由于多年冻土区流域土壤冻融过程对水循环影响的复杂性,水循环物理过程观测存在困难和不足,而利用稳定同位素方法可以有效地解决该问题。因此,基于2009年长江源风火山流域夏季定点降水和河水deltaD和delta~(18)O,对研究区降水河水稳定同位素特征进行分析。结果表明,研究区夏季降水deltaD和delta~(18)O受到降水量和温度的双重影响,即受海洋性和大陆局地气团的交替影响。河水氢氧同位素的季节变化和空间差异与壤中流、地下水补给河流的季节差异和植被覆盖的空间差异有关。随着地温升高和土壤冻融锋面的迁移,河水补给来源和同位素特征发生改变,表明土壤冻融变化对多年冻土流域径流过程起到重要作用。此外,蒸发分馏作用是研究区河水同位素的重要影响因素。

Due to the complexity of the influence of freeze-thaw of active soil layer on water cycle,the hydrological observation is rare and difficult in permafrost watershed.In order to improve hydrological understanding in permafrost watershed,stable isotopes have proven utility since they reflect the integration of processes at smaller scales.Therefore,the spatial-temporal variation of stable isotopes in precipitation and river water of Fenghuoshan permafrost watershed was investigated,on the basis of variations in stable hydrogen and oxygen isotopes ratios(deltaD and delta~(18)O) for precipitation and river water during June to October,2009.The seasonality of stable isotopes for rain water suggests that the alternative influence of both continental air mass and monsoon air mass to local precipitation.The temporal-spatial distribution of stable isotopes for river water was influenced by the seasonality variation of river recharge from soil water and underground water and spatial difference of vegetation coverage.Along with the migration of freeze-thaw front of active soil layer,the source of river water and the variation characteristics of stable isotopes for river water changed.This suggests that the freeze-thaw of active soil layer plays an important role in rainfall-runoff process in permafrost watershed.In addition,evaporation played important role in the fractionation of water isotopes.