Soil-to-pant transfer factors of technetium-99 for various plant collected in the Chernobyl area

Technetium-99 is one of the most important radionuclides for dose assessment because its most stable form pertechnetate, TcO4-, is highly soluble and rarely adsorbed onto soil. The form of Tc may change to other chemical forms under various conditions; and these different chemical forms play an important role in determining the mobility of Tc in soil-plant systems. Determination of physico-chemical forms of 99Tc in soil and plant samples would advance our understanding of its behavior in the environment; however, its scarcity and low levels in samples has limited the available data.In this study, we determined 99Tc contents in 27 plant samples collected in three forest sites in 1994 and 1995 around the Chernobyl area to obtain transfer factors (TFs) of Tc in the soil-plant system under environmental conditions. The samples were leaves of raspberry, strawberry and pink plants, black alder, birch, cowberry and oak trees, and ferns. After chemical separation, 99Tc in the sample was measured by ICP-MS. Tc-95m was used as a yield tracer and the total recovery ranged from 0.48 to 0.92 with an average of 0.76. The determined 99Tc concentrations in plants ranged from <0.006 to 2.3 mBq kg-1 (dry weight basis). TFs were then calculated as concentration ratios on the dry weight basis. The highest TF was found in the leaves of raspberry plants. Values ranged from