Evolution Patterns and Influencing Factors of Volatile Organic Compounds in Mine Water from Goaf of Closed Coal Mines

Volatile organic compounds (VOCs) threaten the quality of coal mine water due to their release from coal-bearing strata into mine water during mining. Understanding VOC evolution in coal mine water is critical for groundwater protection in coal mines. This study examines VOC evolution in closed coal mine water at Xinjulong coal mine, Shandong Province, focusing on oxygen and coal content effects. Lab experiments tracked 52 VOCs (tested via purge-and-trap/GC-MS) alongside hydrochemical and genomic data. Results showed total VOCs peaked at 110d (3.199μg/L) before declining, with year-end reductions of 18.68%, 19.53%, and 45.90% across groups, though toxic benzene/vinyl chloride emerged. In the water samples, VOCs initially underwent aerobic degradation, followed by predominantly anaerobic reduction. As a key electron acceptor, oxygen enhanced the degradation of chlorinated hydrocarbons, with the lowest concentrations of vinyl chloride and benzene observed under high dissolved oxygen conditions. Samples with higher coal content exhibited the lowest VOC concentrations but the highest diversity of benzene derivatives, suggesting that organic matter and clay minerals in coal contribute to VOC release through adsorption–desorption processes. Recommendations include staged redox control, adsorbents, and microbial additives for optimized coal mine water quality. The BRIEF REPORT is available for this paper at http://www.ykcs.ac.cn/en/article/doi/10.15898/j.ykcs.202503260057.