Metal contamination of sediments in the lagoon of Venice: Studio of their geochemical speciation by sequential extraction in order to assess their mobility and their bioavailability

Abstract

Main industrial activities of Porto Marghera include different basic chemical products, oil refining and storage, shipbuilding, metal extraction and metallurgy, as well as energy production and distribution, wastewater treatment, hazardous waste incineration and petrochemical plants thermal power plants, steel, aluminum and fertilizer production sites. These industrial activities led to severe chemical contamination of soil, groundwater, sediment and inner tidal canal, to the point of the regional authorities to classify one third of the Venice lagoon as not suitable for shell fish harvesting (DGR3366/2004 ). The primary aim of this study is, therefore, to determine the concentration of heavy metals in superficial sediments of lagoon Venice and to assess their potential ecological risks. For this goal it was considered the study of height metal element ,Al, Bi Co, Cu, Mo, Mn , Rb using sequential extraction procedure of four fraction of the sediment minerals. Mollusks, crustaceans and other marine invertebrates are known to accumulate high levels of heavy metals in their tissues and yet survive in polluted environments. The second aim of this study is understand the relationship between metal fractionation and bioaccumulations of metal in clams (Ruditapes philippinarum). The manila clam , a filter-feeding organism living in the seafloor sediment, represents the major aquaculture species within the Venice lagoon, and due to its widespread distribution across the entire lagoon, it is considered an excellent “sentinel” species for bio-monitoring Venice lagoon areas and metal mobility on sediments. The Inductively Coupled Plasma Optical Emission and mass spectrometry was used for making an analytical procedure i.e. a quantitative analysis of multielements.