title: Bioavailability and assessment of heavy metal pollution in sediment cores off the Mejerda River Delta (Gulf of Tunis): How useful is a multiproxy approach?
abstract: Three core samples were taken from zones offshore from the Mejerda River Delta (Tunisia) and analyzed for major and trace elements to assess their relationships with organic matter, monosulfides and carbonates, as well as for pollution and bioavailability. Chemical speciation, ∑ SEM/AVS, the enrichment factor (EF) and the geo-accumulation index (I-geo) were used. Iron, cadmium, lead and zinc - the most frequently mined metals in the Mejerda catchment - were found as contaminants in the offshore areas. Estimations of trace element accumulation using the EF and the I-geo index show that lead, and to a lesser extent zinc, are the most polluting metals off the Mejerda outlet. According to their bioavailability, these metals are also the most toxic. Only cadmium is heavily present in delta sediment (EF>100) though deeply sequestrated (100% bound to the residual fraction) and thus presents no toxicity.
authors.affiliation: Laboratoire des Ressources Minérales et Environnement, Département de Géologie, Faculté des Sciences de Tunis, Université Tunis-El Manar, 2092, Tunisia.
authors.forename: Mohamed Amine
authors.initials: MA
authors.lastname: Helali
authors.affiliation: Laboratoire des Ressources Minérales et Environnement, Département de Géologie, Faculté des Sciences de Tunis, Université Tunis-El Manar, 2092, Tunisia.
authors.forename: Walid
authors.initials: W
authors.lastname: Oueslati
authors.affiliation: Laboratoire du Milieu Marin, Institut National des Sciences et Technologies de la Mer, 2025 Salammbô, Tunisia.
authors.forename: Noureddine
authors.initials: N
authors.lastname: Zaaboub
authors.affiliation: Laboratoire des Ressources Minérales et Environnement, Département de Géologie, Faculté des Sciences de Tunis, Université Tunis-El Manar, 2092, Tunisia.
authors.forename: Ayed
authors.initials: A
authors.lastname: Added
authors.affiliation: Université de Bourgogne Franche-Comté, Laboratoire de Chrono-Environnement, UMR CNRS 6249, La Bouloie, F-25030 Besançon Cedex, France. Electronic address: lotfi.aleya@univ-fcomte.fr.
authors.forename: Lotfi
authors.initials: L
authors.lastname: Aleya
mesh_terms: D002104:Cadmium / Q000032:analysis; D002254:Carbonates; D004784:Environmental Monitoring / Q000379:methods*; D004787:Environmental Pollution; D019015:Geologic Sediments / Q000737:chemistry*; D019216:Metals, Heavy / Q000032:analysis*; D008906:Mining; D045483:Rivers / Q000737:chemistry; D014131:Trace Elements; D014416:Tunisia; D014874:Water Pollutants, Chemical / Q000032:analysis*; D015032:Zinc / Q000032:analysis
chemical_list: D002254:Carbonates; D019216:Metals, Heavy; D014131:Trace Elements; D014874:Water Pollutants, Chemical; D002104:Cadmium; D015032:Zinc
keywords: Chemical speciation; Coastal areas; Enrichment factor; Geo-accumulation index; Toxicity