A21A-0091
Online Measurements and Modeling of Isoprene Photo-oxidation Products: Insights from the Laboratory and SOAS Field Campaign
Tuesday, 15 December 2015
Poster Hall (Moscone South)
Emma D'Ambro1, Felipe Lopez-Hilfiker2, Claudia Mohr2, Cassandra Gaston2, Ben H. Lee2, Jiumeng Liu3, Anna Lutz4, Mattias Hallquist4, John Shilling3, Avram Gold5, Zhenfa Zhang5, Jason D Surratt6, Joel A Thornton1 and SOAS science team, (1)Univ Washington - Seattle, Seattle, WA, United States, (2)University of Washington Seattle Campus, Seattle, WA, United States, (3)Pacific Northwest National Laboratory, Richland, WA, United States, (4)University of Gothenburg, Department of Chemistry, Atmospheric Science, Gothenburg, Sweden, (5)University of North Carolina at Chapel Hill, Chapel Hill, NC, United States, (6)UNC-Environment Sci & Eng, Chapel Hill, NC, United States
Abstract:
Isoprene, the most abundant non-methane volatile organic compound emitted globally, has the potential to produce large quantities of secondary organic aerosol (SOA) with implications for climate, air quality, and human health. However, much remains unknown about the mechanisms and processes that lead to isoprene derived SOA. We present measurements and modeling of a suite of newly detected compounds from isoprene oxidation from laboratory studies at the Pacific Northwest National Laboratory (PNNL) as well as in the atmosphere from the Southern Oxidant and Aerosol Study (SOAS) field campaign. Measurements were made with a high resolution time of flight chemical ionization mass spectrometer utilizing iodide adduct ionization coupled to the Filter Inlet for Gas and AEROsol (FIGAERO) for the simultaneous sampling of the gas and aerosol phases. In the PNNL chamber, isoprene photo-oxidation with dry neutral seed and IEPOX multiphase chemistry on aqueous particles was investigated at a variety of atmospherically relevant conditions. Isoprene photo-oxidation under high HO2 produced unexpectedly substantial SOA at a yield similar to but from a distinctly different mechanism than that from IEPOX uptake. The high HO2 chemistry also resulted in di hydroxy di hydroperoxides as a dominant component of the aerosol. By utilizing the same instrument and ion chemistry during both field and chamber experiments, together with an MCM-based model, we assess the degree to which the different mechanisms are operable in the atmosphere and relevant aerosol chemical and physical properties of the SOA such as volatility and oligomer content.
