The changing state of contamination in the Lagoon of Venice. Part 1: organic pollutants.
The Lagoon of Venice is a transitional environment suffering from industrial, urban and agricultural impact. Recently the mechanical clam fishing, preventing a regular deposition of sediments has made sampling of cores suitable for radiodating very problematic. Therefore, in this study, in order to assess temporal and spatial trends of contamination, the same sampling scheme was repeated three times over a 12-year period. The concentrations of PCBs, PAHs and organochlorine pesticides were measured in the uppermost 5 cm of sediments collected in 25 sites in the central portion of the lagoon during three campaigns conducted in 1987, 1993 and 1998. Analytical results, validated statistically, indicated that, while PCB and pesticide concentrations tend to decrease during the considered period of time, PAH do not, showing that the input rate of these compounds to the lagoon environment is still important. A spatial trend of pollution was also found in the lagoon for PCBs and pesticides, which decrease from the sources, namely the industrial zone and the mouths of rivers, to areas closer to the sea: a reduction up to 80% and 90%, respectively, was monitored. PAH contamination, originating chiefly from incomplete combustion of fossil fuels, as inferred from ratios of congeners, was mainly located around the historical center of Venice, where most of the boat traffic is concentrated and has an increasing trend.
Secco
Tommaso
T
Dipartimento di Scienze Ambientali, Università Ca' Foscari di Venezia, Calle Larga S Marta 2137, 30123 Venezia, Italia.
Pellizzato
Francesca
F
Sfriso
Adriano
A
Pavoni
Bruno
B
D000383:Agriculture; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000032:analysis*; D005579:Fossil Fuels; D019015:Geologic Sediments / Q000737:chemistry; D007221:Industry; D007558:Italy; D011078:Polychlorinated Biphenyls / Q000032:analysis*; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis*; D001335:Vehicle Emissions; D014874:Water Pollutants, Chemical / Q000032:analysis*
D004785:Environmental Pollutants; D005579:Fossil Fuels; D011084:Polycyclic Aromatic Hydrocarbons; D001335:Vehicle Emissions; D014874:Water Pollutants, Chemical; D011078:Polychlorinated Biphenyls