A5102714637- Radioactive element chemistry and processing
- Selenium in Biological Systems
- Mercury impact and mitigation studies
- Chromium effects and bioremediation
- Heavy metals in environment
- Geochemistry and Elemental Analysis
- Groundwater and Isotope Geochemistry
- Radioactive contamination and transfer
- Groundwater flow and contamination studies
- Isotope Analysis in Ecology
- Analytical chemistry methods development
- Radioactivity and Radon Measurements
- Heavy Metal Exposure and Toxicity
- Arsenic contamination and mitigation
- Coal and Its By-products
- Nuclear Physics and Applications
- Geological and Geochemical Analysis
- Paleontology and Stratigraphy of Fossils
- Water Quality and Resources Studies
- Nuclear reactor physics and engineering
- Kidney Stones and Urolithiasis Treatments
- Mine drainage and remediation techniques
- Chemical Synthesis and Characterization
- Nuclear Materials and Properties
- Wastewater Treatment and Nitrogen Removal
University of Illinois Urbana-Champaign
2014-2024
Birmingham Children's Hospital
2021
University of Illinois System
2021
Urbana University
2013-2019
Jacobs (United States)
2018
University of Calgary
2015
Idaho National Laboratory
2010
Lawrence Berkeley National Laboratory
2010
Pacific Northwest National Laboratory
2010
Creative Thermal Solutions
2009
The oxygenation of Earth's surface fundamentally altered global biogeochemical cycles and ultimately paved the way for rise metazoans at end Proterozoic. However, current estimates atmospheric oxygen (O2) levels during billion years leading up to this time vary widely. On basis chromium (Cr) isotope data from a suite Proterozoic sediments China, Australia, North America, interpreted in context similar depositional environments Phanerozoic time, we find evidence inhibited oxidation Cr...
Measurements of chromium (Cr) stable-isotope fractionation in laboratory experiments and natural waters show that lighter isotopes reacted preferentially during Cr(VI) reduction by magnetite sediments. The 53 Cr/ 52 Cr ratio the product was 3.4 ± 0.1 per mil less than reactant. shifts water samples indicate extent reduction, a critical process renders toxic environment immobile toxic.
A new way of thinking about groundwater age is changing the field dating. Following a rigorous definition age, sample seen not as water that recharged flow regime at point in past, but mixture waters have resided subsurface for varying lengths time. This recognition resolves longstanding inconsistencies encountered dating and suggests ways to carry out studies. Tomorrow's studies will likely employ sets marker isotopes molecules spanning broad spectrum incorporate wide range chemical...
Chromium stable isotope values can be effectively used to monitor reduction of Cr(VI) in natural waters. We investigate effects sorption during transport which may also shift Cr isotopes values, complicating efforts quantify reduction. This study shows that fractionation caused by is negligible. Equilibrium between dissolved and adsorbed onto γ-Al2O3 goethite less than 0.04‰ (53Cr/52Cr) under environmentally relevant pH conditions. Batch experiments at 4.0 6.0 were conducted series...
A model enabling extraction of hydrologic information from spatial and temporal patterns in measurements isotope ratios water‐rock systems is presented. The describes the evolution response to solute transport interaction. In advective systems, a single dimensionless parameter (a Damköhler number, N D ) dominates determining distance over which isotopic equilibrium between water rock approached. Some act as conservative tracers ( ≪ 1), while others reflect only interaction with local host ≫...
Chromium stable isotope ratios show promise as indicators of Cr(VI) reduction in groundwater, but no published study has yet demonstrated that expected relationships between 53Cr/52Cr and concentration, position, time occur an actual groundwater plume. We present extensive data set from a point-source plume Berkeley, CA; extend over 5 years 14 locations covering the entire interpret using Rayleigh distillation model with effective fractionation factor incorporates intrinsic determined...
Wetlands remove many dissolved pollutants from surface waters by various mechanisms. Stable isotope ratio measurements may provide a means of detecting and possibly quantifying certain removal processes, such as reduction SeO42−, Cr(VI), NO3−, HClO4−, that fractionate isotopes. However, the magnitude isotopic fractionation for given reaction depends on setting in which it occurs. We explore case where shifts are used to detect or quantify reactions occurring pore underlying sediments. A...
Research Article| July 01, 2009 Variations in 238U/235U uranium ore deposits: Isotopic signatures of the U reduction process? Charles John Bopp, IV; IV 1University Illinois at Urbana-Champaign, Department Geology, 245 Natural History Building, 1301 West Green Street, Urbana, 61801, USA Search for other works by this author on: GSW Google Scholar Craig C. Lundstrom; Lundstrom Thomas M. Johnson; Johnson Justin J.G. Glessner Author and Article Information Publisher: Geological Society America...
The attenuation of groundwater contamination via chemical reaction is traditionally evaluated by monitoring contaminant concentration through time. However, this method can be confounded common transport processes (e.g., dilution, sorption). Isotopic techniques bypass the limits methods, and so may provide improved accuracy in determining extent reaction. We apply measurements 238U/235U to a U bioremediation field experiment at Rifle Integrated Field Research Challenge Site Rifle, Colorado....
Cr stable isotope measurements can provide improved estimates of the extent Cr(VI) reduction to less toxic Cr(III). The relationship between observed (53)Cr/(52)Cr ratio shifts and be calibrated by determining isotopic fractionation factor for relevant reactions. Permeable reactive barriers (PRB) made Fe(0) in situ redox manipulation (ISRM) zones effectively remediate Cr-contaminated aquifers. Here, we determine fractionations dominant reductants reduced sediments obtained from an ISRM zone...
Mercury stable isotope abundances were used to trace transport of Hg-impacted river sediment near a coal ash spill at Harriman, Tennessee, USA. δ(202)Hg values for Kingston released into the Emory River in 2008 are significantly negative (-1.78 ± 0.35‰), whereas sediments Clinch River, which flows, contaminated by an additional Hg source (potentially from Y-12 complex Oak Ridge, Tennessee) with near-zero (-0.23 0.16‰). Nominally uncontaminated (12 miles upstream Emory-Clinch confluence) have...
Oceanic oxygen levels are projected to drop in certain areas due warming climate, but the net effect overall ocean redox state is difficult predict. Here we measured "stable" uranium isotope composition (^238^U/^235^U) globally representative hydrogenous ferromanganese crusts order reconstruct evolution of global throughout Cenozoic. Samples averaging ∼3 Myr intervals have analytically indistinguishable ^238^U/^235^U Combined with a U mass balance model, suggest that has remained remarkably...