金塔盆地鸳鸯池灌区地下水水化学特征及控制因素

Hydrochemical Characteristics and Control Factors of Groundwater in Yuanyangchi Irrigation Area,Jinta Basin

为研究金塔盆地鸳鸯池灌区地下水水化学特征及控制因素,采集浅层地下水(201组)和中深层地下水(5组)样品,综合运用Piper三线图、Gibbs图、离子比值关系和因子分析等方法,分析了该区地下水水化学特征、水文地球化学过程以及影响因素.结果表明,研究区浅层孔隙水整体呈弱碱性,ρ(TDS)变化范围328.4~12 400 mg·L^(-1);阴阳离子分别以SO_(4)^(2-)和Mg^(2+)/Na^(+)为主.研究区地下水化学类型主要为HCO_(3)·SO_(4)-Mg型、SO_(4)·HCO_(3)-Mg型、SO_(4)-Mg·Na型和SO_(4)·Cl-Na·Mg型.中深层孔隙水p H均值为8.47,较浅层孔隙水高,属弱碱性水,ρ(TDS)变化范围339.0~493.8 mg·L^(-1),水化学类型主要为HCO_(3)·SO_(4)-Mg型.研究区地下水水化学特征受控于多种自然因素,包括岩石风化、蒸发浓缩和阳离子交换等,其中浅层孔隙水主要控制因素有溶滤和蒸发浓缩作用(贡献率为71.46%)、人类活动影响和碳酸盐岩溶解作用(贡献率为17.07%).

In order to study the groundwater chemical characteristics and control factors of Yuanyangchi Irrigation area in Jinta Basin,shallow groundwater samples of 201 sites and middle-deep groundwater samples of five sites were collected.Piper triangular diagrams,Gibbs plot,ion ratio relationship,and factor analysis were used to analyze and discuss the chemical characteristics,control process,and influencing factors of groundwater.The results showed that the shallow pore water in the study area was weakly alkaline,withρ(TDS)ranging from 328.4 mg·L^(-1) to 12400 mg·L^(-1).The major anions and cations of the shallow pore water were SO_(4)2−and Mg^(2+)/Na^(+),respectively,and the chemical types were mainly HCO_(3)·SO_(4)-Mg,SO_(4)·HCO_(3)-Mg,SO_(4)-Mg·Na,and SO_(4)·Cl-Na·Mg.The average pH of middle-deep pore water was 8.47,which was larger than that of shallow pore water,characterized as weakly alkaline water.The middle-deep pore waterρ(TDS)range was 339.0-493.8 mg·L^(-1),and the chemical type was mainly HCO_(3)·SO_(4)-Mg.The chemical characteristics of groundwater in the study area were controlled by a variety of natural factors,including rock weathering,evaporative concentration,cation exchange,etc.,among which the main controlling factors of shallow pore water were leaching and evaporative concentration(contribution rate of 71.46%),anthropogenic activities,and carbonate rock dissolution(contribution rate of 17.07%).