Abstract
For nuclear safety assessment, it is required to know the behavior of radioiodine in the environment because of its affinity to the thyroid gland. We have already estimated the soil-to-plant transfer factors (TFs) of radioiodine using Andosol, the most abundant soil types in Japan. TF showed the concentration ratio of the nuclide between crop and soil at harvest. It is, however, necessary to obtain the plant/soil ratio at different growth stages in order to understand the uptake pattern during the cultivation. Therefore, we have carried out radiotracer experiments on the transfer of radioiodine from Andosol to radish. The mean values of the concentration ratio (on a wet weight basis) of radioiodine for roots (tubers) of radish at 17, 24, 31 and 38 days after sowing were 0.010, 0.0057, 0.0040 and 0.0028, respectively, suggesting the values decreased with time. Contrary to these, the concentration ratios observed for leaves of radish increased with time, i. e. the ratios at 10, 17, 24, 31 and 38 days after sowing were 0.007, 0.008, 0.013, 0.011 and 0.011, respectively. [J Radiat Res 44:433 (2003)]