SO 2 enhances aerosol formation from anthropogenic volatile organic compound ozonolysis by producing sulfur-containing compounds

[摘要] Sulfur dioxide (SO 2 ) can affect aerosol formation inthe atmosphere, but the underlying mechanisms remain unclear. Here, weinvestigate aerosol formation and composition from the ozonolysis ofcyclooctene with and without SO 2 addition in a smog chamber. Liquidchromatography equipped with high-resolution tandem mass spectrometrymeasurements indicates that monomer carboxylic acids and corresponding dimerswith acid anhydride and aldol structures are important components inparticles formed in the absence of SO 2 . A 9.4–12.6-times increase inparticle maximum number concentration is observed in the presence of 14–192 ppb SO 2 . This increase is largely attributed to sulfuric acid(H 2 SO 4 ) formation from the reactions of stabilized Criegeeintermediates with SO 2 . In addition, a number of organosulfates (OSs)are detected in the presence of SO 2 , which are likely products formedfrom the heterogeneous reactions of oxygenated species with H 2 SO 4 .The molecular structures of OSs are also identified based on tandem massspectrometry analysis. It should be noted that some of these OSs have beenfound in previous field studies but were classified as compounds fromunknown sources or of unknown structures. The observed OSs are less volatilethan their precursors and are therefore more effective contributors toparticle formation and growth, partially leading to the increase in particlevolume concentration under SO 2 -presence conditions. Our results providean in-depth molecular-level insight into how SO 2 alters particleformation and composition.

[学科分类] 医学（综合）