青藏高原多年冻土区热融湖塘沉积物粒度分布特征研究  

Study on the distribution characteristics of sediments grain size of thermokarst lakes in permafrost regions on the Qinghai-Tibet Plateau

作　　者：岳永彧 王俊峰[1] 俞祁浩[1] 游艳辉[1] 

机构地区：[1]中国科学院寒区旱区环境与工程研究所,冻土工程国家重点实验室,兰州730000 [2]中国科学院大学,北京100049

出　　处：《生态科学》2016年第2期1-7,共7页Ecological Science

基　　金：国家自然科学基金项目(41171059);国家自然科学基金青年基金项目(41401088)

摘　　要：在青藏高原五道梁多年冻土区,利用土钻对3个典型热融湖塘不同区域表层沉积物进行取样,并做了粒度分析、粒度参数计算和回归分析,结合有关资料探讨了热融湖塘沉积物的粒度分布特征及其形成原因。结果表明:在沉积物分布类型上,以湖心为圆心、半径15 m的湖心区,表层沉积物平均粒度为4.46—5.37Φ,标准偏差为2.48—2.75,粒度较细,属于粉砂质砂;半径15—30 m的湖滨区,表层沉积物的平均粒度为2.69—3.34Φ,标准偏差为1.67—2.22,粒度较粗,属于砂质;半径30 m至天然地表的过渡区,表层沉积物平均粒度为3.22—3.44Φ,标准偏差为1.93—2.18,粒度较粗,属于砂质。不同区域沉积物粒度差异显著,热融湖塘沉积物的粉砂和黏土含量分布为湖心区>湖滨区>过渡区,而砂含量的分布特征则相反,为过渡区>湖滨区>湖心区。热融湖塘沉积物这种粒度分布特征与冻融循环、水力搬运、风力侵蚀以及地形等因素密切相关,是导致热融湖塘不同区域地表沉积物粒度特征产生显著差异的主要原因,也是造成湖塘周边土壤发生粗砾化的根本动力。In the Wudaoliang permafrost region on the Qinghai-Tibet Plateau, surface sediments were sampled using soil auger from different areas of the three typical thermokarst lakes. The grain sizes were analyzed and the corresponding grain size parameters were calculated and regression analysis was also proceeded. Based on the relevant documents, the characteristics of grain size distribution of thermokarst lakes and their forming reasons were discussed. The results showed that for the sediment types, at the lake center zone, the average grain sizes of surficial sediments varied from 4.46 to 5.37 Φ with standard deviations from 2.48 to 2.75. The grain sizes were fine and classified as silty sand. At the lakeshore zone, the average grain sizes of surficial sediments varied from 2.69 to 3.34 Φ with standard deviations from 1.67 to 2.22. The grain sizes were coarse and classified as sand. At the transitional zone, the average grain sizes of surficial sediments varied from 3.22 to 3.44 Φ with standard deviations from 1.93 to 2.18. The grain sizes also were coarse and classified as sand. The sediment grain sizes were significantly different between different areas of the same thermokarst lake. The distributions of silt and clay content were as follows： lake center zonelakeshore zonetransitional zone, but the distributions of sand content showed a reverse order. These distribution characteristics of sediments in the thermokarst lakes were closely related with the factors such as freezing and thawing actions, hydraulic transportation, wind erosion, topography and so on, which were the main drivers to cause significant differences between the grain sizes at different zones of the thermokarst lake, and also were the main force to lead the soil beside the thermokarst lake coarsening.

关 键 词：热融湖塘 表层沉积物 粒度特征 青藏高原 

分 类 号：P512.2[天文地球—地质学]