A study of secondary organic aerosol formation in the anthropogenic‐influenced southeastern United States

Weber, R. J.; Sullivan, A.; Peltier, Richard E.; Russell, Armistead G.; Yan, Bo; Zheng, Mei; Gouw, J. A. de; Warneke, C.; Brock, C. A.; Holloway, J. S.; Atlas, Elliot L.; Edgerton, Eric S.

doi:10.1029/2007jd008408

Cited by 578 publications

(667 citation statements)

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“…Figure 1A summarizes observed ∆OA/∆CO enhancement ratios from different studies that were influenced by urban emissions. Red lines are estimates of emission ratios (POA) (7,12,13,(22)(23)(24)(25); blue lines were obtained in aged air (POA + SOA) (7,9,(17)(18)(19)22). These results were determined from field studies on three continents and indicate that the ∆OA/∆CO ratios in aged urban air are systematically higher.…”

Section: Urban Sourcesmentioning

confidence: 96%

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Organic Aerosols in the Earth’s Atmosphere

Gouw

Jimenez²

2009

Environ. Sci. Technol.

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Organic particles are abundant in the troposphere and important for air quality and climate, but what are their sources?Aerosols, microscopically small particles suspended in air, are an important species in the Earth's atmosphere and influence both air quality and climate. Aerosols are small enough to penetrate deep into the lungs of people and have been linked to severe short-and long-term health effects such as asthma, cardio-respiratory disease, and lung cancer. Aerosols impact the Earth's climate directly through the scattering and absorption of solar radiation, and indirectly through their role as cloud-condensation nuclei. A large fraction (∼50%) of the submicron aerosol mass in the troposphere consists of organic material (1, 2). Direct emissions of organic aerosol (primary organic aerosol or POA) are distinguished from secondary organic aerosol (SOA) formed in the atmosphere from gas-phase precursors. Both POA and the precursors of SOA can be from urban, biogenic, and biomass burning sources. Our understanding of each of these sources is limited at present (3, 4), which hinders the efforts to mitigate the adverse effects. In this feature article, we briefly review the latest insights from field studies into the sources of organic aerosol (OA). Many results were obtained using two relatively new methods for quantifying OA on time scales of minutes: particle-into-liquid sampling combined with total organic carbon analysis for measurements of water-soluble organic carbon (5) and aerosol mass spectrometry (AMS) (6); both have been evaluated in detail against other reported methods, both in terms of the mass loading (7-10) as well as the source apportionment (11-13) of organic aerosol. Urban SourcesGlobal models predict that urban sources of OA are small compared with biomass burning emissions and biogenic SOA formation (4). Nevertheless, several recent studies found that OA was well correlated with tracers of urban pollution such as CO, acetylene (C 2 H 2 ), iso-propylnitrate, and odd oxygen (O 3 + NO 2 ) (8,(14)(15)(16)(17), suggesting that the influence of urban emissions may be larger than previously recognized. These studies showed that the good correlation is not due to emissions of POA, but to a rapid growth of SOA in urban air that overwhelms the direct POA emissions within a few hours of photochemical processing (8,(18)(19)(20).The atmospheric variability in OA is due to the spatial distribution of emissions, transport, chemical transformation, and removal by deposition. By normalizing OA to an inert combustion tracer such as CO or acetylene, the variability due to emissions and transport can be accounted for to a certain extent (8). Enhancement ratios of OA versus CO are denoted as ∆OA/∆CO, where ∆ indicates the excess amount over the background concentration. Accounting for backgrounds is important particularly when using a long-lived species such as CO. In practice, enhancement ratios are often calculated from correlation slopes between OA and CO (7). CO can also be formed from biogenic volatile ...

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Section: Urban Sourcesmentioning

confidence: 96%

“…Two studies argued that all these findings can be reconciled if biogenic SOA formation is more efficient in polluted air (8,17). In that scenario, the organic carbon is biogenic, but the OA correlates with anthropogenic tracers.…”

Section: Biogenic Sourcesmentioning

confidence: 99%

Organic Aerosols in the Earth’s Atmosphere

Gouw

Jimenez²

2009

Environ. Sci. Technol.

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389

303

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“…The importance of SOC has been recognized for decades due to its impact on visibility, climate, and health; however, most studies have focused on urban areas (Cao et al, 2004;Feng et al, 2009;Weber et al, 2007) and there have been few studies on the remote marine atmosphere. A common method, which was introduced by Turpin (Turpin and Huntzicker, 1995) and developed by Castro (Castro et al, 1999), was used to quantify the contributions of primary organic carbon (POC) and SOC to total organic carbon (TOC).…”

Section: Secondary Organic Carbon (Soc)mentioning

confidence: 99%

Characterization of carbonaceous aerosols over the East China Sea: The impact of the East Asian continental outflow

Wang

Guo

Lin

et al. 2015

Atmospheric Environment

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“…Moreover, none of the models capture the higher PM 2.5 /NO y for Houston relative to Dallas, and if the low emission ratios for WRF/Chem are representative of true emission ratios, a strong photochemical source of organic PM 2.5 missing from the models is required to explain the observations. Possible sources of missing OA in global-and regional-scale models have been the subject of recent inquiry [Heald et al, 2005;Volkamer et al, 2006] with no clear consensus on biogenic versus anthropogenic origin of the missing sources [Weber et al, 2007;de Gouw et al, 2008]. 5.2.5.…”

Section: Co/no Y Emission Ratiosmentioning

confidence: 99%

“…[48] The high correlation between OA and CO has been used to argue for an anthropogenic component to OA formation over the northeast United States [Sullivan et al, 2006;de Gouw et al, 2008], and over Atlanta [Weber et al, 2007]. The U.S. studies imply DOA/DCO of $0.01 mg/m 3 / ppbv from primary emissions [de Gouw et al, 2008] consistent with emission inventories [Bond et al, 2004], reaching peak values of $0.04 mg/m 3 /ppbv on the time scale of 12 to 24 h. Figure 13 shows Dorganic PM 2.5 /DCO excess ratios for Dallas and Houston, and for those transects between 10 km upwind and 50 km downwind of the assigned city centers.…”

Section: Co/no Y Emission Ratiosmentioning

confidence: 99%

An evaluation of real‐time air quality forecasts and their urban emissions over eastern Texas during the summer of 2006 Second Texas Air Quality Study field study

et al. 2009

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[1] Forecasts of ozone (O 3 ) and particulate matter (diameter less than 2.5 mm, PM 2.5 ) from seven air quality forecast models (AQFMs) are statistically evaluated against observations collected during August and September of 2006 (49 days) through the Aerometric Information Retrieval Now (AIRNow) network throughout eastern Texas and adjoining states. Ensemble O 3 and PM 2.5 forecasts created by combining the seven separate forecasts with equal weighting, and simple bias-corrected forecasts, are also evaluated in terms of standard statistical measures, threshold statistics, and variance analysis. For O 3 the models and ensemble generally show statistical skill relative to persistence for the entire region, but fail to predict high-O 3 events in the Houston region. For PM 2.5 , none of the models, or ensemble, shows statistical skill, and all but one model have significant low bias. Comprehensive comparisons with the full suite of chemical and aerosol measurements collected aboard the NOAA WP-3 aircraft during the summer 2006 Second Texas Air Quality Study and the Gulf of Mexico Atmospheric Composition and Climate Study (TexAQS II/GoMACCS) field study are performed to help diagnose sources of model bias at the surface. Aircraft flights specifically designed for sampling of Houston and Dallas urban plumes are used to determine model and observed upwind or background biases, and downwind excess concentrations that are used to infer relative emission rates. Relative emissions from the U.S. Environmental Protection Agency 1999 National Emission Inventory (NEI-99) version 3 emissions inventory (used in two of the model forecasts) are evaluated on the basis of comparisons between observed and model concentration difference ratios. Model comparisons demonstrate that concentration difference ratios yield a reasonably accurate measure (within 25%) of relative input emissions. Boundary layer height and wind data are combined with the observed up-wind and downwind concentration differences to estimate absolute emissions. When the NEI-99 inventory is modified to include observed NO y emissions from continuous monitors and expected NO x decreases from mobile sources between 1999 and 2006, good agreement is found with those derived from the observations for both Houston and Dallas. However, the emission inventories consistently overpredict the ratio of CO to NO y . The ratios of ethylene and aromatics to NO y are reasonably consistent with observations over Dallas, but are significantly underpredicted for Houston.

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A study of secondary organic aerosol formation in the anthropogenic‐influenced southeastern United States

Cited by 578 publications

References 38 publications

Organic Aerosols in the Earth’s Atmosphere

Organic Aerosols in the Earth’s Atmosphere

Characterization of carbonaceous aerosols over the East China Sea: The impact of the East Asian continental outflow

An evaluation of real‐time air quality forecasts and their urban emissions over eastern Texas during the summer of 2006 Second Texas Air Quality Study field study

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