Investigation of the vertical and horizontal distribution of radioactive caesium in the soil of Kashiwa City, Chiba, Japan

To investigate the migrate situation of radioactive cesium in the soil due to the rainfall, the soil was collected at Kashiwa City, Chiba, Japan, before and after rainy season and after the typhoon season of 2013 fiscal year. This research was conducted between a period of 2 - 3 years passed since the accident of Fukushima Daiichi Nuclear Power Plant. More than 95% of radioactive caesium still remained in the first upper 5 cm soil layer. Also, penetration of radioactive caesium to the deeper layer of the soil was not observed during investigation period. In spite of same sampling area (within 150 m²), there were 2 - 3 times of horizontal variations of radioactive caesium depending on sampling point. The soil collected in this study did not show dependent relation between the particle size distribution of the soil and the concentration of radioactive caesium. This phenomenon might be due to the cause of characteristic properties of Kanto Loam particles. (author)