【摘要】 为准确了解青藏高原多年冻土退化过程及其环境效应,中国科学院寒区旱区环境与工程研究所和德国海德堡大学环境物理研究所共同组成科研小组,先后对我国三江源区、西昆仑甜水海地区进行了多年冻土退化过程的前期勘察研究工作.首次在人烟稀少的玉树-不冻泉沿线等地建立了3个长期综合观测研究站.在技术手段上,除应用常规的坑探、水土取样、水分现场观测、地面调查外,主要应用了最新的双天线、多回路探地雷达勘测技术,对不同地貌条件下的活动层结构特征、上限附近冻土结构、冷生组构等诸多方面进行了快速勘察,同时还进行了水分场分布规律、盐份迁移过程的初步研究.研究结果表明:地表景观特征对热质迁移规律、地温场具有重要影响;青藏高原新疆甜水海地区的低温(<-4℃)冻土与高原东部和腹地的高温(>-1℃)冻土在地质背景和地下冰发育情况等方面有所区别;甜水海地区生态环境在过去30多年的时间里已发生重大改变:地表植被发生大面积退化,地表普遍发生不同程度盐渍化;在该地区发现大量小型冻胀丘、石环等冰缘现象的存在.探地雷达勘察结果显示,地表地貌单元、植被分布、地表水分条件的变化均对多年冻土上限变化和地下冰的赋存产生重要影响.更多还原

【Abstract】 The Sino-German joint expedition from the Cold and Arid Regions Environmental and Engineering Research Institute,Chinese Academy of Sciences and the Institute of Environmental Physics,University of Heidelberg,Germany,conducted investigation and preliminary research on the degradation of permafrost on the Tibetan Plateau and its environmental impacts in the source regions of the Yangtze,Yellow and Lancang-Mekong Rivers in the eastern plateau and in the Tianshuihai area in the West Kunlun Mountains.Three long-term monitoring stations were established along the road from Yushu to Budongquan in Qinghai Province.In addition to conventional exploratory methods,such as hand pits,water and soil sampling,in situ measurements of soil moistures and temperatures,and surface surveys,new multi-channel ground penetrating radar(GPR) was applied for investigating structures of the active layer,permafrost,cryogenic phenomena and vegetation differentiations,ground water tables and soil moistures,and migration of salts.The preliminary research shows that the characteristics of surface landscapes have pronounced influences on the heat and mass transfers in soils.Major differences between cold(<-4 ℃) permafrost in the Tianshuihai area and warm(>-1 ℃) permafrost in the interior and eastern plateau can be seen in their tectonics and ground ice development,as well as ground temperatures.The ecological environments in the Tianshuihai area have changed greatly during the past 30 years: vegetation has degenerated or vanished in a large scale,together with considerable surface soil salinization.In the Tianshuihai area, small pingos,unsorted circles,sand wedges and polygons,and other periglacial phenomena were identified.GPR survey indicates that topography,vegetation,and surface moisture conditions have substantial impacts on the permafrost table and ground ice.更多还原