2004 Fiscal Year Final Research Report Summary
Long-range taransport of air pollution studied by Bark Pocket Method
| Project/Area Number |
14403015
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 海外学術 |
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| Research Field |
Environmental dynamic analysis
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| Research Institution | Rissho University (2004)
National Institute for Environmental Studies (2002-2003) |
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Principal Investigator |
SATAKE Kenichi Rissho University, Faculty of Geo-Enviromental Science, Professor, 地球環境科学部環境システム学科, 教授 (50101051)
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| Co-Investigator(Kenkyū-buntansha) |
TAKAMATSU Takejiro National Institute for Environmental Studies, Water and Soil Environmental Division, Head, 水土壌圏環境研究領域, 室長 (60109915)
TSUNODA Kinichi Gunma University, Faculty of engineering, Professor, 工学部, 教授 (30175468)
UMEMURA Tomoya Gunma University, Faculty of engineering, Assistant, 工学部, 助手 (10312901)
MASUNAGA Shigeki Yokohama National University, Faculty of Environment and Information Sciences, Professor, 大学院・環境情報学府, 教授 (50282950)
HOKURA Akiko Tokyo University of Science, Faculty of Science, Assistant, 理学部, 助手 (20343569)
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| Project Period (FY) |
2002 – 2004
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| Keywords | long-range transport / air pollution / continental Asia / deposition / lead isotope / ^<208>Pb / ^<206>Pb / ^<207>Pb / ^<206>Pb / bark pockets |
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| Research Abstract |
Long-range transport of air pollution from the continental Asia is currently an important issue concerning the Japanese environment, especially in regions susceptible to acidification due to low buffering capacity, such as Murakami, Niigata prefecture located in on the west coast of central Japan. Evidence for long range transport was obtained through lead and lead isotopic analysis of 84 archived precipitation filters, showing seasonal changes in lead deposition from May 1999 to May 2002. Lead deposition was highest in winter and spring (November through May) each year and lowest in summer. Computed 72-hour back trajectories showed that in winter air masses were predominantly transported from the northwest, passing over northern China and eastern Russia, whilst in summer air masses predominantly originated from the southeast passing over Japan. Lead isotopie analysis showed higher ^<208>Pb/^<206>Pb during winter, indicating that lead originated from a different source. A plot of ^<207>Pb/^<206>Pb vs.^<208>Pb/^<206>Pb identified a thorogenic component, which is excess ^<208>Pb compared to a standard lead growth carve, indicative of certain lead ores and coals in continental Asia. The data provided evidence of long-range transport of lead from continental Asia to Japan. Bark pockets included within the trunks of two Japanese cedar trees harvested near Murakami, dating between 1972 and 1982,exhibited lead isotope ratios indicative of Japanese sourced lead. In contrast, current (2003) bark showed thorogenic ratios, consistent with a relative decline in Japanese sourced and increase in continental soureed lead. The result is consistent with the scenario of decreasing Japanese sourced lead emission and increasing long range transport of pollution from continental Asia, signifying the threat of transboundary air pollution to the region. Thorogenic lead isotope rations were also measured in tree bark collected at high altitude in the area.
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