 |
| Titel |
Traffic and nucleation events as main sources of ultrafine particles in high-insolation developed world cities |
| VerfasserIn |
M. Brines, M. Dall'Osto, D. C. S. Beddows, R. M. Harrison, F. Gómez-Moreno, L. Núñez, B. Artíñano, F. Costabile, G. P. Gobbi, F. Salimi, L. Morawska, C. Sioutas, X. Querol |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 10 ; Nr. 15, no. 10 (2015-05-28), S.5929-5945 |
| Datensatznummer |
250119764
|
| Publikation (Nr.) |
 copernicus.org/acp-15-5929-2015.pdf |
|
|
|
|
|
| Zusammenfassung |
| Road traffic emissions are often considered the main source of ultrafine
particles (UFP, diameter smaller than 100 nm) in urban environments.
However, recent studies worldwide have shown that – in high-insolation urban
regions at least – new particle formation events can also contribute to UFP.
In order to quantify such events we systematically studied three cities
located in predominantly sunny environments: Barcelona (Spain), Madrid
(Spain) and Brisbane (Australia). Three long-term data sets (1–2 years) of
fine and ultrafine particle number size distributions (measured by SMPS,
Scanning Mobility Particle Sizer) were analysed. Compared to total particle
number concentrations, aerosol size distributions offer far more information
on the type, origin and atmospheric evolution of the particles. By applying
k-means clustering analysis, we categorized the collected aerosol size
distributions into three main categories: "Traffic" (prevailing 44–63% of
the time), "Nucleation" (14–19%) and "Background pollution and
Specific cases" (7–22%). Measurements from Rome (Italy) and Los Angeles
(USA) were also included to complement the study. The daily variation
of the average UFP concentrations for a typical nucleation day at each site
revealed a similar pattern for all cities, with three distinct particle
bursts. A morning and an evening spike reflected traffic rush hours, whereas
a third one at midday showed nucleation events. The photochemically
nucleated particles' burst lasted 1–4 h, reaching sizes of 30–40 nm. On
average, the occurrence of particle size spectra dominated by nucleation
events was 16% of the time, showing the importance of this process as a
source of UFP in urban environments exposed to high solar radiation. Nucleation events lasting for 2 h or more occurred on 55% of
the days, this extending to > 4 h in 28% of the days,
demonstrating that atmospheric conditions in urban environments are not
favourable to the growth of photochemically nucleated particles. In summary,
although traffic remains the main source of UFP in urban areas, in developed
countries with high insolation urban nucleation events are also a main
source of UFP. If traffic-related particle concentrations are reduced in the
future, nucleation events will likely increase in urban areas, due to the
reduced urban condensation sinks. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|