An analysis of the hydrochemical characteristics and influencing factors of different water bodies in the Liangjia coal mine area, North China

The analysis of the hydrochemical characteristics of different water bodies in coal mining areas and the influencing factors is of great important for sustainable water resources management and the regulation of water hazards. This study analyzed 22 sets of samples of mine water (MW), accumulated water (AW) from the surface subsidence area, and Quaternary pore groundwater (QPW) from the Liangjia coal mine area. The results showed that the dominant anion and cation in MW were HCO3− and Na+, respectively, whereas those in AW and PW were Cl− and Na+, respectively. The water of the study area could be characterized as having relatively high salinity and being of weak alkalinity. While most QPW samples were not suitable for drinking, they were suitable for agricultural irrigation water. The hydrochemical types of MW and AW were mainly HCO3-Na and SO4·Cl-Na, respectively, whereas QPW had a relatively complex hydrochemistry, with the SO4·Cl-Ca·Mg type dominating. The dominant factors influencing the water chemistry characteristics of different water bodies in the Liangjia coal mine area were determined to be rock weathering and cation exchange. Silicate rock weathering was the main driver of the hydrochemical characteristics of MW, whereas the weathering of silicate and carbonate rocks and the dissolution of gypsum regulated that of AW and QPW. The hydrochemistry of QPW was clearly affected by coal mining-induced mixing and input. Atmospheric precipitation was determined to be the main source of recharge of the different water bodies, which was impacted by evaporation. In addition, individual water samples may have been affected by seawater intrusion.