Photochemical aging of Volatile Organic Compounds (VOCs) produces secondary organics that can interact with soot particles, yielding secondary organic aerosols (SOAs) with distinctly different properties and profoundly influencing our environment and climate. We have evaluated the impacts of SOA formation on soot properties by exposing monodisperse soot particles to products of the toluene-OH oxidation reaction in an environmental chamber. Particle properties, including size, mass, organic mass faction, morphology, effective density, hygroscopicity, and optical properties were simultaneously monitored, and the changes of these properties were largely determined by the organic coating thickness. The morphology of soot particles was transferred from fractal to compact with the condensation of secondary organics. The coated particles had considerable changes in hygroscopicity, light scattering and absorption. Our results suggest that the photochemical aging of anthropogenic aromatic VOCs can have significant impacts on atmospheric soot particles, considerably altering the climate forcing of soot aerosols.

Impact of secondary organic aerosol formation on soot properties

245th National Meeting (2013)

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