Deuterium and oxygen 18 in precipitation and atmospheric moisture in the upper Urumqi River Basin, eastern Tianshan Mountains

The contribution of stable isotopes in meteorological, climatological and hydrological research is well known. This study analyzed the deuterium and oxygen 18 contents (δD and δ18O) of precipitation in event-based samples at three stations (Glacier No. 1, Zongkong, Houxia) along the upper Urumqi River Basin from May 2006 to August 2007. The δ18O in precipitation revealed a wide range and a distinct seasonal variation at all three stations, with enriched values occurring in summer and depleted values in winter. A statistically significant positive correlation was observed between the δ18O and δD and local surface air temperature, and better linear relationship existed between δ18O and air temperature than that of δD. This suggests that paleoclimatic archives relating to precipitation δ18O and δD can be useful for qualitative temperature reconstruction. The d-excess in precipitation also exhibited a seasonal variability. Based on NCEP/NCAR reanalysis data, three-dimensional isentropic back-trajectories in HYSPLIT model were employed to determine the moisture source for each precipitation event. Results indicate a dominant effect of westerly air masses in summer and the integrated influence of westerly and polar air masses in winter, and d-excess can be used as a sensitive tracer of the moisture transport history.