水库消落区作为陆地与水域的过渡带，既是陆地输入重金属的汇，也可能转变为向水体释放重金属的源。本项目选择世界上最大的水库消落区—三峡水库消落区作为研究对象，针对周期性蓄水泄洪条件下水库消落区沉积物中典型重金属汇源属性转化机制这一科学问题，采用原位观测、野外控制试验以及模型模拟的方法，并结合重金属同位素示踪技术，分析消落区水体、水体悬浮物、沉积物中典型重金属的时空分布特征；示踪重金属在消落区水土两相界面的传输过程，识别在蓄水泄洪不同阶段重金属的汇源功能属性；筛选消落区沉积物中重金属释放的关键控制因子，揭示周期性蓄水泄洪对消落区沉积物重金属汇源属性转换的影响机制。研究成果有助于加深理解水土两相界面重金属传输机理，探明重金属在消落区不同运行阶段的源汇属性，为消落区生态修复和三峡水环境保护提供重要的理论依据。

Water level fluctuating zone in Three Gorges as a transition zoneof water and the terrestrial environment, its ecosystems can be cross-contaminated by both interfacesof land and water. The terrestrial input of heavy metal’s exchange for the water level fluctuating zone, may also be transformed into a heavy-metal source of water to be released.In this study, the response mechanism of heavy-metalsource and sink functionof the water level fluctuating zone in Three Gorgeswill be illustrated using in situ observations, field control arrangement tests, simulation models and heavy-metal isotope tracer techniquesunder the periodically flood conditions. Firstly, the spatial and temporal distributionfor thetypicalheavy metals will be obtained in sediments, overlying water and suspended solidsof the water level fluctuating zone in Three Gorges.Secondly, in order to get the source and sink function of heavy metals with the different stages of the Three Gorges, the microscopic process of heavy-metaltransmission in the soil and water two-phase interface of the water level fluctuating zonewill be traced using heavy-metal isotope tracer techniques. Lastly, the function mechanism of heavy-metal source and sink function conversion will be illustrated by the searching of heavy-metal release factors of control during the different processes of flood storage and discharge using controlled field experiments.The results of this project can make a significant contribution for the understanding of the transmissionmicroscopic mechanism ofheavy metals in soil and water two-phase interface, illustrating the heavy-metal source and sink function in the different processes of the flood storage and discharge, and providing an important theoretical basis for ecological restoration and environmental protection of the Three Gorges water level-fluctuating zone.