Organic Aerosol Formation from Photochemical Oxidation of Diesel Exhaust in a Smog Chamber

Weitkamp, Emily A.; Sage, Amy M.; Pierce, Jeffrey R.; Donahue, Neil M.; Robinson, Allen L.

doi:10.1021/es070193r

Cited by 213 publications

(224 citation statements)

References 33 publications

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“…Fig. 1C shows the experimental observations of SOA mass concentration for the cases of two limiting particle-wall loss corrections (19,20): (i) wall-deposited particles are assumed to cease interaction with the gas phase (lower red line), and (ii) wall-deposited particles are assumed to continue interacting with the gas phase as if they were still suspended (upper red line). Fig.…”

Section: Resultsmentioning

confidence: 99%

Size distribution dynamics reveal particle-phase chemistry in organic aerosol formation

Shiraiwa

Yee

Schilling³

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

173

198

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Organic aerosols are ubiquitous in the atmosphere and play a central role in climate, air quality, and public health. The aerosol size distribution is key in determining its optical properties and cloud condensation nucleus activity. The dominant portion of organic aerosol is formed through gas-phase oxidation of volatile organic compounds, so-called secondary organic aerosols (SOAs). Typical experimental measurements of SOA formation include total SOA mass and atomic oxygen-to-carbon ratio. These measurements, alone, are generally insufficient to reveal the extent to which condensed-phase reactions occur in conjunction with the multigeneration gas-phase photooxidation. Combining laboratory chamber experiments and kinetic gas-particle modeling for the dodecane SOA system, here we show that the presence of particlephase chemistry is reflected in the evolution of the SOA size distribution as well as its mass concentration. Particle-phase reactions are predicted to occur mainly at the particle surface, and the reaction products contribute more than half of the SOA mass. Chamber photooxidation with a midexperiment aldehyde injection confirms that heterogeneous reaction of aldehydes with organic hydroperoxides forming peroxyhemiacetals can lead to a large increase in SOA mass. Although experiments need to be conducted with other SOA precursor hydrocarbons, current results demonstrate coupling between particle-phase chemistry and size distribution dynamics in the formation of SOAs, thereby opening up an avenue for analysis of the SOA formation process.

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Section: Resultsmentioning

confidence: 99%

Size distribution dynamics reveal particle-phase chemistry in organic aerosol formation

Shiraiwa

Yee

Schilling³

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

173

198

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“…The POA and BC concentrations were corrected for wall losses using the approach of Weitkamp et al (2007) …”

Section: Wall Loss Correctionsmentioning

confidence: 99%

Temperature Dependence of Gas–Particle Partitioning of Primary Organic Aerosol Emissions from a Small Diesel Engine

Ranjan

Presto

May

et al. 2012

Aerosol Science and Technology

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A new experimental technique has been developed to study the gas-particle partitioning behavior of primary organic aerosol (POA) emissions from combustion sources at atmospherically relevant concentrations. The technique involves slowly filling a Teflon chamber with a constant emission source. As aerosol concentrations increase inside the chamber, the gas-particle partitioning of semivolatile organics shifts to the particle phase, thus increasing the fuel-based POA emission factor. The technique allows characterization of partitioning under isothermal conditions and atmospherically relevant concentrations. The technique was evaluated using emissions from a small diesel engine; the measured changes in gas-particle partitioning agreed well with previously published data for this engine measured with a dilution sampler. The temperature dependence of the gas-particle partitioning was investigated by conducting experiments at three different temperatures (15• C, 26• C, and 33 • C). Increasing organic aerosol concentration and decreasing temperature increased the fuel-based POA emission factor. The gas-particle partitioning data were fit using absorptive partitioning theory to determine the volatility distribution and enthalpy of vaporization ( H v ) of the emissions. We have derived two fits; one using the volatility basis set approach and a second using a two-product model. Both fits are suitable for use in chemical transport models. These fits were tested using previously published thermodenuder data. Partitioning calculations predict that the gas-particle partitioning from POA emissions from this engine vary by about a factor of 4 across the atmospherically relevant range of temperature and organic aerosol concentrations. This underscores the semivolatile nature of POA emissions.

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“…Directly emitted, intermediate volatility organic compounds (IVOCs, defined as having an effective saturation concentration C * of 10 3 to 10 6 µg/m 3 ) and semi-volatile organic compounds (SVOCs, C * of 10 −1 to 10 3 µg/m 3 ) have been proposed as a substantial, yet unaccounted for source of secondary organic aerosol (SOA) precursors Weitkamp et al 2007). Estimated atmospheric abundances of directly emitted I/SVOCs can be an order of magnitude larger than primary organic aerosol (POA; Robinson et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Development of an In Situ Thermal Desorption Gas Chromatography Instrument for Quantifying Atmospheric Semi-Volatile Organic Compounds

Zhao

Kreisberg

Worton

et al. 2012

Aerosol Science and Technology

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Semi-volatile organic compounds (SVOCs) play a significant role in the formation of secondary organic aerosol, but their atmospheric abundance and chemical composition are poorly understood. We have developed a new system for the thermal desorption aerosol gas chromatograph (TAG) that extends its capability to quantitatively speciate SVOCs (semi-volatile TAG) having vapor pressures lower than tetradecane (C 14 ) with hourly time resolution. The key component is a passivated stainless steel fiber filter that quantitatively collects both gas and particle phase organic compounds. A separation between gas and particle phase collection is determined through a difference method by periodically sampling ambient air through a multichannel charcoal denuder that efficiently removes gas-phase compounds. Measurements made with this new instrument will provide constraints on the abundance, chemical composition, and gas-to-particle partitioning of atmospheric SVOCs and provide opportunities to improve our understanding of secondary organic aerosol formation in the atmosphere.

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Organic Aerosol Formation from Photochemical Oxidation of Diesel Exhaust in a Smog Chamber

Cited by 213 publications

References 33 publications

Size distribution dynamics reveal particle-phase chemistry in organic aerosol formation

Size distribution dynamics reveal particle-phase chemistry in organic aerosol formation

Temperature Dependence of Gas–Particle Partitioning of Primary Organic Aerosol Emissions from a Small Diesel Engine

Development of an In Situ Thermal Desorption Gas Chromatography Instrument for Quantifying Atmospheric Semi-Volatile Organic Compounds

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