Field evidence of selenium bioreduction in a uranium-contaminated aquifer

Journal Article · Sat Jun 01 04:00:00 EDT 2013 · Environmental Microbiology Reports, 5(3):444-452

DOI:https://doi.org/10.1111/1758-2229.12032· OSTI ID:1086410

Williams, K. H.; Wilkins, Michael J.; N'Guessan, A. Lucie; Arey, Bruce W.; Dodova, Elena N.; Dohnalkova, Alice; Holmes, Dawn; Lovley, Derek R.; Long, Philip E.

Removal of selenium from groundwater was documented during injection of acetate into a uraniumcontaminated aquifer near Rifle, Colorado (USA). Bioreduction of aqueous selenium to its elemental form (Se0) concentrated it within mineralized biofilms affixed to tubing used to circulate acetate-amended groundwater. Scanning and transmission electron microscopy revealed close association between Se0 precipitates and cell surfaces, with Se0 aggregates having a diameter of 50-60 nm. Accumulation of Se0 within biofilms occurred over a three-week interval at a rate of c. 9 mg Se0m-2 tubing day-1. Removal was inferred to result from the activity of a mixed microbial community within the biofilms capable of coupling acetate oxidation to the reduction of oxygen, nitrate and selenate. Phylogenetic analysis of the biofilm revealed a community dominated by strains of Dechloromonas sp. and Thauera sp., with isolates exhibiting genetic similarity to the latter known to reduce selenate to Se0. Enrichment cultures of selenate-respiring microorganisms were readily established using Rifle site groundwater and acetate, with cultures dominated by strains closely related to D. aromatica (96-99% similarity). Predominance of Dechloromonas sp. in recovered biofilms and enrichments suggests this microorganism may play a role in the removal of selenium oxyanions present in Se-impacted groundwaters and sediments.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1086410
• Report Number(s): PNNL-SA-95467; 44725; KP1704020
• Journal Information: Environmental Microbiology Reports, 5(3):444-452, Journal Name: Environmental Microbiology Reports, 5(3):444-452
• Country of Publication: United States
• Language: English

Related Subjects

Environmental Molecular Sciences Laboratory
Selenium
contamination
reduction
uranium