Transfer of Technetium from Paddy Soil to Rice Seedling

Tracer experiments on the chemical transformation of technetium in paddy soil and the transfer to rice seedlings have been carried out using ^95mTc as a tracer. Two common Japanese soils, Andosol and Gray lowland soil were used in the soil incubation experiments. The chemical form of soluble Tc in soil water was a mixture of Tc-organic matter complex, Tc-iron complex and pertechnetate. An uptake experiment with rice seedlings using nutrient solution showed that the Tc-organic matter complex was less available than pertechnetate or the Tc-iron complex. These chemical forms of Tc were also observed in the root bleeding sap of rice seedlings when introduced to the nutrient solution containing soluble Tc. These results suggested that the transfer of technetium from soil to rice would depend on the chemical form of Tc and they would transport from the root to the leaf without chemical transformation.