AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Understanding Spatial-temporal Variation and Sources of Black Carbon Using Stratified Mobile Monitoring
YI TAN, Eric Lipsky, Rawad Saleh, Albert A. Presto, Allen Robinson, Carnegie Mellon University
Abstract Number: 216 Working Group: Urban Aerosols
Abstract Pittsburgh’s air quality is affected by a complex combination of local industrial and commercial sources, motor vehicles, terrain (e.g. river valleys) and regional transport. To better understand the spatial-temporal distribution of air pollution in Pittsburgh, we developed a mobile measurement platform to characterize a suite of air pollutants (black carbon (BC), particle-bound polycyclic aromatic hydrocarbons (PAH), benzene, and toluene). 42 sites were randomly selected based on stratification of elevation, influence of point sources and traffic. More than 270 hours of data were collected in winter (Nov 2011 – Feb 2012) and summer (Jun 2012 – Aug 2012). Mobile measurements were performed in 3 different sessions (afternoons/evenings, mornings, and midnights) in both seasons.
Pollutants displayed substantial spatial and temporal variation. Specifically, black carbon showed larger spatial variation than seasonal variation and diurnal variation in winter. Highest concentrations were observed in summer mornings due to the combination of meteorology and traffic. Black carbon concentrations were statistically different between valley sites and upland sites. Unlike other pollutants, the difference of black carbon between low and high traffic sites was insignificant. BC/PAH ratio was used to understand the sources of black carbon. BC/PAH ratios in winter and summer mornings resembled measurements in tunnels and near local point sources. However, higher BC/PAH ratios were observed at low traffic sites in summer afternoons and nights, suggesting additional sources and/or regional transport of black carbon.