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| Titel |
Organic aerosol evolution and transport observed at Mt. Cimone (2165 m a.s.l.), Italy, during the PEGASOS campaign |
| VerfasserIn |
M. Rinaldi, S. Gilardoni, M. Paglione, S. Sandrini, S. Fuzzi, P. Massoli, P. Bonasoni, P. Cristofanelli, A. Marinoni, V. Poluzzi, S. Decesari |
| 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 ; 15, no. 19 ; Nr. 15, no. 19 (2015-10-12), S.11327-11340 |
| Datensatznummer |
250120092
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| Publikation (Nr.) |
 copernicus.org/acp-15-11327-2015.pdf |
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| Zusammenfassung |
| High-resolution aerosol mass spectrometer measurements were performed,
for the first time, at the Mt. Cimone Global Atmosphere Watch (GAW) station
between June and July 2012, within the EU project PEGASOS and the
ARPA–Emilia-Romagna project SUPERSITO. Submicron aerosol was dominated by
organics (63 %), with sulfate, ammonium and nitrate contributing the
remaining 20, 9 and 7 %, respectively. Organic aerosol (OA) was in
general highly oxygenated, consistent with the remote character of the site;
our observations suggest that oxidation and secondary organic aerosol (SOA)
formation processes occurred during aerosol transport to high altitudes. All
of the aerosol component concentrations as well as the OA elemental ratios
showed a clear daily trend, driven by the evolution of the planetary
boundary layer (PBL) and by the mountain wind regime. Higher loadings and
lower OA oxidation levels were observed during the day, when the site was
within the PBL, and therefore affected by relatively fresh aerosol
transported from lower altitudes. Conversely, lower loadings and higher OA
oxidation levels were observed at night, when the top of Mt. Cimone resided
in the free troposphere although affected by the transport of residual
layers on several days of the campaign. Analysis of the elemental ratios in
a Van Krevelen space shows that OA oxidation follows a slope comprised
between −0.5 and −1, consistent with addition of carboxylic groups, with or
without fragmentation of the parent molecules. The increase of carboxylic
groups during OA ageing is confirmed by the increased contribution of
organic fragments containing more than one oxygen atom in the free
troposphere night-time mass spectra. Finally, positive matrix factorization
was able to deconvolve the contributions of relatively fresh OA (OOAa)
originating from the PBL, more aged OA (OOAb) present at high altitudes
during periods of atmospheric stagnation, and very aged aerosols (OOAc)
transported over long distances in the free troposphere. |
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