Abstract
Technetium was rare nuclide in the natural environment but now the nuclides are increasing in the environment by nuclear weapon tests, nuclear accidents, nuclear fuel fabrication and reprocessing. Especially 99Tc attracts public concern because of its long physical half-times as 2.1 × 105 years. To get information for accumulation of the nuclide by aquatic organisms, radioisotopes tracer experiments using 95mTc(chemical form : TcO4−) was made in laboratory conditions. Among the mollusca seaweed-eating gastropods(abalone and turbo) showed higher accumulation of 95mTc from water than other carnivorous mollusca. The abalone Haliotis discusgave the highest concentration factor as 400 for whole body in the mollusca. The mollusca absorbed well the nuclide from labelled food regardless of feeding habit. The organisms retained more than 50% of radioactivity in food 3 to 5 days after feeding. Fishes except a shark(elasmobranch fish) showed lower accumulation ability than the mollusca for the nuclide from water and also from food. The shark Scyliorhinus torazame indicated a whole-body concentration factor of 20 in the uptake experiment from water and retained about 60% of radioactivity in food 3 to 5 days after feeding. [J Radiat Res 44:433 (2003)]
