Grantee Research Project Results
Final Report: Fundamental Experimental and Modeling Studies of Secondary Organic Aerosol
EPA Grant Number: R831075Title: Fundamental Experimental and Modeling Studies of Secondary Organic Aerosol
Investigators: Seinfeld, John
Institution: California Institute of Technology
EPA Project Officer: Chung, Serena
Project Period: July 1, 2003 through June 30, 2006
Project Amount: $449,991
RFA: Measurement, Modeling, and Analysis Methods for Airborne Carbonaceous Fine Particulate Matter (PM2.5) (2003) RFA Text | Recipients Lists
Research Category: Particulate Matter , Air Quality and Air Toxics , Air
Objective:
Ambient particulate matter (PM) has been implicated strongly in human health effects, in that elevated instances of morbidity and mortality are associated with elevated concentrations of PM. In order to devise effective strategies for abating PM levels, it is necessary to know the sources of the chemical components of ambient aerosol. Carbonaceous compounds constitute as much as one-half the mass of ambient PM, and a principal source of carbonaceous PM is so-called secondary organic aerosol, that is, organic compounds that enter the particulate phase as a result of the gas-phase oxidation of volatile organic compounds. This research has as its goal developing a fundamental understanding of the process that leads to secondary organic aerosol in the atmosphere through well-controlled laboratory chamber studies.
Summary/Accomplishments (Outputs/Outcomes):
The current STAR project has led to a number of important findings about the nature and formation of ambient secondary organic aerosol. These include:
Isoprene (C5H8) is the second most abundant hydrocarbon emitted into the Earth’s atmosphere after methane. Emitted almost entirely by vegetation, isoprene is known to react readily in the atmosphere, but it has long been assumed that when isoprene reacts all its products remain in the gas phase and no particles are formed. If isoprene were to produce even a small amount of aerosol when it reacts, because it is emitted in such enormous amounts, this would have a profound effect on the sources of organic aerosol in the atmosphere. In a comprehensive series of laboratory chamber experiments, we have shown that isoprene does produce secondary organic aerosol upon atmospheric oxidation at a mass yield of about 2 percent. We have worked out the detailed photochemistry and have shown that the mechanism of particle formation depends critically on the level of nitrogen oxides in the atmosphere. Airborne measurements by the P.I.’s group and others, such as in ACE-Asia, revealed a ubiquitous level of organic aerosol in the troposphere that is not explained by current atmospheric models. The finding that isoprene, the atmosphere’s second most abundant hydrocarbon, produces aerosol appears to explain in part this globally uniform blanket of organic particles.
It has long been assumed that the chemical reactions that lead to organic PM occur exclusively in the gas phase. Under this STAR grant, we have shown that submicron-sized atmospheric organic particles are a fertile site for aerosol-phase chemistry, including organic polymerization reactions that may be catalyzed by particle-phase acidity arising from the ubiquitous sulfate compounds that are present in PM. This particle-phase chemistry profoundly affects the rate of secondary organic aerosol formation.
Conclusions:
A significant fraction of atmospheric organic aerosols are formed through in-situ oxidation of precursor hydrocarbons followed by partitioning of low-volatility products into the aerosol phase. This component of atmospheric organic aerosols is referred to as secondary organic aerosol (SOA). Understanding the mechanisms of formation of SOA represents an outstanding problem. Recent discoveries have indicated that full understanding of the molecular mechanisms of SOA formation is lacking. A number of laboratory studies, including the present work, have identified polymeric species as potentially major components in secondary organic aerosols from the ozonolysis of a-pinene, isoprene, and a number of cycloalkenes. It has been proposed that these polymers are formed in the aerosol phase through heterogeneous reactions involving oxidation products with low mw (below 200 Da). In light of these results, it becomes crucial to understand heterogeneous reactions that occur and the effect of such reactions on formation of SOA. Another factor that is emerging as crucial in SOA formation is the NOx level. We have carried out a comprehensive study of SOA formation from key biogenic and anthropogenic precursor hydrocarbons, spanning a range of particle acidity, temperature, and relative humidity.
In summary, this STAR grant has led to 19 publications on the chemistry and formation of secondary organic aerosols, which have literally changed the way we view (and represent in atmospheric models) secondary organic aerosol formation.
Journal Articles on this Report : 24 Displayed | Download in RIS Format
| Other project views: | All 24 publications | 24 publications in selected types | All 24 journal articles |
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Asa-Awuku A, Nenes A, Gao S, Flagan RC, Seinfeld JH. Water-soluble SOA from alkene ozonolysis: composition and droplet activation kinetics inferences from analysis of CCN activity. Atmospheric Chemistry and Physics 2010;10(4):1585-1597. |
R831075 (Final) |
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Bahreini R, Keywood MD, Ng NL, Varutbangkul V, Gao S, Flagan RC, Seinfeld JH, Worsnop DR, Jimenez JL. Measurements of secondary organic aerosol from oxidation of cycloalkenes, terpenes, and m-xylene using an Aerodyne aerosol mass spectrometer. Environmental Science & Technology 2005;39(15):5674-5688. |
R831075 (2005) R831075 (Final) |
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Clegg SL, Seinfeld JH. Thermodynamic models of aqueous solutions containing inorganic electrolytes and dicarboxylic acids at 298.15 K. 1. The acids as nondissociating components. The Journal of Physical Chemistry A 2006;110(17):5692-5717. |
R831075 (Final) |
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Clegg SL, Seinfeld JH. Thermodynamic models of aqueous solutions containing inorganic electrolytes and dicarboxylic acids at 298.15 K. 2. Systems including dissociation equilibria. The Journal of Physical Chemistry A 2006;110(17):5718-5734. |
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Gao S, Ng NL, Keywood M, Varutbangkul V, Bahreini R, Nenes A, He J, Yoo KY, Beauchamp JL, Hodyss RP, Flagan RC, Seinfeld JH. Particle phase acidity and oligomer formation in secondary organic aerosol. Environmental Science & Technology 2004;38(24):6582-6589. |
R831075 (2004) R831075 (2005) R831075 (Final) |
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Gao S, Keywood M, Ng NL, Surratt J, Varutbangkul V, Bahreini R, Flagan RC, Seinfeld JH. Low-molecular-weight and oligomeric components in secondary organic aerosol from the ozonolysis of cycloalkenes and α-pinene. The Journal of Physical Chemistry A 2004;108(46):10147-10164. |
R831075 (2004) R831075 (2005) R831075 (Final) |
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Henze DK, Seinfeld JH. Global secondary organic aerosol from isoprene oxidation. Geophysical Research Letters 2006;33(9):L09812 (4 pp.). |
R831075 (Final) R832158 (2006) R832158 (2007) R832158 (Final) |
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Keywood MD, Varutbangkul V, Bahreini R, Flagan RC, Seinfeld JH. Secondary organic aerosol formation from the ozonolysis of cycloalkenes and related compounds. Environmental Science & Technology 2004;38(15):4157-4164. |
R831075 (2004) R831075 (Final) |
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Keywood MD, Kroll JH, Varutbangkul V, Bahreini R, Flagan RC, Seinfeld JH. Secondary organic aerosol formation from cyclohexene ozonolysis:effect of OH scavenger and the role of radical chemistry. Environmental Science & Technology 2004;38(12):3343-3350. |
R831075 (2004) R831075 (Final) |
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Kroll JH, Ng NL, Murphy SM, Varutbangkul V, Flagan RC, Seinfeld JH. Chamber studies of secondary organic aerosol growth by reactive uptake of simple carbonyl compounds. Journal of Geophysical Research-Atmospheres 2005;110(D23):D23207 (10 pp.). |
R831075 (2005) R831075 (Final) |
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Kroll JH, Seinfeld JH. Representation of secondary organic aerosol laboratory chamber data for the interpretation of mechanisms of particle growth. Environmental Science & Technology 2005;39(11):4159-4165. |
R831075 (2005) R831075 (Final) |
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Kroll JH, Ng NL, Murphy SM, Flagan RC, Seinfeld JH. Secondary organic aerosol formation from isoprene photooxidation under high-NOx conditions. Geophysical Research Letters 2005;32(18):L18808 (4 pp.). |
R831075 (2005) R831075 (Final) |
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Kroll JH, Ng NL, Murphy SM, Flagan RC, Seinfeld JH. Secondary organic aerosol formation from isoprene photooxidation. Environmental Science & Technology 2006;40(6):1869-1877. |
R831075 (Final) |
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Kroll JH, Chan AWH, Ng NL, Flagan RC, Seinfeld JH. Reactions of semivolatile organics and their effects on secondary organic aerosol formation. Environmental Science & Technology 2007;41(10):3545-3550. |
R831075 (Final) |
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Lee A, Goldstein AH, Keywood MD, Gao S, Varutbangkul V, Bahreini R, Ng NL, Flagan RC, Seinfeld JH. Gas-phase products and secondary aerosol yields from the ozonolysis of ten different terpenes. Journal of Geophysical Research--Atmospheres 2006;111(D7):D07302 (18 pp.). |
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Lee A, Goldstein AH, Kroll JH, Ng NL, Varutbangkul V, Flagan RC, Seinfeld JH. Gas-phase products and secondary aerosol yields from the photooxidation of 16 different terpenes. Journal of Geophysical Research--Atmospheres 2006;111(D17):D17305 (25 pp.). |
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Ng NL, Kroll JH, Keywood MD, Bahreini R, Varutbangkul V, Flagan RC, Seinfeld JH, Lee A, Goldstein AH. Contribution of first-versus second-generation products to secondary organic aerosols formed in the oxidation of biogenic hydrocarbons. Environmental Science & Technology 2006;40(7):2283-2297. |
R831075 (Final) |
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Ng NL, Kroll JH, Chan AWH, Chhabra PS, Flagan RC, Seinfeld JH. Secondary organic aerosol formation from m-xylene, toluene, and benzene. Atmospheric Chemistry and Physics 2007;7(14):3909-3922. |
R831075 (Final) |
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Surratt JD, Murphy SM, Kroll JH, Ng NL, Hildebrandt L, Sorooshian A, Szmigielski R, Vermeylen R, Maenhaut W, Claeys M, Flagan RC, Seinfeld JH. Chemical composition of secondary organic aerosol formed from the photooxidation of isoprene. The Journal of Physical Chemistry A 2006;110(31):9665-9690. |
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Surratt JD, Lewandowski M, Offenberg JH, Jaoui M, Kleindienst TE, Edney EO, Seinfeld JH. Effect of acidity on secondary organic aerosol formation from isoprene. Environmental Science & Technology 2007;41(15):5363-5369. |
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Surratt JD, Kroll JH, Kleindienst TE, Edney EO, Claeys M, Sorooshian A, Ng NL, Offenberg JH, Lewandowski M, Jaoui M, Flagan RC, Seinfeld JH. Evidence for organosulfates in secondary organic aerosol. Environmental Science & Technology 2007;41(2):517-527. |
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Szmigielski R, Surratt JD, Vermeylen R, Szmigielska K, Kroll JH, Ng NL, Murphy SM, Sorooshian A, Seinfeld JH, Claeys M. Characterization of 2-methylglyceric acid oligomers in secondary organic aerosol formed from the photooxidation of isoprene using trimethylsilylation and gas chromatography/ion trap mass spectrometry. Journal of Mass Spectrometry 2007;42(1):101-116. |
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VanReken TM, Ng NL, Flagan RC, Seinfeld JH. Cloud condensation nucleus activation properties of biogenic secondary organic aerosol. Journal of Geophysical Research-Atmospheres 2005;110(D7):D07206 (9 pp.). |
R831075 (2005) R831075 (Final) |
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Varutbangkul V, Brechtel FJ, Bahreini R, Ng NL, Keywood MD, Kroll JH, Flagan RC, Seinfeld JH, Lee A, Goldstein AH. Hygroscopicity of secondary organic aerosols formed by oxidation of cycloalkenes, monoterpenes, sesquiterpenes, and related compounds. Atmospheric Chemistry and Physics 2006;6(9):2367-2388. |
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Supplemental Keywords:
RFA, Air, Ecosystem Protection/Environmental Exposure & Risk, Scientific Discipline, POLLUTANTS/TOXICS, particulate matter, Environmental Chemistry, Monitoring/Modeling, Air Pollution Effects, air toxics, Chemicals, Environmental Engineering, Environmental Monitoring, aerosol particles, health effects, atmospheric dispersion models, secondary organic aerosol, air sampling, carbon particles, emissions, monitoring stations, measurement methods, modeling studies, secondary organic aerosols, particulate matter mass, air quality model, analysis of organic particulate matter, aerosol analyzers, air quality models, atmospheric particulate matter, particle phase molecular markers, transport modeling, Volatile Organic Compounds (VOCs), human health effects, atmospheric measurements, modelingProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.