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Biogeochemical Controls of Uranium R...

Dangelmayr, Martin A.

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Biogeochemical Controls of Uranium Remediation and Transport.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Biogeochemical Controls of Uranium Remediation and Transport./
Author:	Dangelmayr, Martin A.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2018,
Description:	150 p.
Notes:	Source: Dissertation Abstracts International, Volume: 79-08(E), Section: B.
Contained By:	Dissertation Abstracts International79-08B(E).
Subject:	Environmental science. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10744338
ISBN:	9780355768572

Biogeochemical Controls of Uranium Remediation and Transport.
Dangelmayr, Martin A.

Biogeochemical Controls of Uranium Remediation and Transport. - Ann Arbor : ProQuest Dissertations & Theses, 2018 - 150 p.

Source: Dissertation Abstracts International, Volume: 79-08(E), Section: B.

Thesis (Ph.D.)--Colorado School of Mines, 2018.

In the U.S. almost 140 sites have been contaminated by uranium mining and milling operations or by the storage of radioactive materials. In-situ recovery (ISR) facilities still face challenges restoring water to pre-mining conditions and leave behind elevated uranium concentrations. Bioremediation and reactive transport modeling are potential tools to mitigate the impact of uranium contamination on human and environmental health, through their ability to immobilize uranium and assess the effectiveness of natural uranium attenuation. This project investigated biogeochemical aspects of both active and natural remediation of uranium contaminated subsurface for two field sites: The Smith Ranch Highland (SRH) site in WY, and the Rifle, Integrated Field Research Challenge (IFRC) site in CO. Our project objectives were to study the transformation of organic substrate during biostimulation and assess uranium retardation due to sorption with sediments taken from an ISR site. This thesis presents two research projects that address the remediation and risk assessment of uranium contaminated sites.

ISBN: 9780355768572Subjects--Topical Terms:

677245
Environmental science.

Biogeochemical Controls of Uranium Remediation and Transport.
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100 1 $a Dangelmayr, Martin A. $3 3429153
245 1 0 $a Biogeochemical Controls of Uranium Remediation and Transport.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2018
300 $a 150 p.
500 $a Source: Dissertation Abstracts International, Volume: 79-08(E), Section: B.
500 $a Advisers: Linda A. Figueroa; James J. Stone.
502 $a Thesis (Ph.D.)--Colorado School of Mines, 2018.
520 $a In the U.S. almost 140 sites have been contaminated by uranium mining and milling operations or by the storage of radioactive materials. In-situ recovery (ISR) facilities still face challenges restoring water to pre-mining conditions and leave behind elevated uranium concentrations. Bioremediation and reactive transport modeling are potential tools to mitigate the impact of uranium contamination on human and environmental health, through their ability to immobilize uranium and assess the effectiveness of natural uranium attenuation. This project investigated biogeochemical aspects of both active and natural remediation of uranium contaminated subsurface for two field sites: The Smith Ranch Highland (SRH) site in WY, and the Rifle, Integrated Field Research Challenge (IFRC) site in CO. Our project objectives were to study the transformation of organic substrate during biostimulation and assess uranium retardation due to sorption with sediments taken from an ISR site. This thesis presents two research projects that address the remediation and risk assessment of uranium contaminated sites.
520 $a The first project evaluated the impact of added organic carbon on the long-term biogeochemical attenuation of uranium in the subsurface of a former mill tailings site. Fluorescence and specific ultraviolet absorption (SUVA) analyses were used together with dissolved organic carbon (DOC) measurements to track organic carbon dynamics during and post-biostimulation of the 2011 Rifle IFRC experiment. An electron mass balance was performed on well CD01 to determine if any carbon sinks were unaccounted for. DOC values increased to 1.76 mM-C during biostimulation, and 3.18 mM-C post-biostimulation over background DOC values of 0.3--0.4 mM-C. Elevated DOC levels persisted 90 days after acetate injections ceased. The electron mass balance revealed that assumed electron acceptors would not account for the total amount of acetate consumed. Fluorescence spectra showed an increase in signals associated with soluble microbial products (SMP), during biostimulation, which disappeared post-biostimulation despite an increase in DOC. SUVA analyses, indicated that DOC present post-biostimulation is less aromatic in nature, compared to background DOC. Our results suggest that microbes convert injected acetate into a carbon sink that may be available to sustain iron reduction post-stimulation.
520 $a The second project consisted of two sets of column experiments and attempted to evaluate the impact of alkalinity and pH on the sorption of uranium in sediments from an ISR site. The ability of thermodynamic models to predict uranium behavior under conditions relevant to ISR restoration sites was also tested. Sediments at three different depths from a monitoring well at the SRH site were used in nine column studies and six batch experiments to study the sorption capacity of SRH sediments and estimate uncertainties associated with fitted parameters. Sediments were characterized by X-Ray Diffraction (XRD) and X-Ray Fluorescence (XRF) for dominant mineralogy and Brunauer-Emmett Teller (BET) measurements to determine sediment surface area. Uranium transport in the columns was modeled with PHREEQC using a generalized composite surface complexation model (GC SCM). A parameter estimation program (PEST) was coupled to PHREEQC to derive best parameter fits according to correlation coefficients and lowest sums of residuals squared.
520 $a In the first set of sorption experiments a GC SCM utilizing one, two, and, three generic surfaces, was evaluated in 5 column studies to find the simplest model with the best fit. A 2-pK model with strong and very strong sorption sites was found to produce model results in best agreement with observed data. Uranium breakthrough was delayed by a factor of 1.68, 1.69 and 1.47 relative to the non-reactive tracer for three of the 5 experiments at an alkalinity of 540 mg/l. while a sediment containing smectite and kaolinite retained uranium by a factor of 2.80 despite a lower measured BET surface area. Decreasing alkalinity to 360 mg/l from 540 mg/l in the kaolinite containing sediments increased retardation by a factor of 4.26. Model fits correlated well to overall BET surface area in the three columns where clay content was less than 1%. For the sediment with clay, models consistently understated uranium retardation when reactive surface sites were restricted by BET results. Calcite saturation was shown to be a controlling factor for uranium desorption as the pH of the system changed to a lower value. A pH of 6 during a secondary background water flush remobilized previously sorbed uranium resulting in a secondary uranium peak at twice the influent concentrations. The first set of sorption experiments demonstrated the potential of GC SCM models to predict uranium transport in sediments with homogenous mineral composition, but highlighted the need for further research to understand the role of sediment clay composition and calcite saturation in uranium transport.
520 $a The second set of experiments consisted of duplicate column studies on two sediment depths. (Abstract shortened by ProQuest.).
590 $a School code: 0052.
650 4 $a Environmental science. $3 677245
650 4 $a Geochemistry. $3 539092
650 4 $a Environmental engineering. $3 548583
690 $a 0768
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690 $a 0775
710 2 $a Colorado School of Mines. $b Civil and Environmental Engineering. $3 3183130
773 0 $t Dissertation Abstracts International $g 79-08B(E).
790 $a 0052
791 $a Ph.D.
792 $a 2018
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10744338