Some Long-lived Radionuclides in Marine Organisms on the Pacific Coast of Japan

Abstract

The analytical procedure for the radionuclides of Mn, Fe, Co, Zn, Zr, Ru and Ce in biological materials was improved and these radionuclides in marine organisms in the coastal waters of Japan collected in the period of 1964 to 1966 were analysed. The marine biota examined consisted of plankton, benthic algae, . molluscs and fishes, and freshwater organisms were also analysed for comparison. The radionuclides, 55Fe, 106Ru+106Rh and 144Ce+144Pr, were recognized as the main contaminants in the organisms, and their concentrations were generally higher in organisms in open seashore than those in estuary or embayment. The presence of 106Ru + 106Rh and 144Ce + 144Pr was observed commonly in plankton, littoral seaweeds and benthic molluscs, whereas these radionuclides were negligible in the muscle of nektonic organisms. The concentrations were particularly high in red algae, Gelidium spp., and benthic molluscs. In the latter the concentration of 106Ru+106Rh was higher than that of 144Ce+144Pr, which was reverse to the relative concentration in sea water, and the major portion of these radionuclides was found in the viscera. In the muscle of nekton, 55Fe was dominant and in the mackerel a value ten times higher than those in the bottom fish, shark and squid was observed. 54Mn was found in the oyster and fan shell which were collected respectively in estuary and embayment, and also in a bottom fish, Beryx splendens. 60Co was detected in red algae, Gelidium spp., hard clam and top shell in open seashore, but 65Zn was found in none of the organisms assayed here.