Grantee Research Project Results
2006 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, 2005 through October 31, 2006
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 general objective of this 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 nine different collection strategies was used to collect samples from the diluted exhaust of a 35 kW diesel generator running at 25 percent load. Ambient samples previously collected in Riverside CA receptor site in conjunction with the Study of Organic Aerosols at Riverside (SOAR) and in a source dominated site in Pico Rivera, CA, were analyzed for organic carbon (OC) and elemental carbon (EC). Table 1 shows measurement data from a typical day. The following conclusions were drawn:
- The POC accounted for approximately 25 percent of the PM2.5 mass.
- Artifact POC was typically 30-40% by the traditional method of estimating from the quartz filter behind a Teflon filter.
- The EC on impactor substrates was variable and may be better estimated 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.
- The denuders under these conditions were not highly efficient.
- 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 or leakage by the impactors or enhanced adsorption of volatile organic carbon (VOC) and volatilized particulate organic carbon (VPOC) at lower pressures.
- The background of the carbon-impregnated filters was more than half of the amount from sampling and led to variable results.
Table 1. Summary of the Results (μg/m3) of the Sample Set Collected 10/02/05 at Pico Rivera, CA
* corrected for background equivalent of 2.98 μg/m3.
Future Activities:
Source samples will be analyzed for OC and EC content. As a quality control step, an independent laboratory will analyze selected samples for OC and EC. The full data set will be analyzed with respect to collection artifacts and a final report will be submitted.
Journal Articles:
No journal articles submitted with this report: View all 2 publications for this projectSupplemental Keywords:
POC, OC, EC, sampling artifact, denuder, filter,, 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/publications.asp 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.