Monitoring OF Radioactivity In Mussel Mytilus Galloprovincialis In The Northern Adriatic Sea

The source of radionuclides in the Adriatic Sea is global fallout primarily from the Chernobyl accident in 1986 and indirectly from the rivers discharges. A monitoring program for radioactivity in the northern Adriatic Sea was conducted by determination 137Cs, 40K, 232Th (228Ra), 226Ra, 238U and 7Be in the tissues of mussels Mytilus galloprovincialis, in spring and autumn periods from 2008 to 2014. A comparison of radioactive contamination was made between three locations of the northern Adriatic Sea (Lim Bay, Rasa bay and Bakar bay) under significant fresh water discharges. In Lim Bay 137Cs activity concentrations in surface seawater were low (1.83 Bq/m³). In mussels 137Cs activity concentrations (less than 0.3 Bq/kg dry weight) were below the detection limit at all locations. In the spring activity concentrations of 7Be in mussels were similar or greater than in autumn. In the autumn activity concentrations of 40K in mussels were higher than in the spring, while in 2011 and 2013 the situation was reversed. Activity concentrations of primordial radionuclides 232Th (228Ra), 238U and 226Ra in mussels were mostly below the detection limit with no seasonal changes. Increased activity concentrations of individual radionuclides in the mussels tissues proved the exceptional ability of seawater filtration and indicator potential of these organisms. The activity concentrations of radionuclides in the northern Adriatic Sea have returned to the pre-Chernobyl level, generally taking into consideration their natural fluctuations due to the physico - chemical and hydrological parameters of the investigated area. (author).