Groundwater chemical characteristics and circulation mode in the Suixiao coal-mining district

Abstract

Groundwater recharge and runoff conditions are ascertained in the Suixiao coal-mining district using the hydrogen and oxygen isotopes and the trace elements in the unconsolidated pore aquifer of the Cenozoic group, the fissured sandstone aquifer of the Permian system, and the karst fissured limestone aquifer of the Carboniferous Taiyuan Formation and the Ordovician system, which are the main recharge aquifers during coal mining. The main water–rock interactions are pyrite oxidation, cation exchange and adsorption, and carbonate acidification, which are educed by principal component analysis of conventional ions. These results combined with geological conditions prove that hydraulic connection exists generally between the main recharge aquifers, and the groundwater circulation is controlled by faults in the sandstone and limestone aquifers. The water–rock interaction is very weak in the east of the district, which is proved to be a recharge area by Fisher discriminant analysis. This study provides the theoretical basis for the hydrochemistry exploration and the establishment of a water-inrush warning system in a concealed coalfield.