| Title: | Formation and evolution of molecular products in alpha-pinene secondary organic aerosol |
| Author(s): | Zhang X; McVay RC; Huang DD; Dalleska NF; Aumont B; Flagan RC; Seinfeld JH; |
| Address: | "Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA 91125; Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125; Department of Chemical and Biomolecular Engineering, Hong Kong University of Science and Technology, Hong Kong, China; Laboratoire Interuniversitaire des Systemes Atmospheriques, UMR CNRS 7583, Universite Paris Est Creteil and Universite Paris Diderot, 94010 Creteil, France. Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA 91125; Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125; Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA 91125; Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125; seinfeld@caltech.edu" |
| ISSN/ISBN: | 1091-6490 (Electronic) 0027-8424 (Print) 0027-8424 (Linking) |
| Abstract: | "Much of our understanding of atmospheric secondary organic aerosol (SOA) formation from volatile organic compounds derives from laboratory chamber measurements, including mass yield and elemental composition. These measurements alone are insufficient to identify the chemical mechanisms of SOA production. We present here a comprehensive dataset on the molecular identity, abundance, and kinetics of alpha-pinene SOA, a canonical system that has received much attention owing to its importance as an organic aerosol source in the pristine atmosphere. Identified organic species account for approximately 58-72% of the alpha-pinene SOA mass, and are characterized as semivolatile/low-volatility monomers and extremely low volatility dimers, which exhibit comparable oxidation states yet different functionalities. Features of the alpha-pinene SOA formation process are revealed for the first time, to our knowledge, from the dynamics of individual particle-phase components. Although monomeric products dominate the overall aerosol mass, rapid production of dimers plays a key role in initiating particle growth. Continuous production of monomers is observed after the parent alpha-pinene is consumed, which cannot be explained solely by gas-phase photochemical production. Additionally, distinct responses of monomers and dimers to alpha-pinene oxidation by ozone vs. hydroxyl radicals, temperature, and relative humidity are observed. Gas-phase radical combination reactions together with condensed phase rearrangement of labile molecules potentially explain the newly characterized SOA features, thereby opening up further avenues for understanding formation and evolution mechanisms of alpha-pinene SOA" |
| Keywords: | air quality climate particulate matter secondary organic aerosol; |
| Notes: | "PubMed-not-MEDLINEZhang, Xuan McVay, Renee C Huang, Dan D Dalleska, Nathan F Aumont, Bernard Flagan, Richard C Seinfeld, John H eng Research Support, U.S. Gov't, Non-P.H.S. 2015/11/19 Proc Natl Acad Sci U S A. 2015 Nov 17; 112(46):14168-73. doi: 10.1073/pnas.1517742112. Epub 2015 Nov 2" |
