小昌马河流域地表水地下水同位素与水化学特征及转化关系

利用小昌马河流域上游大雪山老虎沟冰雪融水及下游昌马洪积扇区地下水的稳定同位素和水化学资料, 对流域稳定同位素和水化学的组分特征和季节变化进行了分析. 结果表明: 小昌马河流域内从上游冰雪融水区到下游昌马洪积扇地下水排泄区矿化度不断增高, 水化学类型由HCO₃-Mg-Ca过渡到HCO₃-SO₄-Ca-Mg; 上游冰雪融水与下游地下水δ¹⁸O的季节变化基本一致, 洪积扇区地下水来源于冰雪融水的补给. 水文地球化学模型模拟显示地下水形成过程中水岩作用以析出方解石, 吸收二氧化碳, 溶解石膏、 岩盐和绿泥石等为主要特征, 溶蚀的含盐矿物使地下水中氯化物、 硫酸根和钠离子含量升高, 地下水水质恶化. 同位素和水化学证据均揭示了小昌马河流域地表水-地下水的化学环境转化关系.

Isotopic,Chemical Characteristics and Transforming Relationship between Surfacewater and Groundwater in the Xiaochangma River Basin

Based on the data of stable isotopes and chemical components in meltwater from the headwater areas and groundwater in the lower reaches of the Xiaochangma River,the characteristics and seasonal variations of isotopes and main ions were analyzed.It is found that the mineralization continuously increases and the type of water chemical component transfers from HCO3-Mg-Ca to HCO3-SO4-Ca-Mg from the headwaters to Changma alluvial fan.The coherence of seasonal variations of isotopes indicates that the groundwater in the lower reaches is recharged by the meltwater in upper reaches.Simulation of hydro-geochemical model highlights the water-rock interaction along the flow path.There are deposition reaction of calcite and dissolution reactions of gypsum and halite along the flow path.In addition,dissolution reactions of dolomite,chlorite,illite and hornblende take place as well.A large amount of CO2 has entered into water.The increasing trend of Cl,SO4 and Na reveals a deterioration of water quality.This evidence of stable isotopes and hydrochemistry demonstrates a transformation between meltwater in upper reaches and groundwater in the lower reaches of the river.