Abstract:

The environmental effects of stable isotope and water vapor precipitation sources in the Yinchuan Plain, Ningxia Hui Autonomous Region, China, were studied using backward trajectory clustering analysis, the potential source contribution function, and the concentration-weighted trajectory analysis method to resolve vapor sources and potential evaporation source areas. Our results showed that (1) there were obvious seasonal variations in the hydrogen-oxygen stable isotope composition of precipitation in the Yinchuan Plain, and the hydrogen-oxygen stable isotope composition of precipitation in the winter half-year (-38.6‰±51.6‰ and -4.5‰±5.2‰) was significantly more positive than that in the summer half-year (-40.9‰±17.7‰ and -5.7‰±3.0‰); The local meteoric water line was greatly improved. The slope and intercept of the LMWL in the summer half-year (5.43, -9.71) were lower than that in the winter half-year (9.10, 5.08), and that of the whole year (6.79, -2.79). (2) The temperature effect was significant at three time periods: (0.473±0.210) ‰·°C^-1, (0.258±0.037)‰·°C^-1 and (0.211±0.031)‰·C^-1 under the entire year, summer and winter half-year, respectively, the precipitation effect was not significant. (3) During the summer and winter half-years, the vapor sources of precipitation in the study area were primarily westerly water vapor, but were also influenced by local evaporative vapor. In the summer half-year, the evaporative vapor source areas were mainly distributed in the area surrounding the study area and the western, southwestern, and southern parts of the study area; During the winter half-year, they were mostly found in the area surrounding the study area and to the west. The study’s findings may provide a theoretical foundation for selecting methods for identifying water vapor sources in arid regions using stable isotope techniques.

Key words: atmospheric precipitation, stable isotope effect, water vapor source, potential evaporation source, different time scales, Yinchuan Plain