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(46-36) Estimation of PCDD/Fs historical trend in the Venice lagoon, Italy. Dalla Valle, Matteo*,1,2, Marcomini, Antonio1, Sweetman, Andrew2, Jones, Kevin2, 1 University of Venice, Calle Larga S.ta Marta 2137, Venezia, Italy2 Lancaster University, Lancaster, UK ABSTRACT- As high concentrations of PCDD/Fs have been recently reported in the Venice lagoon (Italy) sediment, there has been growing concern about their impact on the lagoon and its effect on human health. In order to place the contemporary situation in context, an understanding of the historical input, fate and behaviour in the lagoon system is required. Therefore a dynamic multimedia environmental model, a modified version of the fugacity-based QWASI (Quantitative Water Air Sediment Interaction), was applied to PCDD/Fs in the Venice lagoon. Inputs into the system were estimated from dated sediment cores collected in two salt marshes in the lagoon area. Calculations were run for congeners with a comprehensive set of experimental data in different media (sediment, water particulate matter, biomass, etc.). Results from the model show a peak of sediment concentrations delayed by 10-20 years from the emissions peak ('60s) and estimated concentrations are in good agreement with experimental results. Degradation and exchange with the sea cause a rapid decrease in concentration for most congeners except for OCDD, that shows a very slow reduction due to its slow biodegradability and low volatility. A key role in PCDD/Fs recycling in the lagoon system is played by the suspended particulate matter in water. Key words: PCDD/Fs, model, Venice lagoon, trend |
