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This dissertation is an examination of the use of uranium-232 as a tracer in nuclear fuel. Decay daughters from 232U, particularly thallium-208, produce high energy gamma rays that, when added to uranium, may increase detectability in case of theft or diversion, but are also hazardous in high quantities. Previous studies of the 232U decay chain are examined. This work will go in to a dosimetry study to determine how hazardous varying levels of 232U are, and how to efficiently produce 232U in sufficient quantities. A dosimetry study was performed to determine the dose hazards due to the addition of 232U to uranium. This dosimetry study determined that the concentration of 232U to add to uranium is between 100 parts per trillion. A production scoping study was performed to determine the preferred target materials for producing 232U via neutron irradiations. Calculations performed using SCALE 6.2 ORIGEN determined that 231Pa and 230Th are the optimum target materials, and that reactor irradiations are preferred. ORIGEN Calculations using flux spectra from the High Flux Isotope Reactor determined that 231Pa calculations that the optimum irradiation time is 2 HFIR cycles, yielding 0.35 grams of 232U per gram 231Pa. Thorium-230 irradiations yielded 0.15 grams 232U per gram 230Th after five cycles. Neutronics analyses examined the neutron spectra in targets modeled in MCNP, and determined that self-shielding is a concern that may reduce yield, especially in 230Th, lowering the yield to 0.1 grams after five cycles. A study of 238Pu contaminated with 236Pu produced at the Advanced Test Reactor was also conducted base on work from the CSNR. This examined strategies for mitigating against 236Pu contamination by chemical removal of 232U. Only material irradiated close to the center of the ATR needed this extra processing, and only a few micrograms of 232U is recoverable. However, these small quantities may still have a use for small stockpiles or testing purposes.

During the past decade, carbon capture, utilization, and storage (CCUS) has gained considerable recognition as a viable option to mitigate carbon dioxide (CO2) emissions. This process involves capturing CO2 at emission sources such as power plants, refineries, and processing plants, and safely and permanently storing it in underground geologic formations. Many CO2 injection tests have been successfully conducted to assess the storage potential of CO2 in saline formations, oil and natural gas reservoirs, organic-rich shales, and unmineable coal reservoirs. Coal seams are an attractive reservoir for CO2 storage due to coal's large capacity to store gas within its microporous structure, as well as its ability to preferentially adsorb CO2 over naturally occurring methane resulting in enhanced coalbed methane (ECBM) recovery. A small-scale CO2 injection test was conducted in Southwest Virginia to assess the storage and ECBM recovery potential of CO2 in a coalbed methane reservoir. The goal of this test was to inject up to 20,000 tons of CO2 into a stacked coal reservoir of approximately 15-20 coal seams. Phase I of the injection test was conducted from July 2, 2015 to April 15, 2016 when a total of 10,601 tons of CO2 were injected. Phase II of the injection was conducted from December 14, 2016 to January 30, 2017 when an additional 2,662 tons of CO2 were injected, for a total of 13,263 total tons of CO2 injected. A customized monitoring, verification, and accounting (MVA) plan was created to monitor CO2 injection activities, including surface, near-surface, and subsurface technologies. As part of this MVA plan, chemical tracers were used as a tool to help track CO2 plume migration within the reservoir and determine interwell connectivity. The work presented in this dissertation will discuss the development and implementation of chemical tracers as a monitoring tool, detail wellbore-scale tests performed to characterize CO2 breakthrough and interwell connectivity, and present results from both phases of the CO2 injection test.

The ocean’s biological pump is crucial for the carbon balance of the climate system, and the control of its three-dimensional “plumbing” on pump efficiency needed to be quantified. The nutrient cycles driving the biological pump are limited by dissolved iron (dFe). However, the iron cycle is poorly constrained, and the effects of iron source perturbations had never been quantified in a data-constrained model. In this thesis, we quantify the pathways and timescales of the biological pump, build an inverse model of the coupled phosphorus, silicon, and iron cycles, and explore the response of these cycles to changes in the aeolian iron supply. We use Green-function methods to show that the Southern Ocean (SO) is where (62±2)% of regenerated phosphate (PO4) reemerges after a mean sequestration time of 240±60yr. The pathways from productive regions to the SO contribute most to the biological pump, with a mean sequestration time of 130±70yr. Most PO4 is carried by abyssal paths with transit times exceeding 700yr, while ~1/3 of the regenerated PO4 from the equatorial Pacific that is destined for the SO is carried in Antarctic Intermediate Water. We use the model of the coupled nutrient cycles in inverse mode to objectively determine biogeochemical parameters by minimizing the mismatch with observed nutrient and phytoplankton concentrations. We generate a family of estimates, all consistent with the observations, for a wide range of iron source strengths, themselves not constrainable by current observations. The carbon and opal exports are well constrained in magnitude and pattern. We quantify the systematics of the carbon and opal exports supported by aeolian, hydrothermal, and sedimentary dFe and find that aeolian dFe is the most efficient for supporting production. The response to aeolian source perturbations is sensitive to the state of the iron cycle that is fitted to observations. A shutdown of the aeolian source does not completely untrap nutrients from the SO because sedimentary and hydrothermal dFe suffice to sustain production. A globally uniform 50-Gmol/yr aeolian iron addition fertilizes macronutrient-rich regions leading to increased deep regenerated and recycled dFe. This perturbation actually reduces iron fertilization supported by long-range transport because increased scavenging removes dFe before it can reach its destination. The response of the opal export is muted because the iron dependence of the Si:P uptake ratio counteracts fertilization.

This thesis investigates the ventilation of the Southern Ocean in terms of its state in the early 1990s, its decadal changes from the 1990s to the early 2000s, and the implications of these changes for anthropogenic carbon (CANT) storage. A maximum entropy (ME) approach is used to deconvolve tracer measurements to estimate the boundary propagator, which is the joint distribution of the locations and times since last ventilation. We use Southern Ocean data from five meridional repeat hydrography sections (P16, P18, A16, I8S/I9N and S3) of the World Ocean Circulation Experiment and the Climate Variability and Predictability project for CFC-11, CFC-12 temperature, salinity, oxygen, and phosphate, as well as data from the Global Ocean Data Analysis Project (GLODAP) for radiocarbon, combined with surface histories derived from atmospheric CFC-11 and CFC-12 measurements and the World Ocean Atlas and GLODAP databases. We quantify Southern Ocean ventilation in terms of the water-mass fraction older than 30 years, the fractions of water last ventilated in specific regions that tile the global ocean surface, the global and regional mean transit times, and the width-to-mean ratio of the global transit-time distribution (TTD). By independently deconvolving the original and repeat hydrographies for the boundary propagator, we find that Circumpolar Deep Water (CDW) has become older with a narrower TTD and an increased fraction last ventilated in the North Atlantic. Subantarctic Mode Water (SAMW) has become younger with a broader TTD and an increased fraction last ventilated in the Southern Ocean. Antarctic Bottom Water (AABW) has become younger. The inferred decadal changes in ventilation are consistent with increased upwelling of CDW and enhanced SAMW formation driven by strengthened mid-latitude westerly winds. The inferred boundary propagators are used to propagate CANT into the ocean interior assuming constant disequilibrium. We estimate that the section-averaged water-column CANT storage per unit area has increased by 0.56+/-0.02 mol/m2/yr in the 60S-20S latitude strip along the sections. The changes in CANT storage due to changes in ventilation correspond to a pronounced increase of CANT in SAMW. There are no significant changes in CANT for CDW due to changes in ventilation. The net effect of the changes in ventilation contributes 0.08+/-0.02 mol/m2/yr to the CANT storage in the Southern Ocean.

Part 1: Development and validation of an analytical method by liquid chromatography-tandem mass spectrometry to detect putrescine, cadaverine, spermidine, spermine, n8-acetylspermidine, and n1-acetylspermine as benzyl amide derivatives in biological samples were completed. The derivatization conditions were optimized for all PAs, and method validation was completed for putrescine (PUT) and spermidine (SPD) using isotope dilution techniques. The method exhibited: high accuracy (22 days; linearity within concentration range of 0.40-50 ng/mL for PUT and 0.42-530 ng/mL for SPD; level of detection (LOD) of 2.8 and 2.4 picograms (pg); and level of quantitation (LOQ) of 20 and 21 pg for PUT and SPD, respectively. Matrix effects and interferences were shown to not affect accuracy. The method developed provided superior with shorter analysis time than other published methods. Levels of PUT and SPD were determined to be 5.75 ± 0.1 and 43.8 ± 1 ng/mL, respectively in a sample as small as 4 fruit flies. Part 2: This project was a proof of concept study that used breath component analysis (BCA) to determine if a unique volatile organic compound (VOC) could be measured in human breath 72 hours or longer following a brief exposure. A portable breathing mask with a pressurized canister was constructed to provide 1-2 ppm exposures of the tracer chemicals to the subjects. An EBC sample collection device and canister cleaning system were modified to provide clean sample blanks. Analytical protocols were established to collect BCA from subjects using canisters and adsorbent traps. The chemicals tested and the maximum duration they were detectable in a subjects’ breath (days) were methoxyflurane (1.2), enflurane (7.7), sevoflurane (1.2), α,α,α-trifluorotoluene (14), 4-chlorobenzotrifluoride (7.2), and 3-fluorobenzotrifluoride (1.2). The rate constants for the most promising candidate chemicals followed a one-compartment (first order kinetics) model. Other compounds of similar chemical properties are potential candidates for further study. The applications of this proof of concept study may lead to the development of tools for use in toxicology, forensics, and security.

Perfluorocarbon tracers (PFTs) are commonly proposed tracers for use in carbon capture and sequestration (CCS) leak detection and vadose zone monitoring programs. Tracers are co-injected with supercritical CO₂ and monitored in the vadose zone to identify leakage and calculate leakage rates. These calculations assume PFTs exhibit “ideal” tracer behavior (i.e. do not sorb onto or react with porous media, partition into liquid phases or undergo decay). This assumption has been brought into question by lab and field evaluations showing PFT partitioning into soil contaminants and sorbing onto clay. The objective of this study is to identify substrates in which PFTs behave conservatively and quantify non-conservative behavior. PFT breakthrough curves are compared to those of a second, conservative tracer, sulfur hexafluoride (SF₆). Breakthrough curves are generated in 1D flow-through columns packed with 5 different substrates: silica beads, quartz sand, illite, organic-rich soil, and organic-poor soil. Constant flow rate of carrier gas, N₂, is maintained. A known mass of tracer is injected at the head of the columns and the effluent analyzed at regular intervals for tracers at picogram levels by gas chromatography. PFT is expected to behave conservatively with respect to SF₆ in silica beads or quartz sand and non-conservatively in columns with clay or organics. However, results demonstrate PFT retardation with respect to SF₆ in all media (retardation factor is 1.1 in silica beads and quartz sand, 2.5 in organic-rich soil, >20 in organic-poor soil, and >100 in illite). Retardation is most likely due to sorption onto clays and soil organic matter or condensation to the liquid phase. Sorption onto clays appears to be the most significant factor. Experimental data are consistent with an analytical advection/diffusion model. These results show that PFT retardation in the vadose zone has not been adequately considered for interpretation of PFT data for CCS monitoring. These results are preliminary and do not take into account more realistic vadose zone conditions such as the presence of water, in which PFTs are insoluble. Increased moisture content will likely decrease sorption onto porous media and retardation in the vadose zone may be less than determined in these experiments.

Perfluorocarbon tracers (PFTs) are commonly proposed tracers for use in carbon capture and sequestration (CCS) leak detection and vadose zone monitoring programs. Tracers are co-injected with supercritical CO₂ and monitored in the vadose zone to identify leakage and calculate leakage rates. These calculations assume PFTs exhibit “ideal” tracer behavior (i.e. do not sorb onto or react with porous media, partition into liquid phases or undergo decay). This assumption has been brought into question by lab and field evaluations showing PFT partitioning into soil contaminants and sorbing onto clay. The objective of this study is to identify substrates in which PFTs behave conservatively and quantify non-conservative behavior. PFT breakthrough curves are compared to those of a second, conservative tracer, sulfur hexafluoride (SF₆). Breakthrough curves are generated in 1D flow-through columns packed with 5 different substrates: silica beads, quartz sand, illite, organic-rich soil, and organic-poor soil. Constant flow rate of carrier gas, N₂, is maintained. A known mass of tracer is injected at the head of the columns and the effluent analyzed at regular intervals for tracers at picogram levels by gas chromatography. PFT is expected to behave conservatively with respect to SF₆ in silica beads or quartz sand and non-conservatively in columns with clay or organics. However, results demonstrate PFT retardation with respect to SF₆ in all media (retardation factor is 1.1 in silica beads and quartz sand, 2.5 in organic-rich soil, >20 in organic-poor soil, and >100 in illite). Retardation is most likely due to sorption onto clays and soil organic matter or condensation to the liquid phase. Sorption onto clays appears to be the most significant factor. Experimental data are consistent with an analytical advection/diffusion model. These results show that PFT retardation in the vadose zone has not been adequately considered for interpretation of PFT data for CCS monitoring. These results are preliminary and do not take into account more realistic vadose zone conditions such as the presence of water, in which PFTs are insoluble. Increased moisture content will likely decrease sorption onto porous media and retardation in the vadose zone may be less than determined in these experiments.

Several studies have looked at the importance of man-made water resources to wildlife in desert regions. To our knowledge, however, none have attempted to directly quantify their importance to both resident and Neotropical migratory birds. During the spring and summer from 2007-2009, we enriched man-made water developments in the Sonoran Desert on the Kofa National Wildlife Refuge, Arizona. We enriched water developments using deuteriated water and sampled the body water pools of resident and migrant birds to quantify development use. We used a simple two end-point mixing model to estimate the proportion of an individual birds body water pool that was derived from the development water. We mist netted birds at distances ranging from 2 to 1000 m from the development to assess the distance an individual would travel to use these permanent water sources. We analyzed samples from 1,431 birds and found that resident species (253 out of 394 individuals sampled) such as Gambel's Quail (Callipepla gambelii), White-winged Doves (Zenaida asiatica), Mourning Doves (Zenaida macroura), and House Finches (Carpodacus mexicanus) made extensive use of the water developments. Water developments contributed as much as 90% of the water found in the body water pools of some species (e.g. White-winged Doves, Mourning Doves and House Finches). Other species such as Northern Mockingbirds (Mimus polyglottos), Gila Woodpeckers (Melanerpes uropygialis), and Phainopeplas (Phainopepla nitens) made limited use (29 out of 91 individuals sampled) of these developments during the summer months. In contrast, very few Neotropical migrants (9 out of 364 individuals sampled) used these developments during their northward migration in the spring. For small, resident species, such as Verdin (Auriparus flaviceps), Black-tailed Gnatcatcher (Polioptila melanura), Lucy's Warbler (Vermivora luciae), and Black-throated Sparrow (Amphispiza bilineata), these permanent water sources appear to be of limited importance to their daily water balance.

Hybrids of Corylus avellana, C. americana and C. cornuta, are proposed as an alternative crop for the Upper Midwest. Current nitrogen (N) recommendations for European hazelnut production are based on research from Oregon and may not be applicable to hybrids in Minnesota due to differing soils, climate, genetics, and growing systems. In 2003, I initiated three years of N rate trials on three new plantings and on four young established plantings, from four to seven years old, using N rates of 0, 2.75, 5.5, 11, 22, 33, and 44 g N·plant-1. I observed a strong negative linear effect on survival when new transplants were fertilized within the first year of transplanting. Survival was not affected when fertilization was postponed one year, but even then these hybrid hazelnuts responded only to low N rates relative to those recommended in Oregon. Leaf N concentrations were within the expected ranges established for European hazelnuts in Oregon, suggesting that Oregon standards may be applied to hybrid hazelnuts, except that 2.2% leaf N should be considered adequate, rather than a threshold to sufficiency. In another experiment conducted at two sites with young bearing bushes, I used 15N-labeled ammonium nitrate to compare N uptake efficiency (NUE) from soil applications in mid-April, late April, late May, early August, and mid-September 2005. N uptake was slow before bud-break. N applied in the spring after bud-break was quickly translocated to plant parts with the greatest near-term demand for N: first to leaves, then to nuts and catkins. Nitrogen applied in August and September appeared in new shoots the following April, showing that N applied late in the season may be stored below ground over the winter. NUE was highest for August and September applications at one site and August and mid-April applications at the other, suggesting that summer is generally the best time to apply N for most efficient uptake. However, overall NUE was low, only 9% for the treatment with the highest efficiency, supporting our conclusion that hybrid hazelnuts have a low demand for N during establishment and early maturity. Nitrogen requirements may, however, increase with nut production.

An alternative on-site wastewater treatment and disposal system (OSWTDS) consisting of a soil infiltrator with low pressure distribution was evaluated in a soil that was unsuitable for a conventional OSWTDS under current Commonwealth of Virginia Sewage Handling and Disposal Regulations, due to a shallow seasonally perched water table and low hydraulic conductivity. The absorption field consisted of two subsystems numbered as 1 and 2 with effluent design loading rates of 5.1 and 10.2 Lpd/m2, respectively (actual loading rates of 2.4 and 4.9 Lpd/m2, respectively). Soil matric potentials compared seasonally for each subsystem and indicated that both provided similar hydraulic performance. Background water quality was generally improved by subsurface movement through the absorption fields. A bacterial tracer was found in shallow (45.7 cm) and deep (213.4 cm) sampling wells within 24 h in the two subsystems (but in low numbers) over both summer and winter sampling periods. A viral tracer was detected within 48 h in both shallow and deep wells, but only in subsystem 2 in the winter. In evaluating denitrification potential, the addition of glucose to soil core samples did increase quantitatively, although not significantly, nitrous oxide production in each subsystem, at each depth, during each season. Overall, the performance of both subsystems was very similar. The soil infiltrator functioned very well, as designed for the site and soil limitations. It appears to be a potential alternative OSWTDS for use in problem soils.