坡面径流中水沙影响重金属离子输移的规律研究

Transport of heavy metal ions influenced by flow and sediment, is not only the main spread path of heavy metal pollution in water, but also one of the key scientific focuses in the environmental sediment field of Sediment Transport Mechanics. However, it is found that the previous achievements rarely present discussion of the influences of flow and sediment on transport of heavy metal ions in slope runoff. Therefore, based on the method of erosion experiment with a Movable System for Simulation of Soil and Water Loss, data and theoretical analysis, this project will first investigate the impacts of hydrodynamic conditions including flow velocity and runoff duration on the transport of heavy metal ions in slope runoff, and then the effects of sediment characteristics including grain size and transport rate will be studied. At last, the inner relation between the transport results of heavy metal ions and the flow velocity, runoff duration, sediment grain size and transport rate will be analyzed according to the principle of Sediment Transport Mechanics and Interface Chemistry, and subsequently a micro-interface model for heavy metal ions transport impacted by the mentioned factors in slope runoff will be established through improvement of the most frequently used adsorption- desorption model. The results here will demonstrate the law of influences of flow and sediment on the transport of heavy metal ions in slope runoff, which will promote the cross development of Sediment Transport Mechanics with environmental science, and also provide a theoretical support for the control of water environmental pollution induced by heavy metal ions transport.

水沙作用下重金属离子的输移，不仅是流域水环境重金属污染迁移的主要途径，而且是泥沙运动力学学科环境泥沙领域研究的关键科学问题之一，但目前关于坡面径流中水沙影响重金属离子输移的研究尚不充分。对此，本项目采用坡面径流侵蚀实验、资料分析及理论分析相结合的方法，首先对坡面径流流速、径流历时等水动力条件因素影响重金属离子输移的规律进行研究，然后对坡面径流中泥沙粒径、输移率等特性因素影响下重金属离子的输移规律进行探讨，最后基于上述两方面的结果，对重金属离子输移与坡面径流流速、径流历时、泥沙粒径及输移率之间的内在联系进行分析，通过对现有吸附解吸模式的改进，建立坡面径流中重金属离子输移的微观界面模型。研究成果将在理论上弄清坡面径流中水沙对重金属离子输移影响的规律，促进泥沙运动力学与环境学科的交叉发展；在应用上为重金属引起的水环境污染的防控与治理提供理论支撑。

随着工业化和城市化的发展，世界上许多国家和地区，矿产资源开发产生的废弃物进入水体，不仅造成水环境的严重污染，而且给土壤环境也带来巨大威胁。本项目采用现场径流冲刷试验、室内模拟降雨试验、资料分析及理论分析相结合的方法，对坡面径流中多因素影响下重金属离子的输移特征进行了较为系统的研究。在总结天然状态下重金属离子赋存形态的基础上，分析了长江、黄河、海河及珠江流域河水中重金属离子的含量特征，确定了重金属的特征离子；基于径流冲刷和室内模拟降雨试验，研究了溶解态和颗粒态重金属离子输移结果随径流历时的变化，探讨了降雨强度对不同形态重金属离子输移结果的影响；对径流冲刷和模拟降雨条件下泥沙输移率的变化特征进行了研究，并在此基础上，阐述了泥沙输移率对溶解态和颗粒态重金属离子输移结果的影响；分析了泥沙颗粒粒径与颗粒态重金属离子输移结果的关系；在综合试验结果的基础上，分析了重金属离子液固相浓度比（溶解态重金属离子含量与颗粒态重金属离子含量的比值）随径流历时的变化特征，并以此为基础，依据界面化学等理论，构建了反映重金属离子释放结果的半经验微观界面数学模式，同时对所构建的模式进行了验证；另外，作为参照，以Ca2+为特征离子，基于室内模拟降雨试验，研究了溶解性物质输移与径流历时、泥沙输移率、泥沙粒径之间的变化关系，建立了泥沙粒径与溶解性物质输移结果之间的经验关系。本项目成果在揭示重金属离子在水与泥沙颗粒之间微观界面上的平衡过程、不同因素对重金属离子输移的影响机制等方面取得了创新性进展，丰富了泥沙运动力学与环境学科的交叉，为防控与治理重金属引起的水环境污染提供了一定的理论支撑。