黑河上游葫芦沟流域不同水体稳定同位素特征

Stable Isotope Characteristics of Different Water Bodies in the Hulugou Catchment of the Upper Heihe River

以祁连山区黑河上游葫芦沟流域为研究区,确定了流域各水体的稳定同位素特征并分析了各水体间的水力联系。在此基础上,通过端元混合分析模型(EMMA)定量化了冻土活动层的水分来源。研究得出:葫芦沟流域大气降水线(LMWL)方程为δD=8.65δ^18O+22.82;河水蒸发线方程(LEL)为δD=5.92δ^18O+2.56,斜率与截距均比全球大气降水线(GMWL)与LMWL的小,表明河水经历了强烈的蒸发作用,且河水的δ18O值从下游流域出口至上游源区逐渐降低,呈现明显的海拔效应(-0.46‰/100 m)。浅层地下水的蒸发线(LEL-S)的表达式为δD=7.69δ^18O+8.24,主要补给来源是降水,并排泄进河水;深层地下水的蒸发线(LEL-D)表达式为δD=6.09δ^18O+3.24,主要来源于古老水补给,也会接收现代水的补给。冻土活动层水分主要来源于降水(占比77.26%),其次来源于活动层季节性冰(占比22.74%)。

In this paper,the Hulugou catchment in the Upper Heihe River in the Qilian Mountains was used as the study area,and stable iso tope characteristics of each water body in the catchment were determined and hydraulic connections between the water bodies were analyzed.On this basis,water source of the frozen soil active layer was quantified by End-Member Mixing Analysis(EMMA)model.The study results show that the equation of Local Meteoric Water Line(LMWL)in Hulugou catchment isδD=8.65δ^18O+22.82;The river water Local Evapo ration Line Equation(LEL)isδD=5.92δ^18O+2.56,and the slope and intercept are smaller than those of the Global Meteoric Line(GM WL)and LMWL,which indicates that the river has experienced strong evaporation and theδ^18O value of river water value gradually decrea ses from the downstream watershed to the upstream source region,showing a significant altitude effect(-0.46‰/100 m).The equation of the shallow groundwater Local Evaporation Line(LEL-S)isδD=7.69δ^18O+8.24,and main source of shallow groundwater is precipitation and shallow groundwater is discharged into river.The equation of the deep groundwater Local Evaporation Line(LEL-D)isδD=6.09δ^18O+3.24,mainly being from ancient water,be also replenished by modern water.The water source of frozen soil active layer mainly comes from rainfall(accounting for 77.26%);secondly,it comes from seasonal ice of active layer,with a contribution rate of 22.74%.