Hydrochemical Characteristics and Quality Assessment of Limestone Groundwater in the Taiyuan Formation: A Case Study from the Qingdong Coal Mine, China

Abstract

This study investigates the hydrochemical characteristics and water quality of limestone water in the Taiyuan Formation at Qingdong Coal Mine, China. A total of 20 water samples were collected and analyzed for major ions. Statistical analysis, Piper and Gibbs diagrams, and ion correlation methods were applied to understand the hydrochemical characteristics and water-rock interactions. Water quality was assessed using single-factor, Nemerow, and fuzzy comprehensive evaluation methods. The results show that the groundwater is slightly alkaline and brackish, dominated by Na+, Ca2+, SO42‒, and Cl‒, with the primary hydrochemical type being Ca·Na+K-SO4·Cl. Water quality assessment indicates that the groundwater is predominantly Class IV and V, with sulfate as the most significant pollutant. These findings provide a scientific basis for the sustainable management of groundwater resources in coal mining regions by elucidating the evaporation-driven hydrochemical evolution of the Taiyuan Formation limestone aquifer.