A5007402620- Radioactive element chemistry and processing
- Groundwater flow and contamination studies
- Radioactive contamination and transfer
- Geochemistry and Geologic Mapping
- Microbial Community Ecology and Physiology
- Atmospheric and Environmental Gas Dynamics
- Electric Motor Design and Analysis
- High voltage insulation and dielectric phenomena
- Genomics and Phylogenetic Studies
- Mercury impact and mitigation studies
- Radioactivity and Radon Measurements
- Geophysical and Geoelectrical Methods
- Power Transformer Diagnostics and Insulation
- Geophysical Methods and Applications
- Geochemistry and Elemental Analysis
- Environmental remediation with nanomaterials
- Seismic Imaging and Inversion Techniques
- Seismic Waves and Analysis
- Wastewater Treatment and Nitrogen Removal
- Mine drainage and remediation techniques
- Reservoir Engineering and Simulation Methods
- Nuclear and radioactivity studies
- Electric Power Systems and Control
- Lightning and Electromagnetic Phenomena
- Groundwater and Isotope Geochemistry
Oak Ridge National Laboratory
2011-2022
National Research Council Canada
2016-2020
United Nations Industrial Development Organization
2017
Queensland Health
2009-2015
Georgia Institute of Technology
2010-2013
Stanford University
2005-2011
University of Oklahoma
2003-2011
Argonne National Laboratory
2008-2010
Florida State University
2010
University of Tennessee at Knoxville
2003-2010
Here, we report a catalytic beacon sensor for uranyl (UO 2 2+ ) based on an in vitro -selected UO -specific DNAzyme. The consists of DNA enzyme strand with 3′ quencher and substrate ribonucleotide adenosine (rA) the middle fluorophore at 5′ ends, respectively. presence causes cleavage rA position release thus dramatic increase fluorescence intensity. has detection limit 11 parts per trillion (45 pM), dynamic range up to 400 nM, selectivity >1-million-fold over other metal ions. most...
The potential to stimulate an indigenous microbial community reduce a mixture of U(VI) and Tc(VII) in the presence high (120 mM) initial NO3- co-contamination was evaluated shallow unconfined aquifer using series single-well, push−pull tests. In absence added electron donor, NO3-, Tc(VII), reduction not detectable. However, ethanol, glucose, or acetate serve as rapid utilization observed. accumulation NO2-, detectable NH4+ accumulation, production N2O during situ acetylene-block experiments...
Biological sensors can be engineered to measure a wide range of environmental conditions. Here we show that statistical analysis DNA from natural microbial communities used accurately identify contaminants, including uranium and nitrate at nuclear waste site. In addition contamination, sequence data the 16S rRNA gene alone quantitatively predict rich catalogue 26 geochemical features collected 93 wells with highly differing geochemistry characteristics. We extend this approach sites...
In situ microbial reduction of soluble U(VI) to sparingly U(IV) was evaluated at the site former S-3 Ponds in Area 3 U.S. Department Energy Natural and Accelerated Bioremediation Research Field Center, Oak Ridge, TN. After establishing conditions favorable for bioremediation (Wu, et al. Environ. Sci. Technol. 2006, 40, 3988−3995), intermittent additions ethanol were initiated within conditioned inner loop a nested well recirculation system. These initially stimulated denitrification...
There is a limited amount of information about the effects mineral precipitates and corrosion on lifespan long-term performance in situ Fe0 reactive barriers. The objectives this paper are (1) to investigate through an permeable barrier (2) examine cementation filings order estimate barrier. This field scale (225' long × 2' wide 31' deep) has been installed remove uranium from contaminated groundwater at Y-12 plant site, Oak Ridge, TN. According XRD SEM-EDX analysis core samples recovered...
ABSTRACT Low-biomass samples from nitrate and heavy metal contaminated soils yield DNA amounts that have limited use for direct, native analysis screening. Multiple displacement amplification (MDA) using φ29 polymerase was used to amplify whole genomes environmental, contaminated, subsurface sediments. By first amplifying the genomic (gDNA), biodiversity gDNA library construction of microbes found in were made possible. The MDA method validated by analyzing amplified genome coverage...
ABSTRACT The effect of long-term mixed-waste contamination, particularly uranium and nitrate, on the microbial community in terrestrial subsurface was investigated at field scale Oak Ridge Integrated Field Research Challenge (ORIFRC) site Ridge, TN. abundance, composition, distribution groundwater microorganisms were examined across during two seasonal sampling events. At representative locations, sediment also from boreholes, one sampled most heavily contaminated area another an with low...
Groundwater within Area 3 of the U.S. Department Energy (DOE) Environmental Remediation Sciences Program (ERSP) Field Research Center at Oak Ridge, TN (ORFRC) contains up to 135 μM uranium as U(VI). Through a series experiments pilot scale test facility, we explored lower limits groundwater U(VI) that can be achieved by in-situ biostimulation and effects dissolved oxygen on immobilized uranium. Weekly 2 day additions ethanol over 2-year period stimulated growth denitrifying,...
To evaluate the potential for in situ bioremediation of U(VI) to sparingly soluble U(IV), we constructed a pilot test facility at Area 3 U.S. Department Energy Natural and Accelerated Bioremediation Research (NABIR) Field Center (FRC) Oak Ridge, TN. The is adjacent former S-3 Ponds which received trillions liters acidic plating wastes. High levels uranium are present, with up 800 mg kg-1 soil 84−210 μM groundwater. Ambient groundwater has highly buffered pH ∼3.4 high aluminum (12−13 mM),...
ABSTRACT Microbial enumeration, 16S rRNA gene clone libraries, and chemical analysis were used to evaluate the in situ biological reduction immobilization of uranium(VI) a long-term experiment (more than 2 years) conducted at highly uranium-contaminated site (up 60 mg/liter 800 mg/kg solids) U.S. Department Energy Oak Ridge, TN. Bioreduction was achieved by conditioning groundwater above ground then stimulating growth denitrifying, Fe(III)-reducing, sulfate-reducing bacteria through weekly...
ABSTRACT In terrestrial subsurface environments where nitrate is a critical groundwater contaminant, few cultivated representatives are available to verify the metabolism of organisms that catalyze denitrification. this study, five species denitrifying bacteria from three phyla were isolated sediments exposed metal radionuclide and contamination as part U.S. Department Energy's Oak Ridge Integrated Field Research Challenge (OR-IFRC). Isolates belonged genera Afipia Hyphomicrobium (...
Bacterial strains 2APBS1 T and 116-2 were isolated from the subsurface of a nuclear legacy waste site where sediments are co-contaminated with large amounts acids, nitrate, metal radionuclides other heavy metals. A combination physiological genetic assays indicated that these represent first member genus Rhodanobacter shown to be capable complete denitrification. Cells strain Gram-negative, non-spore-forming rods, 3–5 µm long 0.25–0.5 in diameter. The isolates facultative anaerobes, had...
Although humic substances occur ubiquitously in soil and groundwater, their effect on the biological reduction of uranium(VI) subsequent reoxidation U(IV) is poorly understood. This study investigated role humics enhancing bioreduction U(VI) laboratory kinetic studies, field push−pull tests, presence or absence metal ions such as Ca2+ Ni2+, which are known to inhibit U(VI). Results from experiments indicate that, under strict anaerobic conditions, materials enhanced rates (up 10-fold)...
A variable-speed generating system is described which uses a 3-phase squirrel-cage induction machine with self-excitation capacitors. The variable-frequency/variable-voltage generated then fed through controlled rectifier to provide d.c. supply at constant voltage. proposed scheme suitable for wind power sources as it allows wide changes in turbine speed and, all speeds, optimum can be set up by delay angle control.
The success of sequestration-based remediation strategies will depend on detailed information, including the predominant U species present as sources before biostimulation and products produced during after in situ biostimulation. We used X-ray absorption spectroscopy to determine valence state chemical speciation sediment samples collected at a variety depths through contaminant plume Field Research Center Oak Ridge, TN, approximately 400 days biostimulation, well duplicate bioreduced...
Massively parallel sequencing has provided a more affordable and high-throughput method to study microbial communities, although it mostly been used in an exploratory fashion. We combined pyrosequencing with strict indicator species statistical analysis test if bacteria specifically responded ethanol injection that successfully promoted dissimilatory uranium(VI) reduction the subsurface of uranium contamination plume at Oak Ridge Field Research Center Tennessee. Remediation was achieved...
The effects of nitrate on the stability reduced, immobilized uranium were evaluated in field experiments at a U.S. Department Energy site Oak Ridge, TN. Nitrate (2.0 mM) was injected into reduced region subsurface containing high levels previously U(IV). to nitrite, ammonium, and nitrogen gas; sulfide decreased; Fe(II) increased then deceased. Uranium remobilization occurred concomitant with nitrite formation, suggesting nitrate-dependent, iron-accelerated oxidation Bromide tracer results...
Summary A pilot‐scale system was established for in situ biostimulation of U(VI) reduction by ethanol addition at the US Department Energy's (DOE's) Field Research Center (Oak Ridge, TN). After achieving reduction, stability bioreduced U(IV) evaluated under conditions (i) resting (no injection), (ii) reoxidation introducing dissolved oxygen (DO), and (iii) reinjection ethanol. GeoChip, a functional gene array with probes N, S C cycling, metal resistance contaminant degradation genes, used...
In order to elucidate the potential mechanisms of U(VI) reduction for optimization bioremediation strategies, structure-function relationships microbial communities were investigated in microcosms subsurface materials cocontaminated with radionuclides and nitrate. A polyphasic approach was used assess functional diversity populations likely catalyze electron flow under conditions proposed situ uranium bioremediation. The addition ethanol glucose as supplemental donors stimulated nitrate...
Subsurface amendments of slow-release substrates (e.g., emulsified vegetable oil [EVO]) are thought to be a pragmatic alternative using short-lived, labile for sustained uranium bioimmobilization within contaminated groundwater systems. Spatial and temporal dynamics subsurface microbial communities during EVO amendment unknown likely differ significantly from those populations stimulated by soluble substrates, such as ethanol acetate. In this study, one-time injection resulted in decreased U...
This research evaluated a method of controlled base addition for immobilizing uranium (U) and technetium (Tc) through coprecipitation with aluminum (Al) other metal ions which coexist in highly contaminated acidic environment. The batch column experiments indicate that the strong (NaOH) provided rapid yet effective means sequestering U, Tc, toxic such as nickel (Ni2+) cobalt (Co2+) sediment groundwater. Greater than 94% soluble U (as UO2(2+)) > 83% Tc TcO4-) can be immobilized at pH above...
To understand how contaminants affect microbial community diversity, heterogeneity, and functional structure, six groundwater monitoring wells from the Field Research Center of U.S. Department Energy Environmental Remediation Science Program (ERSP; Oak Ridge, TN), with a wide range pH, nitrate, heavy metal contamination were investigated. DNA was analyzed gene array containing 2006 probes to detect genes involved in resistance, sulfate reduction, organic contaminant degradation, carbon...