鄂尔多斯白垩系地下水盆地硫酸盐的水文地球化学特征及来源

鄂尔多斯白垩系地下水盆地蕴藏有丰富的地下水资源,地下水赋存于白垩系砂岩中.为了查明地下水微咸水的成因,对40件地下水样品的水化学组成、SO42-的区域分布特征和28件硫同位素组成进行了分析,并对34件岩石样品进行了溶滤试验研究.结果表明:SO42-是地下水中主要阴离子组分,具有东部低西部高,北部低南部高的区域分带特征;硫酸盐是自垩系地层中主要的易溶盐组分,并以石膏和芒硝形式存在;地下水中SO42-主要来源于地层中石膏和芒硝,其次是地层中的硫化物,少量来源于有机硫.

Hydrochemical Characteristics and Sources of Sulfate in Groundwater of the Ordos Cretaceous Groundwater Basin

There are abundant groundwater resources in the Ordos Cretaceous groundwater basin, which exist in Cretaceous sandstone. The purpose of this study is to identify the origin of brackish groundwater. Based on analyzing hydrochemical compositions of 40 groundwater samples and the regional distribution pattern of sulfate in groundwater as well as making leaching experiments on 34 groundwater-bearing rock samples, the authors have reached the following conclusions: the sulfate is the mainly component assuming zoned distribution throughout the basin; the concentration of sulfate in groundwater is lower in the eastern area than in the western area of the basin, and is lower in the northern area than in the southern area; the soluble components in Cretaceous strata are dominated by sulfate existent in the forms of gypsum and mirabilite; the sulfate in groundwater originates mostly from gypsum and mirabilite in rocks, partly from sulfide in aquifers, and insignificantly from organic sulfur.