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Microbial Reduction of Arsenic-Doped Schwertmannite by Geobacter sulfurreducens

Cutting, Richard S.; Coker, Victoria S.; Telling, Neil D.; Kimber, Richard L.; van der Laan, Gerrit; Pattrick, Richard A. D.; Vaughan, David J.; Arenholz, Elke; Lloyd, Jonathan R.

Authors

Richard S. Cutting

Victoria S. Coker

Richard L. Kimber

Gerrit van der Laan

Richard A. D. Pattrick

David J. Vaughan

Elke Arenholz

Jonathan R. Lloyd



Abstract

The fate of As(V) during microbial reduction by Geobacter sulfurreducens of Fe(III) in synthetic arsenic-bearing schwertmannites has been investigated. During incubation at pH7, the rate of biological Fe(III) reduction increased with increasing initial arsenic concentration. From schwertmannites with a relatively low arsenic content (<0.3 wt %), only magnetite was formed as a result of dissimilatory iron reduction. However, bioreduction of schwertmannites with higher initial arsenic concentrations (>0.79 wt %) resulted in the formation of goethite. At no stage during the bioreduction process did the concentration of arsenic in solution exceed 120 μgL1, even for a schwertmannite with an initial arsenic content of 4.13 wt %. This suggests that the majority of the arsenic is retained in the biominerals or by sorption at the surfaces of newly formed nanoparticles.

Subtle differences in the As K-edge XANES spectra obtained from biotransformation products are clearly related to the initial arsenic content of the schwertmannite starting materials. For products obtained from schwertmannites with higher initial As concentrations, one dominant population of As(V) species bonded to only two Fe atoms was evident. By contrast, schwertmannites with relatively low arsenic concentrations gave biotransformation products in which two distinctly different populations of As(V) persisted. The first is the dominant population described above, the second is a minority population characterized by As(V) bonded to four Fe atoms. Both XAS and XMCD evidence suggest that the latter form of arsenic is that taken into the tetrahedral sites of the magnetite.

We conclude that the majority population of As(V) is sorbed to the surface of the biotransformation products, whereas the minority population comprises As(V) incorporated into the tetrahedral sites of the biomagnetite. This suggests that microbial reduction of highly bioavailable As(V)-bearing Fe(III) mineral does not necessarily result in the mobilization of the arsenic.

Citation

Cutting, R. S., Coker, V. S., Telling, N. D., Kimber, R. L., van der Laan, G., Pattrick, R. A. D., …Lloyd, J. R. (2012). Microbial Reduction of Arsenic-Doped Schwertmannite by Geobacter sulfurreducens. Environmental Science and Technology, 46(22), 12591-12599. https://doi.org/10.1021/es204596z

Journal Article Type Article
Online Publication Date Oct 30, 2012
Publication Date Nov 20, 2012
Deposit Date May 22, 2024
Journal Environmental Science & Technology
Print ISSN 0013-936X
Electronic ISSN 1520-5851
Publisher American Chemical Society
Peer Reviewed Peer Reviewed
Volume 46
Issue 22
Pages 12591-12599
DOI https://doi.org/10.1021/es204596z
Public URL https://keele-repository.worktribe.com/output/831392
Publisher URL https://pubs.acs.org/doi/10.1021/es204596z