伊犁河谷西北部地下水化学特征及成因分析

Chemical characteristics and genesis analysis of groundwater in northwest Yili River Valley

为探究新疆伊犁河谷西北部地下水化学特征及成因,运用数理统计以及Piper三线图、Gibbs图、离子比图等方法,对2018年伊犁河谷西北部地下水取样监测数据进行分析。结果表明:(1)研究区地下水属于总硬度偏高的弱碱性水,地下水化学组分含量整体变异性不大,主要阳离子为Ca^(2+),主要阴离子为HCO_(3)^(-)。(2)地下水水化学类型以HCO_(3)-Ca、HCO_(3)·SO_(4)-Ca、HCO_(3)·SO_(4)-Ca·Mg、HCO_(3)·SO_(4)-Ca·Na和HCO_(3)^(-)Ca·Mg型为主。(3)研究区地下水化学组分主要受岩石溶滤作用控制,蒸发-浓缩作用及阳离子交换作用对地下水化学组分有一定的贡献,个别地下水水样点可能受到人为活动的影响。(4)地下水中的Na^(+)、Cl^(-)和SO_(4)^(2-)主要来自岩盐、石膏等蒸发岩的溶解,Ca^(2+)和Mg^(2+)主要来自方解石、白云石和石膏等矿物溶解。

To analyze groundwater genesis and chemical characteristics in Yili River Valley,Xinjiang China,we used descriptive statistical analysis,trilinear chart by Piper,Gibbs diagrams,ion ratio diagrams,and saturation index methods to systematically analyze 35 groundwater samples collected from June to October 2018.Groundwater in the study area is weakly alkaline,with a high total hardness level.The chemical components in groundwater showed little variation throughout the study area;Ca^(2+) was the main cation,and HCO_(3)^(-) the main anion.The hydrochemical characteristics in the study area can be divided into five groundwater types,HCO_(3)-Ca,HCO_(3)·SO_(4)-Ca,HCO_(3)·SO_(4)-Ca·Mg,HCO_(3)·SO_(4)-Ca·Na,and HCO_(3)-Ca·Mg.Although rock lixiviation is the main contributor to groundwater chemical composition,evaporation-concentration and cation exchange also contribute to the chemical composition of groundwater in the study area.Moreover,some groundwater samples might be affected by human activities.Na^(+),Cl^(-),and SO_(4)^(2-) in groundwater are present due to the dissolution of rock salt,gypsum,and other evaporates;the dissolution of minerals such as calcite,dolomite,and gypsum contributes to Ca^(2+) and Mg^(2+) in groundwater.