滹沱河地下水超采区人工回灌的水岩相互作用模拟

人工回灌条件下回灌水与地下水混合带的水岩相互作用是决定地下水水质演化和含水层发生化学堵塞的关键过程。为研究人工回灌对滹沱河地下水超采区水质演化的影响，以石家庄市人工回灌场地为例，利用石津灌渠水作为回灌水源，通过室内实验结合反向水文地球化学模拟揭示回灌层位地表水与地下水混合带的水-岩相互作用机理。结果显示：混合带水的TDS（total dissolved solids）变化特征表现为先增大后缓慢降低，且地表水占比越大、含水介质粒径越细，则其变幅越大；混合带水中主要离子质量浓度变化特征受混合、碳酸平衡、溶解-沉淀、阳离子交换及硝化作用控制，其中K⁺、Ca²⁺、SO₄^2-质量浓度主要受溶解-沉淀作用控制，Na⁺、Cl^-、HCO₃^-、NO₃^-质量浓度主要受混合NO₃^-作用控制，Mg²⁺质量浓度主要受阳离子交换作用...

Water-rock interaction simulation of artificial recharge in the groundwater over-exploited area of the Hutuo River Basin

The water-rock interaction in the recharge water and groundwater mixed zone of aquifer under artificial recharge is the key process that determines the evolution of groundwater quality and leads to the chemical clogging of aquifer. To study the effect of artificial recharge on the groundwater quality evolution in the groundwater over-exploited area of the Hutuo River Basin, taking the groundwater artificia recharge site in Shijiazhuang as an example and using the Shijin irrigation canal water as the recharge water, we revealed the mechanism of water-rock interaction of surface water and groundwater mixed zone in the aquifer by carrying out the laboratory experiments and reverse hydrogeochemical simulation. The results show that the evolution characteristics of total dissolved solids(TDS) in the mixed zone firstly increase and then slowly decrease. The larger the proportion of surface water mixed with water is and the smaller the particle size of medium is, the larger the variation amplitude of TDS is. The change of main ion concentrations is controlled by mixing action, carbonic acid balance, dissolution-precipitation, cation exchange and nitrification. Among them, the concentrations of K⁺, Ca²⁺and SO₄^2- are mainly controlled by dissolution-precipitation, the concentrations of Na⁺, Cl^-, HCO₃^-, NO₃^- are mainly controlled by mixing action, and the concentration of Mg²⁺ is mainly controlled by cation exchange. In the water-rock reaction, the dissolved minerals include anhydrite, albite, K-feldspar and halite, whereas the precipitated minerals included calcite, calcium montmorillonite and quartz. Moreover, in the aquifer with larger proportion of surface water and finer particle size of medium, the calcite precipitation is greater, indicating that there is a high risk of carbonate chemical clogging in the recharge aquifer with fine particle size when the surface water is the recharge source.