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Article

Diagenetic processes and sediment–water exchanges of heavy metals in the Mejerda River Delta (Gulf of Tunis)

HELLALI Mohamed Amine, ZAABOUB Noureddine , OUESLATI Walid, ADDED Ayed, ALEYA Lotfi, 2015

Environmental Earth Sciences, 74, 9, 6665-6679, Novembre 2015

Résumé

An in situ benthic flux study of iron (Fe), manganese (Mn), lead (Pb), zinc (Zn), cadmium (Cd), copper (Cu) and cobalt (Co) was conducted at three stations at the Mejerda River outlet in the Gulf of Tunis, at depths of 10, 20 and 40 m in March and August 2012. Simultaneously, three sedimentary cores were taken at the same locations to evaluate the diffusive flux of these heavy metals and to determine the early diagenetic mechanisms occurring below the sediment–water interface and their impact on heavy metal mobility. The concentrations of Fe2+ in pore waters were similar to those observed in the rest of the Gulf of Tunis; flux, both benthic (275 µmol m−2 day−1) and diffusive (9 µmol m−2 day−1), confirmed that sediment was a source of Fe2+ for the water column, at least for the 10- and 20-m stations. The diffusive flux of Mn2+ was greater in August (11–14 µmol m−2 day