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

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.