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Environ Sci Technol

Title:		"Photodegradation of Secondary Organic Aerosol Particles as a Source of Small, Oxygenated Volatile Organic Compounds"
Author(s):		Malecha KT; Nizkorodov SA;
Address:		"Department of Chemistry, University of California , Irvine, California 92697, United States"
Journal Title:		Environ Sci Technol
Year:		2016
Volume:		20160902
Issue:		18
Page Number:		9990 - 9997
DOI:		10.1021/acs.est.6b02313
ISSN/ISBN:		1520-5851 (Electronic) 0013-936X (Linking)
Abstract:		"We investigated the photodegradation of secondary organic aerosol (SOA) particles by near-UV radiation and photoproduction of oxygenated volatile organic compounds (OVOCs) from various types of SOA. We used a smog chamber to generate SOA from alpha-pinene, guaiacol, isoprene, tetradecane, and 1,3,5-trimethylbenzene under high-NOx, low-NOx, or ozone oxidation conditions. The SOA particles were collected on a substrate, and the resulting material was exposed to several mW of near-UV radiation (lambda approximately 300 nm) from a light-emitting diode. Various OVOCs, including acetic acid, formic acid, acetaldehyde, and acetone were observed during photodegradation, and their SOA-mass-normalized fluxes were estimated with a Proton Transfer Reaction Time-of-Flight Mass Spectrometer (PTR-ToF-MS). All the SOA, with the exception of guaiacol SOA, emitted OVOCs upon irradiation. Based on the measured OVOC emission rates, we estimate that SOA particles would lose at least approximately 1% of their mass over a 24 h period during summertime conditions in Los Angeles, California. This condensed-phase photochemical process may produce a few Tg/year of gaseous formic acid, the amount comparable to its primary sources. The condensed-phase SOA photodegradation processes could therefore measurably affect the budgets of both particulate and gaseous atmospheric organic compounds on a global scale"
Keywords:		Aerosols Air Pollutants *Photolysis Smog Volatile Organic Compounds/*chemistry;
Notes:		"MedlineMalecha, Kurtis T Nizkorodov, Sergey A eng Research Support, U.S. Gov't, Non-P.H.S. 2016/08/23 Environ Sci Technol. 2016 Sep 20; 50(18):9990-7. doi: 10.1021/acs.est.6b02313. Epub 2016 Sep 2"