Hydrochemical characteristics, water quality assessment and driving forces of coal base in Shanxi Province, China

Abstract

Abstract Explore the hydrochemical characteristics of surface water (SW) and groundwater (GW) under coal mining activities and controlling factors is essential to ensure water security. This research concentrates on the Changhe River Basin (CRB). Water samples were collected from 27 sites within the CRB in May, July and December 2022. A qualitative analysis of hydrochemical characteristics and major ion sources was conducted based on Piper plots, Gibbs plots, Pearson correlation analysis and ion ratio methods. The PCA ~ RSR model was used to assess the current status of SW and GW quality in the CRB. We found that the hydrochemical type of SW and GW is HCO3- Ca, with HCO3− accounting for 62.2% ~ 87.9% of the total anions and Ca2+ accounting for 27.4% ~ 31.3% of the total cations. Rock weathering is the main factor affecting the hydrochemical of CRB. SW is affected by the weathering and dissolution of both silicate and carbonate rocks, while GW is mainly affected by the weathering and dissolution of silicate. The cation exchange also has influence on GW. The cations in the water are mainly derived from rock weathering dissolution and exchange reactions, while the SO42− in anions is mainly imported from outside. The results of the water quality assessment showed that water quality in the midstream of the study area is poor and coal mining has seriously affected water safety issues. The study reveals the impact of coal mining on hydrochemical. It provides a scientific basis for the protection and management of water resources under coal mining activities in arid and semi-arid regions.