Seasonal change in the deposition of particulate matter on foliar surface of forest trees grown in the northern Kyushu region which faces the problem of transboundary air pollution

2018 Fiscal Year Final Research Report

• Project/Area Number: 17K17951
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Environmental impact assessment; Environmental risk control and evaluation
• Research Institution: Nagasaki University
• Principal Investigator: YAMAGUCHI Masahiro 長崎大学, 水産・環境科学総合研究科(環境), 准教授 (60736338)
• Research Collaborator: MURAO Naoto ; OGATA Kasumi ; TSUJI Sayaka ; SAKAI Mai
• Project Period (FY): 2017-04-01 – 2019-03-31
• Keywords: 越境大気汚染 / 粒子状物質 / 乾性沈着 / 森林 / 植物影響 / 濃縮係数 (EF値) / 後方流跡線解析 / PM2.5

Outline of Final Research Achievements

We periodically collected particulate matter (PM) deposited on foliar surface of two Japanese evergreen forest tree species, Chamaecyparis obtusa and Cinnamomum camphora, grown in Nagasaki, Japan from April 2017 to November 2018. In both tree species, the amount of PM on foliar surface was high during spring when there was a high atmospheric concentration of PM with diameter less than 2.5 μm (PM2.5) due to influence of outflow from Asian continent. In spring, concentrations of Pb, As and Zn, which could be originated from anthropogenic source, in the PM on foliar surface were also high. Most of the Pb isotope ratios (207Pb/206Pb and 208Pb/206Pb) in the PM were close to those observed in the Chinese coal and Pb ore. Therefore, Pb on the foliar surface could have originated from the coal combustion in China. As compared with C. camphora, the PM amount on the foliar surface of C. obtusa was high throughout the research period, indicating that C. obtusa could be sensitive to PM.

Free Research Field

植物生理生態学, 大気環境学

Academic Significance and Societal Importance of the Research Achievements

近年、中国大陸からの微小粒子状物質（PM2.5）などによる越境大気汚染が問題視されている。PM2.5の健康影響に関する研究はかなりの進展をみせているが、その植物影響に関する知見は非常に限られている。さらに、野外で生育する植物の葉にどのような成分の粒子状物質（PM）がどの程度沈着しているかといった、PMの植物への沈着実態も殆ど未解明である。そこで本研究では、越境大気汚染が顕著な長崎を調査地として、そこに生育する樹木であるヒノキやクスノキの葉面に沈着したPMの量と金属組成を調査した。その結果、中国大陸から越境輸送された鉛やヒ素を含むPMが長崎に生育する樹木の葉に沈着している実態が明らかになった。