Phytoremediation of seleniferous soil leachate using the aquatic plants Lemna minor and Egeria densa

Abstract

Phytoremediation of selenium (Se)-containing Hoagland solution and seleniferous soil leachate using two aquatic plants Lemna minor and Egeria densa was evaluated. L. minor showed the highest Se removal efficiency (97%) in the Hoagland solution with a bioconcentration factor (BCF) of 504.35 (±0.83). In artificial soil leachate with addition of 2 mg L−1 MnSO4, L. minor and E. densa showed a Se removal efficiency of 77% and 60%, respectively. The addition of K2S2O8 decreased the Se uptake by both plants by 40% and the medium pH decreased from 7 to 3, whereas the addition of SO42− decreased the removal efficiency of both aquatic plants by 30%, in which only 3% of Se was taken up by the plants. L. minor was selected to remove Se from a real seleniferous soil leachate which contained 74 μg L−1 Se and a 76% efficiency was achieved, with a Se uptake of 29 µg g−1 dry weight and a BCF of 393.2 (±13.6). This study demonstrates that aquatic plants such as Lemna minor and Egeria densa can be used to remove Se from seleniferous soil leachate and that the phytoremediation efficiency depends on the composition of the extractant used for soil washing.