Multi elemental compound specific isotope analysis of water-soluble organic carbon for source apportionment

• Project/Area Number: 19K20463
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 63040:Environmental impact assessment-related
• Research Institution: Japan Automobile Research Institute
• Principal Investigator: Suto Nana 一般財団法人日本自動車研究所, 環境研究部, 研究員 (70791424)
• Project Period (FY): 2019-04-01 – 2024-03-31
• Project Status: Completed (Fiscal Year 2023)
• Budget Amount: ¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000); Fiscal Year 2021: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000); Fiscal Year 2020: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000); Fiscal Year 2019: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
• Keywords: 粒子状物質 / 水溶性有機炭素 / 安定同位体比 / 発生源推定 / 有機エアロゾル / 安定同位体 / 植物燃焼 / 微小粒子状物質

Outline of Research at the Start

微小粒子状物質（PM2.5）は人体への健康影響が懸念されており，これまで様々な環境対策が進められてきた．しかし，PM2.5の約3割を占める炭素成分の中でも水溶性有機炭素は，発生源が多く生成プロセスが複雑であるため未だに実態が解明されていない．そこで本研究では，水溶性有機炭素の成分ごとの安定同位体比を分析することで発生源を解明することを目的とする．成分ごとの分析に加えて，多元素の安定同位体比を使うことで，より一層明確な発生源の識別が可能になると考えられる．

Outline of Final Research Achievements

The sources and seasonal trends of water-soluble organic carbon (WSOC) in carbonaceous aerosols are of significant interest. From July 2017 to July 2019, we collected samples of PM2.5 from one suburban and one rural site in Japan. At the rural site, the average carbon isotope ratio of WSOC (δ13CWSOC) was significantly heavier from autumn to spring than in summer. The heaviest δ13CWSOC was observed from February to April 2019, which may be explained by long-range transport of C4 plant burning such as corn from overseas. Thus, the present study indicates that δ13CWSOC is potentially useful for elucidating the sources and atmospheric processes that contribute to seasonal variations of WSOC concentration.

Academic Significance and Societal Importance of the Research Achievements

本研究では，PM2.5中の水溶性有機炭素の炭素安定同位体比を測定することで，国内および国外からの影響について発生源の特定につながる知見が得られたことは，学術的に大きな意義があると考えている．また，安定同位体を用いて詳細な発生源を特定することは，環境対策の視点からも社会的に意義のある結果だと思われる．

Research Products

• [Journal Article] Long-Term Source Apportionment of Ammonium in PM_2.5 at a Suburban and a Rural Site Using Stable Nitrogen Isotopes (2023)
  • Author(s): Kawashima Hiroto、Yoshida Otoha、Suto Nana
  • Journal Title: Environmental Science & Technology Volume: 57 Issue: 3 Pages: 1268-1277
  • DOI: 10.1021/acs.est.2c06311
  • Peer Reviewed
• [Journal Article] Measurement report: Source characteristics of water-soluble organic carbon in PM2.5 at two sites in Japan, as assessed by long-term observation and stable carbon isotope ratio (2021)
  • Author(s): Nana Suto, Hiroto Kawashima
  • Journal Title: Atmospheric Chemistry and Physics Volume: 21 Issue: 15 Pages: 11815-11828
  • DOI: 10.5194/acp-21-11815-2021
  • Peer Reviewed
• [Journal Article] Ion‐exchange resin and denitrification pretreatment for determining δ15N‐NH4+, δ15N‐NO3-, and δ18O‐NO3- values (2021)
  • Author(s): Kawashima Hiroto, Yoshida Otoha, Suto Nana
  • Journal Title: Rapid Communications in Mass Spectrometry Volume: 35 Issue: 6
  • DOI: 10.1002/rcm.9027
  • Peer Reviewed
• [Presentation] Stable carbon isotope ratio measurement of water-soluble organic aerosol using online wet oxidation/isotope ratio mass spectrometry (2019)
  • Author(s): Nana Suto, Hiroto Kawashima
  • Organizer: 7th Conference of the Forensic Isotope Ratio Mass Spectrometry Network
  • Int'l Joint Research