Beryllium-7 Deposition and Its Relation to Sulfate Deposition |
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| Authors: | Yasuhito Igarashi Katsumi Hirose Makiko Otsuji-Hatori |
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| Institution: | (1) Geochemical Research Department, Meteorological Research Institute, 1-1 Nagamine, Tsukuba, Ibaraki, 305, Japan |
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| Abstract: | Deposition of 7Be, a cosmogenic radionuclide, was observed at the Meteorological Research Institute in Tsukuba, Japan from 1986 to 1993 and compared with those of several chemical species observed in Tsukuba over the same period. We found a correlation between the monthly depositions of 7 Be and SO 4 2 -, a major acidic species. The correlation was especially strong for late spring and fall, when both species had high depositional fluxes. This correlation was also observed in precipitation samples collected daily in 1992 at the same site. The cause of this correlation is discussed in connection with the fact that the stratospheric aerosol is composed largely of SO 4 2 -. 7 Be is produced in the upper atmosphere, and detection of 7Be, especially in spring and fall in Japan, can be regarded as detection of stratospheric aerosol. However, we conclude that the bulk of the SO 4 2 - observed did not have a stratospheric or an upper tropospheric origin. The correlation, therefore, may present a new question regarding acidic deposition: Why does the deposition of stratospheric aerosol in Japan coincide with that of nss-SO 4 2 - originally from anthropogenic sources on the Earth's surface? |
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| Keywords: | 7Be deposition SO
4
2
- deposition correlation stratospheric aerosol |
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