中文摘要：

通过同位素分馏模型的物理意义分析及实验模拟分析,探讨空气湿度对蒸发过程水体稳定同位素富集过程的影响机理,研究认为：1空气相对湿度决定了扩散系数和自由空气同位素组成对分馏系数的影响比例,空气相对湿度越小,分馏系数受扩散分馏系数影响越大,分馏系数受自由空气水汽同位素组成影响则越小,反之亦然;2空气相对湿度与蒸发残余水体氢氧稳定同位素富集程度具有负相关性,即空气湿度越大越不利于残余水体重同位素富集;3模拟残余水体同位素丰度对空气相对湿度的敏感性呈负指数关系。在无外界气态水介入的蒸发实验中,残余系数为0.194条件下,当相对湿度小于80%时,H、O稳定同位素模拟结果对湿度的敏感性均小于0.0002,即相对湿度变化对模拟残余水体同位素丰度影响很小;当湿度大于80%时,湿度变化对模拟结果的影响呈指数关系急剧增加,湿度大于80%的蒸发实验需要准确观测相对湿度值。

英文摘要：

The physical meaning of parameters in isotopic fractionation model, was discussed, and the sensitivity of enriched isotopic components of liquid to free air relative humidity was emphatically studied. Some conclusions have been reached： 1The free air relative humidity determines the dominant range of diffusion fractionation factor, αdiff, and isotopic components of free air in the equation of evaporation fractionation factor, α. The smaller the relative humidity, the smaller the impact of free air components on α,and the larger the influence of αdiffon α, and vice versa. 2 The enrichment degree of hydrogen and oxygen stable isotopes in the process of evaporation is negatively related to the relative humidity of free air. 3 The sensitivity of enriched liquid components to free air relative humidity is an exponential function. The sensitivity simulation shows that the sensitivity is smaller than 0.0002 when relative humidity is smaller than 80% under Boaz’s experiment condition, which indicates that the dynamics of air humidity in the range from 0% to 80% can barely affect the isotopic components of liquid water in the end of the evaporation stage, while the sensitivity exponentially increases with relative humidity when it is larger than 80%, which indicates that experiments with a free air relative humidity larger than 80% should measure humidity accurately.