Accumulation, elimination and retention of 99Tc by duckweed

This study deals with the accumulation dynamics of the long-lived fission product technetium (⁹⁹Tc) in duckweed. Duckweed serves as model for aquatic plants, because of its representative foliar uptake for ⁹⁹Tc. This study shows that ⁹⁹Tc is irreversibly accumulated and distributed over cytoplasm, chloroplasts and mitochondria. Autoradiography showed that ⁹⁹Tc was not transported to new biomass. Irreversible storage of ⁹⁹Tc in plant biomass means that steady-state situations cannot be interpreted as a balance between uptake and elimination of ⁹⁹Tc, but that ⁹⁹Tc continuously builds up in each single duckweed plant and overall Tc concentrations are averaged over new biomass.