Transuranic elements in fishes compared to 137Cs in certain lakes in Finland

Transuranic elements from Chernobyl fallout were detected in freshwater fish sampled in Finland after the accident. Maximum concentrations of 239,240Pu, 241Pu, 241Am and 242Cm were 3.3, 110, 2.6 and 340 mBq kg–1, respectively. In certain samples, 238Pu/239,240Pu ratios were between 1.0 and 7.2 while the expected value was 0.5. This could indicate differences in environmental mobilization between 238Pu and 239,240Pu. The concentration factor (CF) for Am from water to fish flesh, 230, was more than 2 times higher than the figure of 84 for Pu. The CF for Cm, 5100, was considerably higher than that of Am and does not confirm the presence of similar biological behaviour for Am and Cm. The average transfer factor (TF) from deposition to fish was highest for 137Cs, 44 x 10–3 m2 kg–1. This was somewhat higher than the TF for Am but more than 10 times higher than that for Pu. Transuranic depositions that could cause the European Council regulation limit in freshwater fish to be exceeded are, Pu and Am respectively, 3000 and 1500 times higher than the highest fallout of Pu and Am recorded in Finland following the Chernobyl accident.