HR: 0800h
AN: A31C-0080    [Abstracts]
TI: Chemical characteristics of aerosols involved in Asian dust of March 2002 collected at Rokkasho Village, Aomori, in northern part of Japan
AU: * Akata, N
EM: nao@ies.or.jp
AF: Department of Radioecology, Institute for Environmental Sciences, 1-7 Ienomae, Obuchi, Rokkasho, Aomori, 039-3212 Japan
AU: Hasegawa, H
EM: hhidenao@ies.or.jp
AF: Department of Radioecology, Institute for Environmental Sciences, 1-7 Ienomae, Obuchi, Rokkasho, Aomori, 039-3212 Japan
AU: Kawabata, H
EM: hkawa@ies.or.jp
AF: Department of Radioecology, Institute for Environmental Sciences, 1-7 Ienomae, Obuchi, Rokkasho, Aomori, 039-3212 Japan
AU: Chikuchi, Y
EM: chiku@ies.or.jp
AF: Department of Radioecology, Institute for Environmental Sciences, 1-7 Ienomae, Obuchi, Rokkasho, Aomori, 039-3212 Japan
AU: Takaku, Y
EM: ytakaku@ies.or.jp
AF: Department of Radioecology, Institute for Environmental Sciences, 1-7 Ienomae, Obuchi, Rokkasho, Aomori, 039-3212 Japan
AU: Sato, T
AF: Tohoku Nuclear Ltd., 41-14 Higashiokamisawa, Aomori, 033-0024 Japan
AU: Kondo, K
EM: k-kondo@ies.or.jp
AF: Department of Radioecology, Institute for Environmental Sciences, 1-7 Ienomae, Obuchi, Rokkasho, Aomori, 039-3212 Japan
AU: Inaba, J
EM: inaba@ies.or.jp
AF: Department of Radioecology, Institute for Environmental Sciences, 1-7 Ienomae, Obuchi, Rokkasho, Aomori, 039-3212 Japan
AB: The Asian dust (Kosa), generated when the surface soil in the arid and semi-arid region of the Asian continental landmass is lifted by winds, is the major mineral aerosol transported from East Asia to the Pacific region. The Kosa particles are thought to be an important factor in the earth_fs climate via radiative forcing. The frequency of dust events giving rise to Kosa aerosols has increased rapidly in the East Asian region since 2000. Therefore, it is important to clarify the physico-chemical properties of the Kosa aerosols. The large-scale Kosa event was observed in northern Japan in March 2002. In this study, the chemical characteristics of aerosols in the Asian dust event of March 2002 were investigated. We collected aerosols using middle volume air sampler (flow rate: 100 L/min) of the Andersen type (size-fractionated aerosols) and high volume air sampler (bulk aerosols). The soluble and insoluble major chemical components in size-fractionated aerosols and total concentration of REE, 232Th, 238U and 137Cs in bulk aerosols were quantitatively measured. In this Kosa event, the aerosol size distribution pattern was a peak mainly derived from soil particles sized 1.1-3.3 micron and over11 micron. During this Kosa event, the atmospheric concentrations of nssCa2+ (nssX : non-sea salt component) and insoluble Al of size-fractionated aerosols increased 7 - 9 times and 50 - 100 times in comparison with the non-Kosa period in the particle size range of 1.1 - 3.3 micron, respectively. The concentration of 137Cs in bulk aerosols also increased. The aerosol size distribution patterns of some components during the Kosa and non-Kosa periods were different. The Kosa particles take in polluted materials along their transportation route. In this Kosa period, the atmospheric concentration of nssSO42- increased in comparison with the non-Kosa period, but the NO3- concentration decreased. In general, NO3- does not exist in arid and semi-arid regions. This means that the amounts of anthropogenic SO42- and NO3- adsorbed on the Kosa aerosol surfaces were small during their transportation process in this Kosa event. The REE patterns (chondrite normalized) of Kosa aerosols (bulk) were characterized by being enriched in light REE, and depleted in hige REE. The negative values of the Eu anomaly are 0.80 - 0.85. The REE patterns of Kosa aerosols are similar to the non-Kosa period aerosols. However, there was a difference in the 238U/232Th ratios.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0305 Aerosols and particles (0345, 4801)
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting