AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Formation of Reactive Oxygen Species by Size-Segregated Particles Collected in Forest and Urban Environments
BRIAN HWANG, Ting Fang, Michihiro Mochida, Manabu Shiraiwa, University of California, Irvine
Abstract Number: 504 Working Group: Aerosol Chemistry
Abstract Reactive oxygen species (ROS) including hydroxyl (OH), superoxide (O2), and organic radicals play a central role in chemical aging of ambient organic aerosols and mediating physiological processes. Environmentally persistent free radicals (EPFRs) are stable radicals with similar chemical characteristics as semiquinones and are important ROS sources in water. Recent findings have shown that biogenic secondary organic aerosols release OH and organic radicals by decomposition of organic hydroperoxides and Fenton-like reactions of metal ions with organic hydroperoxides. The sources of ROS and how various chemical components in ambient particles with different particle sizes from biogenic and anthropogenic sources influence ROS formation are not well understood. In this study, ambient size-segregated particles were collected in a forest site in Japan, where biogenic SOA are major component of ambient particles. EPFRs are directly measured from the particles on filters using an electron paramagnetic resonance (EPR) spectrometer. A spin trapping technique is applied to measure OH·, O2·, and organic radicals from aqueous filter extracts using EPR. In addition, we plan to collect size-segregated particles in the Los Angeles basin and conduct same EPR analysis. We investigate how different chemical nature in forest and urban sites affect ROS formation by ambient particles with different particle sizes.