Geochemical behaviour of the Tunisian background aerosols in Sirocco wind circulations |
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| Authors: | Chafai Azri Habib Abida Khaled Medhioub |
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| Affiliation: | Department of Geology, Faculty of Sciences of Sfax ( FSS), BP 1171, 3000 Sfax, Tunisia;Department of Geology, Faculty of Sciences of Sfax ( FSS), BP 1171, 3000 Sfax, Tunisia;Institute of Preparatory Engineering Studies of Sfax ( IPEIS), BP 805, 3018 Sfax, Tunisia |
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| Abstract: | This study examines spatial and time evolutions of the principal constituents of the
Tunisian background aerosols under Sirocco wind circulations. Aerosols coming from the Sahara
Desert were found to be loaded with particulate matter, especially silicon. The aerosols were
shown to have varying geochemical behaviour along the ``South-North" displacement of the Saharan
plumes, depending on the wind flow characteristics, geomorphologic features and the nature of
soils swept by the wind. In the south and the center part of the country, the transfer of aerosol
constituents to the soil (by gravity and/or impaction) was probably predominated by localized
enrichment phenomena. The latter are reinforced by the effect of turbulent winds over bare soils,
wind wakes and probably selective disintegration, especially in the vicinity of the geomorphologic
features of central Tunisia. These relatively high features, extending over important distances,
appear to be of paramount importance for the phenomena of redistribution of aerosol constituents
even during periods without Sirocco wind circulations. In the northern section of the country,
aerosol constituent concentrations dropped to almost 50%, in spite of the abundance of localized
turbulent winds. This may be explained by the effect of forests and the relatively dense vegetation
cover, which clearly reinforces the transfer phenomena to the soil and the attenuate of dust
entrainment. |
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| Keywords: | aerosols Sahara Sirocco Tunisia turbulent winds |
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