巴丹吉林沙漠降水稳定同位素特征与水汽再循环

Stable Isotopic Characteristics of Precipitation and Moisture Recycling in Badain Jaran Desert

了解沙漠降水稳定同位素特征,有助于研究干旱区水循环过程.根据2015-2016年取自巴丹吉林沙漠4个站点的降水样品,分析了δ2H、δ^(18)O的时空分布特征及影响因素;借助后向气团轨迹模型分析了降水水汽来源;采用氘盈余模型计算了水汽再循环比.结果显示,降水δ2H、δ^(18)O均表现出季节效应,夏高冬低;沙漠腹地较外围山区δ2H、δ^(18)O偏正,d-excess偏负,反映出腹地降水的蒸发程度更高.年内降水主要来自西风水汽,夏季部分受东南季风影响.沙漠湖泊区再循环比为10.3%~10.9%,略大于山区的8.5%;再循环水汽在总蒸发量中占比11.1%,反映出沙漠强烈的蒸发对本地降水的贡献较为有限.

Understanding the isotopic characteristics of precipitation in desert is helpful to study the water cycle process in arid areas. According to the precipitation samples from 4 stations in the Badain Jaran Desert from 2015 to 2016, the temporal and spatial distribution characteristics and influencing factors of δ2H and δ^(18)O were analyzed. The source of precipitation moisture was analyzed with the backward air mass trajectory model and the recycled moisture fractions were calculated with deuterium excess.The results show that the precipitations of δ2H and δ^(18)O show seasonal effect, which are higher in summer and lower in winter.The precipitations of δ2H and δ^(18)O in the hinterland of desert are more positive and d-excess is more negative than that in the surrounding mountainous areas, reflecting the stronger evaporation of precipitation in the hinterland. The annual precipitation is mainly from the westerly moisture, and the summer precipitation is affected by the southeast monsoon. The recycled moisture fraction in desert is 10.3%-10.9%, which is slightly larger than 8.5% of mountainous area;the recycled moisture accounts for 11.1% of the total evaporation, which reflects that the contribution of strong evaporation in desert to local precipitation is relatively limited.