¹⁰⁶Ruの海水中における化学挙動と海産生物濃縮に関する研究-I

ハマグリによる¹⁰⁶Ruの濃縮と排出

抄録

Accumulation and excretion of crude- and prep'd-¹⁰⁶Ru by the clam, Meretrix meretrix lusoria, were investigated under laboratory conditions. Accumulation of ¹⁰⁶Ru by the clam reached equilibrium approximately 2 weeks after immersion in sea water. The radioactivity ratio of prepared ruthenium-106 complexes was higher than that of the crude ones.
After 100 days of uptake experiment, radioactivity ratio of the edible part with both chemical forms showed less than 5.0. The highest radioactivity ratio was observed in mid gut gland, which was about an order of 40. And approximately 30% of the total radioactivity accumulated in whole soft tissues was concentrated in mid gut gland which occupies only 7% to the whole soft tissues in weight. The concept of the specific surface area should be taken into consideration for the tissues which contact directly with environmental sea water. In both chemical forms of prep'd-¹⁰⁶Ru, approximately 25% of accumulated radioactivity was lost from the whole body of the living clam during 40 days of loss experiment. The biological half lives of the short component and the long component were 49 days and 167 days respectively for prep'd-¹⁰⁶Ru•Cl_x, while 39 days and 121 days were for prep'd-¹⁰⁶RuNO•Cl_x. The radioactivity loss from the whole body of the living clam observed in the initial stage was attributable to the physiological activity of the living clam through the metabolic pathway, because the affinity of ¹⁰⁶Ru with the surface of the shell or the tissues seemed to be fairly tight.