The transfer factors (TFs) from paddy soil to rice plants of radioactive cesium (137Cs and 134Cs) derived from Fukushima Daiichi Nuclear Power Plant (FDNPP) accidents in March, 2011 and grain size distributions were estimated in four paddy fields, A through D, in Fukushima City. Soil and rice samples were obtained in September, 2014. The soil was measured for 137Cs and 134Cs radioactivity by Ge semiconductor detector and separated by the dry sieving classification. The radioactivity of radioactive cesium in the soil was comparatively higher in fields C and D (> 4000 Bq/kg), but the TF in field B was the highest (1.9E-03) among the four fields. Meanwhile, the soil in fields A and B contained a relatively large amount of larger grains, such as medium sand. Grain size distribution might be related to the TF. This study shows a new correlation between the grain size distribution and TF.
Seabed soils of the southern Okhotsk Sea at the Notsuke Strait, Hokkaido were collected, and the radioactivity was measured with a Ge semiconductor detector. Trace amount of radiocesium derived from the Fukushima Daiichi Nuclear Power Plant was detected. It was suggested by combining other results that this radiocesium was originally deposited in western Fukushima from the Fukushima Daiichi Nuclear Power Plant, and migrated to the Japan Sea with the Agano River, and then carried to the Notsuke Strait by Tsushima Warm Current and Soya Warm Current.