Presentation Information
[AAS08-P56]Characterization of organic aerosols at urban sites in Japan: Results from offline aerosol mass spectrometry, FTIR spectroscopy, molecular-level analyses, and model simulation
*Michihiro Mochida1,2, Baboer Yisikandeer2, Daichi Asakawa3, Fumikazu Ikemori4,5, Yu Morino6, Michiko Nishizawa1, Shunya Koizumi1, Virginia Tadei7, Bhagawati Kunwar1, Sho Ohata1, Ruichen Zhou1, Qianzhe Sun2, Satoshi Takahama7, Ann M. Dillner8 (1.Institute for Space-Earth Environmental Research, Nagoya University, 2.Graduate School of Environmental Studies, Nagoya University, 3.Osaka City Research Center of Environmental Science, 4.Graduate School of Integrated Science and Technology, Nagasaki University, 5.Nagoya City Institute for Environmental Sciences, 6.National Institute for Environmental Studies, 7.ENAC/IIE, Ecole polytechnique fédérale de Lausanne (EPFL), 8.Air Quality Research Center, University of California, Davis)
Keywords:
atmospheric aerosol,mass spetrometry,infrared spectroscopy
Organics is among the major chemical components of atmospheric aerosols. In addition to carbon and hydrogen, organics contain heteroatoms such as oxygen, which functionalize the molecules and lead to the complexity of organic aerosol composition depending on the sources and formation pathways, and the degree of aging. For this reason, the quantitative understanding of their atmospheric abundance and underlying mechanisms is limited, which hinders the assessment of their roles on air quality and climate. In this study, intensive atmospheric aerosol samplings and a series of chemical analyses were performed with a focus on functionalized organic components in urban aerosols in Japan, and together with atmospheric model simulation, the abundances and chemical structures of organic aerosols, and further their sources and formation pathways were characterized.
Two intensive field campaigns were conducted in Nagoya and Osaka during two periods, February - March 2024 and August - September 2025. PM2.5 samples were collected on quartz fiber filters using high volume air samplers and on PTFE filters using low volume air samplers. Aerosol samples collected in Nagoya in 2024 were subjected to tentative chemical analyses: offline aerosol mass spectrometry for organic extracts, ion analysis using ion chromatography, thermal/optical carbon analysis for the quantification of organic carbon and elemental carbon, analysis of water-soluble organic carbon using a total organic carbon analyzer, GC-MS analysis for organic tracer compounds, and LC-MS analysis for dicarboxylic acids. Online aerosol number size distribution data collected in Nagoya in 2024 were also utilized in this study. Further, for two sites and two campaign periods, the total organic masses and organic functional groups were quantified by the FTIR analysis for the aerosol samples collected on PTFE filters. Outputs from atmospheric simulations based on a three-dimensional chemical transport model, the Community Multiscale Air Quality (CMAQ, v5.3.2) modeling system, were also used for the characterization of Nagoya aerosols during the campaign in 2024.
The offline aerosol mass spectrometry analysis revealed the chemical structural characteristics of the organic aerosols in Nagoya, showing the difference between the periods when the influence of the Asian outflow was estimated to be high or low. Further, the different contributions of aqueous phase reactions to different types of oxygenated organic aerosol components were inferred based on the comparison with organic molecular composition and aerosol number size distributions. The model simulation characterized the contributions of emission sources abroad to the concentrations of black carbon and organic aerosols. Further, the model analysis indicates the importance of biomass combustion to the studied organic aerosols depending on periods in the campaign. The FTIR-derived concentrations of organic aerosols in Nagoya and Osaka for 2024 showed a positive correlation, suggesting that a common factor such as regional transport controls the temporal variation patterns in two different urban areas. The FTIR analysis was also performed for samples collected in 2025, which provides a basis for further comparison of two urban environments. A unique set of data related to functionalized organic aerosol components has been obtained in this study, and more analyses are expected to provide further insights into organic aerosol components in urban aerosols.
Two intensive field campaigns were conducted in Nagoya and Osaka during two periods, February - March 2024 and August - September 2025. PM2.5 samples were collected on quartz fiber filters using high volume air samplers and on PTFE filters using low volume air samplers. Aerosol samples collected in Nagoya in 2024 were subjected to tentative chemical analyses: offline aerosol mass spectrometry for organic extracts, ion analysis using ion chromatography, thermal/optical carbon analysis for the quantification of organic carbon and elemental carbon, analysis of water-soluble organic carbon using a total organic carbon analyzer, GC-MS analysis for organic tracer compounds, and LC-MS analysis for dicarboxylic acids. Online aerosol number size distribution data collected in Nagoya in 2024 were also utilized in this study. Further, for two sites and two campaign periods, the total organic masses and organic functional groups were quantified by the FTIR analysis for the aerosol samples collected on PTFE filters. Outputs from atmospheric simulations based on a three-dimensional chemical transport model, the Community Multiscale Air Quality (CMAQ, v5.3.2) modeling system, were also used for the characterization of Nagoya aerosols during the campaign in 2024.
The offline aerosol mass spectrometry analysis revealed the chemical structural characteristics of the organic aerosols in Nagoya, showing the difference between the periods when the influence of the Asian outflow was estimated to be high or low. Further, the different contributions of aqueous phase reactions to different types of oxygenated organic aerosol components were inferred based on the comparison with organic molecular composition and aerosol number size distributions. The model simulation characterized the contributions of emission sources abroad to the concentrations of black carbon and organic aerosols. Further, the model analysis indicates the importance of biomass combustion to the studied organic aerosols depending on periods in the campaign. The FTIR-derived concentrations of organic aerosols in Nagoya and Osaka for 2024 showed a positive correlation, suggesting that a common factor such as regional transport controls the temporal variation patterns in two different urban areas. The FTIR analysis was also performed for samples collected in 2025, which provides a basis for further comparison of two urban environments. A unique set of data related to functionalized organic aerosol components has been obtained in this study, and more analyses are expected to provide further insights into organic aerosol components in urban aerosols.