Accumulatlon of Radlonuclldes In Coastal Sedlment of Japan (II) Contents of Fission Products in Some Coastal Sediments Collected in 1966-1972

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The concentrations of fission products ^<90>Sr, ^<137>Cs and ^<144>Ce in the marine sediment of Tokyo Bay and of the coastal seas of Ibaraki, Fukushima and Fukui prefectures were determined during 1966 to 1972. The radioactivity ranged 0 to 23.3 pCi/kg-dry for ^<90>sr, 5.3 to 220 pCi/kg-dry for ^<137>Cs and 0 to 12,700 pCi/kg-dry for ^<144>Ce. Generally speaking, the ^<90>Sr level is one order of magnitude lower than that of ^<137>Cs, and ^<144>Ce concentration is higher than that of ^<90>sr by almost two orders of magnitude. The degree of the radionuclide enrichment in the sediment from sea water is tens for ^<90>Sr, 10^2 for ^<137>Cs and apparently 10^4 for ^<144>Ce, respectively. The wide variation is observed in the horizontal distribution of ^<144>Ce concentration in the sediment of the areas, but the ^<137>Cs concentration shows fairly small horizontal fiuctuation. Since the large fraction of radionuclides entered the coastal sea is known to be removed from sea water and accumulated in the marine sediment, it is necessary to determine the level and distribution of radionuclides in the marine sediment for the evaluation of radioactive pollution in the coastal area.
日本放射線影響学会の論文