AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
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Spatial Variability of Traffic-related PM2.5 Chemical Species and Sources: Comparison between Near-road and Background Environments in Metropolitan Toronto, Canada
CHEOL-HEON JEONG, Jon M. Wang, Nathan Hiker, Jerzy Debosz, Uwayemi Sofowote, Tony Munoz, Dennis Herod, Ewa Dabek-Zlotorzynska, Greg J. Evans, SOCAAR, University of Toronto
Abstract Number: 247 Working Group: Source Apportionment
Abstract Particulate matter (PM) originates from different emission sources and its toxicity can be determined based on chemical composition and sources. Much of PM2.5 mass in urban areas is often associated with regional secondary aerosols resulting in relatively homogeneous contributions across cities. By contrast, metal-rich PM2.5 sources (e.g. urban road dust) are often minor contributors to total PM2.5 mass but their contributions can be spatially inhomogeneous. Furthermore, these metal rich sources may disproportionately contribute to PM2.5 toxicity due to the high oxidative potential of some transition metals. Thus the spatial variability of traffic-related metals are of great interest as these may disproportionately mediate health outcomes arising from PM2.5 exposures across metropolitan areas.
Recently, two near-road (within 20 m of major roadways) and two urban background monitoring stations were established across Toronto, Canada as part of a near roadway monitoring study. Hourly trace metal concentrations in PM2.5 were measured using continuous metals monitors (Xact 625, Copper Environ) at the near-road and urban background sites. In addition to the high time resolution speciation data, 24-hr integrated PM2.5 speciation measurements were conducted every 3 days using filter-based samplers at the multiple sites. The variations of PM2.5 chemical speciation data were examined to identify local pollutants with more spatial variability. The hourly continuous chemical speciation data and the 24-hr integrated PM2.5 speciation data at these sites were analyzed using positive matrix factorization (PMF). Local (e.g. traffic-related metal sources) and regional scale PM2.5 sources were characterized at the multiple sites. The spatial and temporal variations of local traffic-related metal sources at near-road and urban background sites will be discussed.