AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Incremental Secondary Organic Aerosol Formation in Controlled Reactivity Urban Atmospheres with and without Biogenic Influence
MARY KACARAB, Lijie Li, William P. L. Carter, David R. Cocker III, University of California, Riverside
Abstract Number: 563 Working Group: Aerosol Chemistry
Abstract Current SOA models, which are typically based off of aerosol yields from environmental chamber experiments, regularly under predict ambient aerosol formation. The aerosol yields used are determined from classic single precursor chamber experiments. However, yields determined from only one precursor cannot give an accurate representation of a species’ reactivity levels in the ambient atmosphere as the overall reactivity of the chamber system is then dictated by the single precursor itself. This work seeks to overcome this obstacle by using a surrogate mixture of hydrocarbons to control the overall reactivity in the chamber system and thus define an incremental aerosol yield in different representative reactive systems. In this work, two reactive organic gas (ROG) mixtures were developed to represent urban atmospheres with and without a heavy biogenic influence. Experiments were run in the UCR/CE-CERT dual 90m$^3 atmospheric chambers studying the resulting incremental aerosol from two monoaromatic compounds, a monoterpene, and a polyaromatic hydrocarbon. For all compounds studied, slightly higher incremental yields were found in the biogenic influenced ROG mixture than in the strictly anthropogenic mixture. Furthermore, all precursors yielded slightly higher aerosol formation in both surrogate environments than in single precursor experiments. However, aerosol properties of incremental aerosol formed in both systems (including bulk chemical composition from HR-ToF-AMS) are very comparable to aerosol from single precursor experiments. This work presents a novel characterization of aerosol yields in different urban environments and raises an interesting question of how to look at different aerosol yields.