HEAVY-METALS IN SEDIMENTS, SPM AND PHYTOZOONBENTHOS OF THE LAGOON OF VENICE

Heavy metal concentrations were measured in the surface sediment, the settled particulate matter (SPM), the macroalgal biomass and some zoob enthic taxa of three areas (Alberoni, Sacca Sessola and S. Giuliano) s panning the main bio-geo-physico-chemical differences of the central l agoon of Venice. In terms of average metal content the observed contam ination indicates the following sequence: SPM>sediment>macroalgae>zoob enthos. The dominant macroalgal species in the central lagoon of Venic e, that is Ulva rigida C.Ag., showed a preferential enrichment of Zn a nd Mn compared to other metals. Both seasonality and frond age were re sponsible for the heavy metals found in the macroalgae. Finally, consi dering the amount of metals involved in the total gross primary produc tion (GPP) and the total heavy metal quantity flowing into the central lagoon by streams and rivers, in situ turnover is thought to take pla ce.