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Updated: Aug 11, 2026

Speciation and Bioavailability Measurements of Environmental Plutonium Using Diffusion in Thin Films
Published on: November 9, 2015
Uptake, biotransformation, and elimination of 99Tc in duckweed
Jasper Hattink1, Arend V Harms, Jeroen J M de Goeij
1Interfaculty Reactor Institute, Mekelweg 15, 2629 JB Delft, The Netherlands.
Abstract:
Aquatic plants may play an important role in the environmental fate of the long-lived radioactive waste product 99Tc. Aquatic plants show a strong accumulation and retention of Tc, even after they have died. This study focuses on possible bio-organic Tc compounds formed in the water dwelling plant duckweed to possibly explain the accumulation and retention. Moreover, a change in chemical speciation often implies a different fate and behaviour in the biosphere. A mild separation technique was used to distinguish between reduced Tc species and TcO(4)(-). Accumulation experiments suggested that reduction of Tc(VII)O(4)(-) and subsequent complexation are responsible for the accumulation of Tc in duckweed. A steady state concentration of TcO(4)(-) in duckweed was reached within 24 h, but the total concentration of Tc increased continuously. Only a small part (=5%) of Tc was present as TcO(4)(-). Elimination experiments showed that TcO(4)(-) is the only mobile species. Other Tc species are responsible for the retention of Tc in duckweed. It is known that these species are not bio-available and only slowly re-oxidise to pertechnetate, resulting in a longer residence time in ecosystems.
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