Dust-storm Events in Daihai Lake Area, Inner Mongolia During the Past 400 Years Evidence from Grain-size Analysis of Lake Sediments

根据高分辨率的岱海沉积物粒度分布的中值粒径和粗颗粒含量,结合区域降水、历史记载资料,重建了内蒙古岱海地区近 400年来发生的尘暴事件.结果表明,尘暴事件是受冬、夏季风的相对强弱制约的.大量尘暴事件频发于小冰期干冷的气候条件下,表现为中值粒径大,粗颗粒含量高.在转暖的现代气候下,尘暴事件很少,中值粒径也随之降低.但是近十几年尘暴事件又呈上升趋势,部分可能与人类活动造成的土地荒漠化有关.;A 400-year dust-storm history in Daihai Lake area, Inner Mongolia, Northern China, was reconstructed on the basis of high-resolution grain-size analysis of the lake sediments, in combination with reconstructed historical data of regional precipitation from tree ring, frequency of dust storms in China and historical documentary records.The Daihai Lake is located at a climatically transitional zone between semi-arid and semi-humid where front position and intensity of the East Asian summer monsoon and winter monsoon chiefly control the climate change.Both the median grain size and coarse grain content indicate that dust-storm events were controlled mainly by the intensity of the summer and winter monsoon in the past 400 years.Major dust-all events are generally associated with dry and cold climate during the Little Ice Age, when the median grain size of the lake sediments is larger with high contents of coarse grain (> 100μ m)-At time of warm conditions after the Little Ice Age, dust-storm events were limited, both the contents of coarse grain (> 100μ m) and the median grain size also decreased-During the last one to two decades, however, dust-storm events increased gradually, related partly with more desertificated soil by human activity.