Impact of Biostimulated Redox Processes on Metal Dynamics in an Iron-rich Creek Soil of a former Uranium Mining Area


Impact of Biostimulated Redox Processes on Metal Dynamics in an Iron-rich Creek Soil of a former Uranium Mining Area

Burkhardt, E.-M.; Akob, D. M.; Bischoff, S.; Sitte, J.; Kostka, J. E.; Banerjee, D.; Scheinost, A. C.; Kuesel, K.

Understanding the dynamics of metals and radionuclides in soil environments is necessary for evaluating risks to pristine sites. An iron-rich creek soil of a former uranium-mining district (Ronneburg, Germany) showed high porewater concentrations of heavy metals and radionuclides. Thus, this study aims i) to evaluate metal dynamics during terminal electron accepting processes (TEAPs) and ii) to characterize the active microbial populations in biostimulated soil microcosms using a stable isotope probing (SIP) approach. In biostimulated soil slurries, concentrations of soluble Co, Ni, Zn, As, and unexpectedly U increased during Fe(III)-reduction. This suggests that there was a direct reduction of As and a release of sorbed metals during reductive dissolution of Fe(III)-oxides. Subsequent sulfate-reduction was concurrent with a decrease of U, Co, Ni, and Zn concentrations. The relative contribution of U(IV) in the solid phase changed from 18.5 to 88.7% after incubation. The active Fe(III)-reducing population was dominated by δ-Proteobacteria (Geobacter) in 13C-ethanol amended microcosms. A more diverse community was present in 13C lactate amended microcosms including taxa related to Acidobacteria, Firmicutes, δ- Proteobacteria, and β-Proteobacteria. Our results suggested that biostimulated Fe(III)-reducing communities facilitated the release of metals including U to groundwater which is in contrast to other studies.

Keywords: Uranium-mining; heavy metal and arsenic contamination; iron-reduction; sulfate-reduction; metal dynamics; stable isotope probing; bioremediation

  • Environmental Science & Technology 44(2010), 177-183

Permalink: https://www.hzdr.de/publications/Publ-12937
Publ.-Id: 12937