青海湖沙柳河流域土壤水氢氧稳定同位素组成与土壤贮水量关系

Relationship between hydrogen and oxygen stable isotope compositions of soil water and soil water storage in Shaliuhe River Basin of Qinghai Lake

氢氧稳定同位素技术和土壤贮水量是探究区域土壤水分特征的有效手段。基于青海湖沙柳河流域土壤水氢氧稳定同位素组成(δ2H和δ^(18)O)和土壤贮水量数据,分析其在流域的空间分布特征,探讨土壤水氢氧稳定同位素组成和土壤贮水量之间的相关性。结果表明:(1)沙柳河流域土壤水δ^(18)O值从西北向东南呈现富集—贫化—富集的趋势;土壤水d-excess值在流域南部最低,在流域东北部支流上游地区最高。(2)土壤贮水量在流域空间分布上表现为北高南低的趋势。(3)土壤水δ^(18)O值、d-excess值与土壤贮水量间存在分段线性关系。当0—30 cm各土层土壤贮水量≤30 mm时,各土层土壤贮水量与土壤水δ^(18)O值分别显著负相关、与d-excess值显著正相关。青海湖沙柳河流域自然地理环境和植被特征的空间差异导致其土壤水氢氧稳定同位素组成和土壤贮水量表现出明显的空间变异性。温度变化对土壤水氢氧稳定同位素组成与土壤贮水量之间的相关性影响是通过其对土壤蒸发作用的影响来实现的。

Hydrogen and oxygen stable isotope technology and soil water storage are both effective means to explore regional soil moisture characteristics.Based on the data of hydrogen and oxygen stable isotopic composition of soil water(δ~2H andδ^(18)O)and soil water storage in Shaliu River Basin of Qinghai Lake,this paper analyzes the spatial distribution characteristics of soil water in the basin,and discusses the correlations between hydrogen and oxygen stable isotopic composition of soil water and soil water storage.The results show that:(1)Theδ^(18)O value of soil water in the Shaliu River Basin shows a trend of enrichment-dilution-enrichment from the northwest to the southeast;The d-excess value of soil water is the lowest in the southern part of the basin,and the highest in the upper reaches of the tributary in the northeastern part of the basin.(2)During the study period,the spatial distribution of soil water storage in the basin showed a trend of high in the north and low in the south.(3)There is a piecewise linear relationship between soil waterδ^(18)O value,d-excess value and soil water storage.When the soil water storage in each soil layer of 0-30 cm is less than or equal to 30 mm,the soil water storage of each soil layer has a significant negative correlations with theδ^(18)O value of soil water,and a significant positive correlations with the d-excess value.The spatial difference of the natural geographical environment and vegetation characteristics in the Shaliu River Basin of Qinghai Lake leads to obvious spatial variability in the stable isotope composition of hydrogen and oxygen in soil water and soil water storage.The effect of temperature change on the correlations between the hydrogen and oxygen stable isotope composition of soil water and soil water storage is realized through its effect on soil evaporation.