黄羊滩沙地的形成及其对北京沙尘暴天气的影响

FORMATION OF HUANGYANGTAN SANDY LAND AND IT'S EFFECT ON THE SAND-DUST STORMS OF BEIJING

对黄羊滩沙地进行物质成分分析、粒度分析和扫描电镜观察 ,结果表明 :黄羊滩沙地的物质具有二源性特征 ,分别来源于黄羊滩洪积台地洪积物和洋河冲积物 .根据沙地发育条件和历史过程 ,认为黄羊滩沙地不会有大的扩展 .以粒度数据为基础 ,估算出黄羊滩沙地沙丘 φ值大于 4的沙尘年平均输出量为 7.98× 10 2 t·a- 1,φ值大于 7的沙尘年平均输出量为 3.2 3× 10 2 t·a- 1,占年沙尘输出量的 4 0 .5 % .北京沙尘暴沙尘组分以 φ值大于 6 .8的为主 。

Ingredient analysis, grain size analysis and scanning electron microscope observation show that the sands of Huangyangtan sandy land come from the diluvium on Huangyangtan platform and the alluvium of Yanghe river. Based on the surrounding landforms and the evolution history of the sandy land, it is inferred that the sandy land will not expand recently. According to the grain size data, the dust output of the active dunes at Huangyangtan is mainly those grains less than 0.063 mm( φ >4) and it is estimated at 7.98×10 2 t·a -1 . The output of the grains less than 0.008 mm ( φ >7) is estimated at 3.23×10 2 t·a -1 , which occupies a percentage of 40.5% of the total output per year. Because the dust of the sand dust storms of Beijing mainly consists of the particles less than 0.009 mm ( φ > 6.8 ), it is clear that the dust output of Huangyangtan sandy land has some influence on the sand dust storms of Beijing.