铬在包气带－含水层界面的迁移机制及其时间尺度效应研究

Sewage Irrigation relieved the strain on water in north China, at the same time, the excessive and improper using of it has caused a series of environmental problems such as heavy metal pollution. Therefore, it has important practical significance for the protection of the ecological environment and human health of researching on heavy metal migration mechanism and simulation prediction method in the process of sewage irrigation. This study firstly give out the analysis of the time and space distribution rule and influencing factors of chromium in vadose zone in both horizontal direction and vertical direction; secondly, combining with the adsorption-desorption effects of soil, initial concentration of chromium, valence state and other factors, explore the dynamic process of the migration and migration mechanism of chromium in the vadose zone; then, reveal the critical input threshold, quantity and time scale effect of chromium able to enter the aquifer in the process of groundwater table fluctuation caused by human activities and natural conditions change; finally, establish simulation prediction method of chromium removal in the vadose-aquifer interface combining with in situ test, indoor test and the numerical method.

污水灌溉在缓解我国北方地区用水紧张的同时，其过度不当利用导致了重金属污染等一系列环境问题，因此，开展污水灌溉过程中重金属迁移机制及模拟预测方法研究，对生态环境保护与人类健康具有重要的实际意义。本项研究首先分析重金属铬在包气带中水平方向和垂直方向上时空分布规律及影响因素；其次结合土壤吸附－解吸作用、铬初始浓度、价态等因素影响，探讨铬在包气带中迁移的动态过程及迁移机制；然后揭示人类活动和自然条件变化导致地下水位变动过程中，铬能够进入含水层中的临界输入阈值、能够进入含水层中的数量以及进入含水层的时间尺度效应；最后结合原位实验、室内实验以及数值方法，构建铬在包气带—含水层界面迁移的模拟预测方法。

污水灌溉在缓解我国北方地区用水紧张的同时，其过度不当利用导致了重金属污染等一系列环境问题。本研究以开封市污灌区为研究对象，系统分析长期污灌条件下土壤重金属的含量及富集状况，对该区土壤重金属污染现状进行评价；将静态吸附实验、土柱淋滤实验结合起来，研究不同影响因素下Cr（Ⅵ）在不同土壤中的吸附特性；利用实验结果建立了Hydrus模型预测各种污染前提下Cr（Ⅵ）的迁移行为。同时，运用非均质砂箱模拟研究了地下水水位变动时 Cr（Ⅵ）在包气带-饱水带界面上的分异演化机理。本研究为重金属污染的治理提供研究基础，对生态环境保护与人类健康具有重要的实际意义。