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| Titel |
Comparison between simulated and observed chemical composition of fine aerosols in Paris (France) during springtime: contribution of regional versus continental emissions |
| VerfasserIn |
J. Sciare, O. D'Argouges, Q. J. Zhang, R. Sarda-Estève, C. Gaimoz, V. Gros, M. Beekmann, O. Sanchez |
| 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 ; 10, no. 24 ; Nr. 10, no. 24 (2010-12-16), S.11987-12004 |
| Datensatznummer |
250008965
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| Publikation (Nr.) |
 copernicus.org/acp-10-11987-2010.pdf |
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| Zusammenfassung |
Hourly concentrations of inorganic salts (ions) and carbonaceous material in
fine aerosols (aerodynamic diameter, A.D. <2.5 μm) have been
determined experimentally from fast measurements performed for a 3-week
period in spring 2007 in Paris (France). The sum of these two chemical
components (ions and carbonaceous aerosols) has shown to account for most of
the fine aerosol mass (PM2.5). This time-resolved dataset allowed
investigating the factors controlling the levels of PM2.5 in Paris and
showed that polluted periods with PM2.5 > 15 μg m−3 were
characterized by air masses of continental (North-Western Europe) origin and
chemical composition made by 75% of ions. By contrast, periods with clean
marine air masses have shown the lowest PM2.5 concentrations (typically
of about 10 μg m−3); carbonaceous aerosols contributing for most of
this mass (typically 75%).
In order to better discriminate between local and continental contributions
to the observed chemical composition and concentrations of PM2.5 over
Paris, a comparative study was performed between this time-resolved dataset
and the outputs of a chemistry transport model (CHIMERE), showing a
relatively good capability of the model to reproduce the time-limited
intense maxima observed in the field for PM2.5 and ion species.
Different model scenarios were then investigated switching off local and
European (North-Western and Central) emissions. Results of these scenarios
have clearly shown that most of the ions observed over Paris during polluted
periods, were either transported or formed in-situ from gas precursors
transported from Northern Europe. On the opposite, long-range transport from
Europe appeared to weakly contribute to the levels of carbonaceous aerosols
observed over Paris.
The model failed to properly account for the concentration levels and
variability of secondary organic aerosols (SOA) determined experimentally by
the EC-tracer method. The abundance of SOA (relatively to organic aerosol,
OA) was as much as 75%, showing a weak dependence on air masses origin.
Elevated SOA/OA ratios were also observed for air masses having residence
time above ground of less than 10 h, suggesting intense emissions and/or
photochemical processes leading to rapid formation of secondary organic
aerosols. |
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