Abstract    It is well known that the uptake of 137Cs in plants is suppressed by K, the homologous element, which is the same monovalent cation as Cs. It is expected that NH4+, the same monovalent cation, will also affect the uptake of 137Cs in plants. Therefore, the influence of NH4+ and NO3－ on 137Cs uptake in Japanese cedar seedlings was compared. Humus containing 137Cs was mixed with a granular volcanic ash soil, and Japanese cedar seedlings were planted and cultivated while giving 0.7 mmol / L of NH4+ and NO3－ solution once a week for 20 weeks, and analyzed 137Cs of Japanese cedar seedlings.137Cs of NH4+ seedlings was obviously lower than that of NO3－. Also, in the RI experiment of water culture, the uptake of 137Cs was suppressed as the NH4+ ratio increased. It was found that NH4+ suppresses uptake of 137Cs similarly to K, however the effect of NH4+ will decay with progress of nitrification from NH4+ to NO3－.

02 - Effect of NH4+ and NO3－, i.e. nitrification, on uptake of radioactive Cs in Japanese cedar