Constraining condensed-phase formation kinetics of secondary organic aerosol components from isoprene epoxydiols
T. P. Riedel1,a,Y.-H. Lin1,b,Z. Zhang1,K. Chu1,J. A. Thornton2,W. Vizuete1,A. Gold1,and J. D. Surratt1T. P. Riedel et al.T. P. Riedel1,a,Y.-H. Lin1,b,Z. Zhang1,K. Chu1,J. A. Thornton2,W. Vizuete1,A. Gold1,and J. D. Surratt1
1Department of Environmental Sciences and Engineering, Gillings School
of Global Public Health, The University of North Carolina at Chapel Hill,
Chapel Hill, North Carolina, USA
2Department of Atmospheric Sciences, University of Washington, Seattle,
Washington, USA
apresent address: US Environmental Protection Agency, National Exposure
Research Laboratory, Research Triangle Park, North Carolina, USA
bpresent address: Department of Chemistry, Michigan Society of Fellows, University of Michigan, Ann Arbor, Michigan, USA
1Department of Environmental Sciences and Engineering, Gillings School
of Global Public Health, The University of North Carolina at Chapel Hill,
Chapel Hill, North Carolina, USA
2Department of Atmospheric Sciences, University of Washington, Seattle,
Washington, USA
apresent address: US Environmental Protection Agency, National Exposure
Research Laboratory, Research Triangle Park, North Carolina, USA
bpresent address: Department of Chemistry, Michigan Society of Fellows, University of Michigan, Ann Arbor, Michigan, USA
Received: 29 Sep 2015 – Discussion started: 21 Oct 2015 – Revised: 11 Jan 2016 – Accepted: 18 Jan 2016 – Published: 03 Feb 2016
Abstract. Isomeric epoxydiols from isoprene photooxidation (IEPOX) have been shown to produce substantial amounts of secondary organic aerosol (SOA) mass and are therefore considered a major isoprene-derived SOA precursor. Heterogeneous reactions of IEPOX on atmospheric aerosols form various aerosol-phase components or "tracers" that contribute to the SOA mass burden. A limited number of the reaction rate constants for these acid-catalyzed aqueous-phase tracer formation reactions have been constrained through bulk laboratory measurements. We have designed a chemical box model with multiple experimental constraints to explicitly simulate gas- and aqueous-phase reactions during chamber experiments of SOA growth from IEPOX uptake onto acidic sulfate aerosol. The model is constrained by measurements of the IEPOX reactive uptake coefficient, IEPOX and aerosol chamber wall losses, chamber-measured aerosol mass and surface area concentrations, aerosol thermodynamic model calculations, and offline filter-based measurements of SOA tracers. By requiring the model output to match the SOA growth and offline filter measurements collected during the chamber experiments, we derive estimates of the tracer formation reaction rate constants that have not yet been measured or estimated for bulk solutions.
IEPOX, a photooxidation product of isoprene, contributes to ambient secondary organic aerosol concentrations. Controlled atmospheric chamber experiments and modeling are used to extract formation rate information of chemical species that contribute to IEPOX-derived secondary organic aerosol.
IEPOX, a photooxidation product of isoprene, contributes to ambient secondary organic aerosol...
