Behavior of Zinc in Soil-Plant System (II): Estimation of Transfer Factor

Transfer factor (TF) is defined as the amount of material in the plant tissue divided by that in the soil. It is widely used to predict the amount of radionuclides transferred from the soil to edible parts of plant. But TF value varies greatly due to environmental factors and other growth conditions. In order to predict the precise amount taken up through plant roots using TF, the effect of those factors on TF should be considered. In this study, a model to estimate TF through plant root was proposed. This model is described as follows: TF=S·Tc/θr+Kd, where S is the selectivity [-]; Tc, the transpiration coefficient [ml/g]; θr, the soil water content by soil weight [ml/g]; and Kd, the distribution coefficient [ml/g]. In experiments, the fluctuation range of S was investigated. The S was not affected by the zinc concentration level in nutrient solution when there were less than 0.15mmol zinc/l. The decrease of co-existing ion concentration in nutrient solution increased S, but the effect was considered to be small if no problem with the plant growth was observed. The TF calculated from the proposed model had considerably good agreement with the actual TF.