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Oxidation of Proteinaceous Matter by Ozone and Nitrogen Dioxide in PM2.5: Reaction Mechanisms and Atmospheric Implications
Author(s) -
Zhu RenGuo,
Xiao HuaYun,
Wen Zequn,
Zhu Yuwen,
Fang Xiaozheng,
Pan Yuanyuan,
Chen Zhenping,
Xiao Hongwei
Publication year - 2021
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1029/2021jd034741
Subject(s) - chemistry , environmental chemistry , aerosol , nitrogen , ozone , bioavailability , particulates , glycine , organic matter , amino acid , biology , biochemistry , organic chemistry , bioinformatics
Interactions between proteinaceous matter and atmospheric oxidants can affect amino acids (AAs) bioavailability, the climate, and human health. However, atmospheric reactions of proteinaceous matter remain poorly understood. PM2.5 samples were collected during spring (2019) and winter (2020) sampling campaigns conducted in Nanchang, China. Concentrations of combined and free AAs, and the δ 15 N values of combined and free glycine (C‐Gly and F‐Gly) in PM2.5 samples were analyzed. Concentrations of TFAA under different O 3 and NO 2 levels, and correlations of specific FAA species with ambient O 3 and NO 2 concentrations suggest that the ability of O 3 to release TFAA from proteinaceous matter is greater than that of NO 2 . Furthermore, O 3 may trend to release neutral and hydrophilic FAA species, whereas NO 2 tends to generate hydrophobic FAA species. With aerosol aging, the slope of the fitted line between [TFAA] and [TSAA] [O 3 + NO 2 ] increased, indicating that FAAs yield from protein degradation in PM2.5 was affected greatly by aerosol aging. The TCAAs concentration observed in spring was substantially higher than that in winter. Moreover, the δ 15 N F‐Gly and δ 15 N C‐Gly values in PM2.5 exhibited negative correlations with atmospheric O 3 concentration. These results suggest that increased levels of proteinaceous matter in spring were derived from natural sources related to biological activities rather than biomass burning sources. Our study confirms that the reaction of degradation of proteinaceous matter to FAAs could be influenced by aerosol aging, which is a finding that enhances current understanding regarding atmospheric processes of aerosol proteinaceous matter under different ambient O 3 and NO 2 levels.