Study on transfer model of 137Cs in lake Hinuma

A transfer model has been developed to facilitate the environmental monitoring of fallout (Cesium-137) in lake Hinuma. The lake Hinuma is located near the Pacific Ocean in Ibaraki-prefecture in Japan. Transfer of 137Cs between zones (i.e., catchment area, lake water, lake bed sediment) was modeled using standard differential equations based on the results of observations such as fluctuation of 137Cs concentration in the lake water and sediments since 1986. Transfer velocities of 137Cs between zones on the model were determined from expressed as a function of rainfall intensity. The effects of rainfall intensity (i.e., increasing inflow-flux of 137Cs from catchment area and rolling-up of particles of sediments carrying 137Cs) were investigated on this model. (author)