DISTRIBUTION OF RADIONUCLIDES IN MUSSELS, WINKLES AND PRAWNS .2. STUDY OF ORGANISMS UNDER LABORATORY CONDITIONS USING ALPHA-AUTORADIOGRAPHY

Under laboratory conditions, mussels, winkles and prawns have exhibited the ability to accumulate Np-237, Pu-239 and Am-241 from both sea water and food. In general, the soft tissues involved in feeding and digestion accumulated radionuclides most effectively. In digestive glands/hepatopancreas, the site of nuclide uptake was the digestive tubules. Other active tissues were the gill and heart of the Dublin Bay prawn and the pallial complex and operculum of the winkle. The prawn's gill was the only tissue to exhibit a clear preference between food and sea water labelling media - higher accumulation occurring via sea water. Heart tissue contained enhanced levels of Pu-239 relative to Np-237 and Am-241. This unusual observation may be associated with metal-detoxification processes. The various glandular and secretory functions of the winkle's pallial complex may account for the comparable magnitude of nuclide activities in this tissue and the digestive gland Other mucous secretions, on the external layers of the winkle's head and foot, have been observed to accumulate radionuclides but not as efficiently as the pallial complex. The most intense alpha-track distributions encountered were found in the winkle's operculum, these being attributable to its chitinous nature. The laboratory experiments have shown here that the accumulation and distribution of transuranic nuclides in marine in vertebrates are highly influenced by the presence of scleroproteins, chitinous material and mucous secretions. Despite the relatively low activities present in Ravenglass mussels and winkles, their alpha-autoradiographs exhibited tissue activity trends in general accordance with those obtained experimentally. This finding provides some further support for the validity of laboratory-derived information and its extrapolation to environmental conditions.