渭干河流域浅层地下水水化学特征及成因分析

Hydrochemical characteristics and formation mechanism of shallow groundwater in Weigan River Basin

为探明新疆渭干河流域浅层地下水的水化学特征及其主要离子来源,综合运用数理统计、Durov图、Gibbs图、离子比例系数、绝对主成分得分-多元线性回归受体模型(APCS-MLR)等方法对渭干河流域2018年65组浅层地下水水样的检测数据进行分析.研究结果表明,流域内多数地下水取样点总硬度偏高,溶解性总固体中等,地下水以淡水为主.潜水水化学类型种类复杂多变,主要有HCO_(3)·SO_(4)·Cl-Na·Ca、SO_(4)·Cl-Na·Ca·Mg、HCO_(3)·Cl-Na·Ca·Mg和HCO_(3)·SO_(4)-Ca型;浅层承压水水化学类型以SO_(4)·Cl-Na型与HCO_(3)·SO_(4)·Cl-Na·Ca·Mg型为主.流域内地下水形成主要受到蒸发-浓缩作用,其次为岩石溶滤作用,其中Na+主要来自岩盐的溶解,少量来自于硅酸盐岩的溶解,Ca^(2+)和Mg^(2+)主要来源于碳酸盐岩的溶解,部分来源于蒸发盐岩和硅酸盐岩的溶解.此外,阳离子交换作用与人类活动影响对流域内地下水中化学组分的形成也有一定贡献.

Based on 65 groups of shallow groundwater investigation datas in 2018,mathematical statistics,Durov diagram,Gibbs diagram,ion ratio,and absolute principal component score-multiple linear regression receptor model(APCS-MLR)were used to analyze the hydrochemical characteristics and main ion sources.Results showed that the total hardness of most groundwater samples in the basin was high,the total dissolved solid was medium,and the groundwater was mainly freshwater.The hydrochemistry types of phreatic water were complex and varied,mainly HCO_(3)·SO_(4)·Cl-Na·Ca,SO_(4)·Cl-Na·Ca·Mg,HCO_(3)·SO_(4)-Ca and HCO_(3)·Cl-Na·Ca·Mg.The hydrochemistry types of shallow confined groundwater were mainly SO_(4)·Cl-Na and HCO_(3)·SO_(4)·Cl-Na·Ca·Mg.The groundwater formation was mainly affected by evaporation-concentration,followed by rock leaching,of which Na+was mainly derived from the dissolution of halite,and a small amount derived from the dissolution of silicate.Ca^(2+)and Mg^(2+)were mainly derived from the dissolution of carbonate rocks,and partly from the dissolution of evaporite rocks and silicate rocks.In addition,cation exchange and human activities had a certain contribution to the formation of chemical components in groundwater.