Laboratory experiments on the transfer dynamics of plutonium from marine sediments to sea water and to marine organisms

The leachability of 239240Pu from a fine contaminated calcareous sediment to aerated open sea water and to anoxic sea water was measured. The distribution coefficient for 239240Pu from sediment to sea water was 6.1 x 10-5 for aerated water and 2.6 x 10-6 for anoxic water. Experiments on the uptake of 239240Pu by the clams Donax denticulatus, and Lucina pectinata, were done in aquaria containing kilogram quantities of sediment from the Bravo Crater at Bikini Atoll. The concentration factor for 239240Pu by the soft parts of these clams was about 200. All the plutonium taken up in the soft parts was associated with the gill, mantle and siphon. No plutonium was detected in the adductor muscles or hepatopancreas. The smooth surfaces of the shells of the Donax did not show any detectable plutonium, but the rough shell surfaces of the Lucina concentrated plutonium by a factor of 1.10 x 104 over that in the sea water. Marine periphyton cultured on glass plates in an aquarium concentrated 239240Pu by a factor of about 7 x 103 over that in the sea water. (U.S.)