Tracer Experiments on the Transfer of Technetium from Soil to Rice and Wheat Plants

Abstract

Laboratory experiments on the transfer of Tc from soil to rice and wheat plants have been carried out by using a ^95mTctracer, added as TcO₄^-. The soil-plant transfer factors of Tc for rice plants were ≤50.005 for the grains (hulled) and about 1.1 for the lower leaf blade. In contrast to this, higher transfer factors were found for wheat plants, i. e. 0.027 for the grains (hulled) and 230 for the lower leaf blade. The Tc concentrations in the grains of both plants were lower than in the leaves. The level of Tc in the soil solution collected from the flooded soil was found to decrease rapidly with time. In the case of wheat plants grown in a non flooded soil, the decrease in the Tc level in the soil solution was rather slow. It was suggested that the Tc tracer added as TcO₄^- to the paddy soil was readily transformed to insoluble forms under the reducing conditions in the flooded soil. The low transfer factor observed for the rice plants could be explained by a fixation of Tc in the soil.