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University of Crete (2016)

Study of the occurrence of toxic organic compounds in African dust transported from Sahara-Sahel regions over the Eastern Mediterranean

IAKOVIDES MINAS Ιακωβίδης, Μηνάς Ν

Titre : Study of the occurrence of toxic organic compounds in African dust transported from Sahara-Sahel regions over the Eastern Mediterranean

Προσδιορισμός τοξικών ενώσεων στη σκόνη της Σαχάρας μέσω μεταφοράς αερίων μαζών στην Ανατολική Μεσόγειο

Auteur : IAKOVIDES MINAS Ιακωβίδης, Μηνάς Ν

Etablissement de soutenance : University of Crete

Grade : Doctoral theses 2016

Résumé partiel
The key objectives of the present study consisted of : I) the study of the occurrence of PM2.5, PM10 and PM2.5-associated Polycyclic Aromatic Hydrocarbons (PAH) in the urban atmosphere of Heraklion Crete, by following a specific protocol implemented in the framework of the ESCAPE project (http://www.escapeproject.eu) during 2009-2010 ; and II) the study of the occurrence of toxic organic compounds, such as PAHs, Polychlorinated Biphenyls (PCBs) and Organochlorine Pesticides (OCPs), transported by air masses during the presence or absence of African dust incursions in the downwind area of Eastern Mediterranean (island of Crete). To achieve the aforementioned objective, in contrast to previous studies that have been focused to a small amount of dust episodes, a meticulous 3-year sampling campaign was conducted (2012-2015) in the framework of the CHEMISAND project (http://chemisand.chemistry.uoc.gr/). For that purpose, an efficient analytical methodology was developed that allowed the qualitative and quantitative determination of a relatively large number of toxic organic compounds (37 PAH members, 50 PCB congeners and 24 OCP members) by using a high resolution gas chromatographer-mass spectrometer (HRGC-MS) in Electron Ionization (EI) and Electron Capture Negative Ionization (ECNI) mode, respectively. The methodology was characterized by high quality assurance and control levels (enhanced repeatability, low uncertainty, reliable compound separation, high recovery levels). The median adjusted PM2.5 concentration in the urban area of Heraklion was 14.3 and 13.2 μg m-3, for the urban traffic (N=20) and background (N=20) sites, respectively, while the corresponding median adjusted PM10 concentration was 37.7 and 35.7 μg m-3 , respectively. We did not observe a statistically significant differentiation in PM2.5 and PM10 levels between urban traffic and background sites. We measured lower PM2.5 concentrations than the annual arithmetic mean benchmark level, established by EU (25 μg m-3), which is currently in effect from January 1st 2015. On the other hand, relatively higher PM10 concentrations were reported in a few urban sites, having regard to the corresponding EU PM10 annual limit value (40 μg m-3). We measured the highest daily PM concentrations (PM2.5, PM10, TSP) during intensive African dust episodes, while relatively lower PM concentrations were measured during dust episodes mixed with aerosol transport from other areas.

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