Hydrogeochemical Characteristics Of Karst Springs In Front Of Taihang Mountains

Karst water is an important water supply source in northern China.In recent years,influenced by the external environment,the chemical environment of karst water has changed,but its evolution process and control factors are still unclear.According to this,this study selected is located in the taihang mountains in front of the typical karst area-hsu family ditch spring domain as the research object,through the analysis of the water of karst groundwater chemical components and the content of hydrogen and oxygen stable isotope,using multivariate statistical analysis,principal component analysis and cluster analysis methods,the domain of spring karst groundwater hydrochemical characteristics and evolution rules are discussed in this paper,and determines the key influence factors.The results showed that the main ions of karst water in the spring domain were Ca²⁺?Mg²⁺?SO₄^2- and HCO₃^-,and the hydrochemical types were mainly HCO₃-Ca and HCO₃-Ca·Mg.Influenced by precipitation,runoff in dry season is slow,water-rock interaction is sufficient,the correlation between ions is high,and the content of each component is higher than that in wet season.The main controlling factor for the formation of hydrochemical components of karst groundwater in the spring domain is rock weathering.Ca²⁺,Mg²⁺,SO₄^2- and HCO₃^-in karst groundwater have similar sources,mainly from the dissolution of carbonate rocks containing calcite?CaCO₃?,dolomite?CaMg?CO₃?₂? and sulfate rocks?CaSO₄·2H₂O?.The content of Mg²⁺ in the groundwater in the dry season is obviously higher than that in the wet season.The alternating action of cation adsorption reduced the content of Na⁺ and K⁺ in groundwater.In addition to the dissolution of sulphuric acid rocks?CaSO₄·2H₂O?,part of SO₄^2- comes from pyrite oxidation.Meteoric precipitation is the main recharge source of karst groundwater in spring domain.The recharge area is exposed limestone area in the west with the recharge elevation of 464?928m.Delta D and delta ¹⁸O are lower in karst groundwater in recharge area and higher in delta D and delta ¹⁸O in runoff discharge area.In the southern part of the spring basin,karst water groundwater is not only recharged by meteoric precipitation,but also by the seepage of qi river.