土壤吸附对残留农药生物可用性的影响及机制

本项目选用我国常用的杀虫剂毒死蜱、除草剂异丙甲草胺和杀菌剂腈菌唑为代表农药，以农药环境毒理学和土壤污染化学为理论基础，采用批量平衡法等方法，着重研究可溶性有机质、草木灰、矿物粘土和表面活性剂对土壤吸附农药的影响规律及其机理，以及微生物降解、植物吸收和蚯蚓富集农药的规律及途经，探明微生物、植物及蚯蚓利用农药途经与土壤吸附作用之间的量化关系，以揭示土壤吸附对残留农药生物可用性的影响及其机制，阐释土壤吸附作用在残留农药的环境转移归趋中的功能作用。项目成果对发展农药环境毒理学和土壤污染化学的理论和方法、丰富农药环境化学的内容、合理评价和预示土壤残留农药的污染水平、探讨土壤农药污染的治理策略、指导农药的合理使用及新农药的合成均具有重要意义。

Sorption is generally recognized as a key to controlling concentrations of a pesticide in soil solution, and hence its availability to a receptor. However, most research to date concerning effect of soil sorption on bioavailability of pesticides has focused on apparent and empirical description about the relationship between soil sorption and the bioavailability of pesticides. Little work has been done to describe mechanistically the processes soil sorption govern the bioavailability of these chemicals. In the present study, therefore, the insecticide chlorpyrifos, the herbicide metolachlor and the fungicide myclobutanil widely used in China are chosen to research the effect and mechanism of soil sorption on bioavailability of residue pesticides using batch equilibration technique, root-box technique,and microcosmos technique based on the theoretical basis of pesticide environmental toxicology and soil pollution chemistry. The objectives of this work are (i) to determine characteristics and mechanisms of effect of dissolved organic matter,straw-derived ash,mineralclay and surfactants on sorption of pesticides in soil, (ii) to determine characteristics and approaches of microbial degradation, plant uptake and earthworm cumulation of pesticides in soil, (iii) to explore the quantitative relationship between soil sorption and availablility of pesticides to microorganisms, plants and earthworms, and (ⅳ) to reveal the effect and mechanism of soil sorption on bioavailability of residue pesticides in soil, and to interpret the function of soil sorption in the transfermation and fate of the pesticide in environment. The results of this work will have great important significance for developing theories and methods of pesticides environmental toxicology, richening research contents of soil pollution chemistry, rationally assessing and predicting the risk level of residue pesticide contamination, exploring the controll strategy of soil pesticide contamination, guiding the rational use of pesticides and the synthesis of new pesticides.