Grantee Research Project Results

2005 Progress Report: Integrating the Thermal Behavior and Optical Properties of Carbonaceous Particles: Theory, Laboratory Studies, and Application to Field Data

EPA Grant Number: R831085
Title: Integrating the Thermal Behavior and Optical Properties of Carbonaceous Particles: Theory, Laboratory Studies, and Application to Field Data
Investigators: Bond, Tami C.
Institution: University of Illinois Urbana-Champaign
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, 2004 through August 31, 2005
Project Amount: $247,815
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:

This research relates to the measurement of carbonaceous particles with the common thermal/optical analyzers used at U.S. Environmental Protection Agency (EPA) monitoring sites. The objectives of this research project are to: (1) improve the confidence limits of combined thermal/optical transitions of specific fractions of primary carbonaceous aerosols; (2) confirm to 95 percent confidence that elemental carbon can be treated as a conserved tracer; and (3) demonstrate enhanced interpretations of thermal/optical analyses of carbonaceous particles for an existing database of field measurements.

Progress Summary:

We developed computer codes that read and process real-time thermal and optical information from the analyzers. This information is treated statistically: repeatability suggests an opportunity to identify individual particle components, while variation suggests a quantifiable uncertainty. We focus on the inferred relationships between release of total carbon and formation or release of light-absorbing carbon, not limiting our interest to the division between elemental and organic carbon. We propose a method for identifying the nature of transitions in mixed samples and the magnitude of the components in those samples. We have begun to explore this method for samples with simple composition.

We also developed methods for quantifying changes in thermal and optical traces. We applied these to samples in which we simulated atmospheric processing. Exposing elemental carbon to ultraviolet light and ozone did not cause a difference in response. Mixing with ammonium sulfate resulted in a small difference that is not expected to change either the elemental carbon measurement or the carbon released at different temperatures. Adding potassium chloride resulted in large differences in both inferred elemental carbon and the timing of release.

We have finalized an optical model of a particle-laden filter, and have used it to estimate how physical changes in particles would be interpreted as changes in elemental carbon. We have critically reviewed the literature on light-absorbing aerosol and incorporated the conclusions about optics and carbon materials into the filter model.

Future Activities:

During the final year of this project, we will develop the analysis that separates chemical components using the carbon-release and optical information. We will examine specific solvent-extractable components and mixtures of known compounds to determine uncertainties in the calculation statistically. Finally, we will apply the analysis to measurements from an ambient site.

Algorithms for both optical model and analysis interpretation are written in MatLab. We will make them available to the community via a Web site. We also will prepare two journal papers on the results of this research.

Journal Articles on this Report : 1 Displayed | Download in RIS Format

Publications Views
Other project views:	All 19 publications	5 publications in selected types	All 5 journal articles

Publications
Type	Citation	Project	Document Sources
Journal Article	Bond TC, Bergstrom RW. Light absorption by carbonaceous particles: an investigative review. Aerosol Science and Technology 2006;40(1):27-67.	R831085 (2005) R831085 (2006) R831085 (Final)	Full-text: Taylor and Francis-Full Text HTML Exit Abstract: Taylor and Francis-Abstract Exit Other: Taylor and Francis-Full Text PDF Exit

Supplemental Keywords:

ambient air, tropospheric, global climate, environmental chemistry, analytical, measurement methods, carbonaceous particles, carbonaceous aerosols, particle components, thermal, optical,, RFA, Scientific Discipline, Air, Ecosystem Protection/Environmental Exposure & Risk, particulate matter, Air Quality, Environmental Chemistry, Engineering, Chemistry, & Physics, Analytical Chemistry, Monitoring/Modeling, Air Pollution Effects, Atmospheric Sciences, air toxics, Environmental Engineering, Environmental Monitoring, aerosol particles, health effects, particle size, air sampling, carbon particles, emissions, chemical characteristics, air quality modeling, measurement methods, aersol particles, airborne particulate matter, thermal properties, atmospheric particles, modeling studies, thermal desorption, particulate matter mass, air quality model, particulate organic carbon, carbon aerosols, aerosol analyzers, particle phase molecular markers, air quality models, atmospheric particulate matter, ultrafine particulate matter, chemical speciation sampling, particle size measurement, particle dispersion, air modeling

Relevant Websites:

http://cee.uiuc.edu/research/bondresearch Exit

Progress and Final Reports:

Original Abstract

The 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.