被动采样在珠三角典型城市水体沉积物毒性评价中的应用：常见农药体内代谢分配的影响

The bioavailability of sediment-associated contaminants affects not only their bioaccumulation, but also their toxicity, and thus it is necessary to establish the relationship between bioavailability-based dose metrics and sediment toxicity. Recently, there are increasing numbers of studies to measure the freely dissolved concentration of contaminants in sediment using passive sampling techniques and subsequently estimate chemical residues in biota. Nevertheless, the application of passive sampling techniques on toxicity evaluation is limited, particularly for the contaminants which are easy to be biotransformed in organism. The reason is probably related to the difficulty in quantitatively understand the impact of in vivo toxicokinetic processes on the toxicity. With the help of the early understanding on the bioavailability of sediment-associated contaminants, the current project plans to expand the application of passive sampling methods from measuring the bioavailability to evaluating the toxicity. Four pesticides will be selected as the target contaminants because toxicity of these pesticides is affected by the biotranformation process in different ways and the bioassays will be conducted using two benthic invertebrates with distinct capacity to metabolize organic chemicals. The dose-response relationships will be developed for the target pesticides and their metabolites using passive dosing methods. The influences of the biotransformation and the partitioning of the pesticides between the lipids and the proteins in organism on the toxicity will be quantitatively investigated. Then, a novel passive sampling method will be established by incorporating information of bioavailability-based dose-response relationship and in vivo toxicokinetic corrections, e.g. the biotransformation and partitioning between the lipids and the proteins in organism. Finally, the newly developed method will be applied to assess sediment toxicity in urban waterways in Guangzhou, a typical city in the Pearl River Delta. The implementation of the current project will provide theoretical understanding on the biotransformation of pesticide in invertebrates, a passive sampling method for evaluating toxicity of sediment-associated contaminants which are easy to be biotransformed, and valuable information on pesticide occurrence and toxicity in the study areas.

沉积物中污染物生物可利用性不仅与其生物积累相关，且影响其毒性效应，因此有必要建立含生物可利用性的暴露指标与毒性效应的关系。近年来，被动采样方法越来越多用于估算沉积物中有机物的自由溶解态浓度及生物体内的积累量。然而，由于受毒代动力学过程对毒性的影响难定量化的限制，被动采样方法评价毒性有困难，特别是对易代谢污染物。在早期沉积物中污染物生物可利用性的研究基础上，本项目拟选择代谢后毒性变化趋势各异的农药为目标化合物，具有不同代谢能力的底栖无脊椎动物为受试生物，构建农药及其代谢产物对受试生物毒性的剂量-效应关系；探讨污染物的体内代谢及脂肪与蛋白相间的分配对毒性的影响，并对其进行量化；运用生物可利用性暴露指标建立被动采样方法对常见农药的毒性评价的方法，并将其用于城市河道沉积物的毒性评价。其结果将为沉积物中易代谢转化污染物的毒性评价提供理论依据和有效方法，并获得研究区域沉积物中农药的毒性风险的基础数据。

作为水环境中疏水性污染物主要的汇，沉积物也是水体的重要二次污染源，准确评价沉积物毒性，对水环境质量控制至关重要。沉积物中污染物的生物可利用性不仅与其生物积累相关，且直接影响其毒性效应，因此有必要建立考虑生物可利用性的暴露指标与毒性效应的关系。被动采样逐步被用于估算沉积物中有机物的自由溶解态浓度及生物体内的积累量，而被动加标方法被用于维持毒性测试过程中疏水性污染物水浓度恒定。然而，由于受毒代动力学过程对毒性的影响难定量化的限制，这类单纯化学手段（被动采样和被动加标）评价毒性效应有困难，特别是对在生物体内易代谢的污染物。本项目可代谢农药（氟虫腈和滴滴涕）为目标物，具有不同代谢能力的水生动物（罗非鱼、夹杂带丝蚓、摇蚊幼虫、沙蚕）为受试生物，探讨农药母体及其代谢产物对生物毒性的剂量-效应关系；以聚二甲基硅氧烷（PDMS）为吸附相，优化被动加标技术的适用条件，测定污染物在脂肪与蛋白相间的分配系数；运用生物可利用性暴露指标建立被动采样方法对常见农药的毒性评价的方法，建立毒带动力学模型，定量剖析污染物在生物体内的吸收、分配、代谢和消除过程；在此基础上研究了污染物在脂肪和蛋白相间的分配对其生物积累和毒性的影响，并将其用于城市河道沉积物的毒性评价和主要致毒物筛查。通过本项目的实施，已取得了一系列的成果，建立了考虑污染物在环境介质中降解的毒代动力学模型，并获得研究区域水环境中现用农药的生态风险数据，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23篇（第一标注11篇）、中文核心期刊论文4篇（其中第一标注3篇），英文书籍章节1篇。申请发明专利4项，其中2项已授权。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，1名硕士毕业。