农业区水-沉积物体系中常见杀虫剂的迁移降解行为及其对沉积物毒性的影响机制

Agricultural non-point pollution has become increasingly serious nowadays in China, and insecticide residues are regarded as one of major contributors to aquatic risk. Process control is an important step in water pollution control. To effectively implement process control requires to understand the factors that govern the transportation of insecticides from small ditches to large rivers, which results in non-point pollution and ecological risk in agricultural waterways. With the help of the early experience in the bioavailability and toxicity assessments of sediment-bound pesticides, the current project plans to study the fate and transport of current-use insecticides in water-sediment system and evaluate the influence of the processes on their aquatic toxicity with a combination of laboratory testing and field application. The partition and degradation processes of current-use insecticides in water-sediment system will be assessed in laboratory-based studies. The dose-response relationship for insecticides and their degradation products to test species will be set up, with a special focus on endocrine disruption effects and the impact of degradation process of insecticides on their toxicity will be studied. Then, the partition, transport and degradation of current-use insecticides in paddy field-ditch-stream system will be studied by a simulated stormwater runoff and under a real stormwater runoff in a representative rice planting area in Shanghang, Fujian Province. The influence of the fate and transport of various current-use insecticides on their composition and toxicity to aquatic species in adjacent streams will be assessed. The implementation of the current project will provide theoretical understanding on the process control of pesticide non-point source pollution.

我国农药面源污染形势严峻，其中杀虫剂残留是水生态风险的重要因素之一。过程控制是水污染防治的一个重要环节，其有效实施要求明确不同类型杀虫剂经排水沟渠进入周边河流引起面源污染和生态风险的控制因素。基于前期沉积物中当前使用农药的生物可利用性和毒性效应的研究，本项目拟结合实验室机制研究、野外模拟和应用，解析农业区频繁检出的当前使用杀虫剂在水-沉积物体系中的分配和降解过程；获取目标杀虫剂及其降解产物对模式生物毒性的剂量-效应关系，分析内分泌效应相关基因表达，揭示杀虫剂的分配和降解对其毒性的影响机制；选择福建上杭典型水稻种植区为代表区域，模拟杀虫剂在水稻田-排水沟渠-河道中的分配、迁移和降解行为，揭示该过程与河道中杀虫剂组成变化和毒性分布的关联；最后，在水稻田常规施药后，分析农残通过雨水径流冲刷进入沟渠的迁移和降解情况，评估受纳河道中杀虫剂对水生生物的危害效应，为农药面源污染的过程控制提供理论基础。

我国农药面源污染形势严峻，已成为水生态风险的重要因素之一，特别是农业区周边水体。过程控制是水污染防治的一个重要环节，其有效实施要求明确不同类型的农药经排水沟渠进入周边河流引起面源污染和生态风险的控制因素，即明确农药施用排放后在水环境的迁移转化过程，及其对受纳河道中水生生物的毒性效应。本项目选择江西典型水稻种植区，首先通过野外实地勘察及文献调研确定了水稻种植区主要的目标农药及其转化产物。针对污染物种类繁多，以及瞬时采样可能导致较高不确定性的问题，建立了基于混合吸附剂的固相萃取法，并在此基础上发展被动技术，获得了基于混合吸附剂的极性有机物整合采样器（POCIS-MMA）对多类除草剂、杀菌剂、杀虫剂及其转化产物的采样速率。在从上游稻田种植区沟渠、河流，一直到鄱阳湖，布设了24个采样点，同时采集水体主动采样样品、POCIS-MMA被动采样样品、沉积物样品，分析其中除草剂、杀菌剂、杀虫剂及其转化产物，揭示不同类型农药在水环境中的迁移和转化规律，并分析了其在水相与沉积物相中的分配情况，测试野外样品对水生生物毒性。此外，针对研究区域广泛检出的新烟碱类农药和氟虫腈，探究了新烟碱类杀虫剂对水生模式生物的毒性剂量-效应关系，分析了内分泌效应相关基因表达，提出了新烟碱类农药对水生动物毒性的有害结局通路，通过建立降解及毒代动力学模型，揭示了沉积物中氟虫腈在夹杂带丝蚓体内的积累及转化过程。通过项目的实施，已取得了一系列的成果，获得典型水稻种植区施用农药在受纳水体的迁移转化规律及潜在风险，完成了项目原定计划。共发表标注本项目号的国际SCI 期刊论文21篇，申请发明专利3项。项目负责人当选为国际环境毒理与化学协会亚太分会常务理事会主席，且项目参与人员（包括研究生）多次在国际国内会议中通过口头报告和墙报形式分享研究成果。参与项目的人员中，2名博士后出站，5名博士毕业，7名硕士毕业。

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