Advancing ATOFMS to a Quantitative Tool for Source ApportionmentEPA Grant Number: R831083
Title: Advancing ATOFMS to a Quantitative Tool for Source Apportionment
Investigators: Prather, Kimberly A. , Hopke, Philip K.
Institution: University of California - San Diego , Clarkson University
EPA Project Officer: Chung, Serena
Project Period: October 1, 2003 through September 30, 2006 (Extended to September 30, 2007)
Project Amount: $450,000
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
The objective of this project is to further explore the aerosol time-of-flight mass spectrometry data collected during the Supersite program to ascertain if single particle mass spectrometry can: 1) quantitatively measure the carbonaceous component of the ambient aerosol including organic and elemental carbon, specific compounds like PAHs, and to ascertain if it is possible to develop a quantitative and universal calibration that provides results comparable to time resolved OC/EC measurements; 2) provide key markers that distinguish among sources of carbonaceous aerosol including diesel and spark-ignition vehicles, mobile and stationary sources, fossil fuel sources versus biomass burning, and primary biological, and/or secondary organics; 3) provide critical insights into atmospheric processes that can then be better represented in air quality models such as the relationship of secondary OC with primary particle types. Particular type(s) like sulfate or nitrate may be particularly important for providing an effective surface on which the carbonaceous material can condense; and 4) distinguish between primary and secondary OC by examining if primary OC is more related to co-emitted EC particles or gases while secondary OC is found associated with the more abundant sulfate or nitrate particles.
Using multivariate calibration and advanced factor analysis methods, we will analyze the extensive database produced by the Supersites at Atlanta, Fresno, Houston, and New York City. Multivariate calibration methods will be used to develop quantitative relationships between aerosol time-of-flight mass spectrometry (ATOFMS) data and the ambient aerosol composition. Examination of the relationships between class mass fractions and OC/EC concentrations can be used to assess the relative amounts of primary and secondary OC. The ATOFMS data will be used directly in factor analysis models to provide source identification and apportionment.
We will establish how effective it is to use the ATOFMS as a tool to identify and quantitatively apportion the carbonaceous aerosol. In addition, the exploration of the individual particle data will provide significant insights into the processes that give rise to the observed OC concentrations. These results will provide more refined inputs for determining PM sources in ambient data, allowing for more cost effective state and federal control strategies to be established. Information on the major sources of carbonaceous particles in different regions of the U.S. can be used to design appropriate health effects studies on ambient particles.