祁连山中段大冬树山降水稳定同位素的环境意义

Environmental Significance of Precipitation Stable Isotopic in Dadongshu Mountain of Middle Qilian Mountains

为探讨祁连山中段大冬树山降水稳定同位素的环境意义,依据2014年大冬树山垭口站(4146.8 m)的145个降水样品以及同期气象数据,对研究区降水稳定同位素特征及降水稳定同位素与各局地气象因子的相关关系进行分析。结果表明:(1)研究时段内大冬树山垭口站降水稳定同位素年际波动大,季节变化明显,表现为夏、秋季高,冬、春季低的特征;(2)所有次降水事件中δ18O温度效应显著,温度每升高1℃,δ18O增加0.62‰,而降水量效应不明显,仅在夏季降水事件中δ18O存在微弱的降水量效应,表明研究区温度是降水稳定同位素演化的主要因素;(3)研究区δ18O和d-excess与平均气压都呈显著正相关,表明云下二次蒸发对降水稳定同位素的影响显著。研究结果有助于进一步了解祁连山内陆河流域同位素水文过程。

To investigate the environmental significance of precipitation stable isotopic in Dadongshu Mountain of middle Qilian Mountains,the characteristics of precipitation stable isotopic and the correlations between precipitation stable isotopes and local meteorological factors were analyzed in this paper based on 145 precipitation samples from Dadongshu pass site(4146.8 m)and meteorological data at the same period in 2014.The results showed that:(1)The stable isotopes of precipitation showed a significant inter-annual fluctuations and an obvious seasonal variations.The characteristics of precipitation stable isotopes appears as a high value in Summer and autumn season,and a low value in winter and spring season.(2)Temperature effect ofδ18O was significant in all precipitation events.Theδ18O increases by 0.62‰for every 1℃temperature increasing,while the precipitation effect was not noticeable.A weak precipitation effect ofδ18O only appeared in summer precipitation events which can be conclude that the temperature is the mainly factor of precipitation stable isotope evolution in present study area.(3)Theδ18O and d-excess in this study area were significantly positively correlated with the averaged vapor pressure.It indicated that the stable isotopes of precipitation is significant effected on the sub-cloud evaporation in this research area.The present study provided a further understand of isotopic hydrology in inland river basins at the Qilian Mountains.