Enhanced immobilization of U(VI) on Mucor circinelloides in presence of As(V): Batch and XAFS investigation

The combined pollution of radionuclides and heavy metals has been given rise to widespread concernduring uranium mining. The influence of As(V) on U(VI) immobilization by Mucor circinelloides(M. circinelloides) was investigated using batch experiments. The activity of antioxidative enzymes andconcentrations of thiol compounds and organic acid in M. circinelloides increased to respond to differentU(VI) and As(V) stress. The morphological structure of M. circinelloides changed obviously under U(VI)and As(V) stress by SEM and TEM analysis. The results of XANES and EXAFS analysis showed that U(VI)was mainly reduced to nano-uraninite (nano-UO2, 30.1%) in U400, while only 9.7% of nano-UO2 wasobserved in the presence of As(V) in U400-As400 due to the formation of uranyl arsenate precipitate(Tr€ogerite, 48.6%). These observations will provide the fundamental data for fungal remediation ofuranium and heavy metals in uranium-contaminated soils.