内蒙古伊敏盆地地下水水化学特征及其成因OA北大核心CSTPCD

Mining activities have strongly changed the characteristics of the regional hydrological cycle and have a significant impact on the chemical characteristics of groundwater.Revealing the evolutionary characteristics of the groundwater system under the influence of coal mine development can provide theoretical support for ecologi-cal environment protection and sustainable development in coal mine areas.In this paper,taking the Yimin Basin in Inner Mongolia as an example,based on hydrogeological investigation combined with the groundwater flow system theory,Piper three-line diagram,Gibbs diagram,ion proportional coefficient,mineral saturation index,and other analysis methods,the characteristics of groundwater chemical changes under the interference of coal mining activities were explored.Results indicate that the overall water environment in the study area is weakly al-kaline,and the significant influence and noninfluence zones exceed the detection indexes in different degrees.Coal mining in the basin has accelerated the rate of regional hydrological cycle,causing the water quality in the significant impact zone to evolve toward desalination.The development of open-pit coal mining has opened up the previously closed groundwater system,and a series of water-rock interactions stimulated by the oxidation of sulfur-containing coal and sulfurous iron ore and acid production primarily cause the changes in the chemical characteristics of the regional groundwater.The hydrochemistry of groundwater in the basin is affected by evapo-ration,concentration and water-rock interactions.Along the flow direction of groundwater,the hydrochemical type in the significantly affected area changes from HCO3-Ca·Na type to HCO3-Ca,and the concentrations of TDS and Cl-show a downward trend.In the nonaffected zone,the hydrochemical type changed from HCO3-Ca·Na to Cl-Ca·Mg,and the concentrations of TDS and Cl-showed an upward trend.