灵武引黄灌区地下水化学演化特征模拟

Simulation of Groundwater Hydrochemical Evolution Characteristics in Yellow River Irrigation Area of Ling-Wu County

结合以大泉地区为核心的地下水化学特征,利用PHREEQC软件对大泉地区地下水化学演化过程进行了反向模拟,对模拟结果进行了分析讨论,进一步的阐明大泉地区地下水化学演化过程。地下水向大泉地区汇集时水化学类型复杂多变的影响因素包括溶滤作用,阳离子交换吸附作用,地下水的过量开采,以及强烈的混合作用,同时还受地下水补给水源水化学成分的控制。矿物饱和指数及反向水文地球化学模拟结果显示,地下水流向大泉乡过程中,方解石、白云石过饱和产生沉淀,石膏、岩盐、CO2(g)、长石类矿物溶解,伊利石、钙蒙脱石、石英等析出,阳离子发生Mg2+/Na+、Mg2+/Ca2、Ca2+/Na+交换。

Combining with the groundwater chemical characteristics in the research centre of Daquan region, the groundwater chemical evolution process in the region is reversely simulated by using PHREEQC software. The simulation result is analyzed to further clarify the groundwater chemical evolution process. When the groundwater converges towards Daquan region, varieties of factors influence the hydrochemicai type and make it complicated, including leaching effect, cation exchange adsorption effect, excessive ex- traction of groundwater, and strong mixing action. Simultaneously, the water chemical composition of recharge source also controls hydrochemical type. The result of mineral saturation index and reverse hydrogeochemcial simulation shows that during the process of the groundwater flowing towards DaQuan, Calcite and Dolomite become oversaturated then precipitate; Plaster, Halite, CO2 （g） and Feldspathie minerals dissolve; Illite, Calcium montmorillonite and Quartz separate out~ while Cation of Mg2＋/Na＋, Mg2＋/Ca2＋, Ca2＋/Na＋ exchange.