Post-mining Hydrochemistry Characteristics and Influencing Factors for a Metal Mine in Dexing, China

The diversity of hydrochemical types in surface water and groundwater in the Dexing mining area in Jiangxi Province reflects the complexity of the hydrogeochemical environment there. The average pH and total dissolved solids (TDS) of the groundwater were greater during the dry sampling season than during the wet sampling season. In contrast, the average TDS and SO42- concentrations in surface water are greater during the wet season than during the dry season. The concentrations of Fe and Mn in surface water and groundwater exceeded the World Health Organization standard by 1702 and 233 times, respectively. Ion correlation analysis indicated that the hydrochemical evolution of surface water and groundwater were influenced mainly by the weathering and dissolution of carbonatite and silicate, with the carbonates mainly derived from dolomite dissolution. The hydrochemical changes during the dry season were more susceptible to the weathering and dissolution of carbonatite and silicate. The correlations between surface water and groundwater were greater during the wet season than during the dry season, and the level of reverse cation exchange was greater during the dry season. Furthermore, the groundwater is more susceptible to the effects of mining. Based on the regional hydrogeological conditions, a conceptual model of groundwater circulation was established, indicating that metal mining has altered the original groundwater flow pattern and exacerbated groundwater pollution in the Dexing mining area.