Temperature Effect on the Concentration of Radionuclides by Marine Organisms

概要

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The effect of temperature increase of seawater on uptake and release of radionuclides by several marine organisms was studied under laboratory conditions to obtain some basic informations on combined effects of radioactive and thermal effluents. As expected from the poikilothermism of marine organisms whose metabolic activities are controlled by outer temperature, uptake and release of radioactive zinc by mackerel (Scomber japonicus) were increased with temperature of rearing seawater. Concentration factors were raised 1.5 to 2.5 times and release of ^<65>Zn was promoted about 10 to 70 per cent during from 12℃ to 22℃. Temperature dependence of ^<137>Cs concentration by blackfish (Girella punctata) in the range of temperature between 15℃ and 35℃ was most significant at 20-25℃ presenting the maximum value of thermal coefficient (Q_<10>). The thermal coefficients calculated on crimson sea breams (Evynnis japonica) for the concentration of ^<60>Co were higher in scale or gill of the fishes rather than muscle unlike with the case of ^<137>Cs. Although the accumulation of ^<60>Co in midgut gland of clams (Meretrix lamarkii) was also affected by temperature increase, the different mechanism of temperature effect was supposed among the radionuclides or the parts of organisms.