Final 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 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, Tennessee, 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) evaluating 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) evaluating gaseous yields of epoxides from isoprene oxidation under varying initial levels of nitric oxide; (4) experimentally determining the isoprene epoxydiols (IEPOX) and metharcylic acid epoxides (MAE) reaction probability per collision with aerosol particles, γ(MAE), and its dependence on aerosol composition to help improve parameterization of isoprene-derived SOA formation in models; and (5) determining the source of isoprene SOA at the Look Rock, Tennessee, ground site observed during SOAS 2013 that occurs through non-epoxide routes.

Summary/Accomplishments (Outputs/Outcomes):

This project combined field, laboratory, and modeling studies to address the hypothesis and aims of this study. First, a suite of offline and real-time gas- and particle-phase measurements was deployed at Look Rock (LRK), Tennessee; Centerville (CTR), Alabama; and Birmingham (BHM), Alabama, ground sites during the 2013 Southern Oxidant and Aerosol Study (SOAS) to examine the effects of anthropogenic emissions on isoprene-derived secondary organic aerosol (SOA) formation. High- and low-time-resolution PM2.5 samples were collected for analysis of known tracer compounds in isoprene-derived SOA by gas chromatography/electron ionization mass spectrometry (GC/EI-MS) and ultra-performance liquid chromatography/diode array detection-electrospray ionization-high-resolution quadrupole time-of-flight mass spectrometry (UPLC/DAD-ESI-HR-QTOFMS).

At the LRK, source apportionment of the organic aerosol (OA) was determined by positive matrix factorization (PMF) analysis of mass spectrometric data acquired on an Aerodyne Aerosol Chemical Speciation Monitor (ACSM). Campaign average mass concentrations of the sum of quantified isoprene-derived SOA tracers contributed to ~ 9% (up to 28 %) of the total OA mass, with IEPOX chemistry accounting for ~ 97% of the quantified tracers. PMF analysis resolved a factor with a profile similar to the IEPOX-OA factor resolved in an Atlanta study and was, therefore, designated IEPOX-OA. This factor was strongly correlated (r2 > 0.7) with 2-methyltetrols, C5-alkene triols, IEPOX-derived organosulfates, and dimers of organosulfates, confirming the role of IEPOX chemistry as the source. On average, IEPOX-OA accounted for 32% of the total OA. A low-volatility oxygenated organic aerosol (LV-OOA) and an oxidized factor with a profile similar to 91Fac observed in areas where emissions are biogenic-dominated also were resolved by PMF analysis, whereas no primary organic aerosol (POA) sources could be resolved. These findings were consistent with low levels of primary pollutants, such as nitric oxide (NO ~ 0.03 ppb), carbon monoxide (CO ~ 116 ppb), and black carbon (BC ~ 0.2 μg m-3). Particle-phase sulfate is fairly correlated (r2 ~ 0.3) with both methacrylic acid epoxide (MAE)/hydroxymethyl-methyl-a-lactone (HMML)- (henceforth called methacrolein (MACR)- derived SOA tracers) and IEPOX-derived SOA tracers, and more strongly correlated (r2 ~ 0.6) with the IEPOX-OA factor, in sum suggesting an important role of sulfate in isoprene SOA formation. Despite the lack of a clear association of IEPOX-OA with locally estimated aerosol acidity and liquid water content (LWC), box model calculations of IEPOX uptake using the simpleGAMMA model, accounting for the role of acidity and aerosol water, predicted the abundance of the IEPOX-derived SOA tracers 2-methyltetrols and the corresponding sulfates with good accuracy (r2 ~ 0.5 and ~ 0.7, respectively). The modeling and data combined suggest an anthropogenic influence on isoprene-derived SOA formation through acid-catalyzed heterogeneous chemistry of IEPOX in the southeastern United States. Future studies should further explore the extent to which acidity and LWC as well as aerosol viscosity and morphology becomes a limiting factor of IEPOX-derived SOA, and their modulation by anthropogenic emissions.

As one aspect of an investigation to examine how anthropogenic pollutants influence isoprene-derived SOA formation, high-volume PM2.5 filter samples were collected at the BHM ground site during SOAS in 2013. Similar to LRK, sample extracts were analyzed by GC/EI-MS with prior trimethylsilylation and UPLC/ESI-HR-QTOFMS to identify known isoprene SOA tracers. Tracers quantified using both surrogate and authentic standards were compared with collocated gas- and particle-phase data as well as meteorological data provided by the Southeastern Aerosol Research and Characterization (SEARCH) network to assess the impact of anthropogenic pollution on isoprene-derived SOA formation. Results reveal that isoprene-derived SOA tracers contribute a substantial mass fraction of organic matter (OM) (~7 to ~20 %). Isoprene-derived SOA tracers correlated with sulfate (r2 ~ 0.34, n = 117), but not with NOx. Moderate correlations between methacrylic acid epoxide and hydroxymethyl-methyl-a-lactone (together abbreviated MAE/HMML)-derived SOA tracers with nitrate radical production (P[NO3]) (r2 ~ 0.57, n = 40) were observed during nighttime, suggesting a potential role of the NO3 radical in forming this SOA type. However, the nighttime correlation of these tracers with NO2 (r2 ~ 0.26, n = 40) was weaker. Ozone (O3) correlated strongly with MAE/HMML-derived tracers (r2 ~ 0.72, n = 30) and moderately with 2-methyltetrols (r2 ~0.34, n = 15) during daytime only, suggesting that a fraction of SOA formation could occur from isoprene ozonolysis in urban areas. All in all, these field results confirm previous studies suggesting that anthropogenic pollutants enhance isoprene-derived SOA formation.

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 derived estimates of the tracer formation reaction rate constants that have not yet been measured or estimated for bulk solutions. These can now be used in air quality models.

SOA was generated in an indoor smog chamber from isoprene ozonolysis under dark conditions in the presence of non-acidified or acidified sulfate seed aerosol. The effect of OH radicals on SOA chemical composition was investigated using diethyl ether as an OH radical scavenger. Analysis revealed the formation of highly oxidized compounds, including organosulfates and 2-methylterols, which were significantly enhanced in the presence of acidified sulfate seed aerosol. OSs identified in the chamber experiments also were observed and quantified in summertime fine aerosol collected from two rural locations in the southeastern United States during SOAS in 2013. Furthermore, 34 gaseous oligomeric compounds resulting from the addition of sCIs with either organic hydroperoxides or carboxylic acids were identified using iodide chemical ionization high-resolution mass spectrometry. Large reactive uptakes onto acidified sulfate aerosol were observed for most of the characterized gaseous oligomeric species, whereas the presence of organic coatings and the lack of aerosol water significantly reduced or halted the reactive uptake of these species. These results indicate that multiphase chemistry of epoxides and/or hydroperoxides could be significantly influenced by the chemical composition of the seed aerosols. Moreover, in addition to functionalization and accretion, decomposition and re-volatilization should be considered in the formation and aging of SOA.

SOA formation from the oxidation of authentic 1,2-ISOPOOH under low-NOx conditions was systematically examined with varying aerosol compositions and relative humidity. High yields of highly oxidized compounds, including multifunctional organosulfates and hydroperoxides, were chemically characterized in both laboratory-generated SOA and fine aerosol samples collected from the southeastern United States during the 2013 SOAS. IEPOX-derived SOA constituents were observed in all experiments, but their concentrations were only enhanced in the presence of acidified sulfate aerosol, consistent with prior work. High-resolution aerosol mass spectrometry (HR-AMS) reveals that 1,2-ISOPOOH-derived SOA formed through non-IEPOX routes exhibits a notable mass spectrum with a characteristic fragment ion at m/z 91. This laboratory-generated mass spectrum is strongly correlated with a factor recently resolved by PMF of aerosol mass spectrometer data collected in areas dominated by isoprene emissions, suggesting that the non-IEPOX pathway could contribute to ambient SOA measured in the Southeastern United States.

Lastly, the lack of statistically robust relationships between IEPOX-derived SOA (IEPOX SOA) and aerosol liquid water and pH observed during the 2013 SOAS emphasizes the importance of modeling the whole system to understand the controlling factors governing IEPOX SOA formation. We present a mechanistic modeling investigation predicting IEPOX SOA based on Community Multiscale Air Quality (CMAQ) model algorithms and a recently introduced photochemical box model, simpleGAMMA. We aimed to (1) simulate IEPOX SOA tracers from the SOAS LRK ground site, (2) compare the two model formulations, (3) determine the limiting factors in IEPOX SOA formation, and (4) test the impact of a hypothetical sulfate reduction scenario on IEPOX SOA. The estimated IEPOX SOA mass variability is in similar agreement (r2 ∼ 0.6) with measurements. Correlations of the estimated and measured IEPOX SOA tracers with observed aerosol surface area (r2 ∼ 0.5−0.7), rate of particle-phase reaction (r2 ∼ 0.4−0.7), and sulfate (r2 ∼ 0.4− 0.5) suggest an important role of sulfate in tracer formation via both physical and chemical mechanisms. A hypothetical 25% reduction of sulfate results in ∼ 70% reduction of IEPOX SOA formation, reaffirming the importance of aqueous phase chemistry in IEPOX SOA production in the Southeastern United States.

Conclusions:

We have achieved all of our specific objectives outlined above to test our underlying hypothesis. We currently are summarizing recent findings on isoprene-derived hydroperoxides for publication purposes.   


Journal Articles on this Report : 16 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 Barbosa TS, Riva M, Chen Y, da Silva CM, Ameida JCS, Zhang Z, Gold A, Arbilla G, Bauerfeldt GF, Surratt JD. Chemical characterization of organosulfates from the hydroxyl radical-initiated oxidation and ozonolysis of cis-3-hexen-1-ol. Atmospheric Environment 2017;162:141-151. R835404 (2015)
R835404 (Final)
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  • Journal Article Budisulistiorini SH, Li X, Bairai ST, Renfro J, Liu Y, Liu YJ, McKinney KA, Martin ST, McNeill VF, Pye HOT, Nenes A, Neff ME, Stone EA, Mueller S, Knote C, Shaw SL, Zhang Z, Gold A, Surratt JD. Examining the effects of anthropogenic emissions on isoprene-derived secondary organic aerosol formation during the 2013 Southern Oxidant and Aerosol Study (SOAS) at the Look Rock, Tennessee ground site. Atmospheric Chemistry and Physics 2015;15(15):8871-8888. R835404 (2014)
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  • Journal Article Budisulistiorini SH, Nenes A, Carlton AG, Surratt JD, McNeill VF, Pye HOT. Simulating aqueous-phase isoprene-epoxydiol (IEPOX) secondary organic aerosol production during the 2013 Southern Oxidant and Aerosol Study (SOAS). Environmental Science & Technology 2017;51(9):5026-5034. R835404 (2015)
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  • Journal Article Gaston CJ, Riedel TP, Zhang Z, Gold A, Surratt JD, Thornton JA. Reactive uptake of an isoprene-derived epoxydiol to submicron aerosol particles. Environmental Science & Technology 2014;48(19):11178-11186. R835404 (2014)
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  • Journal Article Hu WW, Campuzano-Jost P, Palm BB, Day DA, Ortega AM, Hayes PL, Krechmer JE, Chen Q, Kuwata M, Liu YJ, de Sa SS, McKinney K, Martin ST, Hu M, Budisulistiorini SH, Riva M, Surratt JD, St. Clair JM, Isaacman-Van Wertz G, Yee LD, Goldstein AH, Carbone S, Brito J, Artaxo P, de Gouw JA, Koss A, Whisthaler A, Mikoviny T, Karl T, Kaser L, Jud W, Hansel A, Docherty KS, Alexander ML, Robinson NH, Coe H, Allan JD, Canagaratna MR, Paulot F, Jimenez JL. Characterization of a real-time tracer for isoprene epoxydiols-derived secondary organic aerosol (IEPOX-SOA) from aerosol mass spectrometer measurements. Atmospheric Chemistry and Physics 2015;15(20):11807-11833. R835404 (2014)
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  • 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)
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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)
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  • Journal Article Liu J, D'Ambro EL, Lee BH, Lopez-Hilfiker FD, Zaveri RA, Rivera-Rios JC, Keutsch FN, Iyer S, Kurten T, Zhang Z, Gold A, Surratt JD, Shilling JE, Thornton JA. Efficient isoprene secondary organic aerosol formation from a non-IEPOX pathway. Environmental Science & Technology 2016;50(18):9872-9880. R835404 (2015)
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  • Journal Article Pye HOT, Murphy BN, Xu L, Ng NL, Carlton AG, Guo H, Weber R, Vasilakos P, Appel KW, Budisulistiorini SH, Surratt JD, Nenes A, Hu W, Jimenez JL, Isaacman-VanWertz G, Misztal PK, Goldstein AH. On the implications of aerosol liquid water and phase separation for organic aerosol mass. Atmospheric Chemistry and Physics 2017;17(1):343-369. R835404 (2015)
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  • Journal Article Rattanavaraha W, Chu K, Budisulistiorini SH, Riva M, Lin Y-H, Edgerton ES, Baumann K, Shaw SL, Guo H, King L, Weber RJ, Neff ME, Stone EA, Offenberg JH, Zhang Z, Gold A, Surratt JD. Assessing the impact of anthropogenic pollution on isoprene-derived secondary organic aerosol formation in PM2.5 collected from the Birmingham, Alabama, ground site during the 2013 Southern Oxidant and Aerosol Study. Atmospheric Chemistry and Physics 2016;16(8):4897-4914. R835404 (2014)
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  • Journal Article Riedel TP, Lin Y-H, Budisulistiorini SH, Gaston CJ, Thornton JA, Zhang Z, Vizuete W, Gold A, Surratt JD. Heterogeneous reactions of isoprene-derived epoxides:reaction probabilities and molar secondary organic aerosol yield estimates. Environmental Science & Technology Letters 2015;2(2):38-42. R835404 (2014)
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  • Journal Article Riedel TP, Lin Y-H, Zhang Z, Chu K, Thornton JA, Vizuete W, Gold A, Surratt JD. Constraining condensed-phase formation kinetics of secondary organic aerosol components from isoprene epoxydiols. Atmospheric Chemistry and Physics 2016;16(3):1245-1254. R835404 (2014)
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  • Journal Article Riva M, Budisulistiorini SH, Zhang Z, Gold A, Surratt JD. Chemical characterization of secondary organic aerosol constituents from isoprene ozonolysis in the presence of acidic aerosol. Atmospheric Environment 2016;130:5-13. R835404 (2014)
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  • Journal Article Riva M, Budisulistiorini SH, Chen Y, Zhang Z, D'Ambro EL, Zhang X, Gold A, Turpin BJ, Thornton JA, Canagaratna MR, Surratt JD. Chemical characterization of secondary organic aerosol from oxidation of isoprene hydroxyhydroperoxides. Environmental Science & Technology 2016;50(18):9889-9899. R835404 (2015)
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  • Journal Article Riva M, Budisulistiorini SH, Zhang Z, Gold A, Thornton JA, Turpin BJ, Surratt JD. Multiphase reactivity of gaseous hydroperoxide oligomers produced from isoprene ozonolysis in the presence of acidified aerosols. Atmospheric Environment 2017;152:314-322. R835404 (2015)
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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)
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  • Supplemental Keywords:

    Atmosphere, particulates, biogenic volatile organic compounds, terpenes, aerosols, emissions

    Relevant Websites:

    http://sph.unc.edu/adv_profile/jason-d-surratt-phd/ Exit

     

     

     

     

    Progress and Final Reports:

    Original Abstract
    2013 Progress Report
    2014 Progress Report
    2015 Progress Report