Measurement, Modeling and Analysis Methods for Airborne Carbonaceous Fine Particulate Matter (PM2.5)EPA Grant Number: R831086
Title: Measurement, Modeling and Analysis Methods for Airborne Carbonaceous Fine Particulate Matter (PM2.5)
Investigators: Chow, Judith C. , Arnott, William P. , Barber, Peter W. , Chen, Lung-Wen Antony , Moosmuller, Hans , Watson, John L.
Current Investigators: Chow, Judith C. , Arnott, William P. , Barber, Peter W. , Chen, Lung-Wen Antony , Moosmuller, Hans , Paredes-Miranda, Guadalupe , Watson, John L.
Institution: Desert Research Institute
EPA Project Officer: Chung, Serena
Project Period: September 1, 2003 through August 31, 2006 (Extended to August 31, 2008)
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: Air , Air Quality and Air Toxics , Particulate Matter
A number of different analysis methods are commonly used to measure carbon, with each method yielding somewhat different results. The objectives of this research 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 owing to 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. This research is intended to provide a technical basis for refined thermal evolution analysis methods.
The first task will review literature from within and outside the field of air pollution, identifying OC and CC compounds that are likely to be in ambient air and associating them with ranges of atmospheric concentrations, vapor pressures, vaporization and/or decomposition temperatures, indices of refraction, and approximate abundances in primary source emissions. The second task will model solid layers with different indices of refraction to simulate material deposited on the surface of and throughout different filter media. The modeling will vary real and imaginary components of the refraction index and will calculate changes in reflectance and transmission as a function of filter loading and composition. Effects of internal mixtures and non-spherical particles will also be modeled. The third task will apply more than a dozen commonly used thermal and optical methods, as well as Raman spectroscopy, to Fresno supersite and IMPROVE network samples that were influenced by different sources to determine the causes of differences between methods and their relationship to the graphitic portion of EC. The final task will prepare samples on filters with different loadings from carbon black, carbonate powders, pure graphite, and several combustion source emissions while simultaneously monitoring with a photoacoustic method. Analysis by selected thermal and optical methods will determine the extent to which filter-deposits might be used as transfer standards among methods.
More refined temperature fractions for thermal/optical methods used in long-term networks will result. These will be compatible with previous methods while offering greater specificity for human health, visibility, global climate, and source apportionment applications, thereby facilitating the more productive use of large existing/continuing monitoring datasets.