| Title: | Nonequilibrium atmospheric secondary organic aerosol formation and growth |
| Author(s): | Perraud V; Bruns EA; Ezell MJ; Johnson SN; Yu Y; Alexander ML; Zelenyuk A; Imre D; Chang WL; Dabdub D; Pankow JF; Finlayson-Pitts BJ; |
| Address: | "Department of Chemistry, University of California, Irvine, CA 92697-2025, USA" |
| ISSN/ISBN: | 1091-6490 (Electronic) 0027-8424 (Print) 0027-8424 (Linking) |
| Abstract: | "Airborne particles play critical roles in air quality, health effects, visibility, and climate. Secondary organic aerosols (SOA) formed from oxidation of organic gases such as alpha-pinene account for a significant portion of total airborne particle mass. Current atmospheric models typically incorporate the assumption that SOA mass is a liquid into which semivolatile organic compounds undergo instantaneous equilibrium partitioning to grow the particles into the size range important for light scattering and cloud condensation nuclei activity. We report studies of particles from the oxidation of alpha-pinene by ozone and NO(3) radicals at room temperature. SOA is primarily formed from low-volatility ozonolysis products, with a small contribution from higher volatility organic nitrates from the NO(3) reaction. Contrary to expectations, the particulate nitrate concentration is not consistent with equilibrium partitioning between the gas phase and a liquid particle. Rather the fraction of organic nitrates in the particles is only explained by irreversible, kinetically determined uptake of the nitrates on existing particles, with an uptake coefficient that is 1.6% of that for the ozonolysis products. If the nonequilibrium particle formation and growth observed in this atmospherically important system is a general phenomenon in the atmosphere, aerosol models may need to be reformulated. The reformulation of aerosol models could impact the predicted evolution of SOA in the atmosphere both outdoors and indoors, its role in heterogeneous chemistry, its projected impacts on air quality, visibility, and climate, and hence the development of reliable control strategies" |
| Keywords: | "Aerosols/*analysis Atmosphere/*chemistry Bicyclic Monoterpenes Monoterpenes/analysis Nitrates/analysis Nitrous Oxide/analysis Organic Chemicals/*analysis Particle Size Spectroscopy, Fourier Transform Infrared;" |
| Notes: | "MedlinePerraud, Veronique Bruns, Emily A Ezell, Michael J Johnson, Stanley N Yu, Yong Alexander, M Lizabeth Zelenyuk, Alla Imre, Dan Chang, Wayne L Dabdub, Donald Pankow, James F Finlayson-Pitts, Barbara J eng Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. 2012/02/07 Proc Natl Acad Sci U S A. 2012 Feb 21; 109(8):2836-41. doi: 10.1073/pnas.1119909109. Epub 2012 Jan 30" |
