Persistence of petroleum hydrocarbon contamination in sediments of the canals in Venice, Italy: 1995 and 1998.

Total hydrocarbon and selected polycyclic aromatic hydrocarbon (PAH) levels were examined in sediments collected from known problematic areas in the canals of Venice, Italy, in 1995 and 1998. Hydrocarbon concentrations were greatest in the interior canals, moderate in the partially enclosed locations and lowest in the open-water sites. Total hydrocarbon and PAH concentrations declined from 1995 to 1998. Ancillary data suggest that this decline may have been in response to the elimination of many industrial activities in the lagoon and to initiating an aggressive canal dredging program. The distributions of individual components were generally similar both years regardless of the total PAH concentration or the location of sample collected. PAH alkyl homolog distributions suggest that atmospheric deposition of petrochemical combustion products is the main source of PAHs to Venice's sediments. In some cases however, the presence of low levels of the two-ring naphthalene homologous series indicate additional low-level inputs of fresh oil.