Enhanced Production of Organosulfur Species during a Severe Winter Haze Episode in the Guanzhong Basin of Northwest China

The molecular composition of organic aerosols in ambient PM2.5 was investigated in an urban area in the Guanzhong basin of northwest China during a severe regional haze episode in the winter of 2018/2019. Organic matter, accounting for 20–35% of PM2.5 mass concentration, was characterized using dire...

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Bibliographic Details
Published in:Environmental science & technology 2023-06, Vol.57 (23), p.8708-8718
Main Authors: Han, Yuemei, Zhang, Xin, Li, Lijuan, Lin, Yue, Zhu, Chongshu, Zhang, Ningning, Wang, Qiyuan, Cao, Junji
Format: Article
Language:English
Subjects:
Aerosols - analysis
Air Pollutants - analysis
Anthropogenic factors
Chemical composition
China
Environmental Monitoring
Environmental Pollution - analysis
Haze
Human influences
Ionization
Ions
Mass spectrometry
Mass spectroscopy
Molecular structure
Negative ions
Occurrence, Fate, and Transport of Contaminants in Indoor Air and Atmosphere
Organic chemistry
Organic matter
Oxidation
Particulate matter
Particulate Matter - analysis
Relative humidity
River basins
Seasons
Sulfur
Urban areas
Winter
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Summary:The molecular composition of organic aerosols in ambient PM2.5 was investigated in an urban area in the Guanzhong basin of northwest China during a severe regional haze episode in the winter of 2018/2019. Organic matter, accounting for 20–35% of PM2.5 mass concentration, was characterized using direct infusion and electrospray ionization coupled with high-resolution Orbitrap mass spectrometry. The number of organic molecular formula assignments was primarily dominated by organosulfur species (OrgS, including CHOS and CHONS) in negative ion mode. The number and peak signal intensity of OrgS distinctly increased during the severe haze episode. Organosulfates and nitrooxy-organosulfates constituted the majority number (72–94%) of OrgS over the entire period. Although the OrgS were mostly present in aliphatic molecular structures, an increase in the number of polycyclic aromatic OrgS on haze days revealed the enhanced contribution from anthropogenic sources. The number of OrgS strongly correlated with ambient relative humidity and the oxidation ratios of sulfur and nitrogen, suggesting the important roles of aqueous phase chemistry and atmospheric oxidation in the formation of OrgS. A thorough understanding of the significance of OrgS will be essential to assess and mitigate the adverse impacts of haze pollution.
ISSN:0013-936X
1520-5851
DOI:10.1021/acs.est.3c02914