Research Projects

Project at a Glance

Title: Analysis of ATOFMS datasets for apportionment of PM2.5 in California

Principal Investigator / Author(s): Prather, Kimberly

Contractor: UC San Diego

Contract Number: 07-357

Research Program Area: Atmospheric Processes

Topic Areas: Chemistry & Reactivity, Mobile Sources & Fuels, Modeling


The development of aerosol time-of-flight mass spectrometry (ATOFMS) as a source apportionment tool for atmospheric particulate matter using California Air Resources Board funding has focused on the differentiation of sources by identifying the unique mass spectra of single particles produced in source tests and the atmosphere. By acquiring both the positive and negative spectra of each particle, significant progress has been made in quantifying the contributions from both natural and anthropogenic particles that impact California air quality. Specifically, studies have shown how heavy duty diesel vehicles, gasoline vehicles, biomass burning, ships, sea spray, and dust impact air quality in many regions. This report details efforts to expand the boundaries for on-line chemical analysis methods, such as ATOFMS, that will allow their general implementation in many areas in an effort to increase our understanding of particle sources and processes in the atmosphere. A major focus of one project in this report involves investigating the sources of sulfate and the interplay between anthropogenic and biogenic sources of SO2, sulfate, and particle mass concentrations. To investigate the primary sources of PM, the results of tandem thermal denuder-ATOFMS measurements are described that give information on the volatility and fractions of secondary components within the aerosol including sulfate, nitrate, and organic carbon species. Lastly, the application of the source library that has been developed to match studies to specific sources is tested in two urban areas outside of California to show the broad applicability of this method for source apportionment. Taken together the results of this report demonstrate the level of new information on particle sources that on-line mass spectrometry can provide when applied in new and innovative ways.

Please see the Final Report for Contract 04-336 for related work.


For questions regarding research reports, contact: Heather Choi at (916) 322-3893

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