Journal
ENVIRONMENTAL SCIENCE & TECHNOLOGY
Volume 51, Issue 13, Pages 7496-7501Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acs.est.7b01416
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Funding
- [CHE-1506789]
- [AGS-1546136]
- Directorate For Geosciences
- Div Atmospheric & Geospace Sciences [1546136] Funding Source: National Science Foundation
- Division Of Chemistry
- Direct For Mathematical & Physical Scien [1506789] Funding Source: National Science Foundation
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Photosensitized reactions involving imidazole-2-carboxaldehyde (IC) have been experimentally observed to contribute to secondary organic aerosol (SOA) growth. However, the extent of photosensitized reactions in ambient aerosols remains poorly understood and unaccounted for in atmospheric models. Here we use GAMMA 4.0, a photochemical box model that couples gas-phase and aqueous-phase aerosol chemistry, along with recent laboratory measurements of the kinetics of IC photochemistry, to analyze IC photosensitized SOA formation in laboratory and ambient settings. Analysis of the laboratory results of Aregahegn et al. (2013) suggests that photosensitized production of SOA from limonene, isoprene, alpha-pinene, beta-pinene, and toluene by (IC)-I-3* occurs at or near the surface of the aerosol-particle. Reactive uptake coefficients were derived from the experimental data using GAMMA 4.0. Simulations of aqueous aerosol SOA formation at remote ambient conditions including IC photosensitizer chemistry indicate less than 0.3% contribution to SOA growth from direct reactions of (IC)-I-3* with limonene, isoprene, alpha-pinene, beta-pinene, and toluene, and an enhancement of less than 0.04% of SOA formation from other precursors due to the formation of radicals in the bulk aerosol aqueous phase. Other, more abundant photosensitizer species, such as humic-like substances (HULIS), may contribute more significantly to aqueous aerosol SOA production.
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