Absorption of Sediment-bound Radionuclides through the Digestive Tract of Marine Demersal Fishes

Abstract

Retention of ⁵⁴Mn, ⁵⁹Fe, ⁶⁰Co and ⁶⁵Zn by marine demersal fish, Ishigarei (Kareius bicoloratus) was observed by administering sediment-bound radio-isotopes orally to the fishes to elucidate the contribution of sediment to the accumulation of radionuclides by marine benthic organisms.
The sediment had high distribution coefficients for these radionuclides and from the result of leaching experiments with acidified seawater, considerable fractions of radioactive Mn, Co and Zn in the sediment were assumed to be leached in the stomach of the fishes. Retention patterns of the nuclides in the whole-body of the fishes were analyzed by peeling off method and two components were obtained for all the nuclides. The parameters which which characterized the retention patterns suggested relatively high absorption efficiencies of the radionuclides except ⁵⁹Fe through the digestive tract of the fishes and the retention patterns of the slower component were supposed to be similar to those observed for the nuclides taken up from seawater or food by the fishes. Rapid and higher transfer of the absorbed radionuclides to the particular organs of the fishes suggested the important role of the sediment in the radioactive contamination of marine demersal fishes.