土壤结合态农药的生物可利用性与潜在毒性

农药是一类用量大、毒性高的重要污染物，在土壤中以结合态和游离态两种基本形态存在。传统观念认为，只有游离态农药才具有生物可利用性，进而体现毒性效应。本研究提出结合态农药同样具有某种程度的生物可利用性和潜在毒性的观点，将选用不同理化性质的四种农药和不同成分的四个土壤，在农药-土壤-水-生物体界面上/体系中，对土壤结合态农药的生物可利用性、代谢途径和机制、潜在毒性进行深入的研究，旨在全面准确地评价农药在土壤中的环境行为和生态风险，为我国的环境保护和生态安全提供基础支撑。研究内容包括结合态农药的微生物降解、植物吸收、动物（蚯蚓）积累等方面的生物可利用性；农药生物转化产物鉴定、途径和机制；结合态农药和代谢物混合物的潜在毒性等。课题组由国家杰出青年基金获得者领衔，由包括三位教授等成员组成，研究领域涵盖农药污染的全过程，研究经验丰富，实验室装备齐全，能保证本课题的顺利实施并取得高水平成果。

Pesticides are a large group of important environmental pollutants that are characterized by large usage, high toxicity and thus extensive impact on the environment. Pesticides exist in soils in both aqueous-phase dissolved and soil-bound residues. Existing theory asserts that only aqueous-phase pesticides are bioavailable and therefore possess toxic effects. We hypothesize that soil-bound pesticide residues are also bioavailable to some extent and hence potentially toxic to living organisms. This hypothesis will be tested in this project across the pesticide-soil-water-biota interfaces by determining the bioavailability of bound pesticide residues, pesticide transformation pathways, and pesticide potential toxicity. To this objective, four pesticides differing in physicochemical properties and four soils of different compositions are selected to be used. The results will be analyzed to accurately evaluate the environmental behaviors and ecological risks of pesticides in soils. The conclusions from this study will provide a supportive foundation for the environmental protection and ecological safety of China. The proposed research work includes microbial degradation, plant uptake and animal (earthworm) accumulation of soil-bound pesticide residues; product identification, pathways and mechanisms of biotransformation of pesticides; as well as potential toxicity of mixed pesticides and their transformation products. The research group, led by a recipient of the national natural science foundation outstanding young scholar’s project, comprises of three professors and other members. The research interests of group members are focused on pesticides and organic pollutants with many years of research experience. The laboratories are well equipped with various analytical instruments available for the proposed study. All these resources guarantee the successful implementation of the project leading to high-rank research production.