Grantee Research Project Results
2005 Progress Report: Evaluation and Minimization of Organic Aerosol Sampling Artifacts Using Impactors and Quartz Fiber Filter Denuders
EPA Grant Number: R831087Title: Evaluation and Minimization of Organic Aerosol Sampling Artifacts Using Impactors and Quartz Fiber Filter Denuders
Investigators: Fitz, Dennis R.
Institution: University of California - Riverside
EPA Project Officer: Chung, Serena
Project Period: October 1, 2003 through October 31, 2007
Project Period Covered by this Report: October 1, 2004 through October 31, 2005
Project Amount: $187,030
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 objective of this research project is to provide an enhanced characterization of the magnitude and characteristics of particulate organic carbon (POC) measurement artifacts, so that the contribution and source of POC to fine particulate matter (PM2.5) can be assessed with greater certainty. The goal is to execute a comprehensive sampling study that utilizes the best available and emerging technologies and strategies, resulting in a robust data set from which clear conclusions concerning sampling artifacts can be drawn.
Progress Summary:
The sampling system that could simultaneously collect PM2.5 samples using 9 different collection strategies was used for 11 collection periods at a Riverside, California, receptor site in conjunction with the Study of Organic Aerosols at Riverside (SOAR) and for 8 collection periods in a source dominated site in Pico Rivera, California. Samples collected in 2004 in Riverside were analyzed for organic carbon (OC) and elemental carbon (EC), and Table 1 shows these results in schematic form for two composited days. The following conclusions were drawn:
- Artifact POC based on the amount of material under the quartz was over 50 percent by the traditional method of estimating from the quartz filter behind a Teflon filter.
- The quartz fiber filter denuder reduced this positive artifact by a factor of five and gives POC results similar to the traditional correction.
- A second quartz filter is needed below the Teflon-quartx filter pack to assess denuder efficiency.
- Charring is significant on impactor substrates and may be corrected for by adding together the impactor OC, impactor EC, and impactor back filter EC and subtracting from that sum the EC on the quartz front filter (sample line 1 without a denuder or sample line 2 with a denuder).
- Large amounts of OC were found on quartz filters below impactors (even when a pre-filter was used) whether a quartz fiber filter denuder was used or not. This indicates either contamination by the impactors or enhanced adsorption of volatile organic carbon (VOC) and volatile POC at lower pressures.
- The flows need to be lowered through the denuder or the quartz filter denuder lengthened to gain collection efficiency.
- Denuders at lowered pressure may lose significant efficiency.
Table 1. Summary of the Results From the 2004 Sample Collections
Future Activities:
Source samples will be collected and all samples (source and previously collected ambient) will be analyzed for organic and elemental carbon content. The data will be analyzed with respect to collection artifacts and a final report will be submitted. Reports and publications will be posted on the CE-CERT Web Site http://www.cert.ucr.edu/research/publications.asp Exit .
Journal Articles:
No journal articles submitted with this report: View all 2 publications for this projectSupplemental Keywords:
POC, OC, EC, sampling artifact, denuder, filter, aerosol analyzers, aerosol particles, air modeling, air pollutants, carbon aerosols, carbon particles,, RFA, Air, Scientific Discipline, Ecosystem Protection/Environmental Exposure & Risk, Waste, chemical mixtures, particulate matter, Air Quality, Environmental Chemistry, Engineering, Chemistry, & Physics, Monitoring/Modeling, Air Pollution Effects, Atmospheric Sciences, air toxics, Environmental Engineering, Environmental Monitoring, aerosol particles, health effects, particle size, air sampling, gas chromatography, mass spectrometry, carbon particles, emissions, chemical characteristics, air quality modeling, measurement methods, airborne particulate matter, atmospheric particles, quartz fiber filter denuders, modeling studies, thermal desorption, particulate matter mass, air quality model, particulate organic carbon, carbon aerosols, aerosol analyzers, air quality models, atmospheric particulate matter, impactors, ultrafine particulate matter, chemical speciation sampling, particle size measurement, air pollutants, particle dispersion, air modelingRelevant Websites:
http://www.cert.ucr.edu/research/project.asp?project=239 Exit
Progress 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.