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3A - Biomarker/Biomonitoring (TUP/174) Active biomonitoring studies related to suspended sediment heavy metal content in Venice Lagoon, Italy. Manente, Sabrina 1, Mao, Andrea 1, Perin, Guido1, 1 Ca' Foscari University, Environmental Sciences Dept., Venice, Venice, Italy ABSTRACT- Sediment can be considered sink for a wide variety of pollutants, although they are not necessarily entrapped permanently in it. It is clear, in fact, that remobilisation processes could bring to diffusion of contaminants into water body, because of bioturbation or concentration gradient or resuspension caused by flooding, tide or boat traffic, all process that could change the geochemical parameters, first of all redox potential. In previous studies on Venice Lagoon, Italy, we have looked for the existence of a direct and quite simple correlation between really polluted sediment and bioaccumulation in suspension-feeding bivalve (Mytilus galloprovincialis), using cadmium as heavy metal contamination marker and digestive gland metallothionein (MT) as biomarker. Considerations on the obtained results are that is quite impossible (at least for the Venice lagoon conditions) to reach our initial aim, because of process complexity of this transition environment, otherwise considering suspended particulate matter as primary source of Cd exposure for the mussels. Since, in six lagoon sites (chosen following a hypothetical flow of contaminants from the Porto Marghera industrial area) we have conducted an active biomonitoring, i.e. transplantation of indigenous mussels belonging from the same lagoon breeding zone, in order to ensure comparable biota pools into different sites and to evaluate different behaviour in respect to native ones. Furthermore, we have built suitable sediment-particulate matter boxes, placed on the same height of the bivalve. The experiment was performed in June and November 2002 for five weeks. The results have showed a good correlation between suspended sediment heavy metal content and MT concentration in transplanted mussels, but they confirm a significant difficulty to evaluate bioaccumulation and particularly MT determination, when MT are used as individual biomarkers in order to extrapolate heavy metal sediment pollution transferring to biota information. Key words: mussel, biomonitoring, suspended sediment, metallothionein |
