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Title: Bicarbonate Impact on U(VI) Bioreduction in a Shallow Alluvial Aquifer

Abstract

Field-scale biostimulation and desorption tracer experiments conducted in a uranium (U) contaminated, shallow alluvial aquifer have provided insight into the coupling of microbiology, biogeochemistry, and hydrogeology that control U mobility in the subsurface. Initial experiments successfully tested the concept that Fe-reducing bacteria such as Geobacter sp. could enzymatically reduce soluble U(VI) to insoluble U(IV) during in situ electron donor amendment (Anderson et al. 2003, Williams et al. 2011). In parallel, in situ desorption tracer tests using bicarbonate amendment demonstrated rate-limited U(VI) desorption (Fox et al. 2012). These results and prior laboratory studies underscored the importance of enzymatic U(VI)-reduction and suggested the ability to combine desorption and bioreduction of U(VI). Here we report the results of a new field experiment in which bicarbonate-promoted uranium desorption and acetate amendment were combined and compared to an acetate amendment-only experiment in the same experimental plot. Results confirm that bicarbonate amendment to alluvial aquifer desorbs U(VI) and increases the abundance of Ca-uranyl-carbonato complexes. At the same time, that the rate of acetate-promoted enzymatic U(VI) reduction was greater in the presence of added bicarbonate in spite of the increased dominance of Ca-uranyl-carbonato aqueous complexes. A model-simulated peak rate of U(VI) reduction was ~3.8 times higher duringmore » acetate-bicarbonate treatment than under acetate-only conditions. Lack of consistent differences in microbial community structure between acetate-bicarbonate and acetate-only treatments suggest that a significantly higher rate of U(VI) reduction the bicarbonate-impacted sediment may be due to a higher intrinsic rate of microbial reduction induced by elevated concentrations of the bicarbonate oxyanion. The findings indicate that bicarbonate amendment may be useful in improving the engineered bioremediation of uranium in aquifers.« less

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
1184936
Report Number(s):
PNNL-SA-106900
47984; 830403000
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Geochimica et Cosmochimica Acta, 150:106-124
Country of Publication:
United States
Language:
English
Subject:
uranium; bioremediation; reactive transport modeling; Environmental Molecular Sciences Laboratory

Citation Formats

Long, Philip E., Williams, Kenneth H., Davis, James A., Fox, Patricia M., Wilkins, Michael J., Yabusaki, Steven B., Fang, Yilin, Waichler, Scott R., Berman, Elena S., Gupta, Manish, Chandler, Darrell P., Murray, Christopher J., Peacock, Aaron D., Giloteaux, L., Handley, Kim M., Lovley, Derek R., and Banfield, Jillian F. Bicarbonate Impact on U(VI) Bioreduction in a Shallow Alluvial Aquifer. United States: N. p., 2015. Web. doi:10.1016/j.gca.2014.11.013.
Long, Philip E., Williams, Kenneth H., Davis, James A., Fox, Patricia M., Wilkins, Michael J., Yabusaki, Steven B., Fang, Yilin, Waichler, Scott R., Berman, Elena S., Gupta, Manish, Chandler, Darrell P., Murray, Christopher J., Peacock, Aaron D., Giloteaux, L., Handley, Kim M., Lovley, Derek R., & Banfield, Jillian F. Bicarbonate Impact on U(VI) Bioreduction in a Shallow Alluvial Aquifer. United States. doi:10.1016/j.gca.2014.11.013.
Long, Philip E., Williams, Kenneth H., Davis, James A., Fox, Patricia M., Wilkins, Michael J., Yabusaki, Steven B., Fang, Yilin, Waichler, Scott R., Berman, Elena S., Gupta, Manish, Chandler, Darrell P., Murray, Christopher J., Peacock, Aaron D., Giloteaux, L., Handley, Kim M., Lovley, Derek R., and Banfield, Jillian F. Sun . "Bicarbonate Impact on U(VI) Bioreduction in a Shallow Alluvial Aquifer". United States. doi:10.1016/j.gca.2014.11.013.
@article{osti_1184936,
title = {Bicarbonate Impact on U(VI) Bioreduction in a Shallow Alluvial Aquifer},
author = {Long, Philip E. and Williams, Kenneth H. and Davis, James A. and Fox, Patricia M. and Wilkins, Michael J. and Yabusaki, Steven B. and Fang, Yilin and Waichler, Scott R. and Berman, Elena S. and Gupta, Manish and Chandler, Darrell P. and Murray, Christopher J. and Peacock, Aaron D. and Giloteaux, L. and Handley, Kim M. and Lovley, Derek R. and Banfield, Jillian F.},
abstractNote = {Field-scale biostimulation and desorption tracer experiments conducted in a uranium (U) contaminated, shallow alluvial aquifer have provided insight into the coupling of microbiology, biogeochemistry, and hydrogeology that control U mobility in the subsurface. Initial experiments successfully tested the concept that Fe-reducing bacteria such as Geobacter sp. could enzymatically reduce soluble U(VI) to insoluble U(IV) during in situ electron donor amendment (Anderson et al. 2003, Williams et al. 2011). In parallel, in situ desorption tracer tests using bicarbonate amendment demonstrated rate-limited U(VI) desorption (Fox et al. 2012). These results and prior laboratory studies underscored the importance of enzymatic U(VI)-reduction and suggested the ability to combine desorption and bioreduction of U(VI). Here we report the results of a new field experiment in which bicarbonate-promoted uranium desorption and acetate amendment were combined and compared to an acetate amendment-only experiment in the same experimental plot. Results confirm that bicarbonate amendment to alluvial aquifer desorbs U(VI) and increases the abundance of Ca-uranyl-carbonato complexes. At the same time, that the rate of acetate-promoted enzymatic U(VI) reduction was greater in the presence of added bicarbonate in spite of the increased dominance of Ca-uranyl-carbonato aqueous complexes. A model-simulated peak rate of U(VI) reduction was ~3.8 times higher during acetate-bicarbonate treatment than under acetate-only conditions. Lack of consistent differences in microbial community structure between acetate-bicarbonate and acetate-only treatments suggest that a significantly higher rate of U(VI) reduction the bicarbonate-impacted sediment may be due to a higher intrinsic rate of microbial reduction induced by elevated concentrations of the bicarbonate oxyanion. The findings indicate that bicarbonate amendment may be useful in improving the engineered bioremediation of uranium in aquifers.},
doi = {10.1016/j.gca.2014.11.013},
journal = {Geochimica et Cosmochimica Acta, 150:106-124},
number = ,
volume = ,
place = {United States},
year = {Sun Feb 01 00:00:00 EST 2015},
month = {Sun Feb 01 00:00:00 EST 2015}
}