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| Titel |
Source apportionment of submicron organic aerosol at an urban background and a road site in Barcelona (Spain) during SAPUSS |
| VerfasserIn |
M. Alier, B. L. van Drooge, M. Dall'Osto, X. Querol, J. O. Grimalt, R. Tauler |
| 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 ; 13, no. 20 ; Nr. 13, no. 20 (2013-10-24), S.10353-10371 |
| Datensatznummer |
250085766
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| Publikation (Nr.) |
 copernicus.org/acp-13-10353-2013.pdf |
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| Zusammenfassung |
This study investigates the contribution of potential sources to the
submicron (PM1) organic aerosol (OA) simultaneously detected at an
urban background (UB) and a road site (RS) in Barcelona during the 30 days
of the intensive field campaign of SAPUSS (Solving Aerosol Problems by Using
Synergistic Strategies, September–October 2010). A total of 103 filters at 12 h
sampling time resolution were collected at both sites. Thirty-six neutral
and polar organic compounds of known emission sources and photo-chemical
transformation processes were analyzed by gas chromatography–mass
spectrometry (GC-MS). The concentrations of the trace chemical compounds
analyzed are herein presented and discussed.
Additionally, OA source apportionment was performed by multivariate curve
resolution–alternating least squares (MCR-ALS) and six OA components were
identified at both sites: two were of primary anthropogenic OA origin and three
of secondary OA origin, while a sixth one was not clearly defined. Primary
organics from emissions of local anthropogenic activities (urban primary
organic aerosol, or POA Urban), mainly traffic emissions but also cigarette
smoke, contributed 43% (1.5 μg OC m−3) and 18%
(0.4 μg OC m−3) to OA at RS and UB, respectively. A secondary primary
source – biomass burning (BBOA) – was found in all the samples (average
values 7% RS; 12% UB; 0.3 μg OC m−3), but this component
was substantially contributing to OA only when the sampling sites were under
influence of regional air mass circulation (REG.). Three secondary organic aerosol
(SOA) components (describing overall 60% of the variance) were observed
in the urban ambient PM1. Products of isoprene oxidation (SOA ISO) –
i.e. 2-methylglyceric acid, C5 alkene triols and 2-methyltetrols –
showed the highest abundance at both sites when the city was under influence
of inland air masses. The overall concentrations of SOA ISO were similar at
both sites (0.4 and 0.3 μg m−3, or 16% and 7%, at UB and RS,
respectively). By contrast, a SOA biogenic component attributed to α-pinene oxidation (SOA BIO PIN) presented average concentrations of 0.5 μg m−3 at UB (24% of OA) and 0.2 μg m−3 at RS
(7%), respectively, suggesting that this SOA component did not impact the
two monitoring sites at the same level. A clear anti-correlation was observed
between SOA ISO and SOA PIN during nucleation days, surprisingly suggesting
that some of the growth of urban freshly nucleating particles may be driven
by biogenic α-pinene oxidation products but inhibited by isoprene
organic compounds. A third SOA component was formed by a mixture of aged
anthropogenic and biogenic secondary organic compounds (SOA Aged) that
accumulated under stagnant atmospheric conditions, contributing for 12%
to OA at RS (0.4 μg OC m−3) and for 18% at UB (0.4 μg OC m−3).
A sixth component, formed by C7–C9 dicarboxylic acids and detected
especially during daytime, was called "urban oxygenated organic aerosol"
(OOA Urban) due to its high abundance at urban RS (23%; 0.8 μg
OCm−3) vs. UB (10%; 0.2 μg OCm−3), with a well-defined
daytime maximum. This temporal trend and geographical differentiation
suggests that local anthropogenic sources were determining this component.
However, the changes of these organic molecules were also influenced by the
air mass trajectories, indicating that atmospheric conditions have an
influence on this component, although the specific origin on this component
remains unclear. It points to a secondary organic component driven by
primary urban sources including cooking and traffic (mainly gasoline)
activities. |
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