【摘要】 分析了改变土壤水同位素的主要影响因素,利用土壤同位素蒸发分馏模型模拟了典型情况下饱和、非饱和土柱同位素剖面分布情况,得出地表蒸发为土壤水同位素富集的主要原因。通过土柱同位素交换实验,分析了输入降水与土壤水的交换混合作用。结果表明,输入降水与土壤水同位素交换程度较大,不同同位素组成的降水与土壤水混合是土壤水同位素改变的一种重要方式。最后综合分析了蒸发分馏和降水入渗共同作用下的土壤水同位素变化情况。更多还原

【Abstract】 In this paper,the main influence factors on the variations of stable isotopes in soil water are studied.Firstly,the depth distributions of the stable isotopes in saturated and unsaturated soil under steady-state conditions are simulated by the evaporation models.It is shown that surface evaporation is the main factor causing isotope concentration of soil water.Then,an experiment on isotope exchange in soil columns is carried out,and the mixture action between precipitation and soil water is analyzed.The results show that isotopic variation rate of water in soil columns may reach about 20% while the mass proportion of soil water and input water is about 3∶10,which indicates that the isotope exchange degree is considerable.Therefore,the mixture between precipitation and soil water may be an important way for isotopic variation of soil water.Finally,the stable isotopic distribution of soil water under the mutual effect of evaporation fractionation and precipitation infiltration is synthetically analyzed.更多还原