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| Titel |
Factor analysis of combined organic and inorganic aerosol mass spectra from high resolution aerosol mass spectrometer measurements |
| VerfasserIn |
Y. L. Sun, Q. Zhang, J. J. Schwab, T. Yang, N. L. Ng, K. L. Demerjian |
| 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 ; 12, no. 18 ; Nr. 12, no. 18 (2012-09-21), S.8537-8551 |
| Datensatznummer |
250011462
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| Publikation (Nr.) |
 copernicus.org/acp-12-8537-2012.pdf |
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| Zusammenfassung |
| Positive matrix factorization (PMF) was applied to the merged high
resolution mass spectra of organic and inorganic aerosols from aerosol mass
spectrometer (AMS) measurements to investigate the sources and evolution
processes of submicron aerosols in New York City in summer 2009. This new
approach is able to study the distribution of organic and inorganic species
in different types of aerosols, the acidity of organic aerosol (OA) factors,
and the fragment ion patterns related to photochemical processing. In this
study, PMF analysis of the unified AMS spectral matrix resolved 8 factors.
The hydrocarbon-like OA (HOA) and cooking OA (COA) factors contain
negligible amounts of inorganic species. The two factors that are primarily
ammonium sulfate (SO4-OA) and ammonium nitrate (NO3-OA),
respectively, are overall neutralized. Among all OA factors the organic
fraction of SO4-OA shows the highest degree of oxidation (O/C = 0.69).
Two semi-volatile oxygenated OA (OOA) factors, i.e., a less oxidized
(LO-OOA) and a more oxidized (MO-OOA), were also identified. MO-OOA
represents local photochemical products with a diurnal profile exhibiting a
pronounced noon peak, consistent with those of formaldehyde (HCHO) and
Ox(= O3 + NO2). The NO+/NO2+ ion ratio
in MO-OOA is much higher than that in NO3-OA and in pure ammonium
nitrate, indicating the formation of organic nitrates. The nitrogen-enriched
OA (NOA) factor contains ~25% of acidic inorganic salts,
suggesting the formation of secondary OA via acid-base reactions of amines.
The size distributions of OA factors derived from the size-resolved mass
spectra show distinct diurnal evolving behaviors but overall a progressing
evolution from smaller to larger particle mode as the oxidation degree of OA
increases. Our results demonstrate that PMF analysis of the unified aerosol
mass spectral matrix which contains both inorganic and organic aerosol
signals may enable the deconvolution of more OA factors and gain more
insights into the sources, processes, and chemical characteristics of OA in the
atmosphere. |
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