Increasing Isoprene Epoxydiol-to-Inorganic Sulfate Aerosol Ratio Results in Extensive Conversion of Inorganic Sulfate to Organosulfur Forms: Implications for Aerosol Physicochemical Properties
Résumé
Acid-driven multiphase chemistry of isoprene epoxydiols (IEPOX), key isoprene oxidation products, with inorganic sulfate aerosol yields substantial amounts of secondary organic aerosol (SOA) through the formation of organosulfur compounds. The extent and implications of inorganic-to-organic sulfate conversion, however, are unknown. In this report, we demonstrate that extensive consumption of inorganic sulfate occurs, which increases with the IEPOX-to-inorganic sulfate concentration ratio (IEPOX:Sulf inorg), as determined by laboratory measurements. Characterization of total sulfur aerosol observed at Look Rock, Tennessee, from 2007-2016 shows that organosulfur mass fractions will likely continue to increase with ongoing declines in anthropogenic Sulf inorg , consistent with our laboratory findings. We further demonstrate that organosulfur compounds greatly modifies critical aerosol properties, such as acidity, morphology, viscosity, and phase state. These new mechanistic insights demonstrate that changes in SO 2 emissions, especially in isoprene-dominated environments, will significantly alter biogenic SOA physicochemical properties. Consequently, IEPOX:Sulf inorg will play an important role in understanding historical climate and determining future impacts of biogenic SOA on global climate and air quality.
Origine : Fichiers produits par l'(les) auteur(s)