The accumulation of plutonium by the edible winkle (Littorina littorea L.)

Laboratory experiments were carried out to measure the accumulation of ²³⁷Pu by the edible winkle from labelled sea water, food (seaweed), and silt. The equilibrium whole body concentration factor for ²³⁷Pu accumulation from sea water at 10°C was estimated as 34 with a biological half-time of 9 d. After 50 d accumulation, 83% of the measured whole body activity was present on the shell. In the flesh, the major sites for accumulation were the head/foot complex and the digestive gland. Depuration was found to be biphasic with components having half-times of 10 and 193 d respectively. Pu loss, following uptake from labelled Fucus spiralis, was biphasic with half-times of 1 and 69 d for the two components. Assimilation efficiency was tentatively estimated as 7%. Pu accumulation from labelled silt was low with an estimated transfer factor of 0.004; Pu loss was biphasic, with half-times similar to those for the seaweed experiment. Comparison of the laboratory-derived results with those for winkles from the environment showed that the food pathway was the main route for Pu accumulation, with the ingestion of silt playing a critical role in determining the final flesh Pu burden.