Vertical/spatial movement and accumulation of Cs-137 in a shallow lake in the initial phase after the Fukushima Daiichi nuclear power plant accident

摘要

Movement of Cs-137 in the bottom sediment of a shallow lake was investigated by collecting columnar sediment cores from the entire area once a year, and also from three representative points every 3 months over 3 years from the Cs-137 fallout in March 2011. The Cs-137 inventory in the sediment increased remarkably near the mouths of urban rivers; however, the distribution of the Cs-137 inventory did not change remarkably in most areas, and horizontally slow downstream movement of Cs-137 was observed.