The age, distribution, and geochemical characteristics of groundwater in the Ordovician limestone aquifer in the Huaibei coalfield, China

摘要

In this study, we collected 22 groundwater samples and supporting measurements from different coal-miningrndistricts in the Huaibei coalfield to examine the age, hydro-chemical characteristics, and evolution of groundwaterrnin the Ordovician limestone aquifer (OA). We determined the groundwater concentrations of major ions,rnstable isotopes (hydrogen and oxygen) and a radio isotope (~(14)C). All the samples were alkaline in nature, andrnhad pH values between 7.10 and 10.80. The total dissolved solids (TDS) contents varied from 119 to 2,443 mg/l.rnThe concentrations of δD and δ~(18)O in groundwater varied from u000164.32‰ to u000142.76‰, and from u00018.62‰ tornu00015.40‰, with mean values of u000156.38‰ and u00017.62‰, respectively. The groundwater at OA is recharged by rainfallrnor surface water, and, because of either the long residence time or runoff into the aquifer, is influenced byrnwater-rock interactions. The age of the groundwater in the OA ranged from 2,660a to 10,040a, and the groundwatersrnwere youngest and oldest in the Renlou and Yangzhuang coal mines, respectively. Contour diagrams ofrnTDS in groundwater, the groundwater age, and the spatial distribution of the water types indicated that thernRenlou and Yangzhuang mines were the recharge and discharge areas, respectively.