2013 Progress Report: Impacts of Anthropogenic Emissions in the Southeastern U.S. on Heterogeneous Chemistry of Isoprene-Derived Epoxides Leading to Secondary Organic Aerosol Formation

EPA Grant Number: R835404
Title: Impacts of Anthropogenic Emissions in the Southeastern U.S. on Heterogeneous Chemistry of Isoprene-Derived Epoxides Leading to Secondary Organic Aerosol Formation
Investigators: Surratt, Jason D.
Institution: University of North Carolina at Chapel Hill
EPA Project Officer: Chung, Serena
Project Period: April 1, 2013 through March 31, 2016 (Extended to March 31, 2017)
Project Period Covered by this Report: April 1, 2013 through March 31,2014
Project Amount: $300,000
RFA: Anthropogenic Influences on Organic Aerosol Formation and Regional Climate Implications (2012) RFA Text |  Recipients Lists
Research Category: Air Quality and Air Toxics , Global Climate Change , Climate Change , Air

Objective:

The underlying hypothesis of this study is that anthropogenic emissions enhance isoprene SOA formation through the heterogeneous chemistry of isoprene-derived epoxides, possibly leading to light-absorbing SOA in the southeastern United States. The specific objectives to evaluate this hypothesis include: (1) leveraging our ongoing Look Rock, TN, field site during the community-led Southern Oxidant & Aerosol Study (SOAS) in summer 2013 to evaluate how isoprene SOA formation chemistry varies between regional and urban influenced air masses; (2) evaluate the effects of relative humidity, aerosol acidity, and seed aerosol type on the heterogeneous chemistry of isoprene-derived epoxides leading to SOA and how this might yield light-absorbing aerosol constituents (i.e., brown carbon); (3) evaluate gaseous yields of epoxides from isoprene oxidation under varying initial levels of nitric oxide; (4) experimentally determine the isoprene epoxydiols (IEPOX) and metharcylic acid epoxides (MAE) reaction probability per collision with aerosol particles, g(IEPOX) and g(MAE), and its dependence upon aerosol composition in order to help improve parameterization of isoprene-derived SOA formation in models.

Progress Summary:

Fine aerosol samples were collected from June 1–July 17 at Look Rock, TN, using a suite of online and off-line techniques during the 2013 Southeast Oxidant & Aerosol Study (SOAS). Isoprene-derived SOA tracers were characterized and quantified using gas chromatography/mass spectrometry and liquid chromatography interfaced to an inline diode array detector and high-resolution electrospray ionization mass spectrometry. IEPOX, oxidation products from isoprene under low-nitric oxide conditions, were the dominant source of SOA. On average, known isoprene-derived SOA tracers accounted for 9.4% of total organic aerosol (OA) mass (upwards of 25%) and positive matrix factorization of real-time OA mass spectral data corroborated this finding. Weak association (R2 = 0.3) between sulfate and isoprene-derived SOA was observed at the site; however, IEPOX and sulfate likely synergistically interacted upwind to form SOA.

From our indoor smog chamber experiments we demonstrate the formation of light-absorbing (290 nm < λ < 700 nm) SOA constituents from reactive uptake of trans­­‑β‑IEPOX, the predominant IEPOX isomer, onto preexisting sulfate aerosols as a potential source of secondary light-absorbing aerosol (brown carbon, BrC). IEPOX-derived BrC generated in controlled chamber experiments under dry, acidic conditions has an average mass absorption coefficient of ~300 cm2 g-1. Chemical analyses of SOA constituents using UV-visible spectroscopy and high-resolution mass spectrometry indicate the presence of highly unsaturated oligomeric species with molecular weights separated by mass units of 100 (C5H8O2) and 82 (C5H6O) coincident with the observations of enhanced light absorption, suggesting such oligomers as chromophores, and potentially explaining one source of humic-like substances (HULIS) ubiquitously present in atmospheric aerosol. Similar light-absorbing oligomers were identified in fine aerosol collected in the rural southeastern United States (Look Rock, TN; Centerville, AL; Yorkville, GA), supporting their atmospheric relevance and revealing a previously unrecognized source of oligomers derived from isoprene that contributes to ambient fine aerosol mass. 

Future Activities:

Finalize all data collected from the Look Rock ground site during SOAS 2013 for submission of manuscripts summarizing results from the campaign. Complete chemical analyses of PM2.5 samples collected from Centerville, AL, and Birmingham, AL, ground sites. Evaluate yields of IEPOX and MAE under varying conditions of NOx and their reaction probability per collision with aerosol particles and their dependences on aerosol composition. 


Journal Articles on this Report : 3 Displayed | Download in RIS Format

Other project views: All 36 publications 16 publications in selected types All 16 journal articles
Type Citation Project Document Sources
Journal Article Kristensen K, Cui T, Zhang H, Gold A, Glasius M, Surratt JD. Dimers in α-pinene secondary organic aerosol: effect of hydroxyl radical, ozone, relative humidity and aerosol acidity. Atmospheric Chemistry and Physics 2014;14(8):4201-4218. R835404 (2013)
R835404 (2014)
R835404 (2015)
R835404 (Final)
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  • Abstract: ACP-Abstract
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  • Other: Harvard University-Abstract
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  • Journal Article Lin Y-H, Budisulistiorini SH, Chu K, Siejack RA, Zhang H, Riva M, Zhang Z, Gold A, Kautzman KE, Surratt JD. Light-absorbing oligomer formation in secondary organic aerosol from reactive uptake of isoprene epoxydiols. Environmental Science & Technology 2014;48(20):12012-12021. R835404 (2013)
    R835404 (2014)
    R835404 (2015)
    R835404 (Final)
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  • Abstract: ES&T-Abstract
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  • Journal Article Zhang H, Zhang Z, Cui T, Lin Y-H, Bhathela NA, Ortega J, Worton DR, Goldstein AH, Guenther A, Jimenez JL, Gold A, Surratt JD. Secondary organic aerosol formation via 2-methyl-3-buten-2-ol photooxidation: evidence of acid-catalyzed reactive uptake of epoxides. Environmental Science & Technology Letters 2014;1(4):242-247. R835404 (2013)
    R835404 (2014)
    R835404 (2015)
    R835404 (Final)
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  • Other: ResearchGate-Full Text PDF
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  • Supplemental Keywords:

    Atmosphere, particulates, biogenic volatile organic compounds, terpenes

    Relevant Websites:

    Jason Surratt Exit

    Progress and Final Reports:

    Original Abstract
    2014 Progress Report
    2015 Progress Report
    Final Report