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| Titel |
Sources and mixing state of size-resolved elemental carbon particles in a European megacity: Paris |
| VerfasserIn |
R. M. Healy, J. Sciare, L. Poulain, K. Kamili, M. Merkel, T. Müller, A. Wiedensohler, S. Eckhardt, A. Stohl, R. Sarda-Estève, E. McGillicuddy, I. P. O'Connor, J. R. Sodeau, J. C. Wenger |
| 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 ; 12, no. 4 ; Nr. 12, no. 4 (2012-02-15), S.1681-1700 |
| Datensatznummer |
250010719
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| Publikation (Nr.) |
 copernicus.org/acp-12-1681-2012.pdf |
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| Zusammenfassung |
| An Aerosol Time-Of-Flight Mass Spectrometer (ATOFMS) was deployed to
investigate the size-resolved chemical composition of single particles at an
urban background site in Paris, France, as part of the MEGAPOLI winter
campaign in January/February 2010. ATOFMS particle counts were scaled to
match coincident Twin Differential Mobility Particle Sizer (TDMPS) data in
order to generate hourly size-resolved mass concentrations for the single
particle classes observed. The total scaled ATOFMS particle mass
concentration in the size range 150–1067 nm was found to agree very well
with the sum of concurrent High-Resolution Time-of-Flight Aerosol Mass
Spectrometer (HR-ToF-AMS) and Multi-Angle Absorption Photometer (MAAP) mass
concentration measurements of organic carbon (OC), inorganic ions and black
carbon (BC) (R2 = 0.91). Clustering analysis of the ATOFMS single
particle mass spectra allowed the separation of elemental carbon (EC)
particles into four classes: (i) EC attributed to biomass burning
(ECbiomass), (ii) EC attributed to traffic (ECtraffic), (iii) EC internally
mixed with OC and ammonium sulfate (ECOCSOx), and (iv) EC internally
mixed with OC and ammonium nitrate (ECOCNOx). Average hourly mass
concentrations for EC-containing particles detected by the ATOFMS were found
to agree reasonably well with semi-continuous quantitative thermal/optical
EC and optical BC measurements (r2 = 0.61 and 0.65–0.68 respectively,
n = 552). The EC particle mass assigned to fossil fuel and biomass burning
sources also agreed reasonably well with BC mass fractions assigned to the
same sources using seven-wavelength aethalometer data (r2 = 0.60 and
0.48, respectively, n = 568). Agreement between the ATOFMS and other
instrumentation improved noticeably when a period influenced by
significantly aged, internally mixed EC particles was removed from the
intercomparison. 88% and 12% of EC particle mass was apportioned to
fossil fuel and biomass burning respectively using the ATOFMS data compared
with 85% and 15% respectively for BC estimated from the aethalometer
model. On average, the mass size distribution for EC particles is bimodal;
the smaller mode is attributed to locally emitted, mostly externally mixed
EC particles, while the larger mode is dominated by aged, internally mixed
ECOCNOx particles associated with continental transport events. Periods
of continental influence were identified using the Lagrangian Particle
Dispersion Model (LPDM) "FLEXPART". A consistent minimum between the two
EC mass size modes was observed at approximately 400 nm for the measurement
period. EC particles below this size are attributed to local emissions using
chemical mixing state information and contribute 79% of the scaled ATOFMS
EC particle mass, while particles above this size are attributed to
continental transport events and contribute 21% of the EC particle mass.
These results clearly demonstrate the potential benefit of monitoring
size-resolved mass concentrations for the separation of local and
continental EC emissions. Knowledge of the relative input of these emissions
is essential for assessing the effectiveness of local abatement strategies. |
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