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| Titel |
A one-year comprehensive chemical characterisation of fine aerosol (PM2.5) at urban, suburban and rural background sites in the region of Paris (France) |
| VerfasserIn |
M. Bressi, J. Sciare, V. Ghersi, N. Bonnaire, J. B. Nicolas, J.-E. Petit, S. Moukhtar, A. Rosso, N. Mihalopoulos, A. Féron |
| 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. 15 ; Nr. 13, no. 15 (2013-08-14), S.7825-7844 |
| Datensatznummer |
250085626
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| Publikation (Nr.) |
 copernicus.org/acp-13-7825-2013.pdf |
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| Zusammenfassung |
| Studies describing the chemical composition of fine aerosol (PM2.5) in
urban areas are often conducted for a few weeks only and at one sole site,
giving thus a narrow view of their temporal and spatial characteristics.
This paper presents a one-year (11 September 2009–10 September 2010)
survey of the daily chemical composition of PM2.5 in the region of
Paris, which is the second most populated "Larger Urban Zone" in Europe.
Five sampling sites representative of suburban (SUB), urban (URB), northeast
(NER), northwest (NWR) and south (SOR) rural backgrounds were implemented.
The major chemical components of PM2.5 were determined including
elemental carbon (EC), organic carbon (OC), and the major ions. OC was
converted to organic matter (OM) using the chemical mass closure
methodology, which leads to conversion factors of 1.95 for the SUB and URB
sites, and 2.05 for the three rural ones. On average, gravimetrically
determined PM2.5 annual mass concentrations are 15.2, 14.8, 12.6, 11.7
and 10.8 μg m−3 for SUB, URB, NER, NWR and SOR sites,
respectively. The chemical composition of fine aerosol is very homogeneous
at the five sites and is composed of OM (38–47%), nitrate (17–22%),
non-sea-salt sulfate (13–16%), ammonium (10–12%), EC (4–10%),
mineral dust (2–5%) and sea salt (3–4%). This chemical composition is
in agreement with those reported in the literature for most European
environments. On an annual scale, Paris (URB and SUB sites) exhibits its
highest PM2.5 concentrations during late autumn, winter and early
spring (higher than 15 μg m−3 on average, from December to
April), intermediates during late spring and early autumn (between 10 and
15 μg m−3 during May, June, September, October, and November) and
the lowest during summer (below 10 μg m−3 during July and
August). PM levels are mostly homogeneous on a regional scale, during the
whole project (e.g. for URB plotted against NER sites:
slope = 1.06, r2=0.84, n=330), suggesting the importance
of mid- or long-range transport, and regional instead of local scale
phenomena. During this one-year project, two thirds of the days exceeding the
PM2.5 2015 EU annual limit value of 25 μg m−3 were due to
continental import from countries located northeast, east of France. This
result questions the efficiency of local, regional and even national
abatement strategies during pollution episodes, pointing to the need for a
wider collaborative work with the neighbouring countries on these topics.
Nevertheless, emissions of local anthropogenic sources lead to higher levels
at the URB and SUB sites compared to the others (e.g. 26% higher on
average at the URB than at the NWR site for PM2.5, during the whole
campaign), which can even be emphasised by specific meteorological
conditions such as low boundary layer heights. OM and secondary inorganic
species (nitrate, non-sea-salt sulfate and ammonium, noted SIA) are mainly
imported by mid- or long-range transport (e.g. for NWR plotted against URB
sites: slope = 0.79, r2=0.72, n=335 for OM, and
slope = 0.91, r2=0.89, n=335 for SIA) whereas EC is
primarily locally emitted (e.g. for SOR plotted against URB sites:
slope = 0.27; r2=0.03; n=335). This database will serve as a basis for investigating carbonaceous
aerosols, metals as well as the main sources and geographical origins of
PM in the region of Paris. |
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