呼伦湖西南部咸水湖干涸湖滨带沉积物粒度特征

沙粒是区域地表沙化的重要物质基础,以呼伦湖西南部典型间歇性干涸盐湖的湖滨带为研究对象,通过野外采样和室内测定,分析沉积物粒度组成及平均粒径、标准偏差、偏度和峰态值等粒度参数,探讨粒度与可蚀性特征。结果表明:区内干涸盐湖湖滨带沉积物属沙壤土,干涸湖滨带是潜在的风蚀粉尘释放源;粉砂和细砂是湖滨带沉积物呈现空间变化的主要粒级,从湖心到湖滨带,沉积物粒径频率分布曲线呈三峰态向双峰态渐变,地表粗化现象明显;风力搬运侵蚀是表层沉积物粒度发生变化的主要原因。受主风向影响,呼伦湖西南部咸水湖干涸湖滨带存在沿主风向扩大趋势,如进一步连通成片可能发展为呼伦贝尔沙地新的风蚀区,应该引起重视。

Grain Size Characteristics of Sediments in the Dry Lakeside of Salt Lake in the Southwest of Hulun Lake

Sand component is an important material basis for regional surface desertification. The typical intermittent salt lake in the southwest of Hulun Lake was selected as the research object. Through field survey and measurement, particle size composition and grain size parameters of stratified samples 0-10cm layers in ten sites from the water margin to the lakeside zone in the southwest of the typical playa were measured. After analyzing the particle size distribution, the paper discussed the characteristics of grain size and erodibility. The results indicated that the sediments were sandy loam and aeolian sandy soil and the lakeside zone was a potential source of wind erosion and dust release. There were spatial heterogeneity of particle size composition in the lakeside. The majority of soil particle size was occupied by silt and fine sand which were the main grain grades of sediments showing spatial changes from the water margin to the lakeside zone. The grain size frequency curve of sediments showed the change from a three-peak to a double-peak dominated by fine sand grains from the water margin to the lakeside zone. The rough phenomenon of the surface particle size has been shown obvious from the edge of the lake to the lakeside in the study area. Wind transport and wind erosion were the main reasons for sediment particle size changing on the surface. Affected by the main wind direction, there exists a trend of expansion along the main wind direction at the playas lakesides in the southwest of Hulun Lake in recent years. The desertification of the playas lakesides intensifies, showing a trend of connected slices, which may become a new wind erosion area in Hulunbeier Sandy Land. Therefore, the phenomenon of wind erosion and desertification and the area expansion in the playa lakesides should be paid attention to.