engleski

Using mussels Mytilus galloprovincialis as a indicator species in radioecology monitoring of the northen 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. Mussel Mytilus galloprovincialis is used as a indicator organism in monitoring marine pollution programs. A monitoring program for radioactivity in the northern Adriatic Sea was conducted by determination activity concentrations of artificial 137Cs, naturally occurring 40K, 232Th (228Ra), 226Ra, 238U and cosmogenic 7Be in the soft tissues of mussels M. galloprovincialis, in spring and autumn periods from 2008 to 2017. Radionuclides were determined by gamma-ray spectrometry. A comparison of radioactive contamination was made between three locations of the northern Adriatic sea (Lim bay, Raša bay and Bakar bay) under significant fresh water discharges. These are evident from the salinity’s which were below average for the northern Adriatic Sea (38), especially in the Bakar bay (16). In Lim Bay 137Cs activity concentrations in surface seawater were low (1.70 Bq m-3). In mussels 137Cs activity concentrations (< 0.3 Bq kg-1 dray weight) were below the detection limit at all locations, except it were detected thrice in Raša Bay (0.7 Bq kg-1) and in Bakar Bay (0.6 Bq kg-1). Its presence in mussels tissue could be the consequence of its significant input through heavy rains and riverine outflows prior to sampling periods. The impact of the fresh water influx at all locations and higher the phytoplankton bioproduction proves increased activity concentrations of 7Be in mussels during the spring (26 Bq kg-1) compared to autumn (19 Bq kg-1). Activity concentrations of 40K in mussels did not vary significantly with season or location, the average 40K activity was 322 Bq kg-1. 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 pollutant bioconcentration and indicator potential of these organisms. Radioecological condition of the northern Adriatic Sea is satisfactory without significant radionuclide discharges from fallout and rivers.

northern Adriatic Sea ; mussels Mytilus galloprovincialis ; radionuclides

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