Abstract View
Secondary Organic Aerosol Formation and Product Distributions of α-pinene Oxidation in Ambient Perturbation Experiments
JEAN RIVERA-RIOS, Adam Wright, Zijing Zhang, Jennifer Kaiser, Nga Lee Ng, Georgia Institute of Technology
Abstract Number: 400
Working Group: Urban Aerosols
Abstract
Volatile organic compounds (VOC) are oxidized in the atmosphere leading to the formation of secondary organic aerosols (SOA) and ozone, known pollutants. Usually, VOC oxidation is studied in laboratory chamber experiments with carefully controlled reaction conditions. In this study, we oxidized α-pinene in an outdoor chamber, using ambient air from downtown Atlanta, GA. The experiments began by introducing and sampling ambient air within an outdoor chamber. This was followed by a small α-pinene perturbation. The injected α-pinene was then oxidized under ambient conditions, leading to SOA formation and a variety of oxidation products. Gas-phase products were measured using a Proton Transfer Reaction Mass Spectrometer (PTR-MS) and Iodide adduct Chemical Ionization Mass Spectrometer (I--CIMS). The CIMS was equipped with a Filter Inlet for Gases and Aerosols (FIGAERO) enabling particle-phase measurements along with an Aerosol Mass Spectrometer (AMS) and Scanning Mobility Particle Sizer (SMPS). Our results show a variety of SOA yields and product distributions that depend on ambient conditions. Important variables include but were not limited to NOX and O3 concentrations as well as other variables such as temperature and light intensity. Analysis of experimental and ambient SOA data using positive-matrix-factorization (PMF) showed that distinct environmental conditions influence the formation of LO-OOA and MO-OOA, PMF factors that have been previously observed during ambient measurements. The results of this work highlight the ability of ambient perturbation experiments to shed light on PMF factor identities and origins.