Metals play an important role in the deterioration of the Venice lagoon ecosystem. Since these pollutants are persistent in the environment, they can be hardly removed from the most contaminated sites, where they can reach very high levels and, as a consequence, cause serious problems to the community of organisms living therein. This research was aimed at acquiring knowledge on the relationships between the chemical forms of metals and their bioavailability, on metal mobility in the various environmental compartments, on bioaccumulation mechanisms and on metal metabolism in marine organisms. To this purpose, an investigation on metal contamination in organisms and in sediments from different areas of the lagoon was carried out. Total metal content was determined in mussels (Mytilus galloprovincialis) from four sites: S. Nicolò Celestia Tresse and S.Erasmo. Mussel samples were collected seasonally, starting from October 2001, wheras sediment samples were collected in October 2001 and in July 2002, at the same time of mussel sampling. The results pointed out the importance of a correct treatment of mussel samples, by depuration for 24 h, in order to avoid an overestimation of the tissue content of some metals that are present in high amounts in suspended particles. In addition, the mussel digestive gland, which was analysed separately, was shown to be a preferential site for metal bioaccumulation, with respect to the other soft tissues. The differences between metal concentrations in mussels from the four sites are not very marked. The Celestia site showed higher levels of Cu, Pb and Ni. S. Nicolò and S. Erasmo, chosen as reference sites, had significantly lower levels only for Cd and Zn, whereas they showed the highest concentrations of As. A comparison between the data for the various sampling campaigns indicates that metal concentrations in tissues show a clear seasonal trend, with summer samples showing in general lower metal concentrations. The observed differences can be ascribed to various factors, among which the reproductive cycles of organisms can play an important role. As concerns sediments, in general metal concentration were lower at S. Nicolò, which is situated near one on the inlets that connect the lagoon to the Adriatic sea. Celestia and Tresse presented a higher metal contamination, with similar concentrations in the two sites. The S.Erasmo site, included from July 2002 as a further reference site, showed instead higher concentrations, compared to S. Nicolò. The samples collected in the two different seasons had in general comparable metal levels; only Cd, Cu and Zn seemed to show increased levels in July. Sediment samples were also subjected to a procedure of sequential selective extractions, in order to determine the partitioning of metals among the various components of sediments, which can be related to their bioavailability

Metal bioaccumulation in mussels (Mytilus galloprovincialis) of the Venice lagoon

ARGESE, Emanuele;BETTIOL, Cinzia;RIGO, Chiarafrancesca;GOBBO, Lorena;ZONTA, Riccardo
2003-01-01

Abstract

Metals play an important role in the deterioration of the Venice lagoon ecosystem. Since these pollutants are persistent in the environment, they can be hardly removed from the most contaminated sites, where they can reach very high levels and, as a consequence, cause serious problems to the community of organisms living therein. This research was aimed at acquiring knowledge on the relationships between the chemical forms of metals and their bioavailability, on metal mobility in the various environmental compartments, on bioaccumulation mechanisms and on metal metabolism in marine organisms. To this purpose, an investigation on metal contamination in organisms and in sediments from different areas of the lagoon was carried out. Total metal content was determined in mussels (Mytilus galloprovincialis) from four sites: S. Nicolò Celestia Tresse and S.Erasmo. Mussel samples were collected seasonally, starting from October 2001, wheras sediment samples were collected in October 2001 and in July 2002, at the same time of mussel sampling. The results pointed out the importance of a correct treatment of mussel samples, by depuration for 24 h, in order to avoid an overestimation of the tissue content of some metals that are present in high amounts in suspended particles. In addition, the mussel digestive gland, which was analysed separately, was shown to be a preferential site for metal bioaccumulation, with respect to the other soft tissues. The differences between metal concentrations in mussels from the four sites are not very marked. The Celestia site showed higher levels of Cu, Pb and Ni. S. Nicolò and S. Erasmo, chosen as reference sites, had significantly lower levels only for Cd and Zn, whereas they showed the highest concentrations of As. A comparison between the data for the various sampling campaigns indicates that metal concentrations in tissues show a clear seasonal trend, with summer samples showing in general lower metal concentrations. The observed differences can be ascribed to various factors, among which the reproductive cycles of organisms can play an important role. As concerns sediments, in general metal concentration were lower at S. Nicolò, which is situated near one on the inlets that connect the lagoon to the Adriatic sea. Celestia and Tresse presented a higher metal contamination, with similar concentrations in the two sites. The S.Erasmo site, included from July 2002 as a further reference site, showed instead higher concentrations, compared to S. Nicolò. The samples collected in the two different seasons had in general comparable metal levels; only Cd, Cu and Zn seemed to show increased levels in July. Sediment samples were also subjected to a procedure of sequential selective extractions, in order to determine the partitioning of metals among the various components of sediments, which can be related to their bioavailability
2003
Corila - Programma di Ricerca 2000-2004 – 2a riunione annuale
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10278/25025
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