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Sidi Thabet, Tunisia

Othmani M.A.,Tunis el Manar University | Souissi F.,Laboratoire Materiaux Utiles | da Silva E.F.,University of Aveiro | Coynel A.,CNRS Laboratory of Oceanic Environments and Paleo-environments (EPOC)
Journal of African Earth Sciences | Year: 2015

Wastes of the former Pb-Zn mining district of Touiref (Pb/Zn) can be eroded during strong rainfall. The presence of a downstream lake offers the opportunity to perform geochemical characterisation of lacustrine sediments and analyze the temporal evolution of metal contamination. For this reason, a sedimentary core (C1) has been collected at the outlet of the Oued Sidi Bou Said which runs along the North side of the dike flotation tailings and a second core (C2) was sampled in front of the river flowing outside the mine site and reaching the plain on the East side of the endoreic study area. The scope of the present paper is characterize the temporal variability of major and minor elements in both sedimentary cores. The study of the historical contamination in both Touiref cores shows a clear impact of mining on the total endorheic basin, especially for the period going from 1914 until 1955 as well as the influence of urban development. © 2015 Elsevier Ltd.

Othmani M.A.,Tunis el Manar University | Souissi F.,Laboratoire Materiaux Utiles | Duraes N.,University of Aveiro | Abdelkader M.,Tunis el Manar University | da Silva E.F.,University of Aveiro
Environmental Monitoring and Assessment | Year: 2015

This study aims to evaluate the impact of the former mining Touiref district (NW Tunisia) on the spatial distribution of metal contamination. In order to characterize the metal content of the tailings and to assess how far the soils from the district could be impacted by metals, a sampling campaign was conducted. According to the spatial distribution concentration maps of potential toxic elements (PTE), the highest concentrations occur near the flotation tailings and in mining facilities and decrease abruptly with distance. These results confirm that wind is the main agent capable of dispersing metals in a W–E direction, with concentrations exceeding the standards of soil quality for Cd, Pb and Zn over several hundred metres away from the source, facilitated by the small-size fraction and low cohesion of tailings particles. Chemical fractionation showed that Pb and Cd were mainly associated with the acid-soluble fraction (carbonates) and Fe-(oxy) hydroxides, while Zn was mainly associated with Fe-(oxy) hydroxides but also with sulphides. Thus, the immobilization of metals in solution may be favoured by the alkaline conditions, promoted by carbonates dissolution. However, being carbonate important-bearing phases of Cd and Pb (but also for Zn), the dissolution facility of these minerals may enhance the release of metals, particularly far away from the mine where the physicochemical conditions can be different. Also, the metal uptake by plants in these alkaline conditions may be favoured, especially if secondary phases with high sorption ability are reduced at this site. A remediation plan to this area is needed, with particularly attention in the confinement of the tailings. © 2015, Springer International Publishing Switzerland.

Souissi R.,Laboratoire Materiaux Utiles | Souissi F.,Laboratoire Materiaux Utiles | Souissi F.,Tunis el Manar University | Ghorbel M.,Tunis el Manar University | And 2 more authors.
Environmental Earth Sciences | Year: 2015

Pb-, Zn- and Cd-bearing particles from the flotation tailing heaps of Jebel Ressas mine are carried by wind and water toward the surrounding agricultural areas. These crop-producing areas are made of fersialitic soils and developed on carbonated bedrock. The risk of ecotoxicity depends on the bioavailability fraction of metals which is closely related to their physicochemical and biological environment. The objective of this study was to assess the contamination of the soils surrounding the waste dumps and to estimate the bioavailable fraction of metals present in these soils. The flotation tailings display big amounts of Zn, Pb and Cd, averaging 7.11 %, 2.30 % and 290 mg kg−1, respectively. The concentrations found in soils reach 6.3 % Zn, 2.3 % Pb and 290 mg kg−1 Cd. Analyses of the samples taken between surface and bedrock show that Pb and Zn may reach concentrations as high as 900 mg kg−1 2 m below surface. Simple extraction tests show that with deionized water only Zn is mobile, with 0.02–0.03 mmol l−1 released from soil. The mobilization of contaminants by organic acids, secreted by plants in the rhizosphere, is potentially higher than that achieved in the presence of percolating waters. © 2014, Springer-Verlag Berlin Heidelberg.

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