A STUDY ON PESTICIDE MOBILITY AND PERSISTENCE FOR GEO-ENVIRONMENTAL POLLUTION MANIKAGUPTA. Deparbnent of Civil Engineering.

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1 A STUDY ON PESTICIDE MOBILITY AND PERSISTENCE FOR GEO-ENVIRONMENTAL POLLUTION by MANIKAGUPTA Deparbnent of Civil Engineering Submitted in fiulfihnent of the requirements for the degree of I CGON0)tie)o1w :ii 1 TV19]w:1.1 to the iii INDIAN INSTITUTE OF TECHNOLOGY, DELHI JANUARY 2012

2 Indian Institute of Technology (IIT) Delhi, 2012

3 CERTIFICATE This is to certify that the thesis, entitled "A Study on Pesticide Mobility and Persistence for Geo-Environmental Pollution", being submitted by Ms Manika Gupta to the Indian Institute of Technology, Delhi for the award of Doctor of Philosophy, is a record of bonafide research work carried out by her under our supervision. The thesis work, in my opinion has reached the standard, fulfilling the requirements for the said degree. Further, I certify that this submission is Ms. Gupta's own work and that, to the best of my knowledge and belief, it contains no material previously published or written by another person which to a substantial extent has been accepted for the award of any other degree or diploma of any University or Institute, except where due acknowledgment has been made in the text. (N.K.Garg) Professor Department of Civil Engineering Indian Institute of Technology Delhi (Himanshu Joshi) Professor Department of Hydrology Indian Institute of Technology Roorkee 1

4 ACKNOWLEDGEMENTS I owe my deepest gratitude and consider it a greatest privilege to express my heartfelt appreciation to my supervisor, Prof. N. K. Garg, Department of Civil Engineering, Indian Institute of Technology Delhi for his excellent supervision during the course of this research work. The present work has been possible due to his ardent interest and invaluable suggestions. He has been my mentor to whom I am obliged for unconditional trust, support, patience and also freedom to voice my trivial questions. He has always inculcated the belief to do the best. His sympathetic and logical approach towards any issue is admirable. I would like to acknowledge my joint supervisor, Prof Himanshu Joshi, Department of Hydrology, Indian Institute of Technology Roorkee, for his cooperation during the conduct of experiments and providing lab facilities in Roorkee. I sincerely acknowledge Prof. M. P. Sharma, Department of Alternate Hydro-Energy Centre (AHEC), IIT Roorkee, India, for his utmost cooperation at every stage during the conduct of experiments and lab analysis. I would like to give my sincere thanks to Prof. J. Simunek for his time to time support for HYDRUS-1D. I am thankful to the University Grant Commission (UGC), Government of India and Endeavour International Postgraduate Research Scholarship (EIPRS), Government of Australia for the financial support to this research. I am equally thankful to the Dr. Willem Vervoot, Faculty of Agriculture, Food & Natural Resources, University of Sydney, Australia for giving me this wonderful opportunity to utilize my talents to the best of my capabilities. I would also like to thank other members of this department Dr. Floris van Ogtrop, Dr. Claire Glendenning, Ms. Sue Liang for being there as friend and having discussions while working with R language and Astha Singh who has been good friend and made my stay in Australia an excellent experience. ii

5 I wish to extend my sincere thanks to all faculty members of the Department of Civil Engineering, IIT Delhi, especially to Head of the Department, Prof. A. K. Gosain, Prof. Shashi Mathur (SRC member), Prof. A. K. Nagpal, and Prof. Ashok Gupta (SRC, Chairman) for their support and encouragement. I also express my sincere thanks to all staff members of the Administrative office Mr. Rajveer Agarwal, Mr. Bikram and Mr. Gehlot for their kind cooperation and support and all help rendered by them during my stay at IIT Delhi. This acknowledgement shall remain incomplete unless I thank my senior research fellows Dr. Brijesh Yadav, Mrs. Sushmita Mukherjee Dadhich and Mr. Shailendra Jain who have provided me moral support during my study. I also am thankful to my fellow research scholars in IIT Delhi- Ms. Pratiksha Pandey and Ms Jayshree Patel for their help and encouragement during this study. Heartfelt gratitude is reserved for all my friends, whom I failed to mention, for their help. I express my regards and thanks to my parents as their contribution in whatever I have achieved till date is beyond expression. I also express thanks to my brother and sister-in-law. It was their love, affection and blessed care that has helped me to move ahead in my difficult times and complete my work successfully. I express my regards and thanks to parent in laws for being understanding, loving and blessing me to achieve my targets. I sincerely acknowledge with love, the patience and invaluable support of my husband Prashant. He has been a pillar of strength and made me look beyond the tough times. I am thankful to God for blessing me with him. His faith in my decisions and my abilities never wavered. It was his constant encouragement, which made me continue my work and I dedicate my work to him... Finally, I thank the almighty God for guiding me towards the path of truth and honesty. January 2012 (Manika Gupta) iii

6 ABSTRACT Wheat (Triticum aestivum L.) is an important cereal food crop in India and is considered in the present work to study the behaviour (persistence and mobility in soil) of the pesticides for the wheat crop in the study area, India. In order to study the pesticides under field conditions, the experimental plots were made in the agriculture field itself in Saliyar village, Roorkee, India. The potential movement and persistence of the three pesticides, used in protecting wheat crop, that is, Thiram; 2, 4-D; and Isoproturon was investigated under three different irrigation treatments. The irrigation treatments consisted of irrigation scheduling based on maximum allowable depletion (MAD) of available soil water (ASW) criteria, taken as 25%, 50% and 75%. The soil water contents and pesticides residue were determined in soil at temporal and spatial scale. The studied pesticides showed varied behavior under the three irrigation treatments employed in the three plots. Thiram being a non-polar pesticide was not found to be sensitive to the different irrigation treatments and Thiram residue showed almost same trend spatially and temporally in the three plots. However, for the two pesticides, 2, 4- D, and Isoproturon, mass transport differed among all the plots under different irrigation treatments. For all the three pesticides, the bulk mass of pesticide residue remained confined to the top 15 cm of the soil. The current existing dosage of 0.5 kg ha 1 of 2, 4-D and 0.8 kg ha 1 of Thiram were found to be safe to avoid soil contamination as no residue of any pesticide was traced at the end of the wheat crop season in any of the plots. However, 0.5 kg ha 1 of Isoproturon was not sustainable under low irrigation treatments as low concentrations were persisting in soil at the end of the crop period. Numerical simulations were also carried out by solving the coupled water flow and solute transport equations using numerical model, HYDRUS-1D. The soil hydraulic parameters can either be determined by fitting van Genuchten equation to the experimentally determined soil iv

7 water retention curves (SWRC) or by the use of PTFs. The experimentally determined soil water contents could only be poorly simulated using PTFs with negative model efficiencies. However, experimentally determined soil water contents were simulated with high average efficiencies in the range of 80% when the optimized soil hydraulic parameters were used. Hence, the optimized soil hydraulic parameters were used in the coupled water flow and solute transport equations to simulate pesticide persistence and mobility. Numerically simulated results for pesticides residues showed a good agreement with the experiments with high model efficiencies being above 80%. The pesticide regulation and various scenarios generated, suggested that the irrigation treatments may govern the safe dosage of pesticide application such that it does not have a carry-over effect of the residue in soil at the end of the crop period. The pesticides residues were found to persist in general under rain-fed conditions at the above existing dosage for all the three studied pesticides. v

8 CONTENTS Certificate Acknowledgements Abstract List of Figures List of Tables Notations and Symbols Acronyms and Abbreviations Page No. i ii iv ix xiii xv xviii Chapter 1 Introduction General Soil contamination Focus of the study The objectives of the study Organization of the Thesis 8 Chapter 2 Literature Review General Pesticides used in the present study Thiram , 4-D Isoproturon Experimental studies Laboratory studies General laboratory studies Laboratory studies for Thiram, 2, 4-D, Isoproturon Column studies General column studies Column studies for Thiram, 2, 4-D, Isoproturon Field lysimeter studies General lysimeter studies Lysimeter studies for Thiram, 2,4-D, Isoproturon Limitations of laboratory and column studies Need for field scale experiments Numerical models 26 vi

9 2.5 Need for present study 30 Chapter: 3 Methodology General Study area Field experiments Reagents and apparatus Soil physical properties analysis Soil water retention curve (SWRC) Saturated hydraulic conductivity (K5) Fertilizer and pesticide application Data collection Irrigation treatments Soil nutrient chemical analysis Pesticide residue analysis Thiram extraction and residue analysis , 4-D extraction and residue analysis Isoproturon extraction and residue analysis Numerical simulations Water flow Soil hydraulic parameters Soil hydraulic parameters using experimental data Soil hydraulic parameters using Pedo-transfer functions (PTFs) Schaap, et al., (2001) Wosten, et al., (1999) Vereecken, et al., (1989, 1999) Root growth parameters to estimate S in eq. (3.4) Initial and boundary conditions for eq. (3.5) Solute transport Solute transport and reaction parameters Initial and boundary conditions for eq. (3.22) Space and time discretization Pesticide mass balance Statistical analysis for model validation Simple linear regression analysis Relative root mean square error (RMSER) Nash-Sutcliffe modeling efficiency (E) Pesticide regulation scenarios 67 Chapter 4 Results and Discussions General 68 vii

10 Chapter Soil water content 68 Measured soil water content variation 68 Numerical simulation of soil water content Soil permeability Soil water retention curves (SWRCs) 72 Comparison of soil water content variations 79 Experimental and simulated pesticide behavior 89 Fate of Thiram Thiram mass balance Thiram residue in soil Persistence and mobility of Thiram 91 Fate of 2, 4-D , 4-D mass balance , 4-D residue in soil Persistence and mobility of 2, 4-D , 4-D concentration fronts 101 Fate of Isoproturon Isoproturon mass balance Isoproturon residue in soil Persistence and mobility of Isoproturon 106 Pesticide regulation Regulation of Thiram Regulation of 2, 4-D Regulation of Isoproturon 116 Comparison of behavior of three studied pesticides 119 Conclusions 122 General 122 Conclusions 123 Scope of future work 128 References 129 Appendix-A 149 Publication Brief Bio-Data viii