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| Titel |
On the spatial distribution and evolution of ultrafine particles in Barcelona |
| VerfasserIn |
M. Dall'Osto, X. Querol, A. Alastuey, C. O'Dowd, R. M. Harrison, J. Wenger, F. J. Gómez-Moreno |
| 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. 2 ; Nr. 13, no. 2 (2013-01-21), S.741-759 |
| Datensatznummer |
250017598
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| Publikation (Nr.) |
 copernicus.org/acp-13-741-2013.pdf |
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| Zusammenfassung |
| Sources and evolution of ultrafine particles were investigated both
horizontally and vertically in the large urban agglomerate of Barcelona,
Spain. Within the SAPUSS project (Solving Aerosol Problems by Using
Synergistic Strategies), a large number of instruments was deployed
simultaneously at different monitoring sites (road, two urban background,
regional background, urban tower 150 m a.s.l., urban background tower site
80 m a.s.l.) during a 4 week period in September–October 2010. Particle
number concentrations (N>5 nm) are highly correlated
with black carbon (BC) at all sites only under strong vehicular traffic
influences. By contrast, under cleaner atmospheric conditions (low
condensation sink, CS) such correlation diverges towards much higher
N/BC ratios at all sites, indicating additional sources of particles
including secondary production of freshly nucleated particles. Size-resolved
aerosol distributions (N10–500) as well as particle number
concentrations (N>5 nm) allow us to identify three
types of nucleation and growth events: (1) a regional type event originating
in the whole study region and impacting almost simultaneously the urban city
of Barcelona and the surrounding urban background area; (2) a regional type
event impacting only the regional background area but not the urban
agglomerate; (3) an urban type event which originates only within the city
centre but whose growth continues while transported away from the city to the
regional background. Furthermore, during these clean air days, higher
N are found at tower level than at ground level only in the city
centre whereas such a difference is not so pronounced at the remote urban
background tower. In other words, this study suggests that the column of air
above the city ground level possesses the optimal combination between low CS
and high vapour source, hence enhancing the concentrations of freshly
nucleated particles. By contrast, within stagnant polluted atmospheric
conditions, higher N and BC concentrations are always measured at ground
level relative to tower level at all sites. Our study suggests that the city
centre of Barcelona is a source of non-volatile traffic primary particles
(29–39% of N>5 nm), but other sources, including
secondary freshly nucleated particles contribute up to 61–71% of particle
number (N>5 nm) at all sites. We suggest that organic
compounds evaporating from freshly emitted traffic particles are a possible
candidate for new particle formation within the city and urban plume. |
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