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| Titel |
Mass concentration and ion composition of coarse and fine particles in an urban area in Beirut: effect of calcium carbonate on the absorption of nitric and sulfuric acids and the depletion of chloride |
| VerfasserIn |
H. Kouyoumdjian, N. A. Saliba |
| 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 ; 6, no. 7 ; Nr. 6, no. 7 (2006-05-31), S.1865-1877 |
| Datensatznummer |
250003893
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| Publikation (Nr.) |
 copernicus.org/acp-6-1865-2006.pdf |
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| Zusammenfassung |
| Levels of coarse (PM10-2.5) and fine (PM2.5) particles were determined
between February 2004 and January 2005 in the city of Beirut, Lebanon.
While low PM mass concentrations were measured in the rainy season, elevated
levels were detected during sand storms originating from Arabian desert
and/or Africa. Using ATR-FTIR and IC, it was shown that nitrate, sulfate,
carbonate and chloride were the main anionic constituents of the coarse
particles, whereas sulfate was mostly predominant in the fine particles in
the form of (NH4)2SO4. Ammonium nitrate was not expected to
be important because the medium was defined as ammonium poor. In parallel,
the cations Ca2+ and Na+ dominated in the coarse, and
NH4+, Ca2+ and Na+ in the fine particles. Coarse nitrate
and sulfate ions resulted from the respective reactions of nitric and
sulfuric acid with a relatively high amount of calcium carbonate. Both
CaCO3 and Ca(NO3)2 crystals identified by ATR-FTIR in the
coarse particles were found to be resistant to soaking in water for 24 h
but became water soluble when they were formed in the fine particles
suggesting, thereby, different growth and adsorption phenomena. The seasonal
variational study showed that nitrate and sulfate ion concentrations
increased in the summer due to the enhancement of photochemical reactions
which facilitated the conversion of NO2 and SO2 gases into
NO3- and SO42-, respectively. While nitrate was mainly
due to local heavy traffic, sulfates were due to local and long-range
transport phenomena. Using the air mass trajectory HYSPLIT model, it was
found that the increase in the sulfate concentration correlated with wind
vectors coming from Eastern and Central Europe. Chloride levels, on the
other hand, were high when wind originated from the sea and low during sand
storms. In addition to sea salt, elevated levels of chloride were also
attributed to waste mass burning in proximity to the site. In comparison to
other neighboring Mediterranean countries, relatively higher concentrations
of calcium in Beirut were good indication of calcitic crustal abundance.
Considering the importance of the health and climate impacts of aerosols
locally and regionally, this study constitutes a point of reference for
eastern Mediterranean transport modeling studies and local regulatory and
policy makers. |
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