2021 Fiscal Year Final Research Report
Measurements and microscopic observation for surface wetting properties of water-insoluble soot particles in urban atmosphere
Project/Area Number |
19K20438
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Research Category |
Grant-in-Aid for Early-Career Scientists
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Allocation Type | Multi-year Fund |
Review Section |
Basic Section 63010:Environmental dynamic analysis-related
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Research Institution | Nagoya University |
Principal Investigator |
Ueda Sayako 名古屋大学, 環境学研究科, 研究員 (00612706)
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Project Period (FY) |
2019-04-01 – 2022-03-31
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Keywords | 大気エアロゾル / 黒色炭素 / 都市大気 / 化石燃料 / 電子顕微鏡 |
Outline of Final Research Achievements |
Soot particles strongly absorb solar radiation and contribute to global warming. Wetting properties of soot at emission can affect its lifetime. We investigated surface conditions related to wetting properties of fresh soot by measurements in Tokyo. A cloud condensation nuclei counter was used to clarify surface conditions of particles composed mainly of water-insoluble (WI) materials. Change of number fractions of inactive particles according to setting supersaturation around critical supersaturation of WI particles at rush hour implied that most of the WI particles included small amounts of water-soluble materials although completely hydrophobic soot also existed minor. Based on transmission electron microscope (TEM) analysis of samples collected during rush hour, most of fresh soot particles had Na or K small domains that are regarded as originating in fossil fuels. Results of TEM observation using water dialysis technique indicated water solubility of some Na and K on soot.
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Free Research Field |
大気エアロゾル
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Academic Significance and Societal Importance of the Research Achievements |
近年のグローバルモデルでは、遠隔地のスス濃度や上空のスス濃度は実測値と大きな差があるのが現状である。本研究では、スス粒子の濡れ性に燃料に含まれる物質を起因とした付着物の有無により排出時からばらつきが生じ得ること、さらに、このような付着物がスス表面上での二次生成物質の成長をサポートしている可能性を示唆した。本研究での結果は、ススは排出時から、大気中で変質し易く大気から除かれやすい表面性質、および変質し難く長寿命になり易いものが存在することを示した。本研究で得られた知見は、ススの吸湿性獲得と除去に関する理解を深めるものであり、気候モデルを高度化する上で役立つことが期待される。
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