The effects of sediment transport on temporal variation in radiocesium concentrations in very shallow water off the southern coast of Fukushima, Japan.

We studied the very shallow coastal water off Iwaki City, Fukushima Prefecture, and investigated: (1) temporal variation in Cs concentrations; (2) particle-size distribution of sediments; and (3) the effect on variation by waves, component-fractionated concentration of radiocesium and mineral composition at three sampling stations (Yotsukura, Ena rocky reef and Ena sandy station). There was a decline in Cs concentrations in sediment samples at all sampling stations between 425 and 1173 days after the accident. All stations had fluctuations in Cs concentrations between 425 and 800 days.