2015 年 50 巻 3 号 p. 189-193
Various radionuclides, including radioactive tellurium (Te), were released to the environment by the Fukushima nuclear power plant accident. The total amount of Te-127m released from the power plant was estimated to be 1.1 × 1015 Bq. The radioactive Te may have contributed to the internal radiation dose at the initial stage of the accident. However, data on the environmental behavior of radioactive Te are limited. In this study, therefore, the uptake of Te in plants was investigated. Radishes (Raphanus sativus var. sativus) were cultivated into a nutrient solution, grown for 20-30 days, and then their fine roots (taproots in the plant anatomy) and a part of fleshy roots (hypocotyls in the plant anatomy) were immersed for two hours into nutrient solutions with different Te and Cs concentrations. After soaking, plants were returned to the initial Te- and Cs-free nutrient solution for further maturation. ICP-MS measurements were made to assess concentrations of Te and Cs in the plants' leaves and fleshy roots (the fine roots were removed). Resulting differences among the individual plants were large. The leaf/fleshy root ratios of the concentration of Te and Cs were 0.09-1.14 and 1.59-5.00 on a fresh-matter basis, respectively. Both Te and Cs were absorbed by the radishes through the fine roots. There was a general tendency for Te to be retained in the fleshy roots, whereas Cs was mainly absorbed by the fine roots and then transferred to the leaves.
