Grantee Research Project Results
2007 Progress Report: Source-Oriented Chemical Transport Model for Primary and Secondary Organic Aerosol
EPA Grant Number: R831082Title: Source-Oriented Chemical Transport Model for Primary and Secondary Organic Aerosol
Investigators: Kleeman, Michael J. , Griffin, Robert J. , Clegg, Simon
Institution: University of California - Davis , University of East Anglia , University of New Hampshire
Current Institution: University of California - Davis , University of New Hampshire
EPA Project Officer: Chung, Serena
Project Period: October 1, 2003 through September 30, 2006 (Extended to September 30, 2008)
Project Period Covered by this Report: October 1, 2006 through September 30, 2007
Project Amount: $450,000
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:
Model the formation of secondary organic aerosol using a state-of-the-science air quality model, and to determine source contributions to primary organic aerosol (POA) and secondary organic aerosol (SOA) concentrations in Los Angeles, the San Joaquin Valley, and St. Louis. In the first phase of the project we will determine if the treatment of the aerosol as an internal mixture in bulk equilibrium with the surrounding gas phase biases SOA calculations. In the second phase of the project we will predict source contributions to primary and secondary organic aerosl, and compare these predictions to the results of receptor-oriented source aportionment models where possible. Improvements will be made to the mechanisms that predict SOA formation throughout the project so that the most accurate source apportionment can be achieved.
Progress Summary:
The UCD/CIT source-oriented air quality model has been used to predict source contributions to the regional distribution of primary organic aerosol in the South Coast Air Basin (SoCAB) and the San Joaquin Valley (SJV). Results are in reasonable agreement with CMB source contribution predictions at locations where measurements are available to support CMB analysis.
The latest version of CACM was integrated into the UCD/CIT source-oriented air quality model and comparisons were made to previous mechanisms (SAPRC90) to verify performance during a severe photochemical smog episode in the SoCAB on Sept 7-9, 1993. Total particulate organic carbon concentration predictions were still a factor of two lower than measured values in the SoCAB. Modeling the SOA formation process as a source-oriented external mixture did not have a significant effect on the results due to a general lack of detailed understanding about the effect of composition on SOA formation processes.
Reasonable ranges of vapor pressures for semi-volatile organic surrogate species were calculated using a several alternative compound estimation techniques. Simulations conducted for the South Coast Air Basin during a severe photochemical smog event showed that uncertainty in estimated vapor pressures for surrogate species could change predicted SOA concentrations by a factor of two.
The CACM was expanded so that parent hydrocarbons released from different sources could be tracked through the photochemical mechanism and their contributions to SOA formation could be quantified. Simulations for the South Coast Air Basin on Sept 7-9, 1993 show that transportation is the single largest anthropogenic source of SOA in the region.
Preliminary calculations for the San Joaquin Valley (SJV) show that predicted SOA concentrations during a severe winter stagnation event are 5-7 μg m-3. These concentrations are larger than those predicted in the SoCAB during a much hotter stagnation event. The reason for the increased concentrations is still under investigation. A leading reason may reduced vapor pressures for semi-volatile organic compounds during cold winter conditions.
SOA predictions for St. Louis are currently underway.
Future Activities:
Predictions for source contributions to primary and secondary organic aerosol will be made for St. Louis and the eastern US. Manuscripts describing ongoing work will be submitted for publication.
Journal Articles on this Report : 10 Displayed | Download in RIS Format
| Other project views: | All 28 publications | 13 publications in selected types | All 13 journal articles |
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Chen J, Griffin RJ. Modeling secondary organic aerosol formation from oxidation of α-pinene, β-pinene, and d-limonene. Atmospheric Environment 2005;39(40):7731-7744. |
R831082 (2004) R831082 (2005) R831082 (2006) R831082 (2007) R831082 (Final) |
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Chen J, Mao H, Talbot RW, Griffin RJ. Application of the CACM and MPMPO modules using the CMAQ model for the eastern United States. Journal of Geophysical Research--Atmospheres 2006;111(D23):D23S25 (12 pp.). |
R831082 (2006) R831082 (2007) R831082 (Final) R831454 (2005) R831454 (2006) R831454 (2007) R831454 (Final) |
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Clegg SL, Kleeman MJ, Griffin RJ, Seinfeld JH. Effects of uncertainties in the thermodynamic properties of aerosol components in an air quality model – Part 1: treatment of inorganic electrolytes and organic compounds in the condensed phase. Atmospheric Chemistry and Physics 2008;8(4):1057-1085. |
R831082 (2006) R831082 (2007) R831082 (Final) |
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Clegg SL, Kleeman MJ, Griffin RJ, Seinfeld JH. Effects of uncertainties in the thermodynamic properties of aerosol components in an air quality model – Part 2: predictions of the vapour pressures of organic compounds. Atmospheric Chemistry and Physics 2008;8(4):1087-1103. |
R831082 (2006) R831082 (2007) R831082 (Final) |
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Griffin RJ, Dabdub D, Seinfeld JH. Development and initial evaluation of a dynamic species-resolved model for gas phase chemistry and size-resolved gas/particle partitioning associated with secondary organic aerosol formation. Journal of Geophysical Research – Atmospheres 2005;110(D5):D05304 (16 pp.). |
R831082 (2004) R831082 (2005) R831082 (2006) R831082 (2007) R831082 (Final) |
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Held T, Ying Q, Kleeman MJ, Schauer JJ, Fraser MP. A comparison of the UCD/CIT air quality model and the CMB source-receptor model for primary airborne particulate matter. Atmospheric Environment 2005;39(12):2281-2297. |
R831082 (2004) R831082 (2005) R831082 (2006) R831082 (2007) R831082 (Final) |
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Kleeman MJ, Ying Q, Lu J, Mysliwiec MJ, Griffin RJ, Chen J, Clegg S. Source apportionment of secondary organic aerosol during a severe photochemical smog episode. Atmospheric Environment 2007;41(3):576-591. |
R831082 (2005) R831082 (2006) R831082 (2007) R831082 (Final) |
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Vutukuru S, Griffin RJ, Dabdub D. Simulation and analysis of secondary organic aerosol dynamics in the South Coast Air Basin of California. Journal of Geophysical Research–Atmospheres 2006;111(D10):D10S12 (13 pp.). |
R831082 (2005) R831082 (2006) R831082 (2007) R831082 (Final) |
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Ying Q, Kleeman MJ. Source contributions to the regional distribution of secondary particulate matter in California. Atmospheric Environment 2006;40(4):736-752. |
R831082 (2004) R831082 (2005) R831082 (2006) R831082 (2007) R831082 (Final) |
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Ying Q, Fraser MP, Griffin RJ, Chen J, Kleeman MJ. Verification of a source-oriented externally mixed air quality model during a severe photochemical smog episode. Atmospheric Environment 2007;41(7):1521-1538. |
R831082 (2005) R831082 (2006) R831082 (2007) R831082 (Final) |
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Supplemental Keywords:
Secondary Organic Aerosols, Source-oriented Chemical Transport Model, Source Apportionment, Inorganic - Organic Interactions,, RESEARCH, RFA, Air, Ecosystem Protection/Environmental Exposure & Risk, Scientific Discipline, particulate matter, Air Quality, Environmental Chemistry, Engineering, Chemistry, & Physics, Analytical Chemistry, Monitoring/Modeling, Air Pollution Effects, air toxics, Environmental Engineering, Environmental Monitoring, Monitoring, aerosol particles, health effects, source oriented CMT, atmospheric dispersion models, secondary organic aerosol, particle size, air sampling, gas chromatography, mass spectrometry, carbon particles, emissions, monitoring stations, air quality modeling, measurement methods, human exposure, modeling studies, secondary organic aerosols, thermal desorption, particulate matter mass, air quality model, carbon aerosols, aerosol analyzers, particle phase molecular markers, air quality models, atmospheric particulate matter, transport modeling, particle dispersion, human health effects, atmospheric measurements, modeling, monitoring of organic particulate matterProgress 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.