Abstract

Most sediment dredged in Italian harbours is discharged into coastal areas. Italian legislation provides physical and chemical characterisations of dredged material. However, to determine whether materials are discharged to a dumping site, used for coastal nourishment or other beneficial use, toxicological assessment should be required. In 1995, 12 sediment cores were taken from dredged areas of Viareggio harbour (Tyrrhenian coast). Nine superficial sediments were collected in two coastal areas: a disposal site and a potential nourishment site. Particle size, total organic matter, heavy metals, polycyclic aromatic hydrocarbons and polychlorinated biphenyls were analysed. In order to assess sediment toxicity and evaluate the best destination, three bioassays were performed on two harbour and one offshore superficial samples using Vibrio fisheri, Corophium volutator and larvae of Crassostrea gigas.

The different harbour areas showed an increase of contaminant levels from the entrance to the inner zones. A comparison of sediment quality of the harbour and coastal areas (physical, chemical and ecotoxicological characteristics) suggested that materials dredged from different areas should be handled in different ways depending on contaminant types and loads. Dredged sediments could be dumped off-shore without decontamination or further use, used to build up eroded areas or be subjected to on-site decontamination treatment.

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