Spatial variability of hydrochemistry in coal-bearing karst areas considering sulfur pollution and underground engineering effects.

Coal-bearing karst areas are widely distributed around the world. Coal mining and tunnel construction significantly disturb the natural hydrological cycle and redox environment, leading to spatial variability in hydrochemistry and environmental pollution. Common environmental pollution in coal-bearing karst regions is the elevated sulfate content and the effusion of hydrogen sulfide. This study utilizes hydrochemical, isotope, and microbiological analysis methods to examine the hydrochemical characteristics of groundwater and determine the diversity, population structure, and functional activities of sulfur-associated microbial communities in different locations of underground engineering. Ultimately, based on comprehensively considering the hydrogeological factors such as recharge, water flow system, hydrodynamic characteristics, aquifer characteristics, microbiological characteristics, and underground engineering, the hydrochemical characteristics formation mode of the study area has been proposed. The study provides insights into sulfur biogeochemical processes, aiding efforts to mitigate mine water pollution and hydrogen sulfide issues in these regions.