【摘要】 文章通过内蒙古阿拉善高原古居延泽干涸湖床沉积物、周缘活动沙丘、沙质草原地表土壤及古代弃荒土地的粒度组成分析 ,论述干涸湖床沉积物对沙尘天气的影响。古居延泽湖床沉积粒度分析结果表明 ,干涸湖床的地表湖相沉积物粒径小于 10 μm的颗粒占 6 4 %以上 ,可以在一般风暴条件下在大气中搬运几千公里 ,这意味着西北地区干涸湖床产生的粉尘在风暴作用下可以横扫整个东亚北部地区。中国西北地区冬、春季多西北风造成沙尘暴或扬沙天气 ,西部沙漠、沙地或沙质草场遭遇强风时沙尘被席卷进气流 ,但其中粗砂粒扬起的高度、搬运的距离有限 ,当风力稍稍减弱 ,粗颗粒砂粒沉降 ,而粉尘继续悬浮运移。当强风途径下一个沙区时新的沙尘加入 ,沙尘暴呈“接力方式”继续向东南部移动。更多还原

【Abstract】 Juyan Lake is located at the Alxa Plateau, western Inner Mongolia of China. Samples were collected from lacustrine deposits of ancient Juyan Lakes, active sand dune around, surface soil of grassland and ancient abandoned land. By analyzing their grain-size component, materials with different origins on sand-dust composition are discussed. The grain-size measurement indicates that the particles below 10μm account to more than 64% of the surface lacustrine deposits of dried lake-bed, which could be transported thousands of kilometer away in the air under the condition of normal storm. It means that the dust which came from dried lake in this area and other places in northwestern China could sweep over the north of the East Asia under strong wind storm. Sand-dust storm is a mixture of sand storm and dust storm. Sand and dust were carried into the air from the desert, sandy land and sandy grassland when encountered with strong wind. Strong northwest wind prevails over China during winter and spring, it is easy to induce the sand-dust storm and blowing-sand from northwestern China. For the limited blowing height and transporting distance of coarse sand, it deposits in short distance. Fine dust was still transported further fast. New sand and dust may be added when strong wind swept over another sand area. Accordingly, sand-dust storm move forward to southeast step by step. It is considered that sands from sand storms and dust weathers occurred in deserts in northern China and middle and east Mongolia have little affection on North China and East China, because the raising height and moving distance of coarse grain are limited. The material sources of dust weather affecting East Asia come not only from inner continental deserts in western China, but also, and is more important one, from dried lakes, abounded farmlands and exposed sand and gravel grasslands.更多还原