青海湖沙柳河流域土壤水氢氧稳定同位素组成空间变化特征

Spatial variation of hydrogen and oxygen stable isotope composition of soil water in Shaliu River Basin of Qinghai Lake

土壤水氢氧同位素组成的空间变化特征,对于水循环以及不同水体之间相互关系的研究具有重要意义。以青海湖沙柳河流域为研究对象,基于该流域2018—2019年7、8月土壤水氢氧稳定同位素组成(δ^(2)H、δ^(18)O)数据,借助ARcGIS空间插值方法,对土壤水δ^(2)H和δ^(18)O空间变化特征进行了研究。结果表明:青海湖沙柳河流域2018—2019年7、8月土壤水δ^(2)H和δ^(18)O的变化范围为–126.53‰—–16.13‰和–16.48‰—–1.26‰。研究期内0—30 cm土壤水δ^(2)H和δ^(18)O平均值的土壤水线分别为:SWL_(2018.07 )(δ^(2)H=5.83δ^(18)O–8.36,R^(2)=0.93)、SWL_(2018.08 )(δ^(2)H=6.28δ^(18)O–8.35,R^(2)=0.93)、SWL_(2019.07 )(δ^(2)H=6.53δ^(18)O–5.70,R^(2)=0.94)、SWL_(2019.08 )(δ^(2)H=6.86δ^(18)O–1.37,R^(2)=0.92)。整体上SWL的斜率随深度的变化整体上呈现先增大后减小的趋势,截距则表现出随着深度增加逐渐增大的特点,2019年8月SWL的斜率表现为随着深度增加而逐渐减小,截距的变化差距不大。大气降水是土壤水的重要来源,蒸发富集作用导致不同深度SWL斜率小于局部大气降水线(LWML)斜率。空间分布上,青海湖沙柳河流域土壤水稳定氢氧同位素的海拔效应并不明显,但它还是受到了局地蒸发强度、地形地势、植被盖度等的影响,在流域面上呈现出斑块状分区。研究结果可为进一步研究流域水分循环,土壤水补给机制等提供数据支撑和理论参考。

The spatial variation characteristics of the hydrogen and oxygen isotopic composition of soil water are of great significance to the study of the water cycle and the relationship between different water bodies.This study took the Shaliu River Basin of Qinghai Lake as the research object to collect the data of soil water hydrogen and oxygen stable isotope composition(δ^(2)H,δ^(18)O)from July and August of 2018 to 2019 in the watershed and obtain the spatial changes of soil waterδ^(2)H andδ^(18)O by using the method of ArcGIS spatial interpolation.The results showed that theδ^(2)H andδ^(18)O of soil water varied from–126.53‰to–16.13‰and from–16.48‰to–1.26‰respectively in the Shaliu River Basin of Qinghai Lake in July and August,2018-2019.During the study period,the soil water lines of the average values ofδ^(2)H andδ^(18)O of 0-30 cm soil water were:SWL_(2018.07)(δ^(2)H=5.83δ^(18)O–8.36,R^(2)=0.93),SWL2018.08(δ^(2)H=6.28δ^(18)O–8.35,R^(2)=0.93),SWL2019.07(δ^(2)H=6.53δ^(18)O–5.70,R^(2)=0.94),SWL2019.08(δ^(2)H=6.86δ^(18)O–1.37,R^(2)=0.92).On the whole,the slope of SWL increased first and then decreased with the change of depth,while the intercept increased gradually with the increase of depth.In August 2019,the slope of SWL decreased gradually with the increase of depth,with a small difference in the change of intercept.Precipitation was an important source of soil water,and evaporative enrichment caused the slope of SWL at different depths to be smaller than that of the local atmospheric precipitation line(LWML).In terms of spatial distribution,the altitude effect of soil water stable hydrogen and oxygen isotopes in the Shaliu River Basin of Qinghai Lake was not obvious,but it was still affected by the intensity of local evaporation,topography,vegetation coverage,and water vapor sources,appearing patchy partitions on the watershed surface.The research results can provide data support and theoretical reference for further research on the water cycle of the watershed and the mechanism of soil water replenishment.