焦作地区浅层地下水铬(Ⅵ)污染机理及迁移预测

通过对焦作地区浅层地下水中铬(Ⅵ)污染物分布特征进行调查，分析了研究区浅层地下水中铬(Ⅵ)的污染机理，并运用Visual MODFLOW建立地下水流模型及溶质运移模型，模拟预测了浅层地下水中铬(Ⅵ)的迁移规律。结果表明：研究区浅层地下水铬(Ⅵ)污染严重，污染源是位于老君庙西南方向的焦作某电厂堆灰场，主要原因是露天堆放的粉煤灰中的铬(Ⅵ)污染物在长期淋滤作用下下渗污染含水层。气候条件、包气带岩性、地下水化学环境以及人为因素等也间接使浅层地下水铬(Ⅵ)浓度升高；模拟结果显示在未来的五年时间内，受地形和地下水动力场的影响，浅层地下水中铬(Ⅵ)的迁移方向与地下径流方向一致，沿大沙河水流方向上扩散速度更快，污染区域面积逐渐增大。

Pollution mechanism and migration prediction of Cr(VI) in shallow groundwater in Jiaozuo area

Based on the investigation of the distribution characteristics of pollutant Cr(VI) in the shallow groundwater of Jiaozuo area, the paper analyzed the polluting mechanism of Cr(VI). The groundwater flow model and solute transport model were established with Visual MODFLOW software and using the model simulation, migration prediction of Cr(VI) pollutants in the shallow groundwater was accomplished. The results show that in the shallow groundwater of the study area, Cr(VI) pollution is very serious. The source of the pollution is the ashery of a power plant located in the southwest of Laojunmiao in Jiaozuo. The main pollution reason is that under the long-term leaching effect, Cr(VI) pollutants of fly ash piled up in the open air infiltrated and polluted the aquifer. The climate, the lithology of aeration zone, the groundwater chemical environment and human factors are the indirect causes of the increasing concentration of Cr(VI) of the shallow groundwater in this area. Simulation results show that in the next five years, influenced by landform and groundwater dynamic field, migration directions of Cr(VI) pollutants in the shallow groundwater are consistent with groundwater flow directions. The diffusion rate along the flow direction of Dasha river is more faster,and the pollution area increases gradually with time.