涸沼におけるフォールアウト核種の移行挙動に関する研究(II) -放射性セシウムの移行モデルの開発- [in Japanese] Study on Migration Behavior of Fallout Nuclides in Hinuma Lake(II) -Development of a Transfer Model of Radiocesium- [in Japanese]
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A transfer model has been developed to facilitate the environmental monitoring of fallout (Cesium-<sup>137</sup>) in a lake system. The transfer of radionuclides between zones (i. e., catchment area, lake water, lake bed sediment and fish) was modeled using standard differential equations. Radionuclide transfer velocities between zones were calculated and expressed as a function of rainfall intensity and periodic tidal effects based on observations in Hinuma Lake, Japan. Parameter perturbation analysis of the model showed: (a) <sup>137</sup>Cs concentrations in the lake water (Cw) increased due to the deposition of <sup>137</sup>Cs in the lake and <sup>137</sup>Cs inflow from the catchment area; (b) Cw fluctuates due to the dilution of lake water by precipitation (i. e. Cw decreases) and subsequent inflow of <sup>137</sup>Cs from the catchment area (i. e., Cw increases); (c) Cw increases due to rolling-up of particles of sediments carrying <sup>137</sup>Cs when precipitation increases the current velocity in the lake; and (d) cyclic fluctuation of the flow rate with the tidal level causes variations in Cw.
- Jpn. J. Health Phys.
Jpn. J. Health Phys. 32(1), 53-65, 1997-03-31
Japan Health Physics Society