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Environ Sci Technol

Title:		Significant Contributions of Isoprene to Summertime Secondary Organic Aerosol in Eastern United States
Author(s):		Ying Q; Li J; Kota SH;
Address:
Journal Title:		Environ Sci Technol
Year:		2015
Volume:		20150611
Issue:		13
Page Number:		7834 - 7842
DOI:		10.1021/acs.est.5b02514
ISSN/ISBN:		1520-5851 (Electronic) 0013-936X (Linking)
Abstract:		"A modified SAPRC-11 (S11) photochemical mechanism with more detailed treatment of isoprene oxidation chemistry and additional secondary organic aerosol (SOA) formation through surface-controlled reactive uptake of dicarbonyls, isoprene epoxydiol and methacrylic acid epoxide was incorporated in the Community Multiscale Air Quality Model (CMAQ) to quantitatively determine contributions of isoprene to summertime ambient SOA concentrations in the eastern United States. The modified model utilizes a precursor-origin resolved approach to determine secondary glyoxal and methylglyoxal produced by oxidation of isoprene and other major volatile organic compounds (VOCs). Predicted OC concentrations show good agreement with field measurements without significant bias (MFB approximately 0.07 and MFE approximately 0.50), and predicted SOA reproduces observed day-to-day and diurnal variation of Oxygenated Organic Aerosol (OOA) determined by an aerosol mass spectrometer (AMS) at two locations in Houston, Texas. On average, isoprene SOA accounts for 55.5% of total predicted near-surface SOA in the eastern U.S., followed by aromatic compounds (13.2%), sesquiterpenes (13.0%) and monoterpenes (10.9%). Aerosol surface uptake of isoprene-generated glyoxal, methylglyoxal and epoxydiol accounts for approximately 83% of total isoprene SOA or more than 45% of total SOA. A domain wide reduction of NOx emissions by 40% leads to a slight decrease of domain average SOA by 3.6% and isoprene SOA by approximately 2.6%. Although most of the isoprene SOA component concentrations are decreased, SOA from isoprene epoxydiol is increased by approximately 16%"
Keywords:		"Aerosols/*analysis Air Pollutants/analysis Butadienes/*analysis Carbon/analysis Hemiterpenes/*analysis Models, Theoretical Nitrates/analysis Organic Chemicals/*analysis Oxidation-Reduction Particulate Matter/analysis Pentanes/*analysis Pyruvaldehyde/analy;"
Notes:		"MedlineYing, Qi Li, Jingyi Kota, Sri Harsha eng Research Support, Non-U.S. Gov't 2015/06/02 Environ Sci Technol. 2015 Jul 7; 49(13):7834-42. doi: 10.1021/acs.est.5b02514. Epub 2015 Jun 11"