额济纳旗典型地表沙尘释放潜力及沙尘天气频发成因

额济纳旗位于极端干旱的内陆河下游,绿洲退化严重,沙尘天气频发,已成为内蒙古西部主要沙尘源区。为揭示该区域沙尘频繁成因,对区域4种典型地表(富沙砾戈壁、富沙戈壁、绿洲退化地、绿洲)沉积物组分、风蚀强度、沙尘释放强度、多年平均月沙尘日数及大风日数等进行了综合分析。结果表明:以风沙活动为主要特征的绿洲退化地,粉沙黏土组分含量高,PM10沙尘释放强度大(0.2796 kg·d^-1·m^-2),为研究区强沙尘释放地表;富沙及富沙砾戈壁地表,风蚀强度大,但粉沙黏土组分含量低,PM10沙尘释放强度较大(0.1267kg·d^-1·m^-2,0.0672 kg·d^-1·m^-2);尽管绿洲地表粉沙黏土组分含量高,但由于植被、水分等因素的制约,其PM10沙尘释放强度最小(0.0240 kg·d^-1·m^-2)。额济纳旗绿洲被大面积强沙尘释放源(绿洲退化地和戈壁)包围,局地沙尘内循环过程中粉尘颗粒的富积,为当地高频沙尘天气提供了丰富的尘源,这是额济纳旗沙尘天气频发的主要原因。

Potential of Dust Emission and Causes of Frequent Sandstorm Activities in Ejina Banner,Inner Mongolia,China

Ejina Banner, located in the downstream of Heihe River in extreme arid areas with serious oasis degradation and frequent sandstorm, is one of the dust emission areas in the west of Inner Mongolia of China. Data on sediment components from four types of typical surface area (sand gravel gobi, sand-rich gobi, degraded oasis, and oasis), intensity of wind erosion and dust emission, average days of dust and wind was comprehensively analyzed to reveal causes of frequent sandstorm activities in this region. The results showed that degraded oasis is the high dust emission areas with high content of clay components and PM₁₀ dust emission intensity (0.2796 kg·d^-1·m^-2). The gobi with the surface of sand-rich and sand gravel is a weak dust emission area which showed strong wind-induced erosions with low content of silt clay and low PM₁₀ dust emission intensity (0.1267 kg·d^-1·m^-2 and 0.0672 kg·d^-1·m^-2). Although the oasis surface is rich in clay components, the PM₁₀ dust emission is weak (0.0240 kg·d^-1·m^-2) due to the influence of vegetation and soil moisture. Therefore, the strong sandstorm activity in Ejina Banner is due to its geographic location surrounded by large areas of degraded oasis and gobi as well as possible internal dust circulation process locally.