Hydro-biogeochemical processes of surface water leakage into groundwater in large scale karst water system: A case study at Jinci, northern China

•Leakage of polluted surface water brings extra dissolved constituents and nutrients into groundwater.•Dissolution of calcite, dolomite with gypsum and dedolomitization take place in Jinci.•Human activity affects groundwater quality with 15%–36.4% inputs of coal mine drainage and 3.9%–8.6% of domestic sewage.•Mineral bioweathering processes are identified by δ2H, δ18O, 87Sr/86Sr, δ13C and δ34S.