高山寒区流域侵蚀沉积与痕量元素迁移及其交互作用

It has been one of the hotest topics for scientific research in recent years of the water environment effects caused in the process of sediment transport in basins. It is not only the formative area of water source but also the main formative and transport area of sediment in inland mountain river basins in China arid regions. The studies on trace element pollutant transport characteristics in the sediment process and river deposit in high-cold mountain regions will provide a scientific basis for understanding the physical and chemical process and its environmental meanings in the process of sediment formation, transportation and deposit. This project takes the upstream of Urumqi River in Tianshan Mountain as the research subject and tries to build a coupled model of water-sediment-trace element in a basin distribution way by means of real-time monitoring the runoff, sediment transport process and hydrochemistry characteristics on basis of the analysis on erosion deposit process and hydrochemistry characteristics. Moreover, the basin scale erosion deposit, matter cycle process and rule and the effect of glacier ablation and gravel bed sediment movement during the transformation of trace element transportation will be studied in the methods of morphological, isotope ratio and multivariate statistical analysis, etc. The spatial and temporal relationship will be discussed as well between the geological environment and trace element in river sediment in typical high-cold mountain regions and the mutual mechanics between suspended load sediment transportation and the transportation process of trace element pollutants. All the above are very meaningful for understanding the environmental implications of trace element records in alpine mountain thoroughly and will provide scientific basis for prediction and improvement on ecological environment in inland mountain rivers.

泥沙输移过程中所引起的河流水环境效应已经成为近年来科学研究的热点问题之一。我国西干旱陆河山区流域，不仅是水源形成区，而且是泥沙形成和搬运区，开展泥沙输移过程及流域中痕量元素迁移特征及交互作用研究，为科学认识高寒山区侵蚀沉积的物理化学过程及其环境意义提供科学依据。 项目选择乌鲁木齐河上游作为研究对象，通过对河流流量、泥沙输移过程和水化学特征的野外观测，分析侵蚀沉积过程和水环境特征，构建流域分布式水-沙-痕量元素耦合模型，并运用形态分析和同位素比值分析等方法，结合多元统计分析方法，研究高寒山区流域尺度的侵蚀沉积和物质循环过程和规律，分析冰川消融和卵砾石河床泥沙运动在痕量元素迁移转化中的作用，探讨地质环境与河流泥沙中痕量元素的时空分布关系，揭示泥沙输移与痕量元素迁移过程中的交互机理，对于全面认识高寒山区痕量元素记录的环境内涵具有重要意义，为内陆山区河流的生态环境的变化预测和改善提供科学依据。

泥沙输移过程中所引起的河流水环境效应已经引起了人们的极大关注，成为近年来科学研究的热点问题。高山寒区流域，不仅是我国西北内陆地区最重要的水源形成区，而且是泥沙形成和搬运区，河流泥沙无论从上游的侵蚀，中游的迁移，还是下游的沉积无不表现出与重金属元素迁移之间的紧密联系。项目以天山乌鲁木齐河（以下简称“乌河”）为研究对象，运用野外实测资料和室内分析数据，并结合水文气象观测数据和遥感影像资料，分析了乌河上游水沙过程、河床特征和水环境特征，估算了流域水资源的变化特征和驱动机制，构建流域分布式水—沙—痕量元素耦合模型。. 研究工作主要取得了以下成果：. 1）研究表明，乌河河床的粒度分布在其活动层的规模上是均匀的，除了存在一些局部变化，没有垂直或横向粒度趋势。2）结合野外实测资料，运用GPD模型和Bayes模型对乌河月均径流极值的重现期进行了预测，构建了乌河洪水期与枯水期月均径流量极大值与极小值的分布模型。3）探讨了流域内As、Fe、Hg、Cd、Pb、Cr、Cu、Co、Ni 和Sn 等10 余种痕量元素浓度的时空变化及其在流域侵蚀沉积过程中作用，以及它们年内变化特征及其对人类活动和自然过程变化的响应，探讨了流域水体中氨氮的来源和区域传输模式。4）构建了基于高斯人工蜂群技术的氨氮浓度预测模型，从而提高了河流水体氨氮浓度的预测精度，并应用该模型对乌河上游氨氮浓度进行了预测。5）通过对乌鲁木齐河上游开展的一系列的野外取样和测量工作，分析了其水沙时空变化，从而为高山卵砾石河床的径流与输沙关系的研究提供了理论依据。6）运用对乌鲁木齐河上游的实测数据和历史观测数据，充分考虑水沙过程和痕量元素污染物迁移过程中的交互作用，构建了流域水-沙-痕量元素耦合的机理模型。