乌伦古河流域潜水水化学特征与成因分析

Hydrochemical characteristics and formation of phreatic water in the Ulungur River watershed

为查明乌伦古河流域不同地貌单元潜水水化学空间分布特征及其成因,采用数理统计、舒卡列夫分类、Piper三线图、Gibbs图解、离子比例系数等方法对2018年潜水的水化学测试数据进行了系统分析。结果表明:乌伦古河流域潜水水化学组分主要受蒸发结晶、岩石风化、离子交换作用影响,由山前基岩区至冲洪积-湖积平原矿化度与常量离子组分逐渐增加,不同地貌单元水化学特征差异较大。山前基岩低山区水化学类型以HCO_(3)·SO_(4)-Ca·Na为主,低山丘陵区为SO_(4)·Cl-Na·Ca型,该区水化学成因以蒸发结晶与岩石风化作用为主;山间河谷区水化学类型以HCO_(3)·SO_(4)-Ca·Na为主,受岩石风化作用以及离子交换作用影响;冲洪积-湖积平原水化学类型呈现水平分带,远河道区水化学类型以SO_(4)-Na·Ca、SO_(4)·Cl-Na·Ca型为主,近河道以SO_(4)·HCO_(3)-Ca·Na型为主,受岩石风化、蒸发结晶与离子交换作用共同影响;阳离子演化趋势为Ca^(2+)、Na^(+)→Na^(+)、Ca^(2+)→Na^(+)(Ca^(2+)、Mg^(2+)),阴离子演化趋势为HCO_(3)-(SO_(4)^(2-))→SO_(4)^(2-)(HCO_(3)-)→SO_(4)^(2-)-→SO_(4)^(2-)(Cl^(-))→SO_(4)^(2-)、Cl^(-)。

River watershed,groundwater hydrochemistry datasets in 2018 were analyzed using mathematical statistics,theSchakerev classification,Piper diagrams,Gibbs plots,and ion ratios.The results showed that the hydrochemicalcomposition of phreatic water was mainly controlled by evaporation,rock weathering,and cation exchange.The ioncontent and total salinity in groundwater increased gradually in the water flow direction.The hydrochemical typesvaried depending on the geomorphology.The hydrochemical characteristics of phreatic water in the low mountainarea was HCO_(3)·SO_(4)-Ca·Na,whereas it changed to SO_(4)·Cl-Na·Ca in the hilly area.The formation mechanism wasrock weathering and the evaporation concentration function.The main hydrochemical type near the river where rockweathering and cation exchange were the primary controlling factors was HCO_(3)·SO_(4)-Ca·Na.The distribution ofhydrochemical characteristics in alluvial-proluvial plains had obvious zoning features.The hydrochemicalcharacteristics changed from SO_(4)-Na·Ca and SO_(4)·Cl-Na·Ca to SO_(4)·HCO_(3)-Ca·Na near the river.The chemicalspatial evolution in this area was mainly driven by rock weathering,leaching,and cation exchange.The evolutionamong the major cations was Ca^(2+),Na^(+)→Na^(+),Ca^(2+)→Na^(+)(Ca^(2+),Mg^(2+));the main anion evolution was HCO-3(SO_(4)^(2-))→SO_(4)^(2-)(HCO-3)→SO_(4)^(2-)→SO_(4)^(2-)(Cl^(-))→SO_(4)^(2-)、Cl^(-).