Pesticides in the Soil Environment (Fundamental aspects of pollution control and environmental science)

Fundamental aspects offlODution control ancJ:environmentai science 5 -

Fundamental Aspects of Pollution Control and Environmental Science 5

PESTICIDES IN THE SOIL ENVIRONMENT

Fundamental Aspects of Pollution Control and Environmental Science Edited by R.J. WAKEMAN Department of Chemical Engineering, University of Exeter (Great Britain)

1 D. PURVES Trace-Element Contamination of the Environment

2 R.K. DART and R.J. STRETTON Microbiological Aspects of Pollution Control 3 D.E. JAMES, H.M.A. JANSEN and J.B. OPSCHOOR Economic Approaches to Environmental Problems

4 D.P.ORMROD Pollution in Horticulture

5 S.U. KHAN Pesticides in the Soil Environment

Other titles in this series (in preparation): R.E. RIPLEY and R.E. REDMANN Energy Exchange in Ecosystems W.L. SHORT Flue Gas Desulfurization A.A. SIDDIQI and F.L. WORLEY, Jr. Air Pollution Measurements and Monitoring D.R. WILSON Infiltration of Solutes into Groundwater

Fundamental Aspects of Pollution Control and Environmental Science 5

PESTICIDES IN THE SOIL ENVIRONMENT SHAHAMAT U. KHAN Chemistry and Biology Research Institute Research Branch, Agriculture Canada Ottawa, Ont., Canada

ELSEVIER SCIENTIFIC PUBLISIDNG COMPANY Amsterdam - Oxford - New York 1980

ELSEVIER SCIENTIFIC PUBLISHING COMPANY 335 Jan van Galenstraat P.O. Box 211,1000 AE Amsterdam, The Netherlands

Distributors for the United States and Canada: ELSEVIER/NORTH-HOLLAND INC. 52, Vanderbilt Avenue New York, N.Y. 10017

Library of Congress Cataloging in Publication Data

Kahn, Shahamat U Pesticides in the soil environment. (Fundamental aspects of pollution control and environmental science ; 5) Includes bibliographical references and indexes. 1. Pesticides--Environmental aspects. 2. Soil pollution. I. Title. II. Series.

TD879.P37K33 ISBN 0-444-41873-3

631.4'1

80-11238

ISBN 0-444-41873-3 (Vol. 5) ISBN 0-444-41611-0 (Series)

© Elsevier Scientific Publishing Company, 1980.

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of the publisher, Elsevier Scientific Publishing Company, P.O. Box 330, 1000 AH Amsterdam, The Netherlands Printed in The Netherlands

v

PREFACE

Chemicals for crop protection and pest control - known collectively as pesticides - are being increasingly used to ensure the production of adequate supplies of food and fiber. Some of these pesticides find their way into soils as a result of direct application or through indirect means. \vith the discovery that chlorinated hydrocarbon insecticides persist for years in soil, all pesticides are now being viewed with suspicion and concern by people interested in protecting our agricultural land from widespread pollution. The extent and seriousness of the contamination of soils by pesticides still remains to be determined. Some environmentalists take the view that use of pesticides on agricultural soils should be reduced or banned because of the risk of uptake of these chemicals by crops and their subsequent incorporation into the food chain. On the other hand, agriculturalists and others argue that continued use of large quantities of pesticides is essential to the achievement of maximum yields. A reasonable alternative to these extreme views would be to first gain a better understanding of the behavior of pesticides in soils from the standpoint of the processes affecting these chemicals, and the implication of these processes on persistence, bioactivity and plant uptake. With this knowledge, the environmental impact of using a pesticide in agriculture could be assessed more accurately. This book, Pe~t~c~de~ ~n the So~t Env~~onment, is an attempt to provide this kind of information by bringing together the available data on many aspects of the behavior and fate of pesticides in soils. It is hoped that it will serve as a text book for advanced courses, a reference volume for research workers and a source of detailed information for those who seek knowledge on the topic.

vi I will make no effort to acknowledge individually the many people who assisted me in proof reading, in the preparation of illustrations and the compilation of the indexes. To them I am grateful. I do wish, however, to express my appreciation to Mrs. Anneth Martin for her painstaking efforts in the final typing of the manuscript. My sincere gratitude is also expressed to the Chemistry and Biology Research Institute, Research Branch, Agriculture Canada, for providing opportunity and facilities to produce this book. Finally, I must convey my deepest affection and appreciation to my wife Nighat and to my children, Saira and Zia, for their keen sense of understanding during the preparation of this book.

Shahamat U. Khan

Ottawa, Ontario December, 1979

THE AUTHOR SHAHAMAT U. KHAN is a Senior Research Scientist at the Chemistry and Biology Research Institute, Research Branch, Agriculture Canada, Ottawa. His research is concerned with the fate of pesticides in the environment. He obtained a B.Sc. in Pure Science from Agra University, India, an M.Sc. in Chemistry from Aligarh University, India, and an M.Sc. and a Ph.D. in Soil Chemistry, both from the University of Alberta, Edmonton, Canada. Dr. Khan belongs to numerous scientific societies and is a Fellow of the Chemical Institute of Canada and a Fellow of the Royal Institute of Chemistry (London). He is the Editor of the Jou~nal 06 Env~~onmental SQ~enQe and Health, Pa~t B. He is the author or coauthor of more than 80 scientific research publications and has coauthored a previous book, Hum~Q Sub~tanQe~ ~n the Env~~onment (1972) and coedited another book So~l O~gan~Q Matte~ (1978). In addition he has written a number of chapters in edited books and several review articles.

CONTENTS PREFACE. . . .. .. . . . . . . . . .. .. . . . . .. . . .. . . . . .. .. .. . . . . . . . . . . .. . ..

v

Chllptefl 1.

INTRODUCTION ................................... .

1

CLASSIFICATION OF PESTICIDES.. .......... ........ 2.1. Herbicides............................................ 2.1.1. Arsenicals .................................... 2.1.2. Organophosphates .............................. 2.1.3. Phenoxys ...................................... 2.1.4. Benzoics........ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1.5. Pyridine Acids.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1.6. Chlorinated Aliphatic Acids ................... 2.1.7. Amides ........................................ 2.1. 8. Carbamates and Thiocarbamates..... . . . . . . . . . . .. 2.1.9. Dini troani1ines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1.10. Nitri1es ...................................... 2.1.11. Phenols ....................................... 2.1.12. Bipyridy1i1.lllls ................................. 2.1.13. Uraci1s....................................... 2.1.14. Triazo1es..................................... 2.1.15 . .6-Triazines ................................... 2.1.16. Ureas......................................... 2.2. Insecticides.......................................... 2.2.1. Organophosphorus Compounds .................... 2.2.2. Carbamates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .-)'2. 2. 3. Organoch lorines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.4. Synthetic Pyrethroids ......................... 2.3. Fungicides............................................ 2.4. Fumigants ............................................. References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

9 9 10 11 11 12 12 12 13 l3 15 16 16 17 17 18 18 19 19 20 23 24 25 26 27 28

Chllptefl 2.

Chllptefl 3. PHYSICOCHEMICAL PFOCESSES AFFECTING PESTICIDES IN SOIL........................................... 3.1. Adsorption ............................................ 3.1.1. Characteristics of Soil ....................... 3.1.2. Characteristics of Pesticides ................. 3.1.3. Adsorption Isotherms .......................... 3.1.4. l1echanisms of Adsorption... .. .. .... .. .. .. .. . .. 3.1.5. Adsorption of Specific Types of Pes ticides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1.6. Adsorption of Pesticides by Organo-C1ay Complexes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3.2. Movement in Soil 3.2.1. Diffusion..................................... 3.2.2. Mass Flow..................................... 3.3. Volatilization........................................

29 29 29 36 38 44 56 68 71 75 78

viii 3.4. Chemical Conversion and Degradation ................... 83 3.4.1. Hydrolysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 3.4.2. Oxidation and Reduction....................... 98 3.4.3. N-Nitrosation................................. 99 3.4.4. Other Reactions ............................... 103 3.5. Photodecomposition .................................... 104 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 108 Chapte~

4. MICROBIAL PROCESSES AFFECTING PESTICIDES IN SOIL .................................................... . 4.1. Herbicides •.......................................... 4.1.1. Arsenicals .................................. . 4.1.2. Organophosphates ............................ . 4.1.3. Phenoxys .................................... . 4.1.4. Benzoic Acids ............................... . 4.1.5. Pyridine Acids .............................. . 4.1.6. Arnides ...................................... . 4.1.7. Thiocarbamates, Pheny1carbamates and A