Study on the evolution of groundwater environment and formation potential of acid mine drainage under long-term mining in sulfur-rich coal mine

Acid mine drainage (AMD) has long been a major environmental concern associated with closed mines. During the coal mining period, the hydrochemical environment and hydrodynamic conditions of groundwater change significantly. How the new groundwater environment affects the formation of AMD remains unclear. This paper combines hydrogeochemical simulation, a Bayesian mixing model, laboratory experiments and other methods to analyze changes in both the groundwater hydrochemical environment and the degree of mixing induced by long-term coal mining. Based on groundwater hydrochemical data from different periods, it further assesses differences in the potential for AMD formation under different groundwater environmental conditions. The results indicate that during the coal mining period, over time, the hydrochemical characteristics of different aquifers gradually converged, with the concentrations of Ca 2 + , Mg 2+ , and SO 4 2- progressively increasing, and the hydraulic connectivity between aquifers was gradually enhanced. In the new groundwater environment, the pH exhibited minimal change, while the Fe 3+ concentration increased by 37.6%, and peak pollutant concentrations occurred slightly earlier. The findings elucidate the response mechanism of AMD formation process to changes in the groundwater environment, providing insights for the remediation of mine water pollution.