Accumulation of radioiodine from aqueous solution by hydroponically cultivated sunflower (Helianthus annuus L.)

The suitability of sunflower plants (Helianthus annuus L.) for the phytoremediation of soils and waters contaminated with radioactive iodine was tested following the 125I uptake from a hydroponic medium and translocation during 32-day cultivation. The plants accumulated about 26% of the applied activity in case of combination of 125I (1.3 MBq) and 0.1 mM K127I (“carrier 125I”) and 47% when only 125I (1.3 MBq, “non-carrier 125I”) was added. When hydroponic medium was changed for the fresh one every 4 days, the plants accumulated up to 59% of starting activity of non-carrier 125I. The 125I distribution within the plant was followed using autoradiography. At low iodine level (non-carrier 125I) the radionuclide was localized mainly in the roots. At high iodine concentrations (carrier 125I) it was found mainly in the upper part of sunflower plants. All iodine removed from the liquid medium was found in the plant body. Volatilization of iodine (in the form of I0 or volatile organic compounds) apparently did not occur during accumulation and translocation. The achieved results indicate that sunflower can be used for phytoremediation of radioactive iodine, even if it is not its hyperaccumulator.