黑河下游鼎新谷地浅层地下水水化学特征及演化规律

Hydrochemical characteristics and evolution of shallow groundwater in Dingxin valley,lower reaches of Heihe River

依据地下水流系统及化学平衡理论,运用Gibbs图、Gaillardet端元图、离子比值分析、水文地球化学模拟等方法,系统研究了鼎新谷地浅层地下水化学特征及控制机制。结果表明:1)研究区地下水化学类型主要为SO_(4)·HCO3型、SO_(4)·Cl型、SO_(4)型、Cl型。2)地下水化学组分主要受岩石风化、蒸发浓缩作用控制,部分样品位于Gibbs图"回形镖"范围之外,表明发生了阳离子交换作用。3)大墩门-芨芨村-鼎新镇-航天镇一带地下水主要受蒸发岩、硅酸盐岩不协调风化作用控制,苇坑泉一带地下水受蒸发岩风化作用控制。4)在反向模拟的地下水流路径上,白云石、石膏、盐岩、芒硝、钾盐发生溶解,方解石沉淀,在下游区发生了Ca^(2+)、Mg^(2+)阳离子交换作用。

Based on the theory of groundwater flow system and chemical balance,the chemical characteristics and control mechanism of shallow groundwater in Dingxin valley were systematically studied by using Gibbs diagram,Gaillardet endmember diagram,ion ratio analysis and hydrogeochemical simulation.The results show that:The chemical types of groundwater in the study area are mainly SO_(4)·HCO3 type,SO_(4)·Cl type,SO_(4)type,Cl type.The chemical composition of groundwater is mainly controlled by rock weathering and evaporation concentration,and some samples are located outside the scope of"boomerang"in Gibbs diagram,indicating that cation exchange has occurred.The groundwater in Dadunmen-Jiji village-Dingxin town-Hangtian town area is mainly controlled by evaporite and silicate rock,the groundwater in Weikeng Spring area is controlled by the weathering of evaporite.In the reverse simulated groundwater flow path,dolomite,gypsum,salt rock,mirabilite and potash are dissolved,calcite is precipitated,and Ca^(2+)and Mg^(2+)cation exchange occurs in lower reaches.