Multi-isotopes and hydrochemistry combined to reveal the major factors affecting Carboniferous groundwater evolution in the Huaibei coalfield, North China

• Published in: The Science of the total environment 2021-10, Vol.791, p.148420-148420, Article 148420
• Main Authors: Zhang, Jie, Chen, Luwang, Hou, Xiaowei, Lin, Manli, Ren, Xingxing, Li, Jun, Zhang, Miao, Zheng, Xin
• Format: Article
• Language: English
• Subjects: Huaibei coalfield; Hydrogeochemistry; Mining effects; Stable isotopes; Water-rock interactions
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2021.148420

Both natural processes and anthropogenic activities have significant effects on groundwater evolution in coal mining regions. In this study, the primary controlling mechanism of the groundwater chemistry evolution for the Carboniferous groundwater in the Huaibei coalfield, North China was proposed based on the hydrogeochemical indicators combining with multiple isotope tracers. The diversity of hydrochemical types indicates the complexity of the hydrogeochemical environment in the groundwater, which is recharged by precipitation infiltration with minimal evaporation according to the distributions of δD and δ18O. Additionally, ion correlation analysis suggests that minerals dissolution and cation exchange between Na+ and Ca2+ are the dominant processes within that groundwater. The hydrochemical and δ13CDIC characteristics of the groundwater demonstrate that HCO3− is mainly controlled by the dissolution of carbonate minerals and soil CO2, and the proportion of the latter is believed to be dominated by the hydrogeologic conditions. Similarly, the values of SO42− and δ34SSO4 indicate that a small portion of SO42− in the groundwater in the northern part originates from the meteoric precipitation, while it is mainly derived from the dissolution of gypsum in the southern part. Furthermore, mining activities also alter the groundwater level and flow conditions through pumping and drainage, which enhances the interaction between groundwater and aquifer lithologies, thereby affects the hydrogeochemical processes. The findings of this work are of great significance for promoting the safe exploitation of deep coal resources and the sustainable utilization of groundwater in the Huaibei coalfield, as well as the most of other coalfields in North China. [Display omitted] •The evolution of groundwater in the Huaibei coalfield was investigated from both natural and anthropogenic perspectives.•Corresponding minerals dissolution dominated the hydrochemistry evolution together with the cation exchange.•Hydrogeological conditions play an important role in the spatial distribution of δ13CDIC and δ34SSO4.•Anthropogenic factors have changed the circulation pattern of groundwater and accelerated its evolution.