Radioactivity levels of vegetables, rice, fruits and drinking water in Minami-Souma City

Radioactivity concentration of ¹³⁷Cs, ¹³⁴Cs and ⁴⁰K in vegetables, rice, fruits cultivated in Minami-Souma City after the accident of Fukushima Daiichi Nuclear Power Plant were measured and transfer coefficients from soil-to-vegetables and soil-to-unhulled rice were determined. In 2014, 6 model farms were prepared and 15 kinds of vegetables were produced. The ¹³⁷Cs and ⁴⁰K concentration in soils of paddy field and unhulled rice were measured and the transfer coefficient was determined. Japanese persimmon and chestnut sampled from the same tree in 2013 and 2014, and ¹³⁷Cs and ⁴⁰K concentration were compared for two years. Radiocesium concentration in tap water and ground water were sampled in Minami-Souma City and the results were compared with the regulation limit. It was found that ¹³⁷Cs concentration in vegetables and unhulled rice are much lower than the regulation limit (100 Bq/kg). Radioactivity concentration of ¹³⁷Cs in chestnut was over the regulation limit at one sample, but those in Japanese persimmon and chestnut in 2014 were decreased about half of radioactivity level in 2013. It is noticed that radioactive ¹³⁷Cs was detected both in tap water and ground water but concentration was much lower than the limit (10 Bq/L). Further continuous measurement is necessary to investigate the migration of ¹³⁷Cs in the environment. (author)