青藏高原中部各拉丹冬峰雪冰记录特征

2005年10~11月在青藏高原唐古拉山脉各拉丹冬峰冰川区不同海拔采集了3个雪坑样品,分析结果表明,雪坑中δ¹⁸O和主要离子浓度具有明显的季节变化特征.夏季风期间降水中δ¹⁸O低于其它季节,表明该地区夏季δ¹⁸O的"降水量效应"仍然存在.雪坑中主要离子在非季风期的浓度高于夏季风期.主要离子的相关分析表明,除NH₄⁺、NO₃^-外,雪坑中其它离子浓度之间均存在较好的正相关性.各拉丹冬峰冰川区仍受到南亚季风的影响,但因其位于夏季风影响的边缘区域,其影响程度相对于高原南部较弱;同时也受到大陆性气候的影响,在冬春季节具有较高的粉尘气溶胶沉降.

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^-,SO₄^2-,Na⁺,K⁺,Ca²⁺,Mg²⁺,NH₄⁺),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 NH₄⁺ and NO₃^- concentrations are not very evident.The major ions,except NH₄⁺ and NO₃^-,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.