Temporal Trends of Non-sea Salt Sulfate and Nitrate in Wet Deposition in Japan |
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Authors: | Izumi Noguchi Kentaro Hayashi Masahide Aikawa Tsuyoshi Ohizumi Yukiya Minami Moritsugu Kitamura Akira Takahashi Hiroshi Tanimoto Kazuhide Matsuda Hiroshi Hara |
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Institution: | (1) Hokkaido Inst. of Environ. Sciences, Kita 19 Nishi 12, Kita-ku, Sapporo 060-0819, Japan;(2) National Institute for Agro-Environmental Sciences, 3-1-3 Kannondai, Tsukuba 305-8604, Japan;(3) Hyogo Prefectural Institute of Public Health and Environmental Sciences, 3-1-27 Yukihira Suma-ku, Kobe, Hyogo 654-0037, Japan;(4) Acid Deposition and Oxidant Research Center, 1182 Sowa, Niigata-shi 950-2144, Japan;(5) Ishikawa Prefectural University, 1-308 Suematsu, Nonoichi, Ishikawa 921-8836, Japan;(6) Ishikawa Prefectural Institute of Public Health and Environmental Science, 1-11 Taiyogaoka, Kanazawa, Ishikawa 920-1154, Japan;(7) Central Research Institute of Electric Power Industry, 1646 Abiko, Abiko, Chiba 270-1194, Japan;(8) National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan;(9) Meisei University, 2-1-1 Hodokubo, Hino, Tokyo 191-8506, Japan;(10) Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan |
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Abstract: | Temporal trends of non-sea salt (nss-) sulfate and nitrate were analyzed from nationwide precipitation chemistry measurements
provided by the Ministry of the Environment (MOE) for the 1988–2002 fiscal years (April–March). The concentrations and deposition
of nss-sulfate were found to be decreasing, and those of nitrate were stable or slightly increasing at most sites. These deposition
trends were discussed from the viewpoint of emissions of SO2 and NOX during the period of interest. Because monitoring techniques have changed in the number of active sites, samplers, and analytical
methods during the operation period, the median of all annual depositions measured in Japan in a specific year was selected
as the annual representative. The contribution of specific emission sources was also calculated for 1990 on the basis of the
nss-sulfate and nitrate deposition in Japan obtained with a model simulation in which the model did not include volcanic emissions
from Mt. Oyama, Miyakejima Island, which began to erupt suddenly and violently in 2000. For nss-sulfate, the calculated deposition
agrees well with the intensity and trends of the median up to 1999. After 2000, a higher deposition than calculated in the
preceding years was evident, which is attributable to the volcanic SO2 from Mt. Oyama. For nitrate, both the calculated and observed depositions were slightly increasing; however, the calculation
was found to exceed the observation. |
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Keywords: | Acid deposition Temporal trend Sulfate Nitrate Long-range transport |
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