We analyze the stable isotope characteristics and vapor source of precipitation in a monsoon marginal area in the southern and northern slopes of Wushaoling Mountain, northwestern China, using 97 precipitation samples collected from October 2016 to October 2017. Correlation analysis and HYSPLIT model are used to study the characteristics of stable isotopes in precipitation, local meteoric water line equation, temperature and precipitation effects, and vapor source. The study found the following results. ① The slope and intercept of the southern slope local meteoric water line were lower than of those of the northern slope and global averages. ② Although the isotope temperature effects and seasonal effects of both slopes were obvious, the temperature effect of the northern slope was more obvious than of that of the southern slope. ③ The stable isotopes of precipitation during the summer on the northern slope and the precipitation on the southern slope<5 mm revealed that the precipitation effect was weak. There was no obvious precipitation effect in other seasons or in other precipitation levels on both slopes. ④ Vapor from the northwest and north accounted for>90% of the total. The northern slope was rarely affected by monsoon vapor, but the southern slope was affected by the southeast monsoon during the summer. Local water vapor recycling contributed to water vapor in the southern and northern slopes of Wushaoling Mountain. This study could improve the cognition of precipitation isotopic evolution in alpine regions, and lays a foundation for further research on isotope hydrology in cold and arid regions.
Keywords: Wushaoling Mountain; hydrogen and oxygen isotope; northern and southern slope; precipitation; vapor source.