泾惠渠灌区地下水硫酸盐水文地球化学演化过程研究

Sulfate hydrochemical characteristics and evolution processes in shallow groundwater of Jinghuiqu irrigation district

泾惠区具2200多年的灌溉历史,灌区人口密度大,地下水不仅是工业和农业的主要水源,也是当地主要饮用水源。为了查明灌区地下水硫酸盐的水文地球化学特征、成因及其演化过程,在分析灌区1982年、1990年和2009年地下水水化学特征、SO24时空分布特征的基础上,通过灌溉试验和Hydrus-1D模拟灌溉对地下水SO 42的影响。结果表明,灌区地下水水化学类型由3HCO(1982年)向SO 42(2009年)型演化。2009年SO 42是地下水中主要阴离子组分,具有西部低,北部、东部和南部高的区域分布特征。虽然地下水中最初的SO 42主要来源于地层中Na2SO4和CaSO4等硫酸盐的溶解,但灌溉试验和模拟计算表明,近年来地下潜水中高硫酸盐主要是由于灌溉水源引起的。

Jinghuiqu irrigation district is located in semi-arid regions of northwestern China, where groundwater is the most important source for industry, agriculture and local people. The present work is conducted in the Jinghuiqu irrigation district to identify the geochemical characteristics and the hydrogeochemical evolutionary processes of sulfate in groundwater. Hydrochemical compositions combined with geological and hydrogeological data of sulfate, irrigation test and Hydrus-lD were used for this purpose. The result show that groundwater types changed from HCO3 in 1982 to SO42- water types in 2009. Elevated SO was initially derived from sulfate mineral dissolution, but from 1990 to 2009, the increased SO mainly came from the irrigated groundwater which contained higher SO42 concentrations.