Organic pollution in a Ramsar site (Piallassa Baiona, Northern Adriatic Sea)

A core collected in the Piallassa Baiona lagoon, a salt-marsh area already studied for Hg contamination related to nearby industrial sites, was analys ed for organic micropollutants. Surface sediments show high concentrations of total PCBs (1148 ng g(-1)), PCDD/Fs (64 ng g(-1)) and PAHs (4801 ng g(-1 )). According to a sedimentation rate of 0.4 cm y(-1), the high increases i n total PAH, PCB and PCDD/F concentrations began in the 1960's and peaked i n the 1970s, in parallel with the highest Hg concentrations. Instead, the r ecent contamination, which primarily involves PCBs and PCDD/Fs, has been ob served to be unrelated to Hg concentrations. Organic micropollutant concent rations in the sample core were compared with the sediment quality criteria provided by international guidelines, and revealed high toxic potential. T his heavy contamination was also confirmed by comparison with similar envir onments, particularly the Lagoon of Venice. Further investigations are need ed to understand better the sources of the recent contamination and to expl ain the different transfer pathways involved during sedimentation of the "o ld" material, dumped 20-30 years ago.