论文部分内容阅读
氢、氧稳定同位素方法是研究多年冻土区水文过程的一种有效手段。基于2009年风火山流域降水和河水δD和δ18O数据,结合水文气象资料,分析多年冻土区季节性河流氢、氧同位素组成。研究表明,研究期间(6—10月)δ18O、δD和氘过剩河水与降水均呈下降的趋势,表明研究区降水是河水的重要补给来源。2#、3#流域δD分别为-66.8‰和-69.6‰,与降水δD(-66.7‰)基本相当;5#流域δD为-62.4‰,显著高于降水。5#流域较高的植被覆盖使地表具有更高的有机质含量、水分和蒸散量,其强烈的蒸发分馏作用使河水富集重同位素。6月份,随着土壤向下融化,降水(δD=-12.1‰)驱替冻结封存的重同位素贫化的土壤水(δD=-71.3‰)补给河流;10月份,地表冻结后抑制降水下渗,使降水和河水δD趋于一致,反映了土壤冻融过程在多年冻土区径流过程中起到的重要影响。该研究为多年冻土区水文过程的变化规律提供了同位素证据。
Hydrogen and oxygen stable isotope method is to study the permafrost hydrological process is an effective means. Based on the data of δD and δ18O of the Fenghuo River Basin in 2009 and the river water, combined with the hydrological and meteorological data, the hydrogen and oxygen isotopic composition of the seasonal river in the permafrost region was analyzed. The results show that δ18O, δD and deuterium excess river water and precipitation all show a decreasing trend during the study period (June-October), indicating that precipitation in the study area is an important source of recharge for river water. ΔD of # 2 and # 3 are -66.8 ‰ and -69.6 ‰, respectively, which are basically the same as those of precipitation δD (-66.7 ‰); and δD of # 5 is -62.4 ‰, which is significantly higher than that of precipitation. The higher vegetation coverage in the 5 # watershed makes the surface have higher organic matter content, water content and evapotranspiration, and its intense evaporation fractionation enriches heavy water in the river. In June, heavy-isotope-depleted soil water (δD = -71.3 ‰) was replaced by precipitation (δD = -12.1 ‰) as the soil melted downward. In October, the precipitation was suppressed and precipitation was reduced , Making the δD of precipitation and river water consistent, reflecting the important influence of soil freeze-thaw process on the runoff in the permafrost region. The study provides isotopic evidence for the variation of hydrological processes in permafrost regions.