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Changes in organic aerosol composition with aging inferred from aerosol mass spectra

Ng, N. L. and Canagaratna, M. R. and Jimenez, J. L. and Chhabra, P. S. and Seinfeld, J. H. and Worsnop, D. R. (2011) Changes in organic aerosol composition with aging inferred from aerosol mass spectra. Atmospheric Chemistry and Physics, 11 (13). pp. 6465-6474. ISSN 1680-7316.

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Organic aerosols (OA) can be separated with factor analysis of aerosol mass spectrometer (AMS) data into hydrocarbon-like OA (HOA) and oxygenated OA (OOA). We develop a new method to parameterize H:C of OOA in terms of f_(43)(ratio of m/z 43, mostly C_2H_3O^+, to total signal in the component mass spectrum). Such parameterization allows for the transformation of large database of ambient OOA components from the f_(44) (mostly CO^+_2, likely from acid groups) vs. f_(43) space ("triangle plot") (Ng et al., 2010) into the Van Krevelen diagram (H:C vs. O:C) (Van Krevelen, 1950). Heald et al. (2010) examined the evolution of total OA in the Van Krevelen diagram. In this work total OA is deconvolved into components that correspond to primary (HOA and others) and secondary (OOA) organic aerosols. By deconvolving total OA into different components, we remove physical mixing effects between secondary and primary aerosols which allows for examination of the evolution of OOA components alone in the Van Krevelen space. This provides a unique means of following ambient secondary OA evolution that is analogous to and can be compared with trends observed in chamber studies of secondary organic aerosol formation. The triangle plot in Ng et al. (2010) indicates that f_(44) of OOA components increases with photochemical age, suggesting the importance of acid formation in OOA evolution. Once they are transformed with the new parameterization, the triangle plot of the OOA components from all sites occupy an area in Van Krevelen space which follows a ΔH:C/ΔO:C slope of ~ −0.5. This slope suggests that ambient OOA aging results in net changes in chemical composition that are equivalent to the addition of both acid and alcohol/peroxide functional groups without fragmentation (i.e. C-C bond breakage), and/or the addition of acid groups with fragmentation. These results provide a framework for linking the bulk aerosol chemical composition evolution to molecular-level studies.

Item Type:Article
Related URLs:
URLURL TypeDescription
Ng, N. L.0000-0001-8460-4765
Jimenez, J. L.0000-0001-6203-1847
Seinfeld, J. H.0000-0003-1344-4068
Worsnop, D. R.0000-0002-8928-8017
Additional Information:© 2011 Author(s). Received: 23 February 2011 – Published in Atmos. Chem. Phys. Discuss.: 2 March 2011. Revised: 28 June 2011. Accepted: 28 June 2011. Published: 7 July 2011. We thank grants from DOE (BER, ASR program) DEFG0208ER64627, NOAA NA08OAR4310565, and NSF ATM-0919189. We thank Paola Massoli for sharing the Boston College flow tube data and Jesse Kroll for helpful discussions. We thank the two anonymous reviewers for their helpful comments.
Funding AgencyGrant Number
Department of Energy (DOE)DE-FG02-08ER64627
National Oceanic and Atmospheric Administration (NOAA)NA08OAR4310565
Issue or Number:13
Record Number:CaltechAUTHORS:20110914-114802427
Persistent URL:
Official Citation:Ng, N. L., Canagaratna, M. R., Jimenez, J. L., Chhabra, P. S., Seinfeld, J. H., and Worsnop, D. R.: Changes in organic aerosol composition with aging inferred from aerosol mass spectra, Atmos. Chem. Phys., 11, 6465-6474, doi:10.5194/acp-11-6465-2011, 2011.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:25348
Deposited By: Ruth Sustaita
Deposited On:15 Sep 2011 22:11
Last Modified:03 Oct 2019 03:05

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