黄土高原丘陵沟壑区流域不同水体氢氧同位素特征--以纸坊沟流域为例  

Characteristics of Hydrogen and Oxygen Isotopes in Different Waters of the Loess Hilly and Gully Region

作　　者：王贺[1] 李占斌[2] 马波[1] 马建业[1] 张乐涛[2] 

机构地区：[1]西北农林科技大学水土保持研究所,黄土高原土壤侵蚀与旱地农业国家重点实验室,陕西杨陵712100 [2]中国科学院水利部水土保持研究所,黄土高原土壤侵蚀与旱地农业国家重点实验室,陕西杨陵712100

出　　处：《水土保持学报》2016年第4期85-90,135,共7页Journal of Soil and Water Conservation

基　　金：国家自然科学基金项目(41330858)

摘　　要：为系统、全面地研究黄土高原丘陵沟壑区流域降水、地表水、土壤水的氢氧同位素特征,以纸坊沟流域为研究对象,通过测定流域范围内2015年3—9月降水、地表水、刺槐林土壤水和荒草地土壤水的氢氧同位素组成,分析了各水体氢氧同位素的δD-δ^(18) O关系和季节变化特征,阐明了土层深度、植被类型、坡向和坡位等下垫面因素对土壤水氢氧同位素的影响。结果表明:该流域当地大气降水线方程为δD=6.71δ^(18) O^-_3.22(n=18,R^2=0.96),地表水的蒸发线方程为δD=6.77δ^(18) O-5.32(n=13,R^2=0.72),土壤水的蒸发线方程为δD=3.50δ^(18) O^-_34.00(n=756,R^2=0.76);各水体δ^(18) O富集程度为:刺槐林土壤水≈荒草地土壤水>降水>地表水。降水与土壤水(刺槐林和荒草地)δ^(18) O季节效应明显,浅层50cm土壤水的平均传输时间约为1个月;地表水δ^(18) O变幅较小、组成均一、季节效应不明显,推断其为多次历史降水混合形成;4种下垫面因素对浅层50cm土壤水氢氧同位素影响程度为:土层深度>坡向>植被类型>坡位。其中,土层深度对浅层土壤水δ^(18) O影响达到极显著水平。不同土层间土壤水δ^(18) O差异性随土层深度差值的增大而增大,且深度差超过15cm后呈极显著差异,推断纸坊沟流域地表15cm土层为受降水和蒸发影响的土壤水分活跃区。In order to study the characteristics of hydrogen and oxygen isotopes in precipitation, surface water and soil water of the loess hilly and gully region systematically, the Zhifanggou watershed, which is located in Ansai County, Yan＇ an City of Shaanxi Province, was selected to be the research object. Precipitation samples, surface water samples and soil samples in locust forest and waste grassland were collected from March to September of 2015 to test the compositions of the hydrogen and oxygen isotopes. By analyzing the seasonal variations of hydrogen and oxygen isotopes and the relationships between 3D and δ^18O in the precipitation, surface water and soil water of Zhifanggou watershed and their seasonal changes, the effects of soil depth, vegetation type, and slope direction and position on characteristics of hydrogen and oxygen isotopes in soil water were explored. The results showed that the local meteoric water line equation was 3D= 6.71 δ^18O- 3.22 （n=18, R^2 =0.96）, the evaporation line equation of the surface water was δD=6. 77 δ^18O-5.32 （n= 13, R^2 =0.72）, and the evaporation line equation of the soil water was δD=3. 50 δ^18O-34.00 （n=756,R^2 = 0.76）. δ^18O in different water listed in the order of soil water （locust forest） ≈ soil water （waste grassland）〉 precipitation〉surface water. The seasonal variations of δ^18O in precipitation and soil water were obvious, while that in the surface water was not obvious with small variable amplitude and stable composition. It can be concluded that the average transmission time of soil water in the 0-50 cm soil layer was about a month,and the surface water came from a blend of multiple historical precipitations. Finally, the influence degrees of underlying surface factors （soil depth, vegetation type, slope direction and position） on the hydrogen and oxygen isotopes in soil water were calculated, which listed in the order of soil depth）slope direction）vegetation type〉slope position. The influence of soil depth on δ^1

关 键 词：黄土高原 纸坊沟 氢氧同位素 降水 地表水 土壤水 

分 类 号：X143[环境科学与工程—环境科学] P342[天文地球—水文科学]