2006 Fiscal Year Final Research Report Summary
A study on formation process of anthropogenic organic aerosol using a highly advanced mass spectrometer
| Project/Area Number |
17310006
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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 | 一般 |
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| Research Field |
Environmental dynamic analysis
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| Research Institution | The University of Tokyo |
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Principal Investigator |
TAKEGAWA Nobuyuki The University of Tokyo, Research Center for Advanced Science and Technology, Associate Professor, 先端科学技術研究センター, 助教授 (00324369)
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| Co-Investigator(Kenkyū-buntansha) |
KONDO Yutaka The University of Tokyo, Research Center for Advanced Science and Technology, Professor, 先端科学技術研究センター, 教授 (20110752)
KOMAZAKI Yuichi Japan Agency for Marine-Earth Science and Technology, Frontier Research Center for Global Change, Sub leader, 地球環境フロンティア研究センター, サブリーダー (80286640)
KOIKE Makoto The University of Tokyo, Graduate School of Science, Associate Professor, 大学院理学系研究科, 助教授 (00225343)
MIYAZAKI Yuzo The University of Tokyo, Research Center for Advanced Science and Technology, Research Associate, 先端科学技術研究センター, 助手 (60376655)
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| Project Period (FY) |
2005 – 2006
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| Keywords | Environmental science / Urban air / Organic aerosol / Mass spectrometer / Dicarboxylic acids / Secondary formation |
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| Research Abstract |
1. Improvement of the accuracy of the Aerosol Mass Spectrometer (AMS)
The particle collection efficiency (CE) of the AMS depends on relative humidity (RH) in sample air. The temperature of the AMS inlet manifold was maintained at > 10℃ above the ambient dew point to dry particles in the sample air (RH in the inlet < 53%). Assuming CE = 0.5 for the AMS, the mass concentrations of inorganic species (nitrate, sulfate, chloride, and ammonium) measured by the AMS agree with those measured by an Ion Chromatography analyzer (PILS-IC) to within 〜20%.
2. Analysis of the mass spectra of selected organic compounds
We have evaluated the contribution of selected low molecular weight dicarboxylic acids (diacids) to the m/z 44 signal of the AMS mass spectrum. We used ambient measurement data obtained in Tokyo and laboratory experiment data obtained using authentic standards of the selected organic acids. We have reported for the first time that the selected organic acids could account for 14% of the observed m/z 44 signal on average during the measurement period.
3. Investigation of the seasonal and diurnal variations of anthropogenic organic aerosol in Tokyo
In situ measurements of trace gases and aerosols were conducted at an urban site in Tokyo. Organic aerosol (OA) is classified into primary organic aerosol (POA) and secondary organic aerosol (SOA) using correlation with carbon monoxide (CO). We have found that POA does not exhibit a distinct diurnal variation for the summer, fall, and winter periods, while SOA shows a clear diurnal pattern. We have also found that the OA concentrations can be significantly enhanced within 〜0.5 days under conditions of high photochemical activity.
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