Snow-Ice Records on Mt. Geladaindong in the Central Tibetan Plateau

In October and November,2005,three snowpits were dug at the elevation of 5 591 m,5 750 m and 5 823 m on Mt.Geladaindong in the central Tibetan Plateau.Glaciochemical records recovered from the three snowpits show distinct seasonality of snow chemistry.In general,δ18O is lower in summer while higher in winter,due to "amount effect" like that in the Mt.Qomolangma and Xixabangma in the southern Tibetan Plateau.Of the major ions(Cl-,NO3,SO2-4,Na+,K+,Ca2+,Mg2+,NH+4),the concentrations in winter are higher than those in summer,especially Ca2+,which has the most pronounced seasonal differences: Ca2+ concentration in non-monsoon snow is about 10 times higher than in monsoon snow.However,seasonal variations of NH+4 and NO-3 concentrations are not very evident.The major ions,except NH+4 and NO-3,display strong positive correlations among each other.Summer δ18O values indicate that Mt.Geladaindong is influenced by summer Indian monsoon.However,the influence is much milder than that in the Himalayas,due to the region located on the edge of monsoon effect.On the other hand,Geladaindong is also controlled by arid climate,representing crustal species transported by atmospheric circulation from local/regional sources in the north/west of Tibetan Plateau.