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Biogeochemistry of uranium reduction...

Stanford University.

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Biogeochemistry of uranium reduction and reoxidation.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Biogeochemistry of uranium reduction and reoxidation./
Author:	Boonchayaanant, Benjaporn.
Description:	167 p.
Notes:	Adviser: Craig S. Criddle.
Contained By:	Dissertation Abstracts International70-07B.
Subject:	Biogeochemistry. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3363941
ISBN:	9781109237122

Biogeochemistry of uranium reduction and reoxidation.
Boonchayaanant, Benjaporn.

Biogeochemistry of uranium reduction and reoxidation. - 167 p.

Adviser: Craig S. Criddle.

Thesis (Ph.D.)--Stanford University, 2009.

The processing of uranium for nuclear weapons and nuclear fuel has resulted in extensive uranium contamination of soil and groundwater at U.S. Department of Energy (DOE) sites. While several options are available for remediation of uranium contamination, in situ bioremediation is attractive because it is relatively low cost compared to pump-and-treat methods. This research investigates the biogeochemical processes of uranium reduction and reoxidation that are important for the advancement of bioremediation schemes, including the effects of temperature on growth and cometabolic reduction kinetics of uranium, the importance of hydrogen sulfide-mediated abiotic U(VI) reduction in the presence of sulfate-reducing bacteria, and the reoxidation of microbially reduced uranium under sulfate-reducing and iron-reducing conditions.

ISBN: 9781109237122Subjects--Topical Terms:

545717
Biogeochemistry.

Biogeochemistry of uranium reduction and reoxidation.
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020 $a 9781109237122
035 $a (UMI)AAI3363941
035 $a AAI3363941
040 $a UMI $c UMI
100 1 $a Boonchayaanant, Benjaporn. $3 1043676
245 1 0 $a Biogeochemistry of uranium reduction and reoxidation.
300 $a 167 p.
500 $a Adviser: Craig S. Criddle.
500 $a Source: Dissertation Abstracts International, Volume: 70-07, Section: B, page: .
502 $a Thesis (Ph.D.)--Stanford University, 2009.
520 $a The processing of uranium for nuclear weapons and nuclear fuel has resulted in extensive uranium contamination of soil and groundwater at U.S. Department of Energy (DOE) sites. While several options are available for remediation of uranium contamination, in situ bioremediation is attractive because it is relatively low cost compared to pump-and-treat methods. This research investigates the biogeochemical processes of uranium reduction and reoxidation that are important for the advancement of bioremediation schemes, including the effects of temperature on growth and cometabolic reduction kinetics of uranium, the importance of hydrogen sulfide-mediated abiotic U(VI) reduction in the presence of sulfate-reducing bacteria, and the reoxidation of microbially reduced uranium under sulfate-reducing and iron-reducing conditions.
520 $a Bioremediation of contaminated soils and aquifers is subject to spatial and temporal temperature changes that can alter the kinetics of key microbial processes. This study quantified temperature effects on the kinetics of an ethanol-fed sulfate-reducing mixed culture derived from a uranium contaminated site at the Field Research Center (FRC) in Oak Ridge, TN. Microbial growth rate, ethanol utilization rate, and biomass decay rate of the sulfate-reducing mixed culture increased with increased temperatures. U(VI) reduction can be better described by pseudo second-order kinetics when the term describing inhibition was included.
520 $a This study also evaluated the relative importance of cell-associated reducing agents and hydrogen sulfide on U(VI) reduction by a sulfate-reducing bacterium. Desulfovibrio aerotolerans, a sulfate-reducing bacterium isolated from the uranium-contaminated site at the Oak Ridge FRC was used in this study. The observed rate of SRB-mediated U(VI) reduction at 5 mM and 15 mM bicarbonate can be explained by the abiotic reaction of U(VI) with the microbially-generated H2S. The presence of trace ferrous iron increased rates of hydrogen sulfide-mediated U(VI) reduction at 5 mM bicarbonate, but had no clear effect at 15 mM. During the hydrogen sulfide-mediated reduction of U(VI), a floc formed containing uranium, sulfur, and phosphorus. U(VI) sequestered in the floc was not available for further reduction.
520 $a Oxidation and mobilization of microbially-generated U(IV) is of great concern for in situ uranium bioremediation. This study investigated the reoxidation of uranium by oxygen and nitrate in a sulfate-reducing enrichment dominated by Desulfovibrio spp. and an iron-reducing enrichment dominated by Clostridium spp. In both the sulfate-reducing enrichment and the iron-reducing enrichment, oxygen reoxidized the previously reduced uranium, but to a lesser extent in the iron-reducing enrichment. In contrast, uranium reoxidation did not occur in the presence of nitrate in both the sulfate-reducing and iron-reducing enrichments.
590 $a School code: 0212.
650 4 $a Biogeochemistry. $3 545717
650 4 $a Engineering, Environmental. $3 783782
650 4 $a Environmental Sciences. $3 676987
690 $a 0425
690 $a 0768
690 $a 0775
710 2 $a Stanford University. $3 754827
773 0 $t Dissertation Abstracts International $g 70-07B.
790 $a 0212
790 1 0 $a Criddle, Craig S., $e advisor
791 $a Ph.D.
792 $a 2009
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3363941