Accumulation of 60Co by marine organisms under reduction of radioactivity in sea water.

In order to know the effect of topography on the contamination of marine organisms by radionuclides, the accumulation of 60Co was observed under the reducing level of 60Co in rearing sea water. The level of 60Co in sea water was exponentially reduced by 90% in 1, 7 and 14 days assuming the dispersion patterns of radionuclide from nuclear facilities. The radioactivity in organism was expressed by an exponential model which involved biological parameters (uptake and excretion rate) and the reduction coefficient of radioactivity in sea water. On the 10th day after the start of the experiment, the radioactivity in the fish under the reduction of 60Co in sea water by 90% in 1 day was lower with a factor of 7 and 12 than that of under the reduction in 7 and 14 days, respectively. In this way of thinking, theoretical change in the time of level of 60Co in various marine organisms was illustrated under the reduction of 60Co in sea water by 90% in 7 days. The highest radioactivity was calculated around the 10th day.