Final Report: The role of nitrate radicals (NO3) in aerosol life cycle: Secondary organic aerosol formation and aging of atmospheric organic aerosols

EPA Grant Number: R835403
Title: The role of nitrate radicals (NO3) in aerosol life cycle: Secondary organic aerosol formation and aging of atmospheric organic aerosols
Investigators: Ng, Nga Lee
Institution: Georgia Institute of Technology
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 goal of this project was to experimentally determine the extent to which NO3 radicals (formed from anthropogenic NO2 and ozone) affect organic aerosol (OA) loading and composition over its atmospheric lifetime, taking into account secondary organic aerosol (SOA) formation from NO3 oxidation pathway and both daytime and nighttime aging processes.

Summary/Accomplishments (Outputs/Outcomes):

We performed a series of laboratory experiments in the Georgia Tech Environmental Chamber (GTEC) facility to study SOA formation from the nitrate radical oxidation of biogenic volatile organic compounds (BVOC): α-pinene, ß-pinene and limonene. Results from this project provide fundamental data for estimating the amount of OA from nitrate radical oxidation of monoterpenes in the Southeastern United States, as well as improving the representation and treatment of organic nitrate formation and fates in the Community Multiscale Air Quality (CMAQ) model. Major results are as follows:

1. SOA Yields From Nitrate Radical Oxidation of α-Pinene, ß-Pinene and Limonene

We performed chamber experiments to evaluate the effects of RH, seed acidity, peroxy radical fate and temperature on SOA formation from nitrate radical oxidation of representative monoterpenes. We found that this reaction is an efficient pathway of generating SOA under all conditions (except for α-pinene). For ß-pinene, the SOA yields vary between 27–104.1 percent for organic loadings of 5.1–216.1 μg/m3. It was found that RH, particle acidity and peroxy radical fate do not affect SOA yields in this system. The SOA yields from nitrate radical oxidation of α-pinene are low (but not zero). The SOA yields from limonene + NO3 are approximately constant (∼174%) at 25°C and range from 81 to 148 percent at 40°C. For the limonene system, the difference in aerosol mass loading between two temperatures can be explained by an enthalpy of vaporization ranging from 117–237 kJ mol-1. The high SOA yields underscore the importance of SOA formation from the nitrate radical oxidation of biogenic compounds, especially in environments with higher levels of NOx (and NO3).

2. Formation, Hydrolysis and Photochemical Aging of SOA and Organic Nitrates

We found that organic nitrates are major aerosol components and account for 45–74 percent and ~60 percent of OA formed in the ß-pinene + NO3 and α-pinene + NO3 systems, respectively. For limonene SOA, the average N:C measured by the aerosol mass spectrometer is 0.104. If each organic nitrate compound has 10 carbons, this ratio indicates that the particle-phase products contain 1.04 nitrate groups per molecule.

For ß-pinene, we found that 90 percent and 10 percent of the organic nitrates are primary and tertiary organic nitrates, respectively. While primary organic nitrates do not hydrolyze to a large extent, tertiary organic nitrates hydrolyze with a lifetime of 3–4.5 hr-1. Similar results are found for limonene + NO3 organic nitrates. The extent of organic nitrates hydrolysis formed in the NO3 oxidation systems appears to be substantially lower than that observed in previous photooxidation studies. These results highlight the importance of constraining the relative amounts of primary/secondary/tertiary organic nitrates in photochemical versus nitrate oxidations for other volatile organic compound (VOC) systems.

A large suite of speciated, highly oxygenated organic nitrates are detected in the gas and particle phase. The fraction of particle-phase organic nitrates in the ß-pinene SOA remains fairly constant during photochemical aging, but most evaporate in the α-pinene experiments. These results indicate that nighttime organic nitrates formed through BVOC + NO3 can serve as either permanent or temporary NOx sinks, and this is highly dependent on the hydrocarbon precursor.

3. Effects of Temperature, Dilution and Humidity on Mixing and Evaporation of Aerosols From BVOC + NO3

We performed chamber experiments to investigate the effects of dilution and temperature on SOA and organic nitrates formed from BVOC + NO3 to mimic the night-to-day transition. SOA produced at night may evaporate the following morning due to increasing temperatures or dilution of reaction products. We isothermally diluted the reaction products from the limonene + NO3 reaction at 25°C and found that negligible evaporation of organic aerosol occurs via dilution. When limonene + NO3 aerosol formed at 25°C was heated to 40°C, only about 20 percent of the aerosol evaporated, indicating a resistance to aerosol evaporation. We evaluate the possibility that SOA from limonene + NO3 and ß-pinene + NO3 is viscous. We show that particle morphology and evaporation are dependent on whether SOA from limonene is formed before or during the formation of SOA from ß-pinene. This difference in particle morphology is present even at 70 percent RH.

4. Contribution of Monoterpenes + NO3 to OA in the Southeastern United States

Results from our chamber study provide fundamental data to evaluate the extent to which nitrate radical oxidation of monoterpenes contributes to ambient organic aerosols in the Southeast United States. We identified an OA subtype termed as less-oxidized oxygenated organic aerosol (LO-OOA), which accounts for 32 percent of the total OA at Centreville (Southern Oxidant and Aerosol Study [SOAS] campaign). LO-OOA peaks at night and is well-correlated with particle-phase organic nitrates (which accounts for 5–12% of OA in summer). Using SOA yields from our chamber studies, we estimated that about 50 percent of nighttime OA production at SOAS could be due to the reaction of monoterpenes with nitrate radicals, a large fraction of which may be the ß-pinene + NO3 reaction. We also found that particulate organic nitrates are ubiquitous in different seasons at multiple sites in the Southeastern United States.

5. Effect of Vapor and Particle Wall Loss of SOA Formation

Organic vapor wall loss can play a critical role in SOA formation. We conducted a chamber study to investigate the influence of seed aerosol surface area and oxidation rate on SOA formation. For this work, we chose to focus on α-pinene ozonolysis, as it is the most well-studied SOA system. We found that the SOA growth rate and mass yields were independent of seed surface area. This behavior arose when the condensation of SOA-forming vapors is dominated by quasi-equilibrium growth. Faster α-pinene oxidation rates and higher SOA mass yields were observed at increasing O3 concentrations for the same initial α-pinene concentration. Our results (together with previous studies) indicate that the extent to which vapor wall deposition affects SOA mass yields depends on the particular VOC system, and can be mitigated through the use of excess oxidant concentrations.


Journal Articles on this Report : 14 Displayed | Download in RIS Format

Other project views: All 40 publications 14 publications in selected types All 14 journal articles
Type Citation Project Document Sources
Journal Article Boyd CM, Sanchez J, Xu L, Eugene AJ, Nah T, Tuet WY, Guzman MI, Ng NL. Secondary organic aerosol formation from the β-pinene+NO3 system: effect of humidity and peroxy radical fate. Atmospheric Chemistry and Physics 2015;15(13):7497-7522. R835403 (2014)
R835403 (2015)
R835403 (Final)
  • Full-text: Atmospheric Chemistry and Physics-Full-text PDF
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  • Abstract: Atmospheric Chemistry and Physics-Abstract HTML
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  • Other: ResearchGate-Full-text PDF
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  • Journal Article Boyd CM, Nah T, Xu L, Berkemeier T, Ng NL. Secondary organic aerosol (SOA) from nitrate radical oxidation of monoterpenes:effects of temperature, dilution, and humidity on aerosol formation, mixing, and evaporation. Environmental Science & Technology 2017;51(14):7831-7841. R835403 (2015)
    R835403 (Final)
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  • Journal Article Lee BH, Mohr C, Lopez-Hilfiker FD, Lutz A, Hallquist M, Lee L, Romer P, Cohen RC, Iyer S, Kurten T, Hu W, Day DA, Campuzano-Jost P, Jimenez JL, Xu L, Ng NL, Guo H, Weber RJ, Wild RJ, Brown SS, Koss A, de Gouw J, Olson K, Goldstein AH, Seco R, Kim S, McAvey K, Shepson PB, Starn T, Baumann K, Edgerton ES, Liu J, Shilling JE, Miller DO, Brune W, Schobesberger S, D'Ambro EL, Thornton JA. Highly functionalized organic nitrates in the southeast United States: contribution to secondary organic aerosol and reactive nitrogen budgets. Proceedings of the National Academy of Sciences of the United States of America 2016;113(6):1516-1521. R835403 (2015)
    R835403 (Final)
    R835400 (2014)
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    R835407 (Final)
    R835410 (2013)
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  • Journal Article Murphy BN, Woody MC, Jimenez JL, Carlton AMG, Hayes PL, Liu S, Ng NL, Russell LM, Setyan A, Xu L, Young J, Zaveri RA, Zhang Q, Pye HOT. Semivolatile POA and parameterized total combustion SOA in CMAQv5.2: impacts on source strength and partitioning. Atmospheric Chemistry and Physics 2017;17:11107-11133. R835403 (Final)
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  • Journal Article Nah T, Sanchez J, Boyd CM, Ng NL. Photochemical aging of α-pinene and β-pinene secondary organic aerosol formed from nitrate radical oxidation. Environmental Science & Technology 2016;50(1):222-231. R835403 (2015)
    R835403 (Final)
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  • Journal Article Nah T, McVay RC, Zhang X, Boyd CM, Seinfeld JH, Ng NL. Influence of seed aerosol surface area and oxidation rate on vapor wall deposition and SOA mass yields: a case study with α-pinene ozonolysis. Atmospheric Chemistry and Physics 2016;16(14):9361-9379. R835403 (2015)
    R835403 (Final)
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  • Journal Article Nah T, McVay RC, Pierce JR, Seinfeld JH, Ng NL. Constraining uncertainties in particle-wall deposition correction during SOA formation in chamber experiments. Atmospheric Chemistry and Physics 2017;17(3):2297-2310. R835403 (2015)
    R835403 (Final)
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  • Other: California Institute of Technology-Abstract & Full-text PDF
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  • Journal Article Ng NL, Brown SS, Archibald AT, Atlas E, Cohen RC, Crowley JN, Day DA, Donahue NM, Fry JL, Fuchs H, Griffin RJ, Guzman MI, Herrmann H, Hodzic A, Iinuma Y, Jimenez JL, Kiendler-Scharr A, Lee BH, Luecken DJ, Mao J, McLaren R, Mutzel A, Osthoff HD, Ouyang B, Picquet-Varrault B, Platt U, Pye HOT, Rudich Y, Schwantes RH, Shiraiwa M, Stutz J, Thornton JA, Tilgner A, Williams BJ, Zaveri RA. Nitrate radicals and biogenic volatile organic compounds:oxidation, mechanisms, and organic aerosol. Atmospheric Chemistry and Physics 2017;17(3):2103-2162. R835403 (2015)
    R835403 (Final)
    R835877 (2016)
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  • Other: University of Kentucky-Abstract & Full Text PDF
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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. R835403 (2014)
    R835403 (2015)
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    R835409 (Final)
    R835410 (2013)
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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. R835403 (2015)
    R835403 (Final)
    R835404 (2015)
    R835404 (Final)
    R835407 (Final)
    R835877 (2016)
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  • Journal Article Saha PK, Khlystov A, Yahya K, Zhang Y, Xu L, Ng NL, Grieshop AP. Quantifying the volatility of organic aerosol in the southeastern US. Atmospheric Chemistry and Physics 2017;17(1):501-520. R835403 (2015)
    R835403 (Final)
    R835411 (2014)
    R835411 (2015)
    R835411 (2016)
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  • Journal Article Xu L, Guo H, Boyd CM, Klein M, Bougiatioti A, Cerully KM, Hite JR, Isaacman-VanWertz G, Kreisberg NM, Knote C, Olson K, Koss A, Goldstein AH, Hering SV, de Gouw JA, Baumann K, Lee S-H, Nenes A, Weber RJ, Ng NL. Effects of anthropogenic emissions on aerosol formation from isoprene and monoterpenes in the southeastern United States. Proceedings of the National Academy of Sciences of the United States of America 2015;112(1):37-42. R835403 (2014)
    R835403 (2015)
    R835403 (Final)
    R834799 (2015)
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    R834799 (Final)
    R834799C001 (2015)
    R834799C001 (Final)
    R835410 (2013)
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  • Journal Article Xu L, Middlebrook AM, Liao J, de Gouw JA, Guo H, Weber RJ, Nenes A, Lopez-Hilfiker FD, Lee BH, Thornton JA, Brock CA, Neuman JA, Nowak JB, Pollack IB, Welti A, Graus M, Warneke C, Ng NL. Enhanced formation of isoprene-derived organic aerosol in sulfur-rich power plant plumes during Southeast Nexus. Journal of Geophysical Research: Atmospheres 2016;121(18):11137-11153. R835403 (Final)
    R835410 (2013)
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  • Journal Article Xu L, Guo H, Weber RJ, Ng NL. Chemical characterization of water-soluble organic aerosol in contrasting rural and urban environments in the Southeastern United States. Environmental Science & Technology 2017;51(1):78-88. R835403 (2015)
    R835403 (Final)
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  • Supplemental Keywords:

    organic nitrates, partitioning, semivolatiles, multifunctional oxidation products

    Relevant Websites:

    http://ng.chbe.gatech.edu Exit

    http://www.atmosphere.eas.gatech.edu/no3workshop Exit

    http://meeting2016.aaar.org/special-symposia Exit

    Progress and Final Reports:

    Original Abstract
    2013 Progress Report
    2014 Progress Report
    2015 Progress Report