Aeolian dust transportation and deposition by near-surface winds in arid and semiarid China  

作　　者：JinChang Li ZhiBao Dong GuangQiang Qian WanYin Luo 

机构地区：[1]Institute of Loess Plateau,Shanxi University,Taiyuan,Shanxi 030006,China [2]Cold and Arid Regions Environmental and Engineering Research Institute,Chinese Academy of Science,Lanzhou,Gansu 730000,China

出　　处：《Research in Cold and Arid Regions》2010年第2期137-142,共6页寒旱区科学（英文版）

基　　金：funding from the Natural Science Foundation of China through Grant No. 40638038

摘　　要：Dustfall collections were carried out in April and May 2001 and in March 2002 at six sites in northern China.Our results showed that the total deposition of dust fractions 【250 μm in diameter and the deposition of Fe both decreased exponentially with increasing distances from the source areas,and that the half-attenuation distance (HAD) for dust deposition was about 229 km in this re-gion.The HAD was closely related to the grain-size distribution of the dust,and the 15 to 20 μm fractions had the longest HAD.However,the fractions 【15 μm in diameter can be easily adsorbed to coarse particles and deposited after only short distances,and the HAD for the fractions 15 to 100 μm in diameter showed a power relationship with the grain-size distribution.The HAD for Fe deposition was 233 km,which was a little longer than that of total dust deposition,which suggests that the Fe content is higher in fine particles than in coarse particles,as previous studies have suggested.In addition,our analysis showed that under the control of current climatic conditions,the coarse fractions in dust derived from northwestern China cannot be transported over long distances,instead,it is transported primarily by near-surface winds (【3 km above the ground).The Fe in aeolian dust generated from arid and semiarid regions of China and deposited in the North Pacific region is usually transported by the upper westerlies.Dustfall collections were carried out in April and May 2001 and in March 2002 at six sites in northern China.Our results showed that the total deposition of dust fractions <250 μm in diameter and the deposition of Fe both decreased exponentially with increasing distances from the source areas,and that the half-attenuation distance (HAD) for dust deposition was about 229 km in this re-gion.The HAD was closely related to the grain-size distribution of the dust,and the 15 to 20 μm fractions had the longest HAD.However,the fractions <15 μm in diameter can be easily adsorbed to coarse particles and deposited after only short distances,and the HAD for the fractions 15 to 100 μm in diameter showed a power relationship with the grain-size distribution.The HAD for Fe deposition was 233 km,which was a little longer than that of total dust deposition,which suggests that the Fe content is higher in fine particles than in coarse particles,as previous studies have suggested.In addition,our analysis showed that under the control of current climatic conditions,the coarse fractions in dust derived from northwestern China cannot be transported over long distances,instead,it is transported primarily by near-surface winds (<3 km above the ground).The Fe in aeolian dust generated from arid and semiarid regions of China and deposited in the North Pacific region is usually transported by the upper westerlies.

关 键 词：dust deposition half-attenuation distance near-surface wind arid and semiarid regions of China 

分 类 号：P[天文地球]