Chemical analyses of heavy metal contamination in sediments of the Venice lagoon and toxicological implications

Heavy metals are extracted from sediments using 1 M HCl; then, solutions ar e neutralised with 1 M NaOH, to fit the conditions suitable for the Vibrio Fischeri test. In the neutralised solutions different percentages of initia l metal concentration are present, depending on the individual solubilities . The chemical investigation of the metal fraction extracted from the sedim ent with this procedure and the different metal bioavailability depending o n the presence of natural complexing agents are the subject of this work. T he results obtained confirm the good agreement between heavy metal fraction extracted using 1 M HCI and the anthropogenic component in the sediment. T he use of voltammetric techniques, and the addition of low molecular weight humic acids into extracts show the ability of natural complexing agents in affecting heavy metal bioavailability and toxicity.