FT Organic Aerosol Composition And Formation In Summer At Mt. Fuji.pdf

- Objective: To investigate the composition and formation processes of low molecular weight dicarboxylic acids (LMWDCAs) and other organic aerosols in the free troposphere (FT) during summer at the peak of Mt. Fuji.

- Method: Aerosol samples were collected from July 20 to August 25, 2010, using a High Volume Air Sampler (HV) and a Middle Volume Impactor (MVI). LMWDCAs were analyzed using GC/MS and GC/FID after derivatization with n-butanol.

- Results:
- 23 LMWDCAs, 7 ketocarboxylic acids, and 2 dicarbonyls were detected.
- Oxalic acid (C2) had the highest concentration, followed by succinic (C4) and malonic (C3) acids.
- Total LMWDCAs concentration was 188±163 ng m⁻³, varying with meteorological conditions.
- Oxalic acid showed strong correlation with anthropogenic markers (R²=0.97), suggesting significant influence from polluted air masses.
- The C3/C4 ratio (0.86±0.68) indicated moderate photochemical aging, between fresh and highly aged aerosols.
- Most LMWDCAs were associated with fine particles (<2.5 µm), suggesting secondary formation from gaseous precursors. However, some were also associated with coarse particles, indicating possible transport from the boundary layer.
- Anthropogenic markers (Ph, C9) had different particle size distributions, supporting the influence of polluted air masses on oxalic acid.

- Conclusion: LMWDCAs in the FT were influenced by polluted air masses and were primarily formed secondarily from gaseous precursors.