AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
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SOA Potential of Urban Volatile Chemical Product (VCP) Emissions Explored Using In-Situ Oxidation Flow Reactor
RISHABH SHAH, Matthew Coggon, Georgios Gkatzelis, Brian McDonald, Antonios Tasoglou, Carsten Warneke, Jessica Gilman, Heinz Huber, Allen Robinson, Albert A. Presto, Carnegie Mellon University
Abstract Number: 329 Working Group: Urban Aerosols
Abstract This study proves a significant pool of SOA-forming VCP emissions in urban environments. We used an oxidation flow reactor (OFR) to demonstrate that there is excess SOA potential in densely populated areas because of this pool of vapors.
Mobile sampling studies in the last 5 years have revealed ambient SOA increments in source-rich intra-urban environments (e.g., downtown). While these increments can be from rapidly-reacting combustion emissions from vehicles, McDonald et al. have shown that VCPs have comparable SOA potential. Our objectives are three-fold: 1) measure precursor levels and SOA potential in different intra-urban environments, 2) investigate contributions from vehicles, biogenics, and VCPs to observed SOA potentials, and 3) target specific VCP sources and investigate their SOA potential.
For objective #1, we performed measurements in different urban environments: e.g., urban street canyon, urban residential (UR), etc. We use mass spectrometry coupled with OFR to characterize ambient pollution levels and SOA potential. For objective #2, we use simple kinetic models to explain OFR-SOA. For model inputs, we use ambient concentrations of traditional combustion and biogenic precursors. We are able to constrain OFR-SOA in some environments using these inputs, but unable to explain ~50% of the OFR-SOA in environments with higher VCP levels (e.g., downtown street canyon, with high levels of deodorant tracer), indicating that VCPs are an additional important source of urban SOA.
For objective #3, we performed OFR measurements next to a construction site and observed correlated responses in gas-phase VCP markers and OFR-SOA. In laboratory, we oxidized specific VCP fumes (deodorant, oil-based paint) and calculated their SOA yields. We find 5 orders of magnitude variances in SOA yields of these VCP fumes, implying that further characterization of VCPs is warranted for understanding their urban SOA potential.