Abstract
Aerosol particles were collected at Tsukuba in Japan from February 2001 to June 2002 and their water-insoluble components were analyzed. Mass concentrations of aerosol particles had three peaks at >11.0 µm, 2.1-7.0 µm and 0.43-0.65 µm in diameter. The concentrations of aerosol samples with 2.1-7.0 µm particle size especially increased when a large-scale dust event was observed. Distribution patterns of most elemental concentrations such as Al2O3 were well consistent with size-segregated measurements of aerosol concentration in air. These patterns suggest that coarse particles consist mainly of mineral aerosols. However, some elements such as Cu and Pb were highly enriched in small particles (under 1 µm). These elements are considered to originate in anthropogenic materials. Focusing on the seasonal variation of mass concentrations of aerosol particles, in summer, fall and winter, the mass concentration of fine grains comprised of carbon aerosol was higher than those of coarse grains consisting of mineral aerosol. But their relationship adversely changed in spring. Especially, large-scale dust event supplied coarse grains with mineral aerosol about 10 times than usual case and most elemental concentrations such as Al2O3 in the air became extremely high. Seasonal variation of mass concentrations in fine grains did not correspond to the dust event but had the similar trend to that of Al2O3. Nevertheless the Cu and Pb contents in fine grains extremely increased in spring and had different seasonal trends from the Al2O3 content in fine grains. These results suggest that local surface materials consisting of mineral aerosol and considerable anthropogenic materials were supplied as a fine aerosol at Tsukuba.
