Model Analysis of Secondary Organic Aerosol Formation by Glyoxal in Laboratory Studies: The Case for Photoenhanced Chemistry

The reactive uptake of glyoxal by atmospheric aerosols is believed to be a significant source of secondary organic aerosol (SOA). Several recent laboratory studies have been performed with the goal of characterizing this process, but questions remain regarding the effects of photochemistry on SOA gr...

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Bibliographic Details
Published in:Environmental science & technology 2014-10, Vol.48 (20), p.11919-11925
Main Authors: Sumner, Andrew J, Woo, Joseph L, McNeill, V. Faye
Format: Article
Language:English
Subjects:
Aerosols - analysis
Aerosols - chemistry
Applied sciences
Atmosphere
Atmospheric aerosols
Atmospheric pollution
Computer Simulation
Earth, ocean, space
Exact sciences and technology
Experiments
External geophysics
Glyoxal - chemistry
Laboratories
Meteorology
Models, Theoretical
Organic chemicals
Organic Chemicals - chemistry
Oxidation
Oxidation-Reduction
Particles and aerosols
Photochemical Processes
Photochemistry
Pollutants physicochemistry study: properties, effects, reactions, transport and distribution
Pollution
Water - chemistry
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Summary:The reactive uptake of glyoxal by atmospheric aerosols is believed to be a significant source of secondary organic aerosol (SOA). Several recent laboratory studies have been performed with the goal of characterizing this process, but questions remain regarding the effects of photochemistry on SOA growth. We applied GAMMA (McNeill et al. Environ. Sci. Technol. 2012, 46, 8075–8081), a photochemical box model with coupled gas-phase and detailed aqueous aerosol-phase chemistry, to simulate aerosol chamber studies of SOA formation by the uptake of glyoxal by wet aerosol under dark and irradiated conditions (Kroll et al. J. Geophys. Res. 2005, 110 (D23), 1–10; Volkamer et al. Atmos. Chem. Phys. 2009, 9, 1907–1928; Galloway et al. Atmos. Chem. Phys. 2009, 9, 3331– 306 3345 and Geophys. Res. Lett. 2011, 38, L17811). We find close agreement between simulated SOA growth and the results of experiments conducted under dark conditions using values of the effective Henry’s Law constant of 1.3–5.5 × 107 M atm–1. While irradiated conditions led to the production of some organic acids, organosulfates, and other oxidation products via well-established photochemical mechanisms, these additional product species contribute negligible aerosol mass compared to the dark uptake of glyoxal. Simulated results for irradiated experiments therefore fell short of the reported SOA mass yield by up to 92%. This suggests a significant light-dependent SOA formation mechanism that is not currently accounted for by known bulk photochemistry, consistent with recent laboratory observations of SOA production via photosensitizer chemistry.
ISSN:0013-936X
1520-5851
DOI:10.1021/es502020j