Patterns and sources of polychlorinated dibenzo-p-dioxins and dibenzofurans in sediments from the Venice Lagoon, Italy

This study was a part of a research program concerning the pollution of the Venice Lagoon, in the north of Italy. The purpose was to evaluate the contamination due to polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F), a class of pollutants arising mainly from combustion and chemical manufacture. Six selected stations of the lagoon were investigated by analysis of surface sediment samples using gas chromatography-mass spectrometry (GC-MS). Principal Component Analysis and Regularized Discriminant Analysis, two chemometric approaches, were applied to the data set of the lagoon and to source-related samples from the literature. The results showed a moderate contamination due to PCDD/F in the investigated areas, and the levels within the lagoon were substantially higher than in the open sea. The investigation of the homologue profiles and the comparison with published PCDD/F data indicated different dioxin sources within the lagoon and some similarities of these with two environmental sources. Samples collected near Marghera Harbour and some samples collected at Sacca Sessola were similar to samples contaminated from ethylene dichloride production effluents while the profiles of most of the other samples were similar to those of gasoline and diesel engine emissions.