Potential of Brassica juncea and Helianthus annuus in phytoremediation for uranium

Abstract

To investigate the efficiency of the phytoremediation of uranium-contaminated soil by Brassica juncea and Helianthus annuus, greenhouse experiments with both plant species and soil from the “Fuhrberger Feld” (near Hanover, Germany) with defined enhancement of the uranium concentrations up to approximately 6 mg kg⁻¹ have been carried out. Part of the test plants was treated with citric acid buffer (pH =4.8). Plants of both species were grown in soil from the “Fuhrberger Feld” without any treatment (control plants). The plants were harvested 13 weeks after settling and the uranium concentration in shoots and roots and the remaining soil was measured. The uptake of uranium into the shoot was clearly lower than into the roots. Uranium concentration in the shoots of the control plants was below the detection limit. The addition of the citric acid buffer caused an enhancement of the uranium concentration in the soil water by factors of up to approximately 80. A visible effect of this enhanced concentration on the uptake into the plant and on the distribution on shoot and root was only shown for Brassica juncea, where the concentration in the shoot doubled. The reverse effect was shown for Helianthus annuus, where the citric acid buffer treatment caused a lower concentration in roots and shoots compared to the untreated soil with the same uranium concentration.