不同水动力湖区砷、汞物质多介质迁移和转化过程及水力调控机制

The study of transfer, transportation and bioavailability of arsenic and mercury in multimedia of lake ecosystems under different hydrodynamic conditions is innovative to the research of environmental geochemical and biogeochemical processes of land surface ecosystem. The combinative methods of laboratory studies and field observations, including ecological flume experiment, annular flume experiment, the observation of sediment resuspension in field and field exposure experiment of aquatic organisms, will be used in this project. The major targets of this project are analyzing transport and transformation rules of arsenic and mercury in “water – suspended solid”, “water - sediment”, and “water – colloidal particle” under different hydrodynamics, environmental behavior of arsenic and mercury in multimedia influenced by sediment resuspension processes, and transformation processes of arsenic and mercury in multimedia in different lake districts under the background of hydraulic regulation. arsenic and mercury toxic effects and accumulations of aquatic organisms will also be discussed under the above-mentioned processes. This project still want to indicate hydrodynamic effects on the arsenic and mercury transport and transformation in multimedia and bioavailability in lake ecosystems, establish coupled relation among hydrodynamics, arsenic and mercury transfer in multimedia and bioavailability of arsenic and mercury, and search for hydraulic regulation mechanism of arsenic and mercury transfer and bioavailability in water, and then provide scientific basis for arsenic and mercury pollution assessment, control and restoration in lake ecosystems.

不同水动力条件下湖泊生态系统的砷汞物质多介质迁移和转化及生物有效性研究对于陆地表层系统变化的环境和生物地球化学过程领域研究发展具有重要创新意义。本项目拟通过不同水动力水槽试验、再悬浮环形水槽、沉积物再悬浮现场观测、水生生物现场暴露试验等室内研究和现场观测相结合的研究手段，分析研究不同水动力湖区砷汞物质在水中迁移过程、在“水—悬浮颗粒物”、“水—沉积物”、“水—胶体粒子”微界面间的迁移转化规律、波流扰动下沉积物再悬浮过程及对砷汞物质多介质环境行为影响，并进一步探讨多介质迁移转化对水生生物累积和毒性效应的影响机制，揭示水动力作用对湖泊生态系统中砷汞物质多介质转化及生物有效性的影响机理，建立水动力条件—砷汞物质多介质转化—生物有效性之间的耦合关系，为我国湖泊砷汞污染评估、治理和修复提供科学依据。

不同水动力条件下湖泊生态系统的砷汞物质多介质迁移和转化及生物有效性研究对于陆地表层系统变化的环境和生物地球化学过程领域研究发展具有重要创新意义。本项目利用不同水动力水槽试验、再悬浮环形水槽、沉积物再悬浮现场观测、薄膜扩散梯度技术联合微电极原位观测技术等室内研究和现场观测相结合的研究手段，研究了洪泽湖有效态砷、汞在不同湖区、不同季节的浓度分布特征，揭示了有效态砷、汞在水动力和底栖生物扰动单独或交互影响下浓度和表观通量的变化规律，解析了环境条件和微生物因子对砷、汞迁移、转化的影响机制。取得的重要结果如下：（1）湖区有效态砷、汞浓度季节性差异不大；而由于水动力和底栖扰动的影响，不同湖区沉积物中有效态砷、汞浓度具有显著性差异. 有效态砷、汞浓度的异常值分布受风浪和底栖生物扰动影响，其中湖心区和养殖分布区砷、汞污染较为严重；（2）摇蚊和水动力的扰动增加了溶氧在沉积物中的穿透深度，促进了二价铁的氧化进程，使铁氧结合态砷比例显著上升，进而降低了沉积物中有效态砷的浓度；（3）生物扰动相比，风浪扰动虽然对甲基汞的抑制作用见效较慢但其更加长久且稳定；（4）硫酸盐还原菌和铁还原菌广泛参与砷、汞在沉积物中的迁移转化过程。项目成果建立了水动力条件—砷汞物质多介质转化—生物有效性之间的耦合关系，为我国湖泊砷汞污染评估、治理和修复提供科学依据。