Polychlorinated Dibenzo-p-dioxins and Dibenzofurans in Surficial Sediments of the Venice Lagoon (Italy)

Concentrations of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) have been measured in samples from 24 sites in the Venice Lagoon. They ranged from 16 to 13 642 ng kg−1 (dioxins) and from 49 to 126 561 ng kg−1 (furans), with TEQs spanning between 0.5 and 2857 ng kg−1. The highest concentrations have been found in sediments of the canals of the 1st Industrial Area. These sediments represent a potential risk for the lagoon environment because they can be episodically resuspended by dredging operations or passage of ships. Lagoon sediments are much less contaminated. Three different PCDD/F congener profiles have been identified: one is mainly octachloro dibenzo-p-dioxin (OCDD) and comes from combustion, the second is characterized by the almost exclusive presence of octachloro dibenzofuran (OCDF) and can be associated to the stripping of vinyl chloride monomer (VCM), the third contains significant amounts of different congeners, and was probably originated by different productions within the 1st Industrial Area.