The Persistence, Degradation, and Mobility of Metolachlor in Soil And
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Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1996 The persistence, degradation, and mobility of metolachlor in soil and the fate of metolachlor and atrazine in surface water, surface water/sediment, and surface water/aquatic plant systems Pamela Joan Rice Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Agriculture Commons, Environmental Sciences Commons, Fresh Water Studies Commons, and the Soil Science Commons Recommended Citation Rice, Pamela Joan, "The persistence, degradation, and mobility of metolachlor in soil and the fate of metolachlor and atrazine in surface water, surface water/sediment, and surface water/aquatic plant systems " (1996). 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Contact UMI directly to order. UMI A Bell & Howell Information Company 300 Notth Zsdb Road, Ann Aibor MI 48106-1346 USA 313/761-4700 800/521-0600 The persistence, d^radation, and mobility of metolachlor in soil and the fiite of metolachlor and atrazine in surface water, surface water/sediment, and surface water/aquatic plant systems by Pamela Joan Rice A dissertation submitted to the graduate faculty in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Major: Toxicology Major Professors: Joel R. Coats and Todd A. Anderson Iowa State University Ames, Iowa 1996 UMI Number: 9712595 UMI Microform 9712595 Copyright 1997, by UMI Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. UMI 300 North Zeeb Road Ann Arbor, MI 48103 ii Graduate College Iowa State University This is to certify that the Doctoral dissertation of Pamela Joan Rice has met the dissertation requirements of Iowa State University Signature was redacted for privacy. Signature was redacted for privacy. Co-major Professor Signature was redacted for privacy. For the-Major Program Signature was redacted for privacy. iii TABLE OF CONTENTS LIST OF FIGURES v LIST OF TABLES ix CHAPTER 1. GENERAL INTRODUCTION 1 Introduction 1 Metolachlor; Use I Metolachlor: D^radation 2 Metolachlor: Mobility in Soil 5 Herbicide Contamination of Surface Water 6 Persistence of Metolachlor and Atrazine in Water 8 Problems Associated with Pesticide-Contaminated Water 9 Remediation of Contaminated Water with Aquatic Plants 11 Dissertation Objectives 12 Dissertation Organization 14 CHAPTER 2. THE INFLUENCE OF SOIL MOISTURE AND HERBICIDE CONCENTRATION ON THE DEGRADATION OF METOLACHLOR IN SURFACE AND SUBSURFACE SOILS 16 Abstiract 16 Introduction 17 Materials and Methods 18 Results 24 Discussion 38 Acknowledgments 40 References 41 CHAPTER 3. MOBILITY AND PERSISTENCE OF METOLACHLOR IN UNDISTURBED SOIL COLUMNS 44 Abstract 44 Introduction 45 Materials and Methods 47 Results and Discussion 52 Conclusion 58 Acknowledgment 60 Referoices 60 iv CHAPTER 4. FATE OF METOLACHLOR AND ATRAZINE IN SURFACE WATER AND SURFACE WATER/SEDIMENT INCUBATION SYSTEMS 64 Abstract 64 Introduction 65 Matmals and Methods 65 Results 69 Discussion 86 Conclusion 89 Acknowledgment 89 References 90 CHAPTER 5. PHYTOREMEDIATION OF HERBICIDE-CONTAMINATED WATER WITH AQUATIC PLANTS 93 Abstract 93 Introduction 94 Materials and Methods 96 Results 100 Discussion 117 Acknowledgments 120 Refoences 120 GENERAL CONCLUSIONS 125 Environmental Fate of Metolachlor in Soil 125 Persistence of Metolachlor and Atrazine in Surface Water and the Remediation of Herbicide-Contaminated Water with Aquatic Plants 126 GENERAL REFERENCES 127 ACKNOWLEDGMENTS 133 V LIST OF FIGURES CHAPTER 1. GENERAL INTRODUCTION Figure L Metolachlor and metolachlor degradation products 3 Figure!. Atrazine and atrazine degradation products 10 CHAPTER 2. THE INFLUENCE OF SOIL MOISTURE AND HERBICIDE CONCENTRATION ONTHE DEGRADATION OF METOLACHLOR IN SURFACE AND SUBSURFACE SOILS Figure 1. Metolachlor and its carbinol (CGA-40172) and morpholinone (CGA-40919) metabolites 19 Figure2. Fate of ['"Clmetolachlor in surface (0-30 cm) and subsurface (90-120 cm) soils at two soil moistures (unsaturated (-0.3 bar, -33 ld>a) and saturated (30% above -0.3 bar)). The dissipation of metolachlor (panel A), formation of nonextractable residues (panel B) and the formation of extractable degradation products (panel C) were determined by thin layer chromatography and soil combustion as described in the materials and methods. Abbreviations: 30 = 0-30 cm; 120 = 90-120 cm; U = unsaturated; S = saturated 26 Figure 3. Figure 3. Fate of ["C]metolachlor in sterile and nonsterile surface (0-30 cm) and subsurface (90-120 cm) soils at two soil moistures [unsaturated (-0.3 bar, -33 kPa) and saturated (30% above -0.3 bar)]. The dissipation of metolachlor (panels A&D), formation of nonextractable residues (panels B&E) and the formation of extractable degradation products (panels C&F) were determined by thin-layer chromatography and soil combustion as described in the Materials and Methods. Abbreviations: 30 = 0-30 cm; 120 = 90-120 cm; NS = nonsterile; ST = sterile (autoclaved for 1 hour at 121°C for two consecutive days); U = unsaturated; S = saturated 31 Figure 4. Fate of ['''C]metolachlor in surface (0-30 cm) and subsurface (90-120 cm) soils at two soil moistures [unsaturated (-0.3 bar, -33 kPa) and saturated (30% above -0.3 bar)] and two herbicide concentrations (9 |ig/g and 90 ^g/g). The dissipation of metolachlor (panels A&D), formation of nonextractable residues (panels B&£) and the formation of extractable degradation products (panels C&F) were determined by thin-layer chromatography and soil combustion as described in the Materials and Methods. Abbreviations; 30 = 0-30 cm; 120 = 90-120 cm; U = unsaturated; S = saturated 34 vi Figure S. Microbial respiration in metolachlor-treated surface soils(0-30 cm) 36 Figure 6. Microbial respiration in metolachlor-treated subsurface soils (90-120 cm) 37 CHAPTER 3. MOBILITY AND PERSISTENCE OF METOLACHLOR IN UNDISTURBED SOIL COLUMNS Figure I. Undisturbed soil column 49 Figure 2. Distribution of '"C in the leached soil column 53 Figure 3. Quantity of metolachlor and metolachlor degradation products detected in the soil extracts of the leached soil column 57 Figure 4. Metolachlor and metolachlor degradation products in the leachate of the soil columns 59 CHAPTER 4. FATE OF METOLACHLOR AND ATRAZINE IN SURFACE WATER AND SURFACE WATER/SEDIMENT INCUBATION SYSTEMS Figure 1. Percentage of applied ['^C]metolachlor remaining in the water of the surface water and surface water/sediment incubation system after 60 days 74 Figure 2. Percentage of applied ['"HDJatrazine remaining in the water of the surface water and surface water/sediment incubation system after 60 days 75 Figure 3. Distribution of'"C and [''*C]metolachIor in the surface water (nonsterile)/sediment (nonsterile) incubation systems. (''KH-MET = ["C]metolachlor, sed. = sediment) 76 Figure 4. Distribution of and ['''CJmetolachlor in the surface water (sterile)/sediment (sterile) incubation systems. ('"'C-MET = ["C]metolachlor, sed. = sediment; sterile = autoclaved for 1 h at 120°C for two consecutive days) 77 Figure 5. Distribution of and ["Cjatrazine in the surface water (nonsterile)/sediment (nonsterile) incubation systems. ("'C-ATR= ['"CJatrazine; sed. = sediment) 78 vii Figure 6. Distribution ofand [''*C]atrazine in the sur&ce water (sterile)/sediment (sterile) incubation systems. ('^-ATR = ["C]atrazine; sed. = sediment; sterile = autoclaved for 1 h at 120°C for two consecutive days) 79 CHAPTERS. PHYTOREMEDIATION OF HERBICIDE-CONTAMINATED WATER WITH AQUATIC PLANTS Figure 1. Percentage of applied ['"^jmetolachlor remaining in the water of the nonvegetated- and vegetated-surface water incubation systems after 16 days 101 Figure 2. Percentage of applied ['"Cjatrazine remaining in the water of the nonvegetated-