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Article

Trace elements in different marine sediment fractions of the Gulf of Tunis (Central Mediterranean Sea)

ZAABOUB Noureddine , OUESLATI Walid, HELLALI Mohamed Amine, ABDELJAOUAD Saadi, Javier Huertas F., Lopez Galindo Alberto, 2014

Chemical Speciation and Bioavailability, 26, 1, 1-12, Janvier 2014

Résumé

Over several decades, the mouth of the Mejerda River (northern Tunisia) has received large amounts of mining tailings mainly containing Pb, Zn and Ba. We have measured the concentrations of major and trace elements (Al, Ti, P, K, Mg, Na, Ca, S, Fe, Cl, V, Cr, Co, Ni, Cu, Zn, Ga, Br, Rb, Sr, Y, Zr, Nb, I, Ba and Pb) in three different fractions of 45 surficial sediments using wavelength dispersive X-ray fluorescence. The size distribution of fine particles (<2 μm, 2–20 μm, 20–63 μm) revealed that clay and silt compounds were predominant (75–95%) in the deeper estuarine region. These condensed clay phases were mainly dioctahedral smectite, illite and kaolinite. The total organic carbon (TOC) concentration varies from 0.08 to 1.37 %. The C:N ratio varies from 1 to 17 indicating that the organic matter has a mixed marine and continental origin principal component analysis was used to determine the associations of trace elements with organic and/or inorganic phases of the sediment fractions. The correlations of Fe₂O₃, MnO₂ and P₂O₅with trace elements showed that amorphous Fe and Mn were the most active scavengers of dissolved metals from the Mejerda River. Cluster analysis clearly distinguished local trace element accumulations according to grain size fractions (< 2 μm and 2–20 μm) near the Ghar el Melh Lagoon and th River.