Concentration, size-distribution and deposition of mineral aerosol over Chinese desert regions
Concentration, size-distribution and deposition of mineral aerosol over Chinese desert regions
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DOI：
10.3402/tellusb.v50i4.16131
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发表时间：
1998-09
期刊：
影响因子：
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通讯作者：
Xiao Y. Zhang;R. Arimoto;G. Zhu;Tuo Chen;G. Zhang
中科院分区：
文献类型：
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作者：
Xiao Y. Zhang;R. Arimoto;G. Zhu;Tuo Chen;G. Zhang
测定了中国北方9个主要沙漠地区12个站点在沙尘暴（DS）和非沙尘暴（N - DS）期间地面气溶胶样本中9种元素的质量 - 粒径分布（MSDs）。大气中9种元素（铝、铁、钾、镁、锰、钪、硅、锶和钛）的质量主要由当地矿物沙尘决定，平均为270微克/立方米，且这些元素的质量 - 粒径分布近似对数正态分布。根据铝的数据，小于10微米的颗粒约占沙漠沙尘总质量的84%。在非沙尘暴期间，通过模型计算（“100步”法）得出的9种沙尘源元素的干沉降速度（Vd）介于4.4到6.8厘米/秒之间，中位数为5.6厘米/秒。根据D99%（对应累积质量分布最上面1%的沙尘粒径）和Vd之间的统计关系，也可以预测干沉降速度，特别是当D99%在30到70微米之间时。这为重建沙尘沉积（如黄土高原的风成黄土沉积物）的Vd提供了一种简单的方法。沙尘暴期间估计的每日干沉降通量高于非沙尘暴期间，但在大多数情况下，月平均通量主要归因于非沙尘暴沙尘。确定了两个沙尘含量和通量较高的区域：“西部高沙尘沙漠”和“北部高沙尘沙漠”，分别以塔克拉玛干沙漠和巴丹吉林沙漠为中心。这些是沙漠 - 空气活跃交换的活跃区域，显然是亚洲沙尘的主要源区。
DOI: 10.1034/j.1600 - 0889.1998.t01 - 3 - 00001.x
The mass-particle size distributions (MSDs) of 9 elements in ground-based aerosol samples from dust storm (DS) and non-dust storm (N-DS) periods were determined for 12 sites in 9 major desert regions in northern China. The masses of the 9 elements (Al, Fe, K, Mg, Mn, Sc, Si, Sr and Ti) in the atmosphere were dominated by local mineral dust that averaged 270 μg m −3 , and the MSDs for the elements were approximately log-normal. On the basis of Al data, the < 10 μm particles account for ∼84% of the total dust mass over the deserts. Model-calculated (“100-step” method) dry deposition velocities ( V d ) for the 9 dust-derived elements during N-DS periods ranged from 4.4 to 6.8 cm s −1 , with a median value of 5.6 cm s -1 . On the basis of a statistical relationship between D 99% (the dust particle diameter corresponding to the uppermost 1% of the cumulative mass distribution) and V d , one can also predict dry velocities, especially when D 99% ranges from 30 to 70 μm. This provides a simple way to reconstruct V d for dust deposits (like aeolian loess sediments in the Loess Plateau). The estimated daily dry deposition fluxes were higher during DS vs. N-DS periods, but in most cases, the monthly averaged fluxes were mainly attributable to N-DS dust. Two regions with high dust loading and fluxes are identified: the “Western High-Dust Desert” and the “Northern High-Dust Desert”, with Taklimakan Desert and Badain Juran Desert as their respective centers. These are energetic regions in which desert-air is actively exchanged, and these apparently are the major source areas for Asian dust. DOI: 10.1034/j.1600-0889.1998.t01-3-00001.x