太原市西山岩溶水系统水文地球化学特征分析

Hydrochemical features of Xishan karst groundwater system in Taiyuan

岩溶含水系统的水化学特征能够反映地下水补径排关系、含水介质特征及水岩相互作用等。本文通过分析太原市西山岩溶含水系统地下水中TDS、Sr2+、HCO-3、SO24-的分布特征、相互关系及指示意义,得出以下结论:从补给区到径流排泄区,TDS随着径流途径、径流时间及循环深度的增加而逐渐增加。Sr2+、Mg2+、Ca2+浓度沿着地下水径流方向具有同步增加的趋势,但Sr-Mg的变化斜率小于Sr-Ca,这主要是碳酸盐岩中白云石与方解石含量及溶解度不同造成,CaO与MgO比值越大,相对溶解度越大。沿地下水径流方向,水化学类型由HCO3型过渡为HCO3·SO4型、SO4·HCO3型、SO4型,SO24-离子浓度逐步增加,总体来看,Ca2+、Mg2+离子总含量与HCO3-、SO42-离子总含量达到平衡,说明在西山岩溶区,水中离子的主要来源除碳酸盐外,硫酸盐的溶解也是一个重要途径,且受煤系地层及煤矿开采活动的影响强烈。

Hydrochemical features of karst groundwater system are of important hydrogeologic significance. It reflects the relationship of the recharge, runoff and drainage, and reveals the feature of the medium and the interaction between groundwater and rock. Concentration distribution of TDS,Sr^2＋ ,Mg^2＋ ,Ca^2＋ ,HCO3^-, SO4^2- and their relationships are analyzed in the paper. The results show that TDS increases with the runoff distance along the karst water flow direction and the circulation depth. The increase in Sr^2＋ accompanies an increase in Ca^2＋ and Mg^2＋, but the higher slope of the line of Ca^2＋ versus Sr^2＋ is than that of Mg^2＋ VS Sr^2＋ resulted from the different solubility between calcite and dolomite which indicating a large predominance of calcite in the strata. SO4^2- increase and most of the samples fall above equilibrium between （Ca^2＋ ＋Mg^2＋） and HCO3^- but lie around the 1 ：1 trend line of Ca^2＋ and Mg^2＋ versus HCO2^-and SO4^2-, and the water chemistry changes from HCOatype to HCO3·SO4 type, SO4·HCO3 type and SO4 type from recharge to the discharge areas. All these indicate that carbonates are the major source of these samples, but the dissolution of sulfate rocks is another important source. In addition, human activity such as coal mining also has certain affect.