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Environ Sci Technol

Title:		Exploring Divergent Volatility Properties from Yield and Thermodenuder Measurements of Secondary Organic Aerosol from alpha-Pinene Ozonolysis
Author(s):		Saha PK; Grieshop AP;
Address:		"Department of Civil, Construction, and Environmental Engineering, North Carolina State University , Raleigh, North Carolina, 27695 United States"
Journal Title:		Environ Sci Technol
Year:		2016
Volume:		20160519
Issue:		11
Page Number:		5740 - 5749
DOI:		10.1021/acs.est.6b00303
ISSN/ISBN:		1520-5851 (Electronic) 0013-936X (Linking)
Abstract:		"There are large uncertainties in the parameters dictating the gas-particle partitioning of secondary organic aerosols (SOA), although this process has major influences on their atmospheric lifecycle. Here, we extract parameters that describe the partitioning of SOA from alpha-pinene ozonolysis using measurements from a dual-thermodenuder (TD) system that constrains both the equilibrium and the kinetic properties that dictate SOA phase partitioning. Parallel TDs that vary in temperature and residence time were used with an evaporation-kinetics model to extract parameter values. An evaporation coefficient of an order of 0.1 best describes the observed evaporation, suggesting equilibration time scales of atmospheric SOA on the order of minutes to hours. A total of 20-40% of SOA mass consists of low-volatility material (saturation concentration of <0.3 mug m(-3)) in the TD-derived SOA volatility distribution. While distinct from existing parametrizations from aerosol growth experiments, derived values are consistent with recent observations of slow room-temperature evaporation of SOA and contributions from extremely low volatility organic compounds formed during alpha-pinene ozonolysis. The volatility parameters thus determined suggest that SOA yields and enthalpies of evaporation are substantially higher, and products less volatile, than is currently assumed in atmospheric models. These results will help improve the representation of SOA in air-quality and climate models"
Keywords:		Aerosols Air Pollutants Monoterpenes *Ozone Volatile Organic Compounds *Volatilization;
Notes:		"MedlineSaha, Provat K Grieshop, Andrew P eng Research Support, Non-U.S. Gov't 2016/05/05 Environ Sci Technol. 2016 Jun 7; 50(11):5740-9. doi: 10.1021/acs.est.6b00303. Epub 2016 May 19"