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| Titel |
Organic aerosol components observed in Northern Hemispheric datasets from Aerosol Mass Spectrometry |
| VerfasserIn |
N. L. Ng, M. R. Canagaratna, Q. Zhang, J. L. Jimenez, J. Tian, I. M. Ulbrich, J. H. Kroll, K. S. Docherty, P. S. Chhabra, R. Bahreini, S. M. Murphy, J. H. Seinfeld, L. Hildebrandt, N. M. Donahue, P. F. DeCarlo, V. A. Lanz, A. S. H. Prévôt, E. Dinar, Y. Rudich, D. R. Worsnop |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 10, no. 10 ; Nr. 10, no. 10 (2010-05-20), S.4625-4641 |
| Datensatznummer |
250008466
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| Publikation (Nr.) |
 copernicus.org/acp-10-4625-2010.pdf |
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| Zusammenfassung |
| In this study we compile and present results from the factor
analysis of 43 Aerosol Mass Spectrometer (AMS) datasets (27 of the datasets
are reanalyzed in this work). The components from all sites, when taken
together, provide a holistic overview of Northern Hemisphere organic aerosol
(OA) and its evolution in the atmosphere. At most sites, the OA can be
separated into oxygenated OA (OOA), hydrocarbon-like OA (HOA), and sometimes
other components such as biomass burning OA (BBOA). We focus on the OOA
components in this work. In many analyses, the OOA can be further
deconvolved into low-volatility OOA (LV-OOA) and semi-volatile OOA (SV-OOA).
Differences in the mass spectra of these components are characterized in
terms of the two main ions m/z 44 (CO2+) and m/z 43 (mostly
C2H3O+), which are used to develop a new mass spectral
diagnostic for following the aging of OA components in the
atmosphere. The LV-OOA component spectra have higher f44 (ratio of
m/z 44 to total signal in the component mass spectrum) and lower f43
(ratio of m/z 43 to total signal in the component mass spectrum) than SV-OOA. A
wide range of f44 and O:C ratios are observed for both LV-OOA
(0.17±0.04, 0.73±0.14) and SV-OOA (0.07±0.04, 0.35±0.14)
components, reflecting the fact that there is a continuum of OOA properties
in ambient aerosol. The OOA components (OOA, LV-OOA, and SV-OOA) from all
sites cluster within a well-defined triangular region in the f44 vs.\
f43 space, which can be used as a standardized means for comparing and
characterizing any OOA components (laboratory or ambient) observed with the
AMS. Examination of the OOA components in this triangular space indicates
that OOA component spectra become increasingly similar to each other and to
fulvic acid and HULIS sample spectra as f44 (a surrogate for O:C and an
indicator of photochemical aging) increases. This indicates that ambient OA
converges towards highly aged LV-OOA with atmospheric oxidation. The common
features of the transformation between SV-OOA and LV-OOA at multiple sites
potentially enable a simplified description of the oxidation of OA in the
atmosphere. Comparison of laboratory SOA data with ambient OOA indicates
that laboratory SOA are more similar to SV-OOA and rarely become as
oxidized as ambient LV-OOA, likely due to the higher loadings employed in
the experiments and/or limited oxidant exposure in most chamber experiments. |
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