HE Yuan-qing, PANG Hong-xi, LU Ai-gang, DIAN Zhang, ZHANG Zhong-lin, NING Bao-ying, SONG Bo, ZHAO Jing-dong, YUAN Ling-ling
In order to understand spatial and temporal variations of the stable isotopes in atmospheric precipitation,snow cover and glacial runoff in different regions of China,sampling and isotopic analysis in the systems of snow-cover,ice and glacial runoff in different types of glacial areas in China,Mt.Yulong and Samdain Kangsang in Nyainqê ntanglha Range(temperate-glacier area),the head area of Ürümqi River in Tianshan Mountains(subpolar-glacier area) and Muztag(polar-glacier area),both in summer and winter,has been carried out between 2000 and 2003.The analyzed isotopic results(δ18O) show that there is an apparent "altitude effect" in new snow fell in winter,reflecting the features of winter monsoon,but a reverse pattern,the "amount effect" in summer snow,indicating a varied altitudinal feature of summer monsoon,which is similar with that in Samdain Kangsang in Nyainqêntanglha Range.Differentially,the δ18O values in summer snowpack in the polar-glacier distributing areas of Tianshan Mountains and Muztag decrease with increasing altitude and decreasing air temperature,indicating an "altitude effect" or a "temperature effect".An marked fractionation process has occurred in residual or melting snowpack both in temperate and polar glacier areas,showing that higher δ18O values have been measured in the samples from the residual snowpack containing with meltwater than those in new snow.During the fluvial process,δ18O values in meltwater increase with decreasing altitude,increasing flowing distance and time.