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

Groundwater recharge and runoff conditions are ascertained in Suixiao coal-mining district by the hydrogen and oxygen isotopes and the trace elements in the unconsolidated pore aquifer of Cenozoic group, the fissured sandstone aquifer of Permian system, and the karst fissured limestone aquifer of Carboniferous Taiyuan formation and 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 (PCA) of conventional ions. These results combined with geological conditions prove that hydraulic connection exists generally among the main recharge aquifers. And the groundwater circulation is controlled by faults in the sandstone and the limestone aquifer. 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 (FDA). This study provides the theory basis for the hydrochemistry exploration and the establishment of the water-inrush warning system in concealed coal field.