Final Report: The Role of Oxidation of BVOCs in SOA Production in the Southeastern U.S.

EPA Grant Number: R835409
Title: The Role of Oxidation of BVOCs in SOA Production in the Southeastern U.S.
Investigators: Bertman, Steve , Pratt, Kerri A , Seeley, John , Shepson, Paul , Starn, Tim
Institution: Western Michigan University , Oakland University , Purdue University , West Chester University of Pennsylvania
EPA Project Officer: Hunt, Sherri
Project Period: April 1, 2013 through March 31, 2015 (Extended to March 31, 2016)
Project Amount: $387,483
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 main activity of this project was to conduct field measurements of anthropogenic and biogenic volatile organic compounds (VOCs) and their oxidation  products, including organic nitrate compounds and aerosols, at the Southern Oxidant and Aerosol Study (SOAS) campaign during the summer of 2013. The goals were to better  understand the interactions between anthropogenic and biogenic emissions in the formation of  secondary organic aerosol (SOA) and organic nitrates and the role that organic nitrogen compounds play in SOA formation.

Summary/Accomplishments (Outputs/Outcomes):

We deployed several field measurements (atmospheric peroxyacetyl nitrate [PAN], monoterpenes, isoprene nitrates, filter samples) during SOAS 2013 at the Centreville, AL ground site in collaboration with many other research groups in support of the overall goals of SOAS and in pursuit of specific questions about the involvement of nitrogen chemistry in aerosol formation from biogenic VOC (BVOC).

Isoprene and monoterpene-derived organosulfates and oligomers were identified in both below cloud particles and cloud water, showing the significant influence of BVOC oxidation above this forested region to particle-phase organics. Although the average O:C ratios of the organic compounds were similar between the atmospheric particle and cloud water samples, the chemical composition of these samples was quite different, demonstrating that cloud processing changes the composition of organic aerosol.

Significant levels of di-functional hydroxynitrates derived from isoprene oxidation were observed, and they showed strong diurnal variation. A chemical model was used to estimate the relative concentration of the major isoprene-derived organic nitrates in order to study the timescale for chemical conversion to secondary nitrate products. The modeled and observed [IN]/([MVK]+[MACR]) ratio both peak around 0.07, but the modeled growth rate in the morning appears smaller than observed, leading to a time lag of 1 hour when each reaches maximum. The under prediction in the morning growth rate suggests a small unknown source of isoprene nitrates, which could be downward mixing of these nitrates from the residual layer.

Correlation of gas-phase peroxymethacryloyl nitrate (MPAN) is greater with isoprene nitrates than with its direct precursor, methacrolein. This suggests that there might be an additional pathway to MPAN. As gas phase nitrates, like MPAN, are believed to play a role in particle formation, an additional pathway could impact the ability to predict particle formation.

Single particle characterization techniques were used to assess the variation in the sources of aerosols during different periods during the SOAS campaign. Of particular note were events with coarse particles, specifically sea spray aerosol. The heterogeneous reactivity of sea spray aerosol was shown to play an important role in the formation of secondary nitrate.

Conclusions:

In sum, there was a diversity of sources and secondary processing of aerosols at SOAS that was far more complicated and intricate than simple well mixed ammonium sulfate with secondary organic material in an aqueous solution.


Journal Articles on this Report : 4 Displayed | Download in RIS Format

Other project views: All 22 publications 4 publications in selected types All 4 journal articles
Type Citation Project Document Sources
Journal Article Allen HM, Draper DC, Ayres BR, Ault A, Bondy A, Takahama S, Modini RL, Baumann K, Edgerton E, Knote C, Laskin A, Wang B, Fry JL. Influence of crustal dust and sea spray supermicron particle concentrations and acidity on inorganic NO3 aerosol during the 2013 Southern Oxidant and Aerosol Study. Atmospheric Chemistry and Physics 2015;15(18):10669-10685. R835409 (2014)
R835409 (Final)
R835399 (2014)
R835399 (Final)
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  • Journal Article Boone EJ, Laskin A, Laskin J, Wirth C, Shepson PB, Stirm BH, Pratt KA. Aqueous processing of atmospheric organic particles in cloud water collected via aircraft sampling. Environmental Science & Technology 2015;49(14):8523-8530. R835409 (2014)
    R835409 (Final)
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  • Journal Article Pye HOT, Luecken DJ, Xu L, Boyd CM, Ng NL, Baker KR, Ayres BR, Bash JO, Baumann K, Carter WPL, Edgerton E, Fry JL, Hutzell WT, Schwede DB, Shepson PB. Modeling the current and future roles of particulate organic nitrates in the Southeastern United States. Environmental Science & Technology 2015;49(24):14195-14203. R835409 (Final)
    R835399 (Final)
    R835403 (2014)
    R835403 (2015)
    R835403 (Final)
    R835410 (2013)
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  • Journal Article Xiong F, McAvey KM, Pratt KA, Groff CJ, Hostetler MA, Lipton MA, Starn TK, Seeley JV, Bertman SB, Teng AP, Crounse JD, Nguyen TB, Wennberg PO, Misztal PK, Goldstein AH, Guenther AB, Koss AR, Olson KF, de Gouw JA, Baumann K, Edgerton ES, Feiner PA, Zhang L, Miller DO, Brune WH, Shepson PB. Observation of isoprene hydroxynitrates in the southeastern United States and implications for the fate of NOx. Atmospheric Chemistry and Physics 2015;15(19):11257-11272. R835409 (2014)
    R835409 (Final)
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  • Supplemental Keywords:

    BVOC, organic nitrate, PAN, MPAN, isoprene nitrate, RONO2, GCxGC, terpene, nitrate, NO3;

    Progress and Final Reports:

    Original Abstract
    2013 Progress Report
    2014 Progress Report