r b and i t s m e t a b o l i t e s . In a d d i t i o n , the e f f e c t on base h y d r o l y s i s of temperature and c h l o r i n a t i o n was s t u d i e d and the e f f e c t of using a c t u a l w e l l water as compared to d i s t i l l e d water was determined. S i m i l a r base h y d r o l y s i s data for carbofuran, methomyl and oxamyl w i l l be presented i n t h i s work. P r e l i m i n a r y r e s u l t s of r e a c t i v e i o n exchange batch and column work w i l l a l s o be reported here. Column s t u d i e s n e c e s s a r i l y take more time to do and must r e l y on the wide range of data which can be obtained i n s o l u t i o n . Values of k ^ obtained i n s o l u t i o n are necessary f o r c o r r e l a t i o n with and p r e d i c t i o n of column c o n d i t i o n s . The f i n a l o b j e c t i v e of t h i s research, the development and t e s t i n g of a d e t o x i f i c a t i o n / f i l t e r u n i t , w i l l be pursued i n the near future as soon as column c o n d i t i o n s are s u f f i c i e n t l y c o r r e l a t e d with s o l u t i o n and batch RIEX r e s u l t s so as to permit o p t i m i z a t i o n . Q

s

Experimental Materials. A l d i c a r b standards were obtained from the United States Environmental P r o t e c t i o n Agency (USEPA), Q u a l i t y Assurance Section and from Union Carbide C o r p o r a t i o n . C r y s t a l l i n e samples of carbofuran and 3-hydroxycarbofuran were s u p p l i e d by the A g r i c u l t u r a l Chemical Group of FMC C o r p o r a t i o n . Reference standards of methomyl (99% pure) and oxamyl (99% pure) were obtained from USEPA. HPLC grade methanol was purchased from Burdick and Jackson, Inc. Methylene c h l o r i d e used f o r bulk e x t r a c t i o n s of the carbamate p e s t i c i d e s i n s o l u t i o n was recovered, d i s t i l l e d and reused. A n a l y t i c a l reagent grade chemicals and s o l v e n t s were used i n a l l experiments. Doubly d i s t i l l e d deionized water was used f o r s o l u t i o n r a t e s t u d i e s . Deionized d i s t i l l e d water (DDW) was used f o r d i l u t i o n s i n r e a c t i v e i o n exchange experiments· . B

American Chemical Society Library 1155

16th St.

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W.

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; Washington. American Chemical Washington, DC, 1984. D. Society: C. 2003(1

T R E A T M E N T A N D DISPOSAL OF PESTICIDE WASTES

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C^3 SEP-PAK c a r t r i d g e s (Waters A s s o c i a t e s ) used i n these experiments were p r e t r e a t e d by passing through 5 ml o f HPLC-grade methanol followed by 10 ml o f DDW. Reactive i o n exchange work was performed using macroporous AG MP-1 strong base anion exchanger, 100-200 mesh, converted to the 0H~ or S 03 = form ( C I or S04 were used as c o n t r o l s f o r s o r p t i o n by r e s i n ) and AG MP-50 strong a c i d c a t i o n exchanger, 100-200 mesh, i n the f r e e H form ( N a was used as a c o n t r o l f o r r e s i n s o r p t i o n ) obtained from B i o Rad Laboratories· S o l u t i o n blanks (no r e s i n ) were a l s o used to determine the adsorption due t o the r e a c t i o n f l a s k . 2

=

+

+

Degradation Rates. Procedures f o r determining the p s e u d o - f i r s t o r d e r , k b , and second o r d e r , k , r a t e constants f o r h y d r o l y s i s of carbamate p e s t i c i d e s i n s o l u t i o n were s i m i l a r to those reported f o r a l d i c a r b / m e t a b o l i t e s (_7) . A s o l u t i o n o f known c o n c e n t r a t i o n o f NaOH was added t o a 200 ml f l a s k and brought to the d e s i r e d thermal e q u i l i b r i u t h i s was added 1 ml o s o l u t i o n such that the f i n a l c o n c e n t r a t i o n was known (25-200 ppb). The mixture was shaken immediately, and a s l i g h t excess amount o f HC1 was added a t zero time and p e r i o d i c a l l y t h e r e a f t e r (measured by stopwatch) t o n e u t r a l i z e the base and stop the h y d r o l y s i s r e a c t i o n . The s o l u t i o n was immediately t r a n s f e r r e d t o a separatory funnel f o r e x t r a c t i o n . The progress of base h y d r o l y s i s was followed d i r e c t l y by measuring the disappearance of the p e s t i c i d e using the gas chromatographic procedures d e s c r i b e d i n t h i s paper. Procedures f o r i o n exchange experiments i n general and f o r determination o f k b , the apparent i n s i t u , p s e u d o - f i r s t order r a t e constant o f h y d r o l y s i s f o r a l d i c a r b on OH"" r e s i n , i n batch experiments has been p r e v i o u s l y reported ( 3 ) . 0

s

r

0

s

w

e

r

e

P s e u d o - f i r s t order r a t e c o n s t a n t s , k bs> determined f o r the chemical degradation o f d i l u t e a l d i c a r b s o l u t i o n s (200 ppb) by RIEX as f o l l o w s : 1.0 gram of an a i r d r i e d macroporous i o n exchange r e s i n , e i t h e r AG MP-1 C I " form or AG MP-50 H form, was weighed and allowed to s w e l l i n DDW f o r a minimum of four hours. The r e s i n s l u r r y was t r a n s f e r r e d t o a f r i t t e d g l a s s column (diameter = 0.70 cm.). Conversion t o the appropriate counterion résinâtes was e f f e c t e d by passing 100 ml o f a 0.1 Ν s o l u t i o n o f e i t h e r NaOH, B a ( 0 H ) , K2 2°8> NaS04, or NaNo through the packed, a i r - b u b b l e f r e e r e s i n bed which was then washed with 250 ml DDW. A f t e r a i r d r y i n g i n the column, the r e s i n was t r a n s f e r r e d t o a 250 ml erlenmeyer f l a s k to be used as the " r e a c t i o n f l a s k " and allowed to r e s w e l l i n 50.5 ml o f DDW. The r e a c t i o n f l a s k was placed on a conventional waterbath shaker (Eberbach Corp., 180 o s c i l l a t i o n s / m i n . ) and 50.00 ml of a 400 ppb a l d i c a r b s o l u t i o n was added, and a g i t a t i o n s t a r t e d a t 180 ( l i n e a r ) strokes per minute. The r e a c t i o n was allowed to proceed f o r a s p e c i f i e d period o f time followed by f i l t r a t i o n o f the mixture and c o l l e c t i o n o f the supernatant. The supernatant was Q

+

S

2

3

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

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249

then pumped through a SEP-PAK and e l u t e d with 2.00 ml o f HPLC-grade methanol c o n t a i n i n g a small amount o f a c e t i c a c i d or acetate b u f f e r (_5) . This e l u a t e was passed through a M i l l i p o r e c l a r i f i c a t i o n organic f i l t e r i n a Luer-Lok s y r i n g e before a n a l y s i s by HPLC (see below). A n a l y t i c a l Procedures. The e x t r a c t i o n procedure used f o r s o l u t i o n s t u d i e s was based on the method s u p p l i e d by Union Carbide Corporation ( 8 ) , and was reported i n previous work ( 6 ) . Samples were analyzed using a Microtek GC with a Tracor NP d e t e c t o r as d e s c r i b e d by Lemley and Zhong (6) . Conditions used for the various p e s t i c i d e s analyzed and the r e t e n t i o n times obtained are d e t a i l e d i n Table I . In a l l cases a 4 foot χ 4 mm I.D. g l a s s column packed with 1.5% SP-2250/1 .95% SP-2401 on 100/120 mesh Supelcoport was used. A g l a s s i n j e c t o r was used f o r the a n a l y s i s of carbofura were v a r i e d s l i g h t l y f o inches of the column were packed with 1.5% 0V-17 on 100/120 mesh Supelcoport, and a g l a s s i n j e c t o r was used without g l a s s wool a t the end· , Analyses f o r a l d i c a r b (disappearance) subsequent to r e a c t i v e ion exchange followed the procedures o u t l i n e d by S p a l i k et a l . (5). Analyses were performed using a Waters Model 6000A pump, a Model 440 absorbance d e t e c t o r f i x e d at 254 nm., a μ-Bondapack C13 column and a Model SRG Sargent r e c o r d e r . I n most experiments the e l u t i n g s o l v e n t was methanol:DDW (35:65) with 1% v/v a c e t i c a c i d added to the s o l v e n t mixture. The f l o w - r a t e i n HPLC runs was 1.0 ml/min. Peak heights were used to q u a n t i f y a l d i c a r b i n some o f the e a r l i e r experiments , but a Hewlett-Packard i n t e g r a t o r was used l a t e r . A p o l y s t a l t i c pump (Buchler Instruments) was used to pump s o l u t i o n a t a r a t e of 10 ml/min through a C^g SEP-PAK to preconcentrate it·

Results and Discussion P s e u d o - f i r s t order r a t e c o n s t a n t s , k b , f o r the disappearance o f p e s t i c i d e i n aqueous s o l u t i o n (doubly d i s t i l l e d d e i o n i z e d water) as a f u n c t i o n o f NaOH c o n c e n t r a t i o n were measured f o r s o l u t i o n s of carbofuran (30 ppb) , 3-hydroxycarbofuran (200 ppb) , methomyl (25 ppb), and oxamyl (25 ppb). These r e s u l t s are reported i n Tables II-V. In each case excepting carbofuran a s t r a i g h t l i n e with high c o r r e l a t i o n c o e f f i c i e n t was obtained, confirming p s e u d o - f i r s t order behavior. There i s a short p l a t e a u before the s t r a i g h t l i n e p o r t i o n i n the carbofuran p l o t s as shown i n F i g u r e 1. When experiments are performed a t higher temperature, the p l o t s become s t r a i g h t l i n e s , i n d i c a t i n g the presence o f a s h o r t - l i v e d i n t e r m e d i a t e . The k ^ values obtained from r e g r e s s i o n analyses of the slopes were p l o t t e d v s . hydroxyl i o n c o n c e n t r a t i o n . These p l o t s y i e l d e d s t r a i g h t l i n e s passing through the o r i g i n f o r each s p e c i e s , and the second order Q

0

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Table I . Chromatographic Conditions f o r Analysis of Carbamate P e s t i c i d e s Extracted from Solution Gas Flow Rate (ml/min) He H2 Air A l d i c a r b Sulfone Carbofuran 3-0H Carbofuran Methomyl Oxamyl

Table I I .

Concentration of NaOH χ 10 (mole l i t e r ) 3.73 5.59 6.51 8.14 9.77

38 35 55 80 35

2.8 3.6 3.6 3.6 2.

k

obs

x

1

0

_ 1

(min ) 1 .16 1.67 1.95 2.58 2.95

Table I I I .

Concentration of NaOH χ 10 (mole l i t e r ) 3.02 4.69 6.70 10.7 15.4

300 220 220 220

160 190 210 125

k

r

Standard Error (±) 0.001 0.002 0.001 0.001 0.005

250 250 250 250

99TÎ

1.6 4.9 3.5 1.1

(30 ppb) at

k

2

(%) 99.8 99 .8 99.9 100 99.5

Retention Time (min)

r

1

1

( l i t e r min" mole" ) 31 .1 29.9 30.0 31.7 30.2

3.06 χ 10 ± 0.6

Base Hydrolysis Rate Constants of 3-Hydroxycarbofuran (200 ppb) at 15°C o b s

χ 10

4

_ 1

Injector

Base Hydrolysis Rate Constants of Carbofuran 15°C

3

_ 1

120 120 120 120

Temperature (°C) Column Detector

1

(min" ) 0.47 0.56 1.02 1.50 1.78

Standard Error (±) 0.002 0.002 0.002 0.003 0.004

r

2

(%) 95.8 95.5 99.1 98.7 99.1 96.0

k

r

χ 10" 1

2

1

( l i t e r min" mole" ) 1 .57 1.20 1.52 1.40 1.16 1.19 χ 10 ± 5

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

z

15.

Table IV. Base Concentration of NaOH χ 10 (mole l i t e r " ) 4.06 5.41 8.12 9.47 12.2

Hydrolysis Rate Constants of Methomyl (25 ppb) at 15°C k

obs

x

1

2

1

Table V. Concentration of NaOH χ 10 (mole l i t e r ) 3.77 6.28 7.54 8.79 12.6

0

Standard Error

r

2

(min ) 0.55 0.7 1.05 1.22 1 .64

k

(lite

-1

min

- 1

-1

mole )

1.29 1.29 1 .35 1 .32 ± 0.06

99.8 99.8 99.6 99.2

0.001 0.001 0.002

r

Base Hyrolysis Rate Constants of Oxamyl (25 ppb) at 15°C k

obs

x

1

0

4

- 1

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Degradation Rates of Carbamate Pesticides

LEMLEY ET AL.

-1

(min ) 0.64 1 .05 1.32 1 .55 2.13

Standard Error (±) 0.001 0.001 0.001 0.002 0.001

r

2

(%) 99.2 99.9 99.9 99.7 99.9 99.8

k

r

χ 10

- 2

- 1

-1

( l i t e r m i n mole ) 1.70 1.67 1.75 ' 1.76 1 .69 1 .69 Χ 10 ± 2

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

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TREATMENT AND DISPOSAL O F PESTICIDE WASTES

Time (min) Figure 1. Base h y d r o l y s i s o f 30 ppb s o l u t i o n o f carbofuran with various hydroxy! ion concentrations a t 15 ° C . 1) 3.73 χ 10~ M, 2) 5.59 χ 1 ( Γ Μ , 3) 6.51 χ 10" M, 4) 8.14 χ 10" M, 5) 9.77 χ 10" M. 3

3

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In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

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r e a c t i o n r a t e constant, k , was computed f o r each species as the slope of the r e s p e c t i v e l i n e . A summary of the base h y d r o l y s i s second order r e a c t i o n r a t e constants f o r a l l carbamate p e s t i c i d e s s t u d i e d thus f a r i s presented i n Table V I . The h y d r o l y s i s data c o l l e c t e d f o r t h i s group of carbamate p e s t i c i d e s have s i g n i f i c a n c e f o r s e v e r a l reasons . The k b s values are expected to c o r r e l a t e d i r e c t l y with batch and column RIEX data such as those reported i n t h i s paper ( v i d e i n f r a ) . Since column and batch experiments with i o n exchangers are more time consuming compared to s o l u t i o n s t u d i e s , the data generated i n s o l u t i o n become a u s e f u l base f o r d e c i s i o n s about f u t u r e i o n exchange experiments. In a d d i t i o n , the r e a c t i o n r a t e constants c a l c u l a t e d can be used to compare degradation of i n d i v i d u a l p e s t i c i d e s with each o t h e r . In cases where both the parent compound and o x i d a t i v e metabolites have been s t u d i e d e.g. a l d i c a r b and carbofuran degrades more r a p i d l y b does the parent compound. These r e s u l t s enable one to p r e d i c t that a p r e o x i d a t i o n treatment p r i o r to h y d r o l y s i s should make a more e f f i c i e n t r e a c t i v e i o n exchange procedure. A ranking of these p e s t i c i d e s with respect to ease of d e t o x i f i c a t i o n by h y d r o l y s i s can thus be used as a b a s i s f o r determining treatment of d r i n k i n g water, and can a l s o be used to p r e d i c t the r e l a t i v e environmental f a t e parameters. Assuming s i m i l a r dependence of k b on 0H~ c o n c e n t r a t i o n f o r environmental pH v a l u e s , the rankings obtained i n t h i s study can be a p p l i e d to environmental c o n d i t i o n s and can be u s e f u l f o r p e s t i c i d e application decisions · r

0

0

Table V I .

Name of Compound

s

Base H y d r o l y s i s Rate Constants Carbamate P e s t i c i d e s and M e t a b o l i t e s at 15°C

k ( l i t e r min" Aldicarb 1.15 Aldicarb Sulfoxide 11.4 A l d i c a r b Sulfone 33.0 Carbofuran 30.6 3-Hydroxycarbofuran 119 Methorny1 1.32 Oxamyl 169 r

1

1

mole" )

of

Standard E r r o r (±) 0.02 0.2 0.7 0.6 5 0.06 2

In a d d i t i o n to the above s o l u t i o n s t u d i e s , experiments designed to study the e f f e c t of temperature on the base h y d r o l y s i s of carbofuran were performed at f i v e temperatures between 5 and 35°C. The r e s u l t s are reported i n Table V I I . The

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

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TREATMENT AND DISPOSAL OF PESTICIDE WASTES

s t u d i e s were i d e n t i c a l to the rate s t u d i e s described above, and values f o r k b and k were c a l c u l a t e d f o r each temperature. The r e s u l t s are s i m i l a r to those obtained f o r a l d i c a r b sulfone ( 6 ) , i . e . a f i f t e e n f o l d increase of k was found over the range of temperatures s t u d i e d . The a c t i v a t i o n energy, E , was c a l c u l a t e d as usual (Arrhenius p l o t ) and had a value of 15.1 (± 0.1) kcal/mole· 0

s

r

r

a

Table V I I . Base H y d r o l y s i s Rate Constants of Carbofuran at D i f f e r e n t Temperatures Temperature (°C) ( l i t e r min 11.4 5 10 18.0 15 30.6 25 67 .0 35 163 k

r

1

1

mole

1

*)

Standard E r r o r (±) 0.2

0.4 1.0

r^ (%) 99.3

99.9 99.9

F i r s t r e a c t i v e i o n exchange s t u d i e s have been conducted i n batch, on column, and with s e v e r a l r e s i n forms. For example, the degradation of 200 ppb s o l u t i o n s of a l d i c a r b by n u c l e o p h i l i c cleavage and a c i d c a t a l y z e d h y d r o l y s i s was followed over time and p l o t s of those data are shown i n Figure 2. The k u values c a l c u l a t e d as the slope of the l i n e s are 6.6 χ 10"^ min""* and 9.3 χ 10"^ min""* f o r base and a c i d h y d r o l y s i s , r e s p e c t i v e l y . As expected, the base h y d r o l y s i s was f a s t e r than the a c i d h y d r o l y s i s . This r e s u l t was p r e d i c t e d by s o l u t i o n s t u d i e s reported f o r a l d i c a r b sulfone (7) and from recent r e s u l t s f o r a l d i c a r b and a l d i c a r b s u l f o x i d e . ( 9 ) A minicolumn breakthrough study was performed to evaluate the p r a c t i c a l i t y of the base h y d r o l y s i s RIEX method i n a f i l t e r u n i t . A minicolumn (3.0 χ 0.70 cm) c o n t a i n i n g 1.0 gram of Bio Rad AG MP-1 strong base anion exchange r e s i n (100-200 mesh) converted to the OH" form was used. A 1.1 ppm s o l u t i o n of a l d i c a r b was passed through at a flow r a t e of ^ 1 ml/min. Twenty-five ml samples of i n f l u e n t and e f f l u e n t were removed f o r a n a l y s i s a f t e r each of the volumes i n d i c a t e d i n Table V I I I · The concentration of a l d i c a r b i n these samples (not c o r r e c t e d f o r adsorption by r e s i n ) are reported i n Table V I I I . As can be seen, there appeared to be a "breakthrough" at approximately 2000 ml. Experiments are c u r r e n t l y underway with both higher and lower concentrations and with a l d i c a r b s u l f o x i d e and a l d i c a r b sulfone mixtures s i m i l a r to those found i n a c t u a l w e l l water. Q

s

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15.

Degradation Rates of Carbamate Pesticides

L E M L E Y ET AL.

Table V I I I . Volume (ml) of Passed Through Through Resin Bed 50 100 200 400 600 650 800 1910 2343

255

Breakthrough Capacity

Concentration A I n f l u e n t (ppm) 1 .1 1.1 1.1 1.1 1.1 1.0 1.0 1.0 1.0

Concentration A I n f l u e n t (ppm) 0 0 0 0.1 0.1 0.1 0.1 0.4 0.5

Despite the f a s t e r base h y d r o l y s i s r a t e , the a c i d c a t a l y z e d r e a c t i o n on r e s i n s i s worth pursuing as a p o t e n t i a l d e t o x i f i c a t i o n method of choice f o r two reasons. The a c i d h y d r o l y s i s of carbamate i s a t r u l y c a t a l y t i c process l e a v i n g the protons a v a i l a b l e on the column f o r continuous r e a c t i o n , whereas base h y d r o l y s i s uses up hydroxide ions and would r e q u i r e column recharge from time to time. In a d d i t i o n , the strong a c i d c a t i o n exchanger i s a s t a b l e r e s i n which can be stored f o r extended periods of time without changes, whereas the strong base anion exchanger absorbs C0£ from a i r . In order to study f u r t h e r the f a v o r a b l e aspects of i n s i t u a c i d c a t a l y z e d h y d r o l y s i s , experiments were performed at d i f f e r e n t temperatures so as to evaluate the dependence of r a t e on temperature. S o l u t i o n s of a l d i c a r b were passed through a j a c k e t e d column around which water at 30, 40, or 50°C was c i r c u l a t i n g . The i o n exchange bed (5 cm χ 0.70 cm) contained 2.0 g of Bio-Rad AG MP-50 strong a c i d c a t i o n exchange r e s i n ( H , 100-200 mesh), and the s o l u t i o n flow r a t e was approximately 1.0 ml/min. The percent of i n i t i a l a l d i c a r b remaining at the end of the column f o r each temperature decreased from 76% at 30°C to 56% at 40°C and 35% at 50°C. Future temperature s t u d i e s w i l l be done i n order to e v a l u a t e the p r a c t i c a l i t y of temperature c o n t r o l i n a detoxification f i l t e r unit. Another i n t e r e s t i n g aspect of the RIEX s t u d i e s to t h i s date i s the p o t e n t i a l f o r precolumn or s o l u t i o n pretreatment o x i d a t i o n . For s o l u t i o n s contaminated w i t h a mixture of a l d i c a r b and i t s m e t a b o l i t e s , p r e o x i d a t i o n to a l d i c a r b s u l f o n e would a l l o w more e f f i c i e n t base h y d r o l y s i s s i n c e the degradation r a t e i s f a s t e r f o r t h i s metabolite (Table V I ) . Thus o x i d i z i n g agents were t e s t e d both i n s o l u t i o n and on the r e s i n to determine t h e i r p o t e n t i a l f o r o x i d i z i n g a l d i c a r b . The strong base anion +

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exchanger was converted t o the S2O3 ( p e r o x y d i s u l f a t e ) form and a batch degradation study was performed with a 200 ppb s o l u t i o n o f a l d i c a r b . A p l o t of In [A] v s . time i s shown i n F i g u r e 3. The value f o r k ^ c a l c u l a t e d from a l i n e a r r e g r e s s i o n o f the s l o p e o f the l i n e i s 2.7 χ 1 0 ~ m i n . The products o f t h i s r e a c t i o n are a l d i c a r b s u l f o x i d e and a l d i c a r b s u l f o n e (not q u a n t i f i e d ) i n d i c a t i n g that o x i d a t i o n i s the predominant r e a c t i o n . The f a c t that a s t r a i g h t l i n e i s obtained i n d i c a t e s that one of these two o x i d a t i o n processes i s r a t e determining. When compared t o i n s i t u R I E X , a l d i c a r b o x i d a t i o n by S2O3 i n f r e e s o l u t i o n (no r e s i n present) was much slower. These r e s u l t s a r e s i g n i f i c a n t f o r s e v e r a l reasons. First, p e r o x y d i s u l f a t e , although a n u c l e o p h i l e , when exchanged on an anion exchange r e s i n , does not appear t o e f f e c t n u c l e o p h i l i c cleavage as does the hydroxide i o n , but i s predominantly an o x i d i z i n g agent with a l d i c a r b s t e p has a p s e u d o - f i r s same as the k ^ f o r base h y d r o l y s i s . Since t h i s o x i d a t i o n i s f a i r l y r a p i d with the r e s i n , there suggests i t s e l f the p o s s i b i l i t y of using a p r e o x i d a t i o n column p r i o r to a s t r o n g base anion exchange column ( i n s e r i e s ) f o r even more r a p i d chemical d e g r a d a t i o n . Other o x i d i z i n g agents were a l s o explored f o r use with carbamates· Both perborate and peracetate decomposed when sorbed on the r e s i n . H y p o c h l o r i t e was a p a r t i c u l a r l y e f f i c i e n t oxidant f o r a l d i c a r b i n s o l u t i o n , but d i d not work w e l l i n batch when present on the r e s i n . When s o l u t i o n s of a l d i c a r b (5.0 ppm) were mixed w i t h Ca(0Cl)2 at c o n c e n t r a t i o n s of 4.7 ppm or h i g h e r , there was complete degradation of a l d i c a r b to the s u l f o x i d e and the s u l f o n e as shown i n F i g u r e 4. A 1.9 ppm Ca(0Cl)2 s o l u t i o n oxidized 40% o f the a l d i c a r b . There i s the p o t e n t i a l then f o r using a bulk phase c h l o r i n a t i o n pretreatment s t e p — s i m i l a r t o c l a s s i c a l water c h l o r i n a t i o n — f o r water contaminated with a mixture o f a l d i c a r b and i t s m e t a b o l i t e s . T h i s method may a l s o be e f f e c t i v e w i t h other carbamate p e s t i c i d e s , and f u t u r e work w i l l explore that p o s s i b i l i t y . 0

s

2

0

- 1

s

Conclusion The second order a l k a l i n e h y d r o l y s i s r a t e constants were determined f o r carbofuran, 3-hydroxycarbofuran, methomyl, and oxamyl, and the a c t i v a t i o n energy was c a l c u l a t e d f o r carbofuran from r e s u l t s at d i f f e r e n t temperatures. T h i s i n f o r m a t i o n may be important i n p r e d i c t i n g the environmental f a t e of these s p e c i e s when c o r r e l a t e d with p e r t i n e n t f i e l d d a t a . Thus, one may be able to model environmentally f a v o r a b l e and unfavorable c o n d i t i o n s f o r a p p l i c a t i o n o f these carbamate p e s t i c i d e s . Furthermore, the degradation o f a l d i c a r b i n aqueous s o l u t i o n by d i f f e r e n t r e a c t i v e i o n exchange résinâtes loaded w i t h n u c l e o p h i l i c , a c i d i c and o x i d i z i n g counterions was shown to be f e a s i b l e i n s i t u , i . e . by simple contact during passage over s m a l l r e s i n beds. Combined

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

15.

Degradation Rates of Carbamate Pesticides

L E M L E Y ET AL.

-13.0

K (n)=9.3 χ ICT min

-14.0

4

1

obs

2E < -15.0 c

ί1 ο55(Ι) β.6χΙθ" Γηΐη κ

=

2

Η

-16.0

-17.0

200

-L 400

600

Time (min)

800

1000

Figure 2. N u c l e o p h i l i c cleavage (I) and a c i d c a t a l y z e d ( I I ) h y d r o l y s i s o f a l d i c a r b by r e a c t i v e ion exchange.

K^^TxIO^min"

30

1

40

Time (min) Figure 3. P s e u d o - f i r s t order r a t e determination f o r the o x i d a t i v e degradation o f a l d i c a r b by r e a c t i v e ion exchange.

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INITIAL SOLUTION (5.2 ppm A) 2I°C

KALDICARB

AFTER 2 MINUTE SOLVENT-H I—PRODUCT REACTION WITH CaOCI (4.7 ppm)

Figure 4. HPLC chromatogram before and a f t e r a d d i t i o n o f C a ( 0 C l ) to 5.2 ppm s o l u t i o n o f a l d i c a r b . 9

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

15.

L E M L E Y ET AL. Degradation Rates of Carbamate Pesticides

259

o x i d a t i v e / h y d r o l y t i c systems and/or somewhat elevated temperature with a c i d c a t a l y z e d r e s i n a t e systems may o f f e r a simple means f o r d e t o x i f y i n g carbamate p o l l u t e d d r i n k i n g water. C o r r e l a t i o n of fundamental s o l u t i o n parameters with such RIEX r e s u l t s w i l l be important i n the development of e f f e c t i v e water d e t o x i f i c a t i o n systems based on RIEX. I t i s hoped that planned future work w i l l e v e n t u a l l y l e a d to adaptation of an optimized l a b o r a t o r y system to a preprototype f i e l d u n i t .

Acknowledgments The authors g r a t e f u l l y acknowledge the f i n a n c i a l support of the United States Environmental P r o t e c t i o n Agency and the United States Department of A g r i c u l t u r e . They a l s o appreciate the cooperation o f the Union Carbide C o r p o r a t i o n FMC C o r p o r a t i o n and Ε.1. duPont deNemour

Literature Cited 1.

2.

3.

4. 5. 6. 7. 8. 9.

Shih, C.C.; Dal Porto, D.F. "Handbook for Pesticide Disposal by Common Chemical Methods," NTIS PB-252 864, Springfield, VA. Lande, S.S; "Identification and Description of Chemical Deactivation/Detoxification Methods for the Safe Disposal of Selected Pesticides," NTIS PB-285, 208, Springfield, VA. Janauer, G.E.; Costello, M.; Stude, H . ; Chan, P; Zabarnick, S. in "Trace Substances in Environmental Health"; Hemphill, D.D., E d . ; University of Missouri: Columbia, 1980; V o l . XIV, pp.425-435. Burrows, G.; Janauer, G.E., unpublished data. Spalik, J.; Janauer, G.E.; Lau, M.; Lemley, A.T.; J. Chromatog. 1982, 253, 289-294. Lemley, A.T.; Zhong, W.Z.; submitted for publication. Lemley, A.T.; Zhong, W.Z.; J. Environ. S c i . Health, 1983, B18(2), 189-206. "Determination of the Total Toxic Aldicarb Residue in Water", Union Carbide Corporation, 1980. Lemley, A.T.; unpublished data.

RECEIVED March 5, 1984

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

16 Pesticide Availability Influence of Sediment in a Simulated Aquatic Environment ALLAN R. ISENSEE Pesticide Degradation Laboratory, Beltsville Agricultural Research Center, U.S. Department of Agriculture, Beltsville, MD 20705

Sediment additions were made to model aquatic environments containing DDT equilibrated between sediment, water, and four species of aquatic organisms to determin biota was reduce events. Soil treated with C-labeled DDT at 10, 100, and 1000 ppm was flooded and fish (Gambusia a f f i n i s ) , snails (Helosoma sp.), algae (Oedogonium cardiacum), and daphnids (Daphnia magna) were added. At two-week intervals, untreated sediment additions (equalling 1% of the water weight) were made. Samples of water and organisms, taken before and after sediment additions, were analyzed for DDT, DDE, and DDD and compared to equilibrated systems not treated with sediment. DDT content in water decreased 3-to 9fold by the f i r s t sediment addition. Polar metabolites in water increased as DDT decreased. Fish were k i l l e d at the 1000 ppm level and daphnids succembed at 100 and 1000 ppm levels. Sediment additions substantially reduced the toxicity at lower treatment levels. Sediment additions decreased total C by 6 to 13% in fish, 20 to 40% in algae, 45 to 50% in snails and 55% in daphnids (10 ppm rate). Measureable levels of DDT not diffuse through 1 cm or more of untreated s o i l into water in one year. Covering pesticide contaminated sediment with soil and sediment in situ is an effective contamination control method under certain aquatic conditions. 14

P e s t i c i d e s that enter the aquatic environment from spills or improper treatment of manufacturing waste pose unusually difficult d i s p o s a l problems. For example, the volume of contaminated and d i s p o s a l methods are i m p r a c t i c a l and p r o h i b i t i v e l y expensive. In a d d i t i o n , the p h y s i c a l c o n d i t i o n This chapter not subject to U.S. copyright. Published 1984, American Chemical Society

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

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DISPOSAL OF PESTICIDE WASTES

of the s i t e may severely l i m i t the use of e s t a b l i s h e d techniques and heavy equipment. Thus some i n s i t u means of c o n t r o l l i n g the contamination i s h i g h l y d e s i r a b l e . One p o t e n t i a l i n s i t u abatement procedure i s to bury the contaminant i n place under s o i l or sediment. H i g h l y i n s o l u b l e , s t r o n g l y adsorbed contaminants would, i d e a l l y , be contained and b i o l o g i c a l l y i s o l a t e d by t h i s procedure. In a d d i t i o n , the anaerobic c o n d i t i o n s that develop under the o v e r l a y i n g s o i l or sediment r e s u l t i n a c c e l e r a t e d degradation of c e r t a i n compounds. D e c h l o r i n a t i o n of DDT under anaerobic conditions i s well known (1, 2). Dehalogenation of haloaromatic compounds has also been demonstrated under anaerobic c o n d i t i o n s ( 3 ) . The study was conducted to evaluate i n s i t u sedimentation as an abatement procedure. DDT was chosen as the t e s t p e s t i c i d e since i t i s a p e r s i s t e n t , w a t e r - i n s o l u b l e compound that has created d i f f i c u l t d i s p o s a e x i s t s i n Alabama wher have been found i n the bottom sediment of a 3-mile stream segment. Two experiments were conducted to (1) determine the e f f e c t of s o i l (sediment) a d d i t i o n s i n t o a simulated aquatic environment on the d i s t r i b u t i o n and b i o - a v a i l a b i l i t y of DDT and (2) determine the extent of DDT d i f f u s i o n through layers of untreated sediment. Methods and M a t e r i a l s Microecosystem Chambers The aquatic microecosystem i s shown i n Figure 1 and has been p r e v i o u s l y described ( 4 ) . For t h i s study, 160-g q u a n t i t i e s of a sandy c l a y loam s o i l (58.4, 18.0, 26.6 and 1.94 % sand, s i l t , c l a y and organic carbon, r e s p e c t i v e l y ) were t r e a t e d with [ ^ C - r i n g ] DDT (98+ % p u r i t y , 3.6 m Ci/mmole s p e c i f i c a c t i v i t y ) at 10, 100 and 1000 ppm and placed i n the bottom of 20-L c a p a c i t y glass tanks (41 χ 20 χ 24 cm). The s o i l was obtained from an uncontaminated l o c a t i o n upstream from the DDT contaminated s i t e i n Alabama. Three r e p l i c a t e s of each rate plus two c o n t r o l (160 g untreated s o i l ) were prepared and then flooded with 16-L a c t i v a t e d carbon f i l t e r e d tap water. One day l a t e r 20 f i s h (Gambusia a f f i n i s ) , 20 s n a i l s (Helisoma sp.) and 1-g algae (Oedogonium cardiacum) were added to the tank and about 200 daphnids (Daphnia magna) were placed i n the daphnid chamber (1.5-L c a p a c i t y tank with a s t a i n l e s s s t e e l screen bottom to r e s t r i c t daphnid passage) which was suspended i n the 20-L tank. Water was continuously pumped (about 10 ml/min) i n t o the daphnid chamber which ensured uniform mixing of the water and transport of food to the daphnids. Untreated (no DDT) s o i l a d d i t i o n s (160 g/tank) were made to two of the three r e p l i c a t e s at each c o n c e n t r a t i o n and to one of the c o n t r o l tanks 14, 28 and 42 days a f t e r the a d d i t i o n of organisms. S o i l was f i r s t suspended i n 2-L of water, then

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

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ISENSEE

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Sediment Influence on Pesticide Availability

Figure 1. Microecosystem contains 16 L water and four o f organisms. The chamber measures 41 χ 20 χ 24 cm.

species

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drained into tanks 3 cm below the water surface with the flow d i r e c t e d h o r i z o n t a l l y to minimize d i s r u p t i o n of the bottom treated s o i l . A water volume of 16-L was maintained v i a a properly located d r a i n . The ecosystem was t h e r e f o r e designed t o simulate an i n f l o w o f water and sediment into a p e s t i c i d e e q u i l i b r a t e d pond or l a k e . Sampling and A n a l y s i s Water samples ( t r i p l i c a t e 1-ml) were taken at 2-day i n t e r v a l s and analyzed by standard l i q u i d s c i n t i l l a t i o n (LS) methods f o r t o t a l ^ c - Larger water samples (100 ml) were taken each week and e x t r a c t e d using C 18 Sep-Paks (Waters Associates, Inc.)*. Samples were passed through Sep Paks at 2-4 ml/min. Recovery of *^c~DDT plus metabolites from the Sep Paks was achieved by e x t r a c t i n g with 10 ml acetone followed by 5 ml dichloromethane. DDT e x t r a c t i o n e f f i c i e n c y from water was 97+ %. Combined e x t r a c t spotted on TLC p l a t e s (wit cm GF-254, E. Merck, Darmstadt) and developed f o r 10 cm using heptane:acetone (99:1). P l a t e s were then scraped and t o t a l ^ C determined by LS. Tissue samples (two f i s h , two s n a i l s , 100 mg algae and about 50 mg daphnids) were taken 1, 3, 8, 15, 22, 29, 36, 43, 50 and 57 days a f t e r the s t a r t of the experiment. Whole f i s h and s n a i l s were homogenized i n a c e t o n i t r i l e , and the homogenate was assayed d i r e c t l y by LS. F i l t e r e d samples of the homogenates were analyzed by TLC as described above. Daphnids were weighed, placed i n LS v i a l s , then ruptured with the c o c k t a i l and analyzed d i r e c t l y by LS. Algae samples were o x i d i z e d to determine t o t a l ^ C* DDT was a c u t e l y t o x i c to f i s h (1000 ppm treatment) and daphnids (100 + 1000 ppm treatment) which n e c e s s i t a t e d r e s t o c k i n g . Only l i v i n g f i s h and daphnids were analyzed. Water and organism c o n t r o l samples were taken, processed, and analyzed simultaneously with ^C"DDT t r e a t e d samples. F i n a l ^c-DDT v a l u e s were corrected using the appropriate c o n t r o l . No ^ c i n excess of background was recovered from any c o n t r o l sample. M

11

D i f f u s i o n Experiment Twenty gram q u a n i t i e s of the Alabama s o i l were t r e a t e d with [ ^ c - r i n g ] DDT at 100 ppm and placed i n the bottom o f 1 L beakers. D u p l i c a t e beakers c o n t a i n i n g the t r e a t e d s o i l were covered with 0, 1, 2, or 3 cm o f untreated s o i l and flooded with 800 ml water. Four cm o f untreated s o i l i n d u p l i c a t e beakers flooded with 800 ml water served as c o n t r o l s . T r i p l i c a t e 1-ml water samples were taken p e r i o d i c a l l y . Two weeks a f t e r f l o o d i n g , 3 s n a i l s , 0.5 g algae and about 30 daphnids were ^Mention of a trade name or p r o p r i e t a r y product does not c o n s t i t u t e a guarantee or warranty o f product by the U.S. Dept. A g r i c . and does not imply i t s approval to the e x c l u s i o n of other products that may be s u i t a b l e .

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

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added to each beaker. DDT was acutely t o x i c to the daphnids i n the 0 cm treatments which n e c e s s i t a t e d p e r i o d i c r e s t o c k i n g . Results and D i s c u s s i o n DDT i n Water The e f f e c t of sediment a d d i t i o n s on DDT i n water i s shown i n Table I. There are two DDT data points f o r each sampling day; the f i r s t i s based on t o t a l a n a l y s i s and the second ( i n parentheses) i s based on TLC a n a l y s i s of the water extracts. Total c i n water was not g r e a t l y a f f e c t e d by the 1% (160 g s o i l per 16-L water) sediment a d d i t i o n s . T o t a l c i n the W/0 tanks (not r e c e i v i n g sediment) increased continuously with time while approximate plateau l e v e l s were maintained i n the W tanks ( r e c e i v i n g sediment). In c o n t r a s t , DDT l e v e l s (based on TLC a n a l y s i s ) were g r e a t l y reduced. For example, on day 22, the c o n c e n t r a t i o n of DDT i the concentration i n W treatments, r e s p e c t i v e l y . T o t a l by comparison, was 1.1, 1.7, and 1.5 times lower f o r the same treatments. C l e a r l y then, input of sediment w i l l reduce the concentration of DDT i n s o l u t i o n , p a r t i c u l a r l y at the lower concentrations. However, the r e s u l t s are complicated by the fact that DDT l e v e l s decreased with time ( a f t e r day 8 or 15) i n a l l tanks, i n c l u d i n g those not r e c e i v i n g sediment. TLC a n a l y s i s of e x t r a c t s from 100 ml water samples p a r t l y e x p l a i n t h i s decrease (Figure 2). DDT concentrations i n the e x t r a c t s averaged ( f o r the three treatment r a t e s ) 76, 67, 52 and 9% of the t o t a l recovered a c t i v i t y f o r days 3, 8, 15 and 22, r e s p e c t i v e l y . For days 29 through 57, DDT l e v e l s were below 5% o f the recovered Polar metabolites, remaining at the TLC p l a t e o r g i n , increased as DDT decreased. These data suggest that the DDT i n water was degraded to p o l a r metabolites and that l i t t l e or no a d d i t i o n a l DDT desorbed from the t r e a t e d bottom sediments. The slow increase i n c ( i n the W/0 tanks) with time may represent r e l e a s e of polar metabolites from the bottom sediment. T o t a l c i n water on day 57 represented 1 and 3% of the t o t a l C added to each tank at the s t a r t , for the W and W/0 sediment treatments, r e s p e c t i v e l y . In a d d i t i o n , C recovered from the 100 ml water samples decreased from 88% of the total c (1 ml samples) on day 3 to 51% on day 57. These r e s u l t s i n d i c a t e that polar metabolites increased with time s i n c e they are not recovered by Sep Paks. Only small amounts of DDE and DDD (7 and 13% o f t o t a l c by day 8 and 15, r e s p e c t i v e l y ) were detected i n water. The concentration of DDT i n s o l u t i o n (Table I) often exceeded the g e n e r a l l y accepted water s o l u b i l i t y o f 2 ppb. Two f a c t o r s may account f o r these d i f f e r e n c e s . F i r s t , the water samples were not f i l t e r e d before C 18 Sep Pak e x t r a c t i o n . 1 4

1 4

1 4

1 4

1 4

1

1 4

l 4

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

b c d

a

57

50

d

c

1.8 (0.03 1.7 (0.02) 1.3 100° Camphor > 100 n, Octane + 55,48,42 Salicylate + 46 Naphthalene + 76 Xylene, toluene + 90 Xylene, toluene + N.D. Nicotine, nicotinate + 58 2,4-Dichlorophenoxy-acetic acid + 65 p-chlorobiphenyl Degradative Pathway

D

+ indicates plasmid is transmissible Jexact size unknown N.D. not determined !

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easy to manage package (9). As mentioned above, the required genes exist in one or more opérons activated by the primary substrate. Many plasmids are transmissible, meaning they may be transmitted between strains or even between species simply by culturing donor and recipient cells together. When this is not feasible, techniques exist for isolating plasmids and transferring them to recipient cells. A second, at least theoretical, advantage in using plasmids to engineer pollutant degrading microorganisms is that they may be used to genetically alter microorganisms already present in a polluted environment so that they gain the ability to better degrade a pollutant without losing their ability to survive field conditions. Pollutant degrading microorganisms developed by the more traditional procedure of selection in the laboratory often fail to become established at the polluted site because such strains lack the ability to survive field conditions and to compete with other existing microorganisms. At the same time i to overcome in using Introduced DNA may be recognized by the new host cell as foreign and destroyed or modified in such a way that it is non-functional (19). Also, certain plasmids are incompatible and cannot coexist in the same cell. Presumably this occurs when the plasmids are closely related and under stringent copy number control (20). Barring these obstacles, there may remain poorly understood problems leading to the lack of expression of the plasmid genes in the new host. Attempts to transfer functional degradative plasmids from Pseudomonas species, which have been most frequently studied by scientists in this field, to other microbial species (12-13) usually have not been successful. In 1978 Chakrabarty et al. (21) showed that it is possible to transfer the TOL plasmid, which carries genes encoding enzymes to degrade xylenes, toluene, and trimethylbenzene derivatives, from Pseudomonas putida to E. coli. However, in E. coli the plasmid did not express degradative functions for toluene or salicylate. The fact that the TOL plasmid expresses such a function when it is transferred back to P. putida after cloning in E. coli indicates that expression of degradative DNA's may be controlled by the chromosomal DNA. Jacoby et al. (22) transferred the TOL plasmid from P. putida and P. aeruginosa to E. coli, but they also found that its functional expression was either very low or incomplete. These workers considered that some of the metabolic products from xylene and toluene are toxic to E. coli. Despite these obstacles, the use of plasmids to create new strains of microorganisms with special degradative capabilities has already been demonstrated with some success. For example, by introducing plasmids coding for the degradation of several classes of compounds into the same microorganism Friello et al. (8) developed a new strain of Pseudomonas that can degrade a variety of the components of crude oil. The authors felt this approach was superior to using a mixed culture of microorganisms since it avoids the problem of temporal changes in the relative abundance of the different strains. A second example involves chlorobenzoate metabolism. Pseudomonas B13 can metabolize 3chlorobenzoate, but not 4-chlorobenzoate because of the high substrate

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

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Plasmid Transfer of Degradation Capabilities 331

specificity of its 3-chlorobenzoate oxidase (23). By introducing a plasmid (TOL) coding for a benzoate 1,2-dioxygenase of broader substrate specificity into Pseudomonas B13, Knackmuss and his colleagues were able to derive a strain capable of metabolizing not only 3-chlorobenzoate, but also 4-chlorobenzoate and 3,5-dichlorobenzoate (23). In a similar experiment, Chatterjee and Chakrabarty (24) obtained a new plasmid, apparently coding for 4-chlorobenzoate degradation, from recombination between the TOL plasmid and a 3-chlorbenzoate degradative plasmid (pAC25) during selection in a chemostat. This method of combining strains with different degradative plasmids followed by selection in a chemostat has been termed "plasmid assisted molecular breeding" and has also led to the development of a 2,4,5-T degrading strain of Pseudomonas cepacia (25). Work in the area of genetically engineering new strains to degrade specific hydrocarbons would be greatly facilitated if a system which freely allows the transfe recipient organism was known. We believe our research has the potential for identifying such a system as well as identifying new degradative plasmids from a gram positive microorganism (Bacillus megaterium) that may be used in future genetic engineering work. Bacillus megaterium. We originally became interested in determining B. megaterium^ ability to degrade a variety of xenobiotics because Tt possesses a cytochrome P-450 oxidative system (26-27) and degrades a wide variety of naturally occurring substrates including steroids, long chained fatty acids, amides, and alcohols (26, 28). We have shown that B. megaterium at least partially degrades DDT, parathion, heptachlor, chlordane (29), and 2,3,7,8-tetrachlorodibenzo-p-dioxin (30). In addition to its wide spectrum degradative ability, B. megaterium possesses many copies of a number of different plasmid-like DNA segments (31-33). We therefore wished to determine if this degradative ability is plasmid coded and whether it can be transferred to other bacteria. Chracteristics of B. megaterium's plasmid system have been summarized by Carlton ( 3 p . The plasmids are typical in that they band as covalently closed circular DNA in ethidium bromide-cesium chloride gradients and they are resistant to irreversible alkaline denaturation (17). However, B. megaterium plasmids are atypical in that they exisfln approximately 10 size classes and as many copies per cell (32). In fact, for the smaller plasmids there are hundreds of copies per cell so that plasmid DNA may represent up to 40% of the total extractable DNA (31). This is unusual since for most plasmids there are usually no more than a few copies per cell. Also, hybridization studies suggest that there is extensive homology between three B. megaterium plasmids of different sizes and between these plasmids and the chromosomal DNA (31,33). Carlton (31) concludes that the most likely explanation of the origin of B. megaterium plasmids is that they are molecular hybrids between one or more plasmid elements and various portions of the chromosomal DNA. The only known function for any of the B. megaterium plasmids is megacin A production by the 30.9 megadalton plasmid (34). However, if Carlton's hypothesis on the origin of these plasmids is true, then we may

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

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TREATMENT AND DISPOSAL OF PESTICIDE WASTES

expect many functions coded for by the chromosomal DNA to be duplicated by the plasmids. This should enhance our chances of being able to transform other bacterial species to degrade xenobiotics using B. megaterium plasmids. Materials and Methods Strains. Three derivative strains of Bacillus metagerium (ATCC 13368) were selected for resistance to dibenzofuran, parachlorobiphenyl, and naphthalene by plating the parent strain on nutrient agar plus 0.1% of each compound. These strains served as the DNA donors. While B. megaterium partially degrades each of these compounds, we were not successful in selecting a strain of B. megaterium to grow on any one as a sole carbon source. A streptomycin resistant derivative of Bacillus subtilis Marburg 168 RM 125 arg 15 leu A8 r " m " (35) was kindly supplied by Dr. Teruhiko Beppu (Central Research Laboratories DNA recipient. Isolation of Plasmid Enriched DNA. The three strains of B. megaterium were cultured in yeast-soy broth (4% Bacto-yeast extract and 1.6% Bactosoytone from Difco Laboratories, Detroit, pH 7.2). Plasmid DNA from each strain was isolated and purified by cesium chloride-ethidium bromide equilibrium density centrifugation following the procedure of Carlton and Brown (36). Subsequent gel electrophoresis (0.5% agarose) revealed the presence of some chromosomal DNA contamination. Transformation Procedure. A streptomycin resistant strain of B. subtilis Marburg 168 was used as the recipient strain. The transTormation procedure was the protoplast-polyethylene glycol (PEG) method described by Chang and Cohen (37). Basically, donor DNA is added to a suspension of B. subtilis protoplasts in the presence of PEG. Three transformation experiments were performed using DNA preparations from each of the three B. megaterium strains selected to grow on nutrient agar plus 0.1% of dibenzofuran, parachlorobiphenyl, or naphthalene. Following the regeneration of protoplasts on DM3 medium containing streptomycin (100 yg/ml) transformants were selected for their ability to grow more rapidly than the original B. subtilis strain on the corresponding selective medium. Because even B. megaterium could not use any of these substrates as a sole carbon source we were not able to select directly for degradative capability. However, we did expect some correlation between resistance and degradative capability. We therefore selected for resistance and screened the resistant transformants for degradative ability. Preliminary tests demonstrated that B. megaterium colonies appeared in less than 24 hours after innoculating the selective plates while B. subtilis required longer (generally 48 hours) to show growth. B. subtilis protoplasts regenerated without the addition of B. megaterium DNA also failed to grow on these selective media in less than 24 hours. Transformants selected in this manner were tested for the presence of B. subtilis chromosomal markers (auxotrophic for arginine and leucine).

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

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Plasmid Transfer of Degradation Capabilities 333

Resistance Tests. Several transformants were tested for their ability to grow on all three selective media. These transformants were streaked onto nutrient agar plates containing 0.1% naphthalene, dibenzofuran, or parachlorobiphenyl. The plates were incubated for 18 hours at 25 C before scoring. Screening Transformants. The naphthalene resistant B. subtilis transformants were screened for their ability to degrade naphthalene according to the method of Ensley et al. (38). Cells were cultured in nutrient broth supplemented with naphthalene (1 mg/ml), filtered through glass wool to remove naphthalene crystals, harvested by centrifugation, washed twice with 0.05 M potassium phosphate buffer, pH 7.2, and suspended at a concentration of 40 mg (wet cell weight) per milliliter of buffer^ The reaction system consisted of 5 ml of cell suspension, 0.05 μ Ci C-naphthalene plus 100 μ g cold naphthalene in 100 μΐ ethyl acetate in tightly capped culture tubes to prevent volatilization of the naphthalene. Naphthalen of nonvolatile metabolites of C-naphthalene. After ten hours of incubation at room temperature on a reciprocal shaker, 20 μ 1 samples of the reaction mixtures were spotted on pieces of glass silica gel thin layer chromatography plates (1.5 X 1.0 cm) and the remaining naphthalene was removed under a stream of nitrogen for 15 minutes. The C activity remaining on the squares was determined by liquid scintillation counj^ig. This remaining activity respresented nonvolatile metabolites of Cnaphthalene (38). Controls were done similarly using autoclaved cells. The controls take into account all possible fates of the naphthalene other than metabolism. These possibilities include binding to cells or debris, adsorption to the flasks or plugs, sublimation, autocatalysis, hydrolysis, etc. Differences between control and experimental units must therefore be due to metabolism. Assays of Naphthalene Degradation. Washed cell experiments were used to compare the naphthalene degrading abilities of B. megaterium (both unselected and selected with naphthalene), B. subtilis, and transformants which showed degradative ability in the screening tests. Washed cells were prepared as described above and suspended at a concentration of 25 mg (Experiment 1) or 6 mg (Experiment 2) of cells per milliliter of buffer. Autoclaved cell suspensions were used as controls and account for all possible fates of the naphthalene other than metabolism. Incubation of the reaction mixture was done in screw capped tubes to eliminate losses of naphthalene due to volatilization. The reaction system for Experiment 1 consisted of 10 ml of cell suspension, 0.05 μ Ci of C-naphthalene, and 100 μg of cold naphthalene in 200 μΐ of ethyl acetate. The reaction mixture for Experiment 2 consisted of 5 ml of cell suspension and 0.8 μ Ci of C-naphthalene in 50 μΐ of ethyl acetate. The mixtures were incubated at room temperature for 10 hours with gentle shaking. The reaction mixtures were then extracted three times with equal volumes of ethyl acetate (Experiment 1) or hexane:acetone (4:1, v:v) experiment 2). A statistically significant increase in non-extractable C activity (primarily polar, water soluble metabolite) for live cells over

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

TREATMENT AND DISPOSAL OF PESTICIDE WASTES

334

control dead cells was used as the criterion for degradation. These C activities were determined by liquid scintillation counting. The statistical comparisons between the live and dead cell (control) treatments were made using a one tailed t test, correcting for unequal variances when indicated. Differences were declared significant if the probability of a larger 11 | was less than 0.05 (i.e., Ρ = (1 -α)> 0.95). T L C Analysis. For experiment 2, thin layer chromatographic analysis was carried out by reducing solvent volumes to less than 250 μΐ under a nitrogen stream, spotting on activated silica gel plates, and developing in chloroform:acetone (20:1, v:v). Autoradiography of these plates were prepared by exposing them to X-ray film for 3 or 4 days at -20 C . Results Bacillus subtilis transformant naphthalene, parachlorobiphenyl protoplasts regenerated without the addition of B. megaterium plasmid DNA) exhibited no increased reistance to these three compounds. That each transformant was B. subtilis and not a contaminant was verified by testing for the B. subtilis chromosomal markers. Only streptomycin resistant strains that showed arginine and leucine dependent growth were used in subsequent experiments. Hydrocarbon Resistance. The importance of the source of the DNA (B. megaterium selected on naphthalene, parachlorobiphenyl, or dibenzofurain) on the transformants abilities to grow on media containing each hydrocarbon was determined. DNA from selected strains of B. megaterium was transferred to B. subtilis in three separate transformation experiments. The growth response of the resulting transformants on nutrient agar with or without 0.1% of each hydrocarbon was studied at 24°C. The data (Table II) clearly show that in this transformation system hydrocarbon resisting or degrading abilities which are controlled by the B. megaterium DNA are transferable and are functionally expressed in the recipient system, and also that the substrate specificity acquired by selection prior to transformation is still retained in the recipient strains after transformation. It is interesting to note that the transformants with DNA from B. megaterium selected on dibenzofuran showed some tendency to grow also on the medium containing naphthalene and parachlorobiphenyl in this experiment. 1

Naphthalene Degradation. Twelve transformants showing faster growth on the selective medium plates were screened for their ability to degrade naphthalene according to the method of Ensley et al. (38). Three of these jrpe selected for further study based on their production of nonvolatile C-naphthalene metabolites. The naphthalene degradation abilities of B. megaterium, B. subtilis, and the transformants Nah 1, Nah 25, and Nah 28 were compared in washed cell experiments using C-naphthalene. Both disappearance of solvent extractable radiocarbon and accumulation of water soluble, nonextractable radiocarbon were taken as

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

19.

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Table II.

Plasmid Transfer of Degradation Capabilities 335

Growth Response after 18 Hours of B. subtilis Transformants with B. megaterium DNA

Microorganisms

Nah

Nutrient Agar Containing Dbf pCB

Original microorganisms Β. megaterium B. subtilis B. megaterium selected with: Naphthalene (Nah) Dibenzofuran (Dbf) p-chlorobiphenyl (pCB)

+ +

Transformants with: Naphthalene selected DNA Nah 27 Nah 28 Dibenzoburan selected DNA Dbf 3 Dbf 5 ρ-chlorobiphenyl selected DNA pCB 15 pCB 16 ++ indicates vigorous growth and/or growth started earlier than others indicates moderate growth "s indicates slight or questionable growth - indicates no growth TT

Tt

M

W

B

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

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TREATMENT AND DISPOSAL O F PESTICIDE WASTES

indications of naphthalene degradation. In general, a decrease in solvent extractable radiocarabon was paralleled by an increase in nonextractable, water soluble radiocarbon. However, the greater variation associated with the solvent extractable radiocarbon counts, most likely due to volatilization of naphthalene, made statistically significant differences more difficult to demonstrate. For this reason we considered ^difference between live cells and the controls in the nonextractable C activity (Table III) as the more reliable indication of naphthalene metabolism. Column E - i n Table ΙΠ gives the probabilities that the differences in aqueous C activities recovered between live and dead cells are statistically significant. In Experiment 1 (three replicates) there was no evidence of naphthalene degradation by B. subtilis or unselected B. megaterium. The naphthalene selected B. megaterium did show a significant (P=0.98) increase in nonextractable C activity, and the transformant Nah 28 showed a slight but statistically nonsignficant (P=0.93) increase. However three transformants teste water soluble metabolites, with Nah 1 and Nah 28 giving higher yields. In this experiment B. subtilis also showed an increase in water soluble metabolites, although it was nonsignificant (P=0.94) and of less magnitude than for transformants Nah 1 and Nah 28. The thin layer chromatographic analysis (Figure 1) revealed four solvent extractable metabolites present in the cases of B. megaterium, Nah 28, and three each in the cases of B. subtilis and Nah 1. TRê metabolite Β (R«=0.37) was unique to B. megaterium and the transformants Nah 1 and Nah 28 and occurred in greater quantity as judged by the comparative densities of tip spots in the autoradiographs. As little as 0.4 nCi (0.05% of the input C activity) can be detected in the autoradiographs. Discussion That the traits of B. megaterium can be transferred to B. subtilis by plasmid transfer techniques has been established. These traits are increased resistance to naphthalene, parachlorbiphenyl, and dibenzofuran, and increased ability to degrade C-naphthalene. The transformants increased degradative abilities were demonstrated by the accumulation of greater quantitites of water soluble metabolite and the presence of a unique solvent soluble metabolite. The transformation techniques employed were designed to transfer plasmid DNA from B. megaterium to B. subtilis and the results suggest that these plasmids are involved Th coding for B. megaterium's degradative abilities. Bacillus megaterium contains many plasmids (at least nine according to Carlton and Brown (36), six of which comprise the bulk of closed circular plasmid DNA. Their sizes are listed as 4, 6.2, 15.9, 30.9, 47, and 60 megadaltons. If any of these plasmids are involved in determining B. megaterium's degradative abilities, then they may prove important in engineering microorganisms to degrade organic pollutants. However, at this time we have not been able to demonstrate the presence of B. megaterium plasmids in the transformants, nor can we rule out the 4

1

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984. 516

+

38,221

38,805

B. subtilis

Ν ah 28

648 670

+ 12,161 + 35,272

596,526 551,836

+ 18,776 +

564,348

575,405

Nah 28

B. subtilis

*Only one observation.

647 7,653

+

530,747

1,927

+

547,051

Ν ah 25

6,247

399

+ 41,218

3,648 1,203 3,540 1,958

+ 282

42 12

+ +

+ 188

183 121 843 672

+ + + +

0.94

0.98

0.99

0.99

0.93 232

+

1,394 + 396

910

518,404

934

+

38,760

0.11 363 + 879

2,665

+

0.001

1,888

3,279

+ 33,901

5,883

+

33,014

81

0.98

+

+ 1,317

1,013

+ 302

+ 264

1,595

1,042

593,459

1,062

2,329

+

+

29,902

37,041

+ Standard Deviation) for the

Aqueous Phase Dead Cells Live Cells

Ν ah 1

Experiment II

2,698

+

36,048*

1,242

B. megaterium naphthalene selected

+

Solvent Phase Dead Cells Live Cells

38,592

per Minute

14 OActivity Recovered

Recovered C Activity (Average Disintegrations Naphthalene Degradation Experiments

B. megaterium, not selected

Experiment I

Strain

Table III.

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TREATMENT AND DISPOSAL OF PESTICIDE WASTES

Ε 3 0)

ι»

—

Com pound

Figure 1.

0.68

Naph

0.54

D

0.44

C

0.37

Β

0.00

Α

CO

Φ

ο

CO

Ζ

in οι

00 CM

.c

Σ.

(0 Ζ

Ζ

CO

σ Φ Ε

•

m

Ώ

SU

(0 Ό C

Φ (0

φ ο ad

^

ω

Autoradiograph of thin layer chromatography plate showing solvent extractable naphthalene metabolites (A, B, C , D) produced by transformants Nan 1, Nan 25, Nan 28, B. megaterium, and B. subtilis.

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

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Plasmid Transfer of Degradation Capabilities 339

possibility of chromosomal contamination of our DNA preparations and the resulting possibility that our transformants contain B. megaterium DNA. This may be a moot point, though, as DNA hybridTzation studies suggest considerable sequence homology between the total plasmid DNA and chromosomal DNA (31). Therefore, there is a possibility that B. megaterium plasmids harbor genetic information that also resides on the chromosome. Degradation of hydrocarbons requires quite complex enzyme systems (13, 39, 40). Therefore, to be functional in the recipient cell, first many associated and unassociated genes involved in degradation must be transferred or already present in the recipient. Second, inhibitory factors such as inhibitory genetic regulatory systems must be absent in the recipient cells. Third, sufficient amounts of necessary cofactors (e.g., NADPH, FMN, FAD, etc.) must be made available. And fourth, neither the hydrocarbons nor their degradation products can be toxic to the recipient cells. It appear readily transferable genes are those conferring resistance to the hydrocarbons. Among such transformants a varying degree of degradation capabilities has been.observed. Three of the twelve transformants produced nonvolatile C-activity. Only two of these (Nah 1 and Nah 28) gave solvent -soluble metabolites. Nah 25 also produced less nonextractable C activity than the other two. This could be interpreted to mean that some transformants received most of the genetic information necessary for degradation, while others received only some portion. While we did not test sufficient numbers of regenerated protoplasts to accurately determine the transformation frequency to aromatic hydrocarbon resistance, these frequencies were certainly high. Chang and Cohen (37) reported transformation frequencies of 10-80% using the same lysozyme-PEG method and similar quantities of plasmid DNA. The naphthalene transformants retained their degradative ability through at least six successive transfers. As this research is still in progress we currently are unable to answer questions related to the extent of naphthalene, parachlorbiphenyl, or dibenzofuran degradation by the transformants, or whether the transformants are able to use any of these compounds as carbon or energy sources. While there are many other unanswered questions, it is clear from the current work that this transformation system may be used to explore many avenues of investigation relative to the microbial degradation of complex hydrocarbons. Obviously one of the future possibilities is to study the potential for developing such technology to degrade unwanted organic pollutants by using such transformation systems. Acknowledgments This work was supported in part by the Michigan Agricultural Experiment Station (Journal Article No. 11240) and the Michigan State Biomedical Program, Michigan State University, East Lansing, Michigan. S. Y . Oh performed the DNA extraction and transformation portions of the

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

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TREATMENT A N D DISPOSAL O F PESTICIDE WASTES

laboratory work while supported by the University of Agriculture Malaysia. Literature Cited 1. 2. 3. 4.

5. 6. 7.

8. 9.

10.

11. 12. 13. 14. 15.

16. 17. 18. 19. 20. 21. 22. 23.

Alexander, M. Science 1981, 211, 132-138. Davis, D. B.; Dulbecco, R.; Eisen, H. N.; Ginsberg, H. S.; Wood, W. B. "Microbiology"; Harper and Row: New York, 1983. Chakrabarty, A. M. Ann. Rev. Genet. 1976, 10, 7-30. Farrell, R.; Chakrabarty, A. M. in "Plasmids of Medical, Environmental, and Commercial Importance"; Timmis, Κ. N.; Puhler, Α., Ed.; Elsevier/North Holland Biomedical Press, 1979; 97109. Wheelis, M. L. Ann. Rev. Microbiol. 1975, 29, 505-524. Williams, P. A. TIBS 1981 6 23-26 Franklin, F. C. H.; Degradation of Xenobiotic Leisinger, T.; Hutter, R.; Cook, A. M.; Nuesch, J., Ed.; FEMS SYMPOSIUM NO. 12, Academic Press: London, 1981; pp. 109-130. Friello, D. Α.; Mylroie, J. R.; Gibson, D. T.; Rogers, J. E . ; Chakrabarty, A. M. J. Bacteriol. 1976, 127, 1217-1224. Williams, P. A. in "Microbial Degradation of Xenobiotics and Recalcitrant Compounds"; Leisinger, T.; Hutter, R.; Cook, A. M.; Nuesch, J., Ed.; FEMS SYMPOSIUM NO. 12, Academic Press: London, 1981; pp. 97-107. Gunsalus, J. C.; Hermann, M.; Toscano, W. Α.; Katz, D.; Garg, G. K. in "Microbiology - 1974"; Schlessinger, D. Ed. American Society of Microbiology: Washington, D. C. 1974; pp. 206-212. Chakrabarty, A. M.; Chou, G.; Gunsalus, J. C. PNAS 1973, 70, 11371140. Dunn, N. W.; Gunsalus, I. C. J. Bacteriol. 1973, 114, 974-979. Williams, P. Α.; Murray, K. J. Bacteriol. 1974, 120, 416-423. Fisher, P. R.; Appleton, J.; Pemberton, J. M. J. Bacteriol. 1978, 135, 798-804. Kamp, P. F.; Chakrabarty, A. M. in "Plasmids of Medical, Environmental, and Commercial Importance"; Timmis, Κ. N.; Puhler, Α., Eds.; Elsevier/North Holland Biomedical Press, 1979; pp. 275-285. Guiso, N.; Ullman, A. J. Bacteriol. 1976, 127, 691-697. Carlton, B. C . ; Helinski, D. R. PNAS 1969, 64, 592-599. Helinski, D. R.; Clewell, D. B. Ann. Rev. Biochem. 1971, 40, 899942. Boyer, H. W. Ann. Rev. Microbiol. 1971, 25, 153-176. Meynell, G. C. "Bacterial Plasmids"; MacMillan Press, Ltd.: London, 1972. Chakrabarty, A. M.; Friello, D. Α.; Bopp, L. H. PNAS 1978, 75, 3109-3112. Jacoby, G. Α.; Rogers, J. E.; Jacob, A. E.; Hedges, R. W. Nature 1978, 274, 179-180. Reineke, W. R.; Knackmuss, H. J. J. Bacteriol. 1980, 142, 467-473.

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

19. 24.

25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39.

40.

QUENSEN & MATSUMURA

Plasmid Transfer of Degradation Capabilities 341

Chatterjee, D. K.; Chakrabarty, A. M. in Microbial Degradation of Xenobiotics and Recalcitrant Compounds"; Leisinger, T.; Hutter, R.; Cook, A. M.; Nuesch, J., Eds.; FEMS SYMPOSIUM NO. 12, Academic Press, Inc.: London, 1981; pp. 213-219. Kilbane, J. J.; Chatterjee, D. K.; Karns, J. S.; Kellogg, S. T.; Chakrabarty, A. M. Appl. Environ. Microbiol. 1982, 44, 72-78. Berg, Α.; Carlstrom, K.; Gustafsson, J.; Sundberg, M. I. Biochem. Biophys. Res. Comm. 1975, 66, 1414-1423. Hare, R. S.; Fulco, A. J. Biochem. Biophys. Res. Comm. 1975, 65, 665-672. Miura, Y.; Fulco, A. J. Biochemica et Biophysica Acta 1975, 388, 305-317. Yoneyama, K.; Matsumura, F., Unpublished data. Quensen, J. F., III; Matsumura, F. Environm. Toxicol. Chem. 1983, 2, 261-268. Carlton, B. C. in Society of Microbiology Carlton, B. C.; Smith, M. P. W. J. Bacteriol. 1974, 117, 1201-1209. Henneberry, R. C.; Carlton, B. C. J. Bacteriol. 1973, 114, 625-631. Rostas, K.; Dobritsa, S. V.; Dobritsa, A. P.; Koncy, C.; Alfoldi, L. Mol. Gen. Genet. 1980, 180, 323-329. Uozumi, T.; Hoshino, T.; Miura, K.; Horinouchi, S.; Beppu, T.; Arima, K. Molec. Gen. Genet. 1977, 152, 65-69. Carlton, B. C.; Brown, B. J. Plasmid 1979, 2, 59-68. Chang, S.; Cohen, S. N. Molec. Gen. Genet. 1979, 168, 111-115. Ensley, B. D.; Gibson, D. T.; LaBorde, A. L. J. Bacteriol. 1982, 149, 948-954. Dagley, S. in "Degradation of Synthetic Organic Molecules in the Biosphere"; National Academy of Science: Washington, D. C., 1972; pp. 1-16. Gunsalus, I. C.; Marshall, U . P. CRC Crit. Rev. Microbiol. 1971, 1, 291-310.

RECEIVED April 24, 1984

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

20 Degradation of High Concentrations of a Phosphorothioic Ester by Hydrolase R. HONEYCUTT,L.BALLANTINE, H. LEBARON, D. PAULSON, and V. SEIM— CIBA-GEIGY Corporation, Greensboro, NC 27409 C. GANZ—EN-CAS Laboratories, Winston-Salem, NC 27103 G. MILAD—Biospherics, Inc., Rockville, MD 20852

Greenhouse s o i l was treate with Diazinon 4E. Parathio hydrolas to determine the efficacy of the enzyme to rapidly degrade diazinon during a s p i l l situation. The h a l f - l i f e of the diazinon in the 500 ppm treatment without enzyme present was 9.4 days while the h a l f - l i f e of diazinon in the 500 ppm treatment with enzyme present was one hour. The half-lives of diazinon in the 1000, 2000 and 5000 ppm treatments with enzyme present were 1.2, 5.6 and 128 hours (5.3 days), respectively. These data indicate that parathion hydrolase can be used effectively to rapidly reduce large concentrations of diazinon in s o i l . At diazinon concentrations above 2000 ppm the enzyme is less effective. Parathion hydrolase is readily soluble in water, is reasonably stable and can be easily handled in the f i e l d . Further research is needed to evaluate the efficacy of parathion hydrolase to decontaminate diazinon under actual s p i l l conditions.

Chemical spills can be d e v a s t a t i n g to the environment as w e l l as to the pocketbook of those r e s p o n s i b l e f o r i t s cleanup. The cost of cleanup of a s i n g l e spill can approach $200,000. I t immediately occurs to one that a much e a s i e r and cheaper way must e x i s t to accomplish the cleanup of chemical spills. At CIBA-GEIGY we have formed a task force to study a l t e r n a t e ways to c l e a n up spills. One of the first p r o j e c t s the task force undertook was to develop a simple inexpensive means to c l e a n up d i a z i n o n spills which may occur on land or in water. 0097-6156/84/0259-0343$06.00/0 © 1984 American Chemical Society

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

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TREATMENT AND DISPOSAL O F PESTICIDE WASTES

Chakrabarty has e x t e n s i v e l y reviewed the biodégradation o f p e s t i c i d e s (1). Table I shows the r e s u l t s of s e v e r a l s t u d i e s on the enzymatic a c t i v i t y of m i c r o b i a l c e l l - f r e e e x t r a c t s f o r p e s t i c i d e degradation. C l e a r l y , there i s s u b s t a n t i a l evidence to suggest that enzymes might be used i n the development o f biotechnology f o r use i n degradation of p e s t i c i d e s . D i a z i n o n (Figure 1) i s widely used throughout the U n i t e d States and other c o u n t r i e s f o r c o n t r o l of v a r i o u s i n s e c t s such as cutworms, grubs, ants, cockroaches and s i l v e r f i s h . In the past, d i a z i n o n has been degraded using a c i d or sodium hypoc h l o r i t e degradation (2,3). Recently, enzymatic h y d r o l y s i s f o r decontamination of d i a z i n o n s p i l l s has been studied by Munnecke, et^ j a l . (4,5). Using an enzyme, p a r a t h i o n hydrolase, from a mixed c u l t u r e of pseudomonas sp., Munnecke was able to show that p a r a t h i o n hydrolase would degrade the organophosphate parathion 2450 times f a s t e I I shows the comparativ phosphates using parathion hydrolase vs. a chemical h y d r o l y s i s method. P a r a t h i o n hydrolase outperforms chemical h y d r o l y s i s methods f o r most organophosphates that Munnecke looked a t . Subsequent s t u d i e s showed that the enzyme would degrade 1000 ppm d i a z i n o n (25% EC formulation) i n s o i l by 97% i n 24 hours

Most of the studies done by Munnecke were small scale laboratory s t u d i e s . The e f f i c a c y o f parathion hydrolase has not been tested under f i e l d c o n d i t i o n s . I t was the major obj e c t i v e of our study to determine the usefulness o f parathion hydrolase f o r the decontamination of high concentrations of formulated d i a z i n o n i n s o i l under greenhouse c o n d i t i o n s . A secondary, but very important, o b j e c t i v e was to determine i f the enzyme could be handled i n a p r a c t i c a l f a s h i o n as would be done i n the f i e l d and r e t a i n i t s a b i l i t y to degrade d i a z i n o n . METHODS M a t e r i a l s : Parathion hydrolase was obtained from Doug Munnecke (4,5). The s p e c i f i c a c t i v i t y was measured by a method of Munnecke (4,5) and was found to be 0.1 pmole d i a z i n o n hydrolyzed/mg t o t a l protein/minute. Diazinon 4E was obtained from CIBA-GEIGY, Greensboro, NC. D e s c r i p t i o n o f Greenhouse Study - In 1981, s i x r e c t a n g u l a r flats(2 Χ 3' X 3") of Georgia loamy sand s o i l were prepared. The s o i l i n each f l a t was then placed i n a l a r g e Hobart mixer (80 quart bowl) and the appropriate amount of Diazinon 4E f

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

20.

HONEYCUTT ET AL.

Table I .

Enzymatic A c t i v i t y of M i c r o b i a l C e l l - F r e e E x t r a c t s For P e s t i c i d e Degradation

Pesticide Organaophospate s Acephate Aspon Cyanophos Diazinon Dursban DCVMP DEFP DFP EPN Fenitrothion Fensulfothion Methyl P a r a t h i o n Monocrotophos Paraoxon Parathion Propetamphos Quinalphos Triazophos TEPP Phenylureas Carboxin Chlorbromuron Linuron Metabromuron Monalide Monolinuron Monuron Pyracarbolid

Note:

345

Degradation by Hydrolase

Enzyme C l a s s

Esterase Esterase Esterase Esterase Esteras Lyas Lyase Lyase Esterase Esterase Esterase Esterase Esterase Esterase Esterase Esterase Esterase Esterase Lyase

Acylamidase Acylamidase Acylamidase Acylamidase Acylamidase Acylamidase Acylamidase Acylamidase

Enzyme A c t i v i t y (NMOL o f Substrate Transformed/Min/ mg P r o t e i n )

52 110 58 301,1200,A

A A 12 217 238 600,A 133 13,3600,A 259,3000, 7000,A 50 1410 4350 A

252 11,15 18,20,130 16,18 29,238 15,20 4 35

A = i n s u f f i c i e n t data t o c a l c u l a t e enzyme a c t i v i t y .

Reprinted with permission from Ref. 1. Copyright 1982, CRC P r e s s , Inc.

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

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T R E A T M E N T A N D DISPOSAL O F PESTICIDE WASTES

Table I I .

P a r a t h i o n Hydrolase S t u d i e s . Enzymatic v s . Chemical H y d r o l y s i s of Organophosphate I n s e c t i c i d e s

Solution Concentration MM

Pesticide Parathion Triazophos Paraoxon EPN Diazinon Methyl P a r a t h i o n Dursban

R a t i o Enzymatic H y d r o l y s i s Rate/ Chemical Rate 2450 1005 525 11 143 122

45 110 50 2 72 150

(Λ7.5% a c t i v e i n g r e d i e n t ) was slowly mixed i n t o i t over a p e r i ­ od of 5-10 minutes. At this point, 2 l i t e r s of a s o l u t i o n of parathion hydrolase i n 10 triM trihydroxy-methy1-amino methane b u f f e r (TRIS) - 5 mM cobalt c h l o r i d e , pH 8.5, were sprayed onto the s o i l using a 2-gallon garden hand sprayer. The mixture was then mixed f o r an a d d i t i o n a l 15-30 minutes to achieve homogene­ i t y , at which time 300 grams of s o i l were taken f o r a n a l y s i s . These are r e f e r r e d to as 0.5 hr. samples. Subsequent s o i l samples were taken at 2, 4, 24 and 48 hours, 7 days, and 3 weeks. Table I I I shows the d e s c r i p t i o n of s o i l f l a t s for the greenhouse study. Between sampling periods a l l f l a t s were kept i n the greenhouse at 24-27°C and 50-70% r e l a t i v e humidity.

Table I I I .

Diazinon Concentrations Flats

Soil Soil Soil Soil Soil Soil

-

All

Flat Flat Flat Flat Flat Flat

A Β C D Ε F

i n Georgia Greenhouse

Enzyme Only Diazinon 500 ppm - No Enzyme Diazinon 500 ppm + Enzyme Diazinon 1000 ppm + Enzyme Diazinon 2000 ppm + Enzyme Diazinon 5000 ppm + Enzyme

f l a t s kept at 24-27°C and 50-70% r e l a t i v e

humidity.

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

Soil

20.

HONEYCUTT ET AL.

Degradation by Hydrolase

347

A n a l y t i c a l Methods D i a z i n o n concentrations i n s o i l were measured using e x t r a c t i o n - p a r t i t i o n followed by gas chromatography. F i g u r e 2 gives an o u t l i n e of t h i s procedure. F i f t y grams of s o i l was f i r s t e x t r a c t e d with 200 ml acetone. Water (500 ml) was added t o a 140 ml a l i q u o t of the e x t r a c t and the mixture p a r t i t i o n e d with 35 ml hexane. The hexane was analyzed f o r d i a z i n o n using by GLC and a flame photometric d e t e c t o r ( F i g u r e 3). Oxypyrimidine, the major product o f d i a z i n o n degradation, (4 hydroxy-6methyl-2-isopropyl-pyrimidine) was determined i n s o i l by ext r a c t i o n with methanol:water (80:20) followed by a n a l y s i s by HPLC using a reverse phase Whatman p a r t i s i l ODS-3 column and a 50/50 mixture of methanol and 0.01M Na^PO^ i n the i s o c r a t i c mode (Figure 4 ) . Results S o l u b i l i t y of P a r a t h i o n Hydrolase During S o i l A p p l i c a t i o n P a r a t h i o n hydrolase i s s o l u b l e i n water and e a s i l y handled during a p p l i c a t i o n to s o i l . For p r a c t i c a l use on s o i l , i t was found that l a r g e amounts of the enzyme should be d i s s o l v e d i n t o a minimum amount of 10 mM TRIS - 5 mM c o b a l t c h l o r i d e , pH 8.5, and the mixture blended with a Waring blender at low speed f o r 1-2 minutes to achieve a homogenous suspension. At t h i s time more b u f f e r can be added g r a d u a l l y with constant a g i t a t i o n to f i n a l l y achieve the des i r e d d i l u t e s o l u t i o n . T h i s i s not a complicated procedure. Most workers w i l l have ready access to the equipment needed t o c a r r y out the procedure. Some s e t t l i n g of the enzyme w i l l occur over a p e r i o d of time. However, the s o l u t i o n remains homogeneous enough t o pass through common garden spray equipment. T h i s would make the enzyme q u i t e p r a c t i c a l f o r use i n ground a p p l i c a t i o n equipment. S t a b i l i t y of P a r a t h i o n Hydrolase The s t a b i l i t y of parathion hydrolase was determined f o r r e f r i gerator storage and room temperature storage. The enzyme s o l u t i o n i s stable under r e f r i g e r a t i o n ( 4 ) . The enzyme a l s o remains s t a b l e a t room temperature f o r long p e r i o d s ( 4 ) .

American Chemical Society Library 1155 16th St. N. W. In Treatment and Disposal of Pesticide Krueger, R., et al.; Washington, D. Wastes; C. 20036 ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

348

TREATMENT AND DISPOSAL OF PESTICIDE WASTES

CH,

"

CH 3

DIAZINON

un

^CH I CH-C .

'1 H/ ^c-O-P^ 0

Ν

C I 1

2-CH

J 3

0-CH -CH 2

3

C

^ÇH

OXYPYRIMI DINE

CH 3 \ CH ^ 3

F i g u r e 1.

Chemical S t r u c t u r e s

506 SOIL

EXTRACT 2 0 0 ML ACETONE

FILTRATE

FILTER

FILTER

CAKE

ADD WATER

PARTITION WITH HEXANE

HEXANE

F i g u r e 2.

WATER

A n a l y t i c a l Methods to Determine D i a z i n o n i n S o i l

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

HONEYCUTT ET AL.

Degradation by Hydrolase

COLUMN 6'X2MM GLASS PACKED WITH 10X D C - 2 0 0 ON 8 0 / 1 0 0 GAS CHROfl Q

OVEN TEMPERATURE •

GAS FLOWS:

170*L

CARRIER ( H E ) -

40 M L / M I Ν .

HYDROGEN

50 ML/MIN.

-

AI

DETECTOR:

Figure 3 .

FLAME PHOTOMETRIC (SULFUR MODE)

GC Conditions f o r A n a l y s i s o f D i a z i n o n

10G SOIL EXTRACT 80:20 METHANOL : WATER CENTRIFUGE

PELLET

SUPERNATANT

HPLC REVERSE PHASE WHATMAN PARTISIL ODS-3 ISOCRATIC MODE ME0H/NAH2P0i|(0.01M) 50/50 Figure 4.

HPLC A n a l y s i s o f Oxypyrimidine i n S o i l

In Treatment and Disposal of Pesticide Wastes; Krueger, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

350

TREATMENT AND DISPOSAL OF PESTICIDE WASTES

Degradation lase

of D i a z i n o n i n Greenhouse S o i l by P a r a t h i o n Hydro-

P a r a t h i o n hydrolase degrades d i a z i n o n r a p i d l y at high concent r a t i o n s i n s o i l . Table 4 shows a summary of the r e s u l t s of the attempt to degrade high concentrations of d i a z i n o n with p a r a t h i o n hydrolase. The f i r s t column shows that d i a z i n o n degrades very slowly a t 500 ppm with no enzyme present. The subsequent columns show that p a r a t h i o n hydrolase r a p i d l y and e f f e c t i v e l y degrades high concentrations of d i a z i n o n . At 2000 ppm the h a l f - l i f e of d i a z i n o n , when enzyme i s present, i s about 4-5 hours. At 5000 ppm the enzyme i s not as e f f e c t i v e . This may be due to the l a r g e amount of D i a z i n o n 4E present which could i n h i b i t the enzyme. Table IV.

Efficacy o Diazino

1

Average ppm of D i a z i n o n Remaining i n S o i l from Treatments , Time A f t e r 500 A p p l i c a t i o n (No Enzyme) 0.0 Hour 0.5 Hour 2.0 Hours 4.0 Hours 1 Day 2 Days 1 Week 3 Weeks

3

500 618+ 91 398+133 627+ 25 547+ 26 634+ 12 501+ 9 109+ 11

500

3

500 102+13 33+ 8 15+ 2 3+ 0 2+ 0.7