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Change of Stable Isotopes in Summer Precipitation in Central Inner Mongolia

Li Wenbao  Li Changyou  Jia Debin  Hao Shiqi  Liu Zhijiao  Li Ruizhen   

  1. Inner Mongolia Autonomous Region Key Laboratory of Water Resources Protecting and Utilization, Inner Mongolia Agricultural University, Hohhot 010018

  • Received:2016-10-09 Revised:2017-03-22 Online:2017-11-15 Published:2017-12-20

Abstract: Abstract:Stable isotopes in precipitation,such as δD and δ18O,are two important indicators of analyzing water vapor sources and transport pathways in rainfall process. The values of δD and δ18O can be used to analyze the factors affecting precipitation. In this paper,the samples of summer rainfall in Hohhot,Zhenglan Banner of Xilin Gol League and Dali Nor Lake in Hexigten Banner of Chifeng City,Inner Mongolia were collected. Based on the values of δD and δ18O in precipitation in the study areas,the characteristics of summer precipitation in central Inner Mongolia were discussed in detail. The results are as follows: ① The meteoric water lines over central Inner Mongolia were significantly different,which showed that the water vapor sources were different. The slope and intercept of meteoric water line over Baotou City were both lower,and their values were 5.84 and -8.88 respectively. Correspondingly,the slope and intercept of meteoric water line over the Dali Nor Lake were both higher,and their values were 8.26 and 7.21 respectively,which was similar to the global or Chinese meteoric water line; ② The change of δD and δ18O was mainly affected by the process of rainfall and local evaporation. Meanwhile,the value of deuterium surplus parameter (d) was also different from different months in summer. As a whole,the precipitation intensity and local evaporation might be the main factors affecting the change of d value. The proportion of precipitation in July was higher than that in other three months in summer,which could lead to the lowest d value in July,and also showed that the precipitation intensity might have stronger influence on the change of d value than the local evaporation in July. The d value was high in June and September,which revealed that the local evaporation might have stronger influence on process of rainfall.

Key words: stable isotope, summer precipitation, meteoric water line, Inner Mongolia