Radioecological status in the Bulgarian sector of the Black Sea: Implications for environmental and seafood safety

An extensive survey of anthropogenic and natural radionuclides in fish, surface sediments and sediment cores was conducted as part of the SCIRENA project. As of October 2024, there was no discernible impact of the war in Ukraine on radioactive contamination in Bulgarian waters. Seven demersal and pelagic fish species contained 137 Cs activity concentrations ranging from <MDA to 0.59±0.06 Bq/kg wet weight (ww), all well below international guideline levels. Feeding habits influenced 137 Cs levels, but no consistent pattern emerged. Surface sediments from 37 stations (12.5-97.8 m) contained 137 Cs from <MDA to 90 Bq/kg dry weight (dw); indicating continued secondary inputs from Chornobyl-derived contamination delivered via rivers and coastal runoff. Activity concentrations of the natural radionuclide 226 Ra ranged from