Temporal variation of hydrogeochemical characteristics and processes of aquifers in the Liuqiao coal mine

Studying the characteristics and hydrogeochemical evolution processes of groundwater can contribute to the prevention of water-related hazards and ensure sustainable management of groundwater resources. In this study, the hydrogeochemical characteristics and evolution processes of the coal-bearing sandstone aquifer and Carboniferous limestone aquifer of the Taiyuan formation in the Liuqiao coal mine in Huaibei coalfield were assessed using piper diagram, Gibbs diagrams, ionic proportion ratios, and principal component analysis (PCA). The results showed that Na+ + K+ and SO42− were the dominant cations and anion, respectively, in both aquifers. The coefficients of variation of six hydrochemical parameters increased gradually, reflecting the formation of different water chemical compositions. The formation of hydrochemical compositions was dominated by water-rock interaction, including the dissolution of rock salt, cation exchange adsorption and pyrite oxidation. In addition, the PCA revealed two first components, explaining the highest proportion of variance. Over time, the water sample points were mostly found in the second and third quadrants, indicating the groundwater salinization effect as a result of the gradual increase in the cation alternating adsorption.