人工回灌对地下水水质影响的室内模拟实验

Experiment on Impact of Groundwater Quality During Artificial Recharge Process

人工回灌过程中的水岩相互作用机制较为复杂,目前有关评价人工回灌过程对地下水化学场影响范围和影响程度的研究还十分缺乏。以上海市某人工回灌试验场为例,采用室内模拟实验手段,对人工回灌过程中地下水主要溶质组分的变化趋势及其相关水岩反应进行分析。实验结果表明:回灌过程中,地下水的主要离子成分主要受混合作用、阳离子交换吸附作用及含水层矿物相(方解石、白云石、钾长石)溶解作用的影响;受回灌过程中地下厌氧环境向好氧环境发展的影响,含水介质中的As、Cr、Fe等元素存在溶出趋势,回灌后As-Fe元素的变化量表现出较好的相关性;随着回灌时间的增加,地下水水质的影响范围逐渐扩大,其水化学类型由初始的Cl-HCO3-Na型逐步向Cl-HCO3-Na-Ca型转变。

As a result of the water-rock interaction mechanism in artificial recharge process is more complex,the evaluation on influence of groundwater quality during the artificial recharge process is scarce.The authors discuss the trends of solute component and their associated water-rock interaction during the artificial recharge process based on pilot scale experiments conducted in the laboratory.Experiment results showed that：in the groundwater recharge process,the ion composition of groundwater were mainly affected by the mixing,cations exchange adsorption and aquifer mineral phase（calcite,dolomite,potassium feldspar） dissolution.Due to the influence of underground anaerobic environment developing to the aerobic environment in the artificial recharge process,the elements of As,Cr,Fe in porous media has dissolved out.Besides,the As-Fe element variation showed well correlation.Along with the increase of artificial recharge time,the effect range of groundwater quality was increased.And the chemical type of groundwater was changed from the initial Cl-HCO3-Na to Cl-HCO3-Na-Ca gradually during the recharge process.