AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Laboratory Chamber Study on Organic Acids Production from Biogenic VOC Oxidation
YUNLE CHEN, David Tanner, Greg Huey, Rodney J. Weber, Nga Lee Ng, Georgia Institute of Technology
Abstract Number: 493 Working Group: Carbonaceous Aerosol
Abstract Organic acids are ubiquitous in the atmosphere. They constitute an important fraction of atmosphere organic carbon and can play a role in aerosol chemistry. Recent studies have shown that the sources of atmospheric organic acids (e.g. formic and acetic acid) are largely underestimated by models, and the oxidation of biogenic volatile organic compounds (VOC) can be a predominant source of organic acids. Meanwhile, the formation pathway of organic acids in biogenic VOC oxidation remains largely unexplored.
In this study, we conducted a series of laboratory experiments at the Georgia Tech Environmental Chamber (GTEC) facility to investigate the formation and evolution of organic acids from oxidation of biogenic VOC (α-pinene and isoprene) under various conditions. Gas- and particle-phase organic acids were monitored by a chemical ionization mass spectrometer (CIMS) using SF6- as reagent ion and a Particle-into-Liquid Samplers coupled with ion chromatographs (PILS-IC), respectively, allowing for an inclusive measurement of organic acid yields and gas-particle partitioning. Aerosol composition were comprehensively characterized using a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and a HR-ToF-CIMS coupled with a Filter Inlet for Gases and AEROsols (FIGAERO). The roles of water vapor and aerosol liquid water content are investigated specifically. We found that the formation of organic acids is largely dependent on water abundance and the corresponding yields and mechanisms will be discussed.