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Article

Trace metal pore water geochemistry of Ghar El Melh lagoon sediments (Northern Tunisia)

OUESLATI Walid, HELLALI Mohamed Amine, ZAABOUB Noureddine , ADDED Ayed, 2014

Revue Méditerranéenne de l'Environnement, 5, ., 728-737, Janvier 2014

Résumé

Five cores of 70 cm length were manually collected from Ghar El Melh lagoon sediments in January, April, June, August and November in order to study the dynamic of metals and their seasonal variation. The pore waters were extracted from the sediment under an inert atmosphere, and analyzed for dissolved iron, manganese, lead, zinc, cobalt, nickel, cadmium and copper. In general, iron, manganese, cobalt, lead, zinc and nickel increased with depth below the sediment-water interface and their concentrations are higher in the spring and the summer than in winter and autumn. Contrary to these metals, copper and cadmium are more released from the sediment in winter. Their profiles showed a decrease with depth. The formation of metallic sulfides and/or coprecipitation with iron sulfides apparently controls the distribution of these metals in the pore fluids in the layer 5-15 cm of the sediment. However, metal carbonate precipitation is absent in the sediment and the low values of saturation index can be due to analytical and calculation error.