Transfer factors of technetium from soil to various agricultural products

Laboratory experiments of the transfer of technetium from soil to various kind of agricultural products have been carried out. The soil to plant transfer factors of Tc for rice plants were ≤ 0.005 for the grains 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. In the case of vegetables, transfer of technetium form soil to edible parts of vegetables have also been studied. Transfer factors of Tc for leaf vegetables such as spinach and komatsuna were considerably higher than those for non-leaf vegetable (e.g carrot, onion, sweet potato, tomato). Values for cabbages and Chinese cabbages were intermediate. Older leaves contained higher Tc than younger ones. It was suggested that Tc was readily taken up through roots and transported with water into leaves without any significant deposition in roots and stems. Technetium accumulated in leaves, while water was transpired from the leaves. This nuclide was associated strongly with constituents in leaves and hardly translocated into the other parts of the plants such as tubers, bulbs and fruits. The transfer factors (on a wet weight basis) in edible parts of vegetables obtained in this study were as follows; cabbage: 0.3, Chinese cabbage: 0.1, spinach: 2.4, komatsuna: 1.1, carrot: 0.3, onion: 0.05, sweet potato: 0.03 and tomato: 0.03. (author)