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| Titel |
Chemical characterization of the inorganic fraction of aerosols and mechanisms of the neutralization of atmospheric acidity in Athens, Greece |
| VerfasserIn |
E. T. Karageorgos, S. Rapsomanikis |
| 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 ; 7, no. 11 ; Nr. 7, no. 11 (2007-06-12), S.3015-3033 |
| Datensatznummer |
250005044
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| Publikation (Nr.) |
 copernicus.org/acp-7-3015-2007.pdf |
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| Zusammenfassung |
| The PM10 mass concentration levels and inorganic chemical composition were
determined on 12-h resolution sampling during August 2003 and March 2004,
in the centre of Athens, Greece. The August 2003 campaign mean PM10 mass
concentration, obtained by Beta Attenuation at 5 m above ground in Athinas
Street, was 56 μg m−3 while the corresponding value for March 2004 was 92 μg m−3.
In both campaigns the E.U. imposed daily limit of 50 μg m−3 was
exceeded on several days. During the March campaign, in Athinas Street,
additionally obtained DSFU-PM10 (PM10-2.5+PM2.5) gravimetric mass concentrations
(mean: 121 μg m−3) in the "breathing zone", at 1.5 m above ground were
significantly higher compared to the respective mean PM10 mass concentrations
obtained by the same method at 25 m above ground, in a second site (AEDA; mean:
86 μg m−3) also in the centre of the city. The above findings suggest that, for
a realistic estimation of the exposure of citizens to particulate matter, PM10
sampling in the "breathing zone" (1.5–3 m above ground) is necessary. Such data
are presented for the first time for the centre of Athens. In both campaigns,
calcium was found to be the predominant component of the coarse fraction while
crust-related aluminosilicates and iron were the other major components. The above
elements constitute the most important components of the fine fraction, together
with the predominant sulphur. All toxic metals were found in concentrations below
the established air quality limits, and most of them in lower concentrations
compared to older studies. Lead in particular, appeared mostly in the fine
fraction and in very low concentrations compared to studies dating more than
a decade back. The predominant ions of the coarse fraction have been found
to be Ca2+, NO3−, Na+ and Cl−, while SO42−, Ca2+ and NH4+ were the major
ionic components of the fine fraction. In the fine particles, a low molar
ratio of NH4+/SO42− indicated an ammonium-poor ambient air, and together
with inter-ionic correlations suggested that atmospheric ammonia is the
major neutralizing agent of sulfate, while being insufficient to neutralize
it to full extend. The formation of NH4NO3 is therefore not favored and
additional contribution to the neutralization of acidity has been shown
to be provided by Ca2+ and Mg2+. In the coarse particle fraction, the
predominantly abundant Ca2+ has been found to correlate well with
NO3−
and SO42−, indicating its role as important neutralizing agent in this
particle size range. The proximity of the location under study to the
sea explains the important concentrations of salts with marine origin
like NaCl and MgCl2 that were found in the coarse fraction, while chloride
depletion in the gaseous phase was found to be limited to the fine particulate
fraction. Total analyzed inorganic mass (elemental+ionic) was found to be
ranging between approximately 25–33% of the total coarse particle mass and
35–42% of the total fine particle mass. |
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