Sponsor
This project has been funded with funds from the State of Texas as part of the program of the Texas Air Research Center (Project Number 079ATM0099A, 078ATM2080A and 312ATM0126A).
Published In
Atmospheric Environment
Document Type
Article
Publication Date
2-2015
Subjects
Glyoxal, Air quality -- Computer simulation, Air -- Pollution
Abstract
A modified near-explicit Master Chemical Mechanism (MCM, version 3.2) with 5727 species and 16,930 reactions and an equilibrium partitioning module was incorporated into the Community Air Quality Model (CMAQ) to predict the regional concentrations of secondary organic aerosol (SOA) from volatile organic compounds (VOCs) in the eastern United States (US). In addition to the semi-volatile SOA from equilibrium partitioning, reactive surface uptake processes were used to simulate SOA formation due to isoprene epoxydiol, glyoxal and methylglyoxal. The CMAQ-MCM-SOA model was applied to simulate SOA formation during a two-week episode from August 28 to September 7, 2006. The southeastern US has the highest SOA, with a maximum episode-averaged concentration of ∼12 μg m−3. Primary organic aerosol (POA) and SOA concentrations predicted by CMAQ-MCM-SOA agree well with AMS-derived hydrocarbon-like organic aerosol (HOA) and oxygenated organic aerosol (OOA) urban concentrations at the Moody Tower at the University of Houston. Predicted molecular properties of SOA (O/C, H/C, N/C and OM/OC ratios) at the site are similar to those reported in other urban areas, and O/C values agree with measured O/C at the same site. Isoprene epoxydiol is predicted to be the largest contributor to total SOA concentration in the southeast US, followed by methylglyoxal and glyoxal. The semi-volatile SOA components are dominated by products from β-caryophyllene oxidation, but the major species and their concentrations are sensitive to errors in saturation vapor pressure estimation. A uniform decrease of saturation vapor pressure by a factor of 100 for all condensable compounds can lead to a 150% increase in total SOA. A sensitivity simulation with UNIFAC-calculated activity coefficients (ignoring phase separation and water molecule partitioning into the organic phase) led to a 10% change in the predicted semi-volatile SOA concentrations.
DOI
10.1016/j.atmosenv.2014.11.054
Persistent Identifier
http://archives.pdx.edu/ds/psu/16602
Citation Details
Jingyi Li, Meredith Cleveland, Luke D. Ziemba, Robert J. Griffin, Kelley C. Barsanti, James F. Pankow, Qi Ying, Modeling regional secondary organic aerosol using the Master Chemical Mechanism, Atmospheric Environment, Volume 102, February 2015, Pages 52-61.
Description
To the best of our knowledge, this work was authored as part of the Contributor's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law. This is the publisher’s final pdf. The published article is copyrighted by Elsevier and can be found at: http://dx.doi.org/10.1016/j.atmosenv.2014.11.054
Supplementary data related to this article can be found at http://dx.doi.org/10.1016/j.atmosenv.2014.11.054.