AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Spatial Variation of Organic Aerosol and Source Identification of Temperature-resolved Carbon Fractions
HUGH LI, Timothy Dallmann, Xiang Li, Peishi Gu, Albert A. Presto, Carnegie Mellon University
Abstract Number: 88 Working Group: Urban Aerosols
Abstract Long-term exposure to particulate matter (PM) is the major contributor to air pollution related death in 21st century. Organic aerosol is a major component of PM2.5, ranging from 20% to 90% in mass. A mobile sampling campaign was conducted in 2013 summer and winter in Pittsburgh, PA and to characterize spatial variations in organic aerosol mass and its components. 36 sites were chosen based on three stratification variables—traffic density, proximity to point source, and elevation. Filter samples were collected in three time sessions (morning, afternoon, and night) in each season, and we used Sunset OC/EC instrument to analyze organic carbon (OC) components of different volatility—OC1, OC2, OC3, OC4, and pyrolytic carbon (PC).
We compared OC concentrations in the ambient environment, a traffic tunnel, and dynamometer tests. We found that OC2 and OC3 showed a strong increasing trend with traffic intensity while OC4 and PC were more spatially homogenous. PC was not found on all quartz filters from dynamometer tests, and it suggested traffic (gasoline or diesel) was not a source for ambient PC. Land-use regressions (LUR) models were developed for these OC fractions, and models were good with an average R2 of 0.62 (SD=0.08).
Finally, cumulative probability function of population weighted OC concentrations showed that OC2 and OC3 drove the human exposure patterns.