Transfer of zirconium, niobium and molybdenum from Japanese agricultural fields to edible parts of crops

Soil-to-plant transfer factors (TFs) of stable zirconium (Zr), niobium (Nb) and molybdenum (Mo) for 148 crop samples were determined with the intention to apply these values for those of Zr-93, Nb-94 and Mo-93 under physico-chemical equilibrium conditions. The TF of an element is defined as the concentration ratio of the element in a crop to the element in soil. The geometric means of the TFs for seven crop types (leafy vegetables, tubers, root crops, fruit vegetables, legumes, wheat and barley, and brown rice) had the following ranges: Zr, 4.3x10^-5 (brown rice) - 5.8x10^-4 (leafy vegetables): Nb, 1.5x10^-4 (brown rice) - 1.0x10^-3 (leafy vegetables) and Mo, 1.8x10^-1 (tubers) - 7.8x10^-1 (brown rice and legumes). The TFs of Zr and Nb were higher than the values reported in IAEA-TRS-472, however, almost the same values were observed for Mo. Additionally, the TF ranges of Zr, Nb and Mo for each crop grown in different sampling fields usually varied by one or two orders of magnitude. These TF values will be informative to understand the behaviors of the radionuclides in agricultural fields