干旱半干旱区土壤水含量极低,可提取的土壤水量常不足以分析其稳定性同位素 δD 和 δ18O 组成,制约了稳定同位素技术在该地区的应用.本研究以干旱半干旱地区两种典型土壤为对象,将土壤水与超纯水按一定比例混合,稳定同位素分析发现土壤水、混合水、超纯水的氢氧同位素在同一条直线上,呈极显著线性相关(R2>0.99, P<0.001),与端元混合模型计算结果非常吻合(R2>0.99,P<0.001),且不受土壤质地与有机碳等性质的影响.研究结果为干旱区土壤水氢氧同位素分析提供了有效的技术途径.%Soil water content in arid and semiarid area is very low so that the amount of soil water extracted from soil is often not enough to determine its stable isotope δD and δ18O. In this study, a desert sandy soil and a farmland sandy soil were collected from the semiarid areas, and mixed water samples were extracted from the soils and ultrapure water under different proportions. We found that isotope δD or δ18O values of soil water, mixing water, ultrapure water showed very significant linear correlation (R2>0.99, P<0.001). The measured and theoretically predicted isotopic data by the End-member mixing model were consistent R2>0.99, P<0.001, which was not affected by soil texture and organic C content. This study provides a new method for obtaining stable isotope δD and δ18O of soil water even if it is quite low, and can be used in arid and semiarid areas.
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