Radioactivity Measurement of Soil and Vegetables Arisen from Fukushima Daiichi Nuclear Power Plant Accident—Case Studies of Low Level Contamination in Tokyo and Fukushima

The vegetables grown in the two different fields 60 and 230km apart from the Fukushima Daiichi Nuclear Power Plant accident were examined after the accident to determine the concentration of 134Cs, 137Cs and 40K together with those of soil. For the edible part, the transfer of 134Cs and 137Cs was observed to potato tuber only in the field of about 60km apart from Fukushima Daiichi Nuclear Power Plant. The contamination of radioactive caesium(134Cs+137Cs)was less than 7Bq/kg-wet weight in tuber and that of soil was less than or equal to 1235Bq/kg-dry weight. As to the edible part of cabbage and lettuce grown in each field, the concentration of 134Cs and 137Cs was less than the detection limit. The concentration of soil in each field was 651Bq/kg-dry weight or less. The concentration of 40K of each field was nearly constant in vertical direction, however that of 134Cs and 137Cs showed the vertical distribution of which the highest concentration was observed at soil surface.