Abstract
Comment
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Oral or Poster
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IAPSO
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JMCP19 - Biogeochemical interactions across the atmosphere-ice-ocean interface
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Chemical Structures of Organic Aerosols in the Western North Pacific: Results from FTIR analysis
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1. Nkembeng Kenneth, Fuanke*, Graduate School of Environmental Studies,Nagoya University,Japan
2. Sho Ohata, Institute for Space-Earth Environmental Research,Nagoya University,Japan
3. Satoshi Takahama, Laboratory of Atmospheric and their Impact (LAPI),ENAC/IIE,Ecole Polytechnique federale de Lausanne (EPFL),Switzerland
4. Ann M, Dillner, University of California,Davis,CA,USA
5. Yoko Iwamoto, Graduate School of Integrated Sciences for Life,Hiroshima University,Japan
6. Yuzo Miyazaki, Institute of Low Temperature Science,Hokkaido University,Japan
7. Motomi Igarashi, Murata Keisokuki Service Co.,Ltd,Japan
8. Michihiro Mochida, Institute for Space-Earth Environmental Research,Nagoya University,Japan
*Presenting Author
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Organic aerosol in the marine atmosphere may play an important role in the radiative balance of oceanic regions. However, the temporal and spatial variations of the abundance, composition, and sources of organic aerosol in the marine atmosphere are still not clearly understood. In this study, nondestructive filter-based analysis by Fourier transform infrared spectroscopy (FTIR) was applied to organic aerosol samples collected over the western North Pacific during two cruises: one during July16-30, 2022 (R/V Shinsei-Maru; cruise I) and the other during July 2-29, 2023 (R/V Hakuho-Maru; cruise II). During the cruises, PM2.5 samples were collected on 37 mm polytetrafluoroethylene (PTFE) filters. The concentrations of organic functional groups (OFGs) were quantified using a framework of Aerosol InfraRed Spectroscopy (AIRSpec), which is for the processing of infrared spectra from organic aerosols samples. The concentrations of respective OFGs during cruise I (mean + standard deviation (mean proportion)) were 0.150.9 (34%), 0.140.07 (32%), 0.120.06 (28%), 0.020.04 (4%), and 0.010.02 (3%) for alcohol, alkane, carboxylic acid, nonacid carbonyl, and amine groups, respectively, with overall organic mass concentrations of (0.440.24) ug m-3. During cruise II, the concentrations of OFGs were: 0.430.35 (37%), 0.360.31 (30%), 0.250.17 (27%), 0.050.11 (3%), and 0.030.04 (3%) for carboxylic acid, alkane, alcohol, nonacid carbonyl, and amine groups, respectively, with overall organic mass concentrations of 1.120.8 ug m-3. Whereas cruise II showed on average 2.5 times higher concentration than that from cruise I, the composition of OFGs were on an average similar between the cruises. The obtained composition of OFGs may have representativeness as structural characteristics of organic aerosols in the studied region in July. The results, together with the analysis of other components in the future, are expected to be useful to characterize the studied aerosols and to understand the contributions of terrestrial and marine organic components in the marine atmosphere.