Characteristics of Hydrogen and Oxygen Isotopes for Precipitation in Xiling Gorge Region of Yichang,Hubei Province

Based on the stable isotope analysis of precipitation from May to October in 2009 in Xiling Gorge region of Yichang,characteristics of hydrogen and oxygen isotopes for precipitation were analyzed,and compared to materials of hydrogen and oxygen isotopes for precipitation in 2007.The results show that: the local meteoric water lines is fitted as δD=8.45δ18O +11.55.Its slope and intercept are higher than those of global meteoric water line and Chinese meteoric water line,which are related to non-equilibrium evaporation and rapid enrichment of heavy isotopes of condensation objects in the unsaturated atmosphere.The average of d values for precipitation is lower than that of the globe,and it suggests that the evaporation rate is slow,and vapor source is single,and condition for precipitation is not complicated at the vapor source area.The precipitation amounts have no significant effect on the isotopic compositions of individual precipitation events,but have significant effect on long-term precipitation events.Compared to 2007,precipitation in 2009 have enrichment of δ18O and δD,but lower average of d value,and those phenomena suggest that the vapor source path for precipitation is short and the humidity is large in vapor source areas in 2009,and the phenomena are caused by the circumstance altering in Three Gorge Reservoir after reservoir filling.