Volatile Chemical Product Contributions to the Urban Secondary Organic Aerosol Burden in the United States

SREEJITH SASIDHARAN, Charles He, Qi Li, David Cocker, Karl Seltzer, Brian McDonald, Havala Pye, Jeffrey R. Pierce, Shantanu Jathar, Colorado State University

     Abstract Number: 501
     Working Group: Urban Aerosols

Abstract
Volatile chemical products (VCPs) are an important source of oxygenated volatile organic compound (OVOC) emissions into the urban atmosphere. Although the OVOCs released from VCPs are understood to oxidize in the atmosphere, the chemical pathways that eventually lead to SOA formation in urban environments remain uncertain. In this work, we leveraged high NO_X environmental chamber data gathered at the University of California Riverside to develop parameters to represent SOA formation from a suite of VCP OVOCs. These VCP OVOCs included glycols, glycol ethers, oxygenated aromatics, and acetates. The SOA parameters were developed using SOM-TOMAS, a kinetic model that simulates the oxidation chemistry, thermodynamic properties, and microphysics of SOA. The SOM-TOMAS parameters were able to reproduce time-dependent SOA mass concentrations and the oxygen-to-carbon (O:C) ratios measured in the chamber experiments quite well. These parameters for OVOCs along with historical parameters for SOA precursors were used to develop a box model to study urban SOA formation in select megacities as well as nationwide. Consistent with recent work, the box modeling results found that VCPs account for more than half of all urban SOA formed from anthropogenic sources in Los Angeles, CA and New York City, NY. Of the SOA attributed to VCP use, more than three quarters of it arose from oxidation of VCP hydrocarbons and less than a quarter coming from VCP OVOCs. Ongoing work is focused on (i) identifying the most influential VCP OVOCs for SOA formation to aid design of laboratory and field experiments and (ii) understanding source contributions to anthropogenic SOA in cities across the United States.