Analysis on hydrochemistry and its control factors in the concealed coal mining area in North China:A case study of dominant inrush aquifers in Suxian mining area

Based on the data such as the conventional ions ( K+ +Na+ ,Ca2+ ,Mg2+ ,Cl- ,SO24- ,HCO- ,CO23- ),pH,TDS in dominant inrush aquifers including the fourth aquifer of unconsolidated formation,the fissured aquifer of coal meas-ure and the karst aquifer of Taiyuan formation in the Suxian mining area,the ion ratio and the principal component a-nalysis are combined and used to discuss the hydrochemical formation. Besides,the control factors of hydrochemical formation are further studied by observing the spatial distributions of principal component loading scores and hydro-chemical types. The results show that the difference of hydrochemistry in the dominant inrush aquifers comprehensively reflects the different hydrochemistry actions in the Suxian mining area. The fissured aquifer is characterized by the cat-ion exchange and adsorption or the sulfate reduction while the fourth aquifer and the karst aquifer are characterized by the pyrite oxidation or the carbonate and sulfate dissolution. The hydrochemical formation and hydrochemical type are effected by the mining activity and the geological background in various degree in the Suxian mining area. Obviously,the fourth aquifer is controlled by mining activity,the fissured aquifer is controlled by faults and the karst aquifer is controlled by mining activity,faults and folds.