Experimental studies on the bioaccumulation of plutonium from sea water and a deep-sea sediment by clams and polychaetes

Abstract

The bioavailability of 237Pu in the (III + IV) and (V + VI) oxidation states from sea water and a NE Atlantic deep-sea sediment has been studied for clams ( Venerupis decussata) and polychaete worms ( Hermione hystrix). After 22 days' exposure in sea water transfer factors (TF) had not reached equilibrium, and were 74 ± 5 and 61 ± 1 for clams and 370 ± 10 and 275 ± 11 for polychaetes, for Pu (III + IV) and Pu (V + VI) respectively. Depuration rates after sea water exposure followed a single exponential form ( T b 1 2 = 50 days ) for clams, and for polychaetes at least a two component from with T b 1 2 = 1·3 days and 54 days. TF values for 237Pu bioaccumulation from sediments were very low, 6 × 10 −3 and 5 × 10 −2 for clams and polychaetes, respectively, after 20 days' exposure. Plotonium appears to be about 50% more bioavailable to the same species than americium as measured by laboratory experiments using a similar deep-sea sediment. Depuration experiments with clams after 40 days' exposure to labelled sediment indicated loss followed a single exponential form with a T b 1 2 = 24 days . Significant differences in the behaviour of Pu introduced into the uptake and loss experiments in different oxidation states were not observed in general.