Abstract
In order to clarify the variation and characterization of dust particles, we started the JapanChina joint project, “Studies on origin and transport of aeolian dust and its impact on climate”. We set up sampling instruments in Beijing, Qingdao and Hefei in China and Naha, Fukuoka, Nagoya and Tsukuba in Japan and collected aeolian dust that originated in the desert area of western China. In this study, we collected the aeolian dust from February 2001 to May 2002 and studied the monthly variation of dust concentrations. The one-year observation data show that the aerosol has a bimodal size distribution (one peak at around 0.5μm corresponds to particles of anthropogenic origin and another peak at around 4-5μm reflects aeolian dust of continental origin) and the coarser particles increased when a dust event occurred. The seasonal variations of dust concentration showed that the aeolian dust content in spring is higher than other seasons. It sometimes became high in winter in Qingdao. The aerosol concentration under usual conditions at each observation station in Japan does not differ so much, however that in China is larger than in Japan. During the intensive observation period (April 2002) when a dust storm event occurred in China, the coarser fraction increased in grain size,and the average dust concentration increased. The aerosol concentration seems to be in the order of Beijing > Qingdao > Hefei and Beijing > Fukuoka > Nagoya > Tsukuba > Naha. The main chemical components of water-soluble fraction are supposed to be (NH4)2SO4 in finer particles and Ca(NO3)2, CaCl2, NaNO3 and NaCl in coarser particles. Aluminum content in waterinsoluble fraction was high in coarser particles, and this confirmed that they consist of a mineral component.
