Grantee Research Project Results
2004 Progress Report: Measurement, Modeling and Analysis Methods for Airborne Carbonaceous Fine Particulate Matter (PM2.5)
EPA Grant Number: R831086Title: Measurement, Modeling and Analysis Methods for Airborne Carbonaceous Fine Particulate Matter (PM2.5)
Investigators: Chow, Judith C. , Chen, Lung-Wen Antony , Watson, John L. , Arnott, William P. , Barber, Peter W. , Paredes-Miranda, Guadalupe , Moosmuller, Hans
Institution: Desert Research Institute
EPA Project Officer: Chung, Serena
Project Period: September 1, 2003 through August 31, 2006 (Extended to August 31, 2008)
Project Period Covered by this Report: September 1, 2003 through August 31, 2004
Project Amount: $449,456
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:
The objectives for this project are to: (1) determine which organic carbon (OC), elemental carbon (EC), and carbonate carbon (CC) compounds evolve at different temperatures; (2) specify how optical properties differ and change between particles in the air, particles on a filter, and particles undergoing changes caused by thermal analysis; (3) quantify difference in carbon fractions determined by commonly used thermal and optical analysis methods; and (4) optimize thermal and optical monitoring methods to meet multiple needs of health, visibility, global climate, and source apportionment.
Progress Summary:
Several tasks have been carried out to understand critical questions regarding thermal/optical carbon analysis. A radiative transfer scheme that considers absorption, scattering, and distribution of light-absorbing EC particles collected on a quartz-fiber filter was developed to explain simultaneous filter reflectance and transmittance observations prior to and during thermal/optical analysis. Pyrolized and charred organic carbon (POC) during thermal analysis reduces filter reflectance and transmittance in a way that supports a uniform distribution of POC throughout the filter. Small amounts of POC are found to dominate the incremental absorbance. Visual examination of filter darkening at different temperature stages confirms that much of the substantial charring takes place within the filter, possibly caused by adsorbed organic vapors or diffusion of vaporized particles. It also is observed that thermal/optical analysis using reflectance pyrolysis corrections (i.e., TOR) yields equivalent OC/EC splits for widely divergent temperature protocols. EC determined by simultaneous thermal/optical transmittance (TOT) corrections is lower than by TOR and varies appreciably between different protocols.
It has been found that many detailed specifications of thermal analysis, such as temperature plateau, analysis/residence time per temperature plateau, and analysis atmosphere—usually unreported in the literature, contribute to the variability in the OC/EC split and carbon fraction measurements. Low-temperature (< 250°C) carbon fractions appear to be independent of the trace oxygen level in the analysis atmosphere, but are sensitive to analytical temperature. Higher temperature OC fractions (450-550°C) depend on both temperature and oxidant level. Mineral oxides that coexist with carbonaceous material may decompose during heating, providing the oxygen necessary for EC combustion and changing the OC/EC split. These biases propagate into the current evaluations of health effects, visibility reduction, and climate forcing resulting from carbonaceous aerosol. Audit procedures for temperature, atmosphere, and optics during thermal analysis were developed. These techniques are systematized into procedures that can be applied to a wide variety of instruments, thereby allowing variability in the analysis to be reduced.
Future Activities:
During the next reporting period we plan to:
- Improve the precision of carbon fraction measurements and understand their responses to the analytical protocols, sources, and types of carbonaceous material.
- Develop standard or reference carbonaceous material samples for the calibration of thermal/optical analysis methods.
- Link light-absorption properties of fine particles and related radiative forcing estimates to the thermal/optical EC measurements and quantify their uncertainties.
- Refine the current thermal/optical protocols to meet the needs of health, visibility, global climate, and source apportionment.
Journal Articles on this Report : 3 Displayed | Download in RIS Format
| Other project views: | All 108 publications | 32 publications in selected types | All 29 journal articles |
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Chen L-WA, Chow JC, Watson JG, Moosmuller H, Arnott WP. Modeling reflectance and transmittance of quartz-fiber filter samples containing elemental carbon particles: implications for thermal/optical analysis. Journal of Aerosol Science 2004;35(6):765-780. |
R831086 (2004) R831086 (Final) |
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Chow JC, Watson JG, Chen L-WA, Arnott WP, Moosmuller H, Fung K. Equivalence of elemental carbon by thermal/optical reflectance and transmittance with different temperature protocols. Environmental Science & Technology 2004;38(16):4414-4422. |
R831086 (2004) R831086 (Final) |
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El-Zanan HS, Lowenthal DH, Zielinska B, Chow JC, Kumar N. Determination of the organic aerosol mass to organic carbon ratio in IMPROVE samples. Chemosphere 2005;60(4):485-496. |
R831086 (2004) R831086 (2005) R831086 (Final) |
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Supplemental Keywords:
thermal protocols, optical monitoring methods, visibility, light-absorbing carbon, black carbon, radiative forcing, air toxics, particulate matter, PM2.5, aerosol analyzers, aerosol particles, air sampling, airborne particulate matter, carbon aerosols, carbon particles, carbonaceous particulate,, RFA, Air, Ecosystem Protection/Environmental Exposure & Risk, Scientific Discipline, PHYSICAL ASPECTS, Physical Processes, particulate matter, Air Quality, Environmental Chemistry, Engineering, Chemistry, & Physics, Analytical Chemistry, Monitoring/Modeling, air toxics, Environmental Engineering, aerosol particles, atmospheric dispersion models, particle size, air sampling, gas chromatography, mass spectrometry, carbon particles, emissions, chemical characteristics, air quality modeling, environmental monitoring, measurement methods, aersol particles, airborne particulate matter, atmospheric particles, modeling studies, thermal desorption, particulate matter mass, air quality model, particulate organic carbon, analysis of organic particulate matter, exposure, carbon aerosols, aerosol analyzers, air quality models, atmospheric particulate matter, particle phase molecular markers, ultrafine particulate matter, chemical speciation sampling, particle size measurement, atmospheric measurements, air modeling, carbonaceous particulate matter, PM 2.5Progress 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.