Abstract
We are on the way to remediate radioactive pol-lutants emitted from Fukushima daiichi nuclear power sta-tion after the great east Japan earthquake. Migration and redistribution of radioactive cesium was expected to be very slow. It was thought Cs must remain near the sur-face soil for years. However, rapid migration of radioac-tive cesium into deeper layer was observed in some area in Fukushima. In this article, factors affecting and caus-ing rapid migration of radioactive cesium in soils are dis-cussed. Frayed edge sites (FES) at the edge of illite and vermiculite clays are thought to retain Cs quite strongly. However, it might take time for cesium to reach the FESs. Unexpected migration of Cs may take place if a sort of transport phenomena such as percolation or infiltration of liquid water occurs during an approaching of Cs to the strongly bound sites. Besides, dissolved organic matter in soil would obstruct approach of cesium to FESs. This might be another factor to cause rapid migration of ra-dioactive Cs into deeper layer.
