Evolution of radiocontamination in the Mediterranean Sea in the period 1985-1995

Investigations were carried out on several biotic and abiotic samples to determine the environmental radiocontamination of the Mediterranean Sea after the Chernobyl accident. Special emphasis was put on the determination of Cs-137 in the Adriatic Sea. This caesium isotope was the most abundant radionuclide in a wide variety of samples (seawater, sediment, pelagic and benthic species). Attention was also paid to the neutron activation products Ag-110m and Cs-134, which were first discovered in the Adriatic ecosystem after the Chernobyl event. In particular, although the Ag-110 fallout deposition over the area was negligible in comparison with that of Cs-137, its concentration factors and bioaccumulation in macroalgae and molluscs were much higher, suggesting some particular physiological accumulation mechanism. Concentrations of Sr-90, Pu-238 and Pu-239+240 were monitored in sediment samples collected in the period 1990-1993. A comparison of the radionuclide concentrations between the open sea area and the Po river estuarine ecosystem is also reported.