Zhang Bai-Juan, Li Zong-Xing, Wang Yu, Li Yong-Ge, Lü Yue-Min, Yuan Rui-Feng, Gui Juan
College of Energy and Power Engineering, Lanzhou University of Technology, Lanzhou 730000, China.
Key Laboratory of Ecohydrology of In-land River Basin/Gansu Hydrology and Water Resources Engineering Research Center, Northwest Institute of Eco-environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China.
Huan Jing Ke Xue. 2019 Dec 8;40(12):5272-5285. doi: 10.13227/j.hjkx.201905218.
This study is based on precipitation samples from eight sites at the northern slope of the Qilian Mountains, combined with meteorological factors over the same period. Precipitation isotope characteristics, influence factors and the vapor sources of precipitation were analyzed, and the results show that:① The stable isotopes of precipitation in the study area show obvious seasonal changes, which are characterized by enrichment in the summer half-year and depletion in the winter half-year. The spatial precipitation O value shows a significant downward trend with increasing altitude, and the altitude effect of the annual precipitation O is -0.19‰/100 m, respectively;② At all stations, the slope and intercept of local meteoric water lines show an increasing trend from low altitude to high altitude. The high-altitude mountains above 2000 m are affected by local water vapor recirculation;③ The temperature effect is more significant and the temperature effect of O is 0.64‰, and there is only a weak precipitation effect in summer;④ The results indicate that sub-cloud evaporation has a great influence on the O of precipitation; the average raindrop evaporation rate of O is 23%, 11%, 12%, and 16%,and the O composition has been enriched by 46%, 27%, 38%, and 32% in May, June, July, and August from cloud base to ground, respectively.⑤ Under the condition of continuous rainfall in summer, the vapor sources of precipitation mainly come from the west and are affected by local evaporation of water vapor. The study enhances knowledge of isotopic evolution of precipitation and provides a basis for further study of isotopic hydrology in arid regions.
本研究基于祁连山北坡8个站点的降水样本，并结合同期气象因子。分析了降水同位素特征、影响因素及降水的水汽来源，结果表明：①研究区降水稳定同位素呈现明显的季节变化，表现为夏半年富集、冬半年亏损。空间降水δO值随海拔升高呈显著下降趋势，年降水δO的海拔效应分别为-0.19‰/100 m；②各站点本地大气降水线的斜率和截距均呈现出从低海拔到高海拔递增的趋势。海拔2000 m以上的高山受局地水汽再循环影响；③温度效应更为显著，δO的温度效应为0.64‰，夏季降水效应较弱；④结果表明，云下蒸发对降水δO有较大影响；δO的平均雨滴蒸发率分别为23%、11%、12%和16%，5月、6月、7月和8月从云底到地面δO组成分别富集了46%、27%、38%和32%；⑤夏季连续降雨条件下，降水水汽来源主要来自西部，并受局地水汽蒸发影响。该研究增进了对降水同位素演化的认识，为干旱区同位素水文进一步研究提供了依据。
