Possible change in Asian dust source suggested by atmospheric anthropogenic radionuclides during the 2000s |
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| Authors: | Yasuhito Igarashi Yayoi Inomata Michio Aoyama Katsumi Hirose Hiroshi Takahashi Yoshihiro Shinoda Nobuo Sugimoto Atsushi Shimizu Masaru Chiba |
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| Affiliation: | 1. Meteorological Research Institute, Japan;2. National Institute of Environmental Studies, Japan;1. Department of Engineering Physics, Tsinghua University, Beijing 100084, China;2. CTBT Beijing National Data Centre and Radionuclide Laboratory, Beijing 100085, China;3. Beijing Municipal Center for Disease Prevention and Control, Beijing 100013, China;1. Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan;2. The Hakubi Center for Advanced Research, Kyoto University, Yoshida-Ushinomiya-cho, Sakyo-ku, Kyoto 606-8302, Japan;3. Department of Earth and Space Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan;4. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210, Japan;5. ISS Project Science Office, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 2-1 Sengen, Tsukuba, Ibaraki 305-8505, Japan;6. Department of Applied Physics, University of Miyazaki, 1-1 Gakuen Kibana-dai Nishi, Miyazaki 889-2192, Japan;7. Physics Department, Kogakuin University, 2665-1, Nakano-cho, Hachioji, Tokyo 192-0015, Japan;8. The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan;9. Department of Information Science, Faculty of Liberal Arts, Tohoku Gakuin University, 2-1-1 Tenjinzawa, Izumi-ku, Sendai, Miyagi 981-3193, Japan;1. Department of Material and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioi-cho, Ciyoda-Ku, Tokyo 102-8554, Japan;2. Atmospheric Environment and Applied Meteorology Research Department, Meteorological Research Institute, Tsukuba, Ibaraki 305-0052 Japan;3. Soil Environment Division, National Institute for Agro-Environmental Sciences, Tsukuba, Ibaraki 305-8601, Japan;4. Institute of Meteorology and Hydrology, Ulaanbaatar 46, Mongolia;5. Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, Ookayama 2-12-1, Meguro-Ku, Tokyo 152-8550, Japan;1. Department of Earth and Environmental Sciences, Andong National University, Songchondong, Andong 760-749, Republic of Korea;2. Division of Earth and Environmental Science, Korea Basic Science Institute, Chungbuk 363-883, Republic of Korea;3. Department of Isotope Geochemistry, University of Science and Technology, Daejeon 305-350, Republic of Korea;4. Department of Geological Sciences, Pusan National University, Busan 609-735, Republic of Korea;5. Department of History, Kyunghee University, Seoul 130-701, Republic of Korea;6. Department of Archaeology and Art History, Seoul National University, Seoul 151-742, Republic of Korea |
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| Abstract: | Decades-long monitoring of anthropogenic radionuclides in the atmospheric deposition in Tsukuba, Japan suggests not only the substantial impacts of the Asian dust (Kosa) on the deposition but also the possible change of the Kosa source region, especially during springs of the 2000s. In order to know more about such change, 4 single wet deposition events occurred in the spring of 2007 were scrutinized. The largest anthropogenic radionuclides wet deposition was supplied by the April 2–4 event. It brought several tens % of the monthly depositions (April 2007) of the dust (residue) mass (4.5 g m?2) and anthropogenic radionulides (90Sr: 16, 137Cs: 97 and Pu: 3 mBq m?2). None of the events observed fulfilled both criteria of the specific activities and 90Sr/137Cs activity ratio to the Tsukuba soil; they did not exhibit local soil dust signature. The Kosa events in fact have extensive impacts on the atmospheric environment over Japan in spring season. Considering the elevated specific activities as well as greater 137Cs/90Sr activity ratio in the deposited dust, it is hypothesized that the dust source areas in Asian continent would be shifting from the arid zone to the desert-steppe zone suffering from desertification during the 2000s. This type of the Kosa may be called as the ‘new-regime Kosa’. Chemical observation in the far downwind region of the Kosa dust could allow us to know possible shift in the source regions. |
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