北京南郊平原区地下水总硬度分布特征与来源分析OA

This study systematically investigates the distribution and genesis of total hardness(TH)in groundwater within the southern marginal plain of Beijing,employing hydrochemical tools including Piper trilinear diagrams,Gibbs models,and factor analysis.The key findings are:(1)Groundwater in the study area is predominantly of the HCO3-Ca type.TH concentrations exhibit significant variation among different aquifer layers.In Layer Ⅰ,TH is generally exceed 450 mg·L-1.Layer Ⅱ displays a north-high-south-low pattern.Layer Ⅲ is characterized by higher in the southwest and lower in the east and north.Layer Ⅳ exhibits a more uniform TH spatial distribution.Vertically,TH concentrations decrease with increasing aquifer depth.(2)Ca2+and Mg2+primarily originate from the dissolution of carbonate(calcite,dolomite)and sulfate minerals.(3)Factor analysis extracted three principal components(cumulative variance:83.7％),representing rock leaching,agricultural and domestic/industrial pollutions,respectively.Among these,rock leaching is identified as the dominant factor controlling groundwater TH,accounting for 53.5％of the total variance.