Journal article
Microscale geochemical gradients in Hanford 300 Area sediment biofilms and influence of uranium
Water research (Oxford), Vol.46(1), pp.227-234
2012
Handle:
https://hdl.handle.net/2376/112946
PMID: 22078229
Abstract
The presence and importance of microenvironments in the subsurface at contaminated sites were suggested by previous geochemical studies. However, no direct quantitative characterization of the geochemical microenvironments had been reported. We quantitatively characterized microscale geochemical gradients (dissolved oxygen (DO), H
2, pH, and redox potential) in Hanford 300A subsurface sediment biofilms. Our results revealed significant differences in geochemical parameters across the sediment biofilm/water interface in the presence and absence of U(VI) under oxic and anoxic conditions. While the pH was relatively constant within the sediment biofilm, the redox potential and the DO and H
2 concentrations were heterogeneous at the microscale (<500–1000 μm). We found microenvironments with high DO levels (DO hotspots) when the sediment biofilm was exposed to U(VI). On the other hand, we found hotspots (high concentrations) of H
2 under anoxic conditions both in the presence and in the absence of U(VI). The presence of anoxic microenvironments inside the sediment biofilms suggests that U(VI) reduction proceeds under bulk oxic conditions. To test this, we operated our biofilm reactor under air-saturated conditions in the presence of U(VI) and characterized U speciation in the sediment biofilm. U L
III-edge X-ray absorption spectroscopy (XANES and EXAFS) showed that 80–85% of the U was in the U(IV) valence state.
► Characterized microscale geochemical gradients in Hanford 300A sediment biofilms. ► Our results revealed differences in geochemical parameters across the biofilm-water interface. ► We found microenvironments with high DO levels. ► We found hotspots of H
2 under anoxic conditions.
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Details
- Title
- Microscale geochemical gradients in Hanford 300 Area sediment biofilms and influence of uranium
- Creators
- Hung Duc Nguyen - The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA, USABin Cao - The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA, USABhoopesh Mishra - Argonne National Laboratory, Argonne, IL, USAMaxim I Boyanov - Argonne National Laboratory, Argonne, IL, USAKenneth M Kemner - Argonne National Laboratory, Argonne, IL, USAJim K Fredrickson - Pacific Northwest National Laboratory, Richland, WA, USAHaluk Beyenal - The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA, USA
- Publication Details
- Water research (Oxford), Vol.46(1), pp.227-234
- Academic Unit
- Chemical Engineering and Bioengineering, School of
- Publisher
- Elsevier Ltd
- Identifiers
- 99900548355401842
- Language
- English
- Resource Type
- Journal article