通江湖泊复杂水沙环境下镉的三相交换机制

Many scholars are paying more and more attention to heavy metal pollution for its high toxicity, persistence and hard-degradation. Based on the variable flow conditions and the uneven temporal distributions of sediment in river-connecting lakes, heavy metal cadmium（Cd）was selected to conduct the three-phase exchange experiment in complex water-sediment conditions. The exchange mechanisms of Cd during dissolved-suspension-sedimentary phases in different situations of sediment concentration, disturbance intensity and disturbance mode were studied. The adsorption and desorption parameters between the water-solid phases and the deposition and suspension parameters between the suspension - sedimentary phases were determined by the experiment results. The Inner Lake in Zhenjiang, a tidal river-connecting lake located in the lower reaches of the Yangtze River, was selected for applied research, and the transferring and transforming model of cadmium with different phases was established. By the model, the migration and conversion processes of Cd in a whole tidal cycle during the flood season and dry season were simulated, and the pollution loads of Cd in different phases were evaluated for the two seasons. The results of this project will be beneficial for studying the exchange behaviors of heavy metal in complex water-sediment environments and will have important reference values to the work of water quality protection and improvement for river-connection lakes.

重金属具有高毒性、持久性、难降解性等特点，已日益受到国内外学者的关注。本项目针对通江湖泊水动力条件多变、泥沙浓度时空分布不均的环境特征，以重金属镉为典型因子，开展复杂水沙条件对镉的三相交换影响实验；揭示不同泥沙浓度、水流扰动强度及扰动模式对镉在溶解相-悬浮相-沉积相间迁移转换的影响；凝练水-固(悬浮、沉积)相界面镉的吸附解吸参数以及悬浮-沉积相间的沉降起悬参数；选择长江中下游感潮通江湖泊镇江内湖为应用研究区，构建水沙环境下镉的迁移转换分相数学模型；运用所建模型对内湖洪季、枯季全日潮镉的迁移转换过程进行数值模拟，定量评估两季全潮过程镉的分相污染负荷。项目研究成果对掌握水沙环境下重金属的交换行为具有重要指导作用，对通江湖泊水环境质量保护工作也具有重要参考价值。

重金属具有高毒性、持久性、难降解性等特点，已日益受到国内外学者的关注。本项目针对通江湖泊水动力条件多变、泥沙浓度时空分布不均的环境特征，以重金属镉为典型因子，开展复杂水沙条件对镉的三相交换影响实验。 本项目揭示了不同泥沙浓度、水流扰动强度及扰动模式对镉在溶解相-悬浮相-沉积相间迁移转换的影响；凝练水-固(悬浮、沉积)相界面镉的吸附解吸参数以及悬浮-沉积相间的沉降起悬参数；选择长江中下游感潮通江湖泊镇江金山湖为应用研究区，构建水沙环境下镉的迁移转换分相数学模型；运用所建数学模型对丰水年、平水年、枯水年底泥疏浚后金山湖沉积物重金属镉的释放过程进行数值模拟；选择不同水平年及典型全日潮过程，定量评估了不同时间尺度下金山湖重金属镉污染负荷的波动特征，揭示了重金属镉在不同水沙条件下的释放规律。 项目研究成果对研究区域金山湖水环境保护，尤其是重金属污染防治提供了重要指导，对掌握水沙环境下重金属的交换行为具有重要指导作用。同时，研究成果也为揭示类似通江湖泊，如我国最大的淡水湖——鄱阳湖，重金属迁移转化规律提供了重要参考，对通江湖泊水环境质量保护工作也具有重要参考价值。