Creosote, containing many high molecular weight hydrophobic polycyclic aromatic hydrocarbons (PAH's), is present in the subsurface environment at the Oneida Tie-Yard in Oneida, Tennessee. Phytoremediation using hybrid poplar trees was chosen as the remedial technology on-site. Since monitoring began, the contaminant plume has been shrinking consistently and evidence has shown that remediation is taking place. However, remediation may be rate-limited by the desorption and dissolution kinetics of the PAH's on-site. The objectives of this research are to: (1) estimate the desorption and dissolution rates of 10 PAH's found in the subsurface and (2) estimate the amount of each PAH and total mass of contaminant that is irreversibly sorbed to the soil. Three laboratory desorption and dissolution experiments were performed using contaminated soil samples from the Oneida Tie-Yard site. The first experiment was a batch desorption equilibrium experiment, the second was a batch desorption kinetics experiment, and the third was a soil column dissolution kinetics experiment. The target compounds in this study were: naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, chrysene, and benzo(b)fluoranthene. The resulting data for the desorption equilibrium experiment revealed that rates of equilibrium were truly not instantaneous in the systems studied. However, because approximately 76% of PAH's desorbed by the first sampling event (3 days), an equilibrium isotherm was considered appropriate. Results showed that there is a sorbed reversible concentration that readily desorbs to the aqueous phase for each PAH. Additionally, it was determined that the percent removal of sorbed PAH's decreases with increasing molecular weight. Desorption curves based on experimental data were found to exhibit linear behavior over large variations in aqueous concentration, but showed exponential behavior as concentrations approached zero. Freundlich sorption equilibrium isotherms for the 10 monitored PAH's on-site were generally found to have N coefficient values over 1, especially over large variations in solution phase concentration, indicating a non-uniform sorbent. Dissolution of resistant PAH's under field-like conditions was determined to occur over long periods of time. Dissolution rates calculated from experimental data were shown to generally decrease with increasing molecular weight. Overall, desorption and dissolution kinetics of PAH's were shown to be rate-limiting factors to remediation at the Oneida Tie-Yard. / Master of Science

Poor sanitation infrastructure in rural areas can often lead to high levels of fecal contamination in local waterbodies and subsequent exposure to waterborne disease can occur. Although standard water quality measures such as quantification of E. coli can reveal relative concentrations of fecal contamination, they do not pinpoint the sources of such contamination. Source assessment in rural areas affected by untreated household waste might be improved with the human-specific, microbial source tracking marker HF183. This study attempted to quantify HF183 in two particular Appalachia streams with known discharges of untreated household waste. Water samples were taken above and at multiple points below these discharges on 29 occasions between August 2012 and April 2016, and tested for both HF183 and E. coli. HF183 was detected consistently in one of the study streams, though the concentrations were generally much lower than those previously reported in raw sewage; in the other watershed, HF183 was never detected. Further analysis via a multiple linear regression model showed a positive correlation between the level of E. coli and the proximity and number of known waste discharge points upstream from each sampling site. Primary conclusions of this study include: 1) HF183 is not always detected, even in watersheds with known sources of human fecal contamination, 2) it may be a useful water quality assessment tool where such contamination is suspected, particularly in cases where contaminant source allocation is necessary for setting mitigation priorities. / Master of Science

A <i>Pseudomonas</i> sp. capable of degrading tertiary butyl alcohol (TBA) as a sole carbon source, was isolated from a groundwater aquifer (50 ft. deep) at a petroleum refinery. The most probable number (MPN) of TBA degrading microorganisms was 4.9 x 10³ organisms/g (dry wt) of subsurface soil. Pristine subsurface soils, which did not have a history of petroleum contamination, had MPNs of < 2 TBA degrading organisms/g (dry wt) indicating a natural enrichment process at the refinery site. The Q_O2 of <i>Pseudomonas</i> sp. was 4.2 ml O₂/mg dry wt/h when TBA was the substrate. The optimum pH for growth was 7.0. The organism grew faster in continuous culture when TBA was the sole carbon source with a doubling time 33.6 h. The doubling time in batch culture was 112.3 h. When yeast extract was added to a mineral salts + TBA medium to concentrations greater than 1 mg/ml, TBA degradation was inhibited. When the yeast extract concentration was 0.1 mg/ml, a diauxy effect was seen in the growth rate. This suggested that TBA degradation by <i>Pseudomonas</i> sp. was subject to a regulatory mechanism. / M.S.

GaN has the potential to revolutionize the high power electronics industry, enabling high voltage applications and better power conversion efficiency due to its intrinsic material properties and newly available high purity bulk substrates. However, unintentional impurity incorporation needs to be reduced. This reduction can be accomplished by reducing the source of contamination and exploration of extreme growth conditions which reduce the incorporation of these contaminants. Newly available bulk substrates with low threading dislocations allow for better study of material properties, as opposed to material whose properties are dominated by structural and chemical defects. In addition, very thick films can be grown without cracking due to exact lattice and thermal expansion coefficient match. Through chemical and electrical measurements, this work aims to find growth conditions which reduces contamination without a severe impact on growth rate, which is an important factor from an industry standpoint. The proposed thicknesses of these devices are on the order of one hundred microns and requires tight control of the intentional dopants. / Doctor of Philosophy / GaN is a compound semiconductor which has the potential to revolutionize the high power electronics industry, enabling new applications and energy savings due to its inherent material properties. However, material quality and purity requires improvement. This improvement can be accomplished by reducing contamination and growing under extreme conditions. Newly available bulk substrates with low defects allow for better study of material properties. In addition, very thick films can be grown without cracking on these substrates due to exact lattice and thermal expansion coefficient match. Through chemical and electrical measurements, this work aims to find optimal growth conditions for high purity GaN without a severe impact on growth rate, which is an important factor from an industry standpoint. The proposed thicknesses of these devices are on the order of one hundred microns and requires tight control of impurities.

The purpose of this research was to evaluate the rates, patterns, and pathways involved in the biodegradation of organic contaminants in subsurface environments. Subsurface material was obtained from ten sites in six geographical locations representing diverse environmental conditions. The overall goal was to gain a general understanding of biodegradative mechanisms rather than making site-specific measurements. The biodegradation rates of methanol, phenol, and <i>t</i>-butanol (TBA) were evaluated in static soil/water microcosms. Biodegradation assays were conducted under ambient anoxic conditions, and with the addition of potential electron acceptors (nitrate, nitrite, sulfate) or metabolic inhibitors (molybdate, BESA) to promote different pathways of anaerobic microbial metabolism (nitrate respiration/denitrification, sulfate reduction, or methanogenesis). In unamended systems, biodegradation rates varied considerably between sites. Methanol and phenol were degraded fairly readily. Rates generally ranged from 0.5 to 1.0 mgL⁻¹d⁻¹ for 20°C incubation. Disappearance of methanol and phenol followed zero- to first-order kinetics and was usually immediate, requiring no acclimation period. TBA was relatively recalcitrant in subsurface soils, disappearing at a rate of 0.1-0.3 mgL⁻¹d⁻¹ (20°C). No biodegradation was evident, relative to sterile controls, in certain soils. The pattern of TBA degradation was typically biphasic: a long lag period of slow, linear removal was followed by an abrupt increase in removal rate (albeit still slow). Biodegradation rates were positively correlated with bacterial density for 12 soil samples from 3 sites within a localized area at Blacksburg, Virginia. However, this relationship did not exist between soils from diverse locations. The prevailing electron acceptor conditions govern the catabolic pathways utilized in the anaerobic respiration of organic contaminants. The effects of the added electron acceptors and inhibitors on biodegradation rates varied between sites. Two general types of systems are indicated by relative biodegradation rates, characteristic responses to electron acceptor/inhibitor amendments, and general environmental conditions. "Fast" soils are characterized by a higher flux of water and nutrients, higher biodegradation rates, and rate enhancement upon adding nitrate or sulfate. In "slow" soils, organic contaminants are degraded at lower rates, rates are decreased by adding nitrate, sulfate, or BESA (which inhibits methanogenesis), and rates are increased by adding molybdate (which inhibits sulfate reduction). Nearly all soils tested were capable of sulfate-reducing and methanogenic metabolism, but those populations were more active, and competition between the two groups was less severe, in "fast" soils. In contrast, "fast" soils appeared to harbor an active population of nitrate respiring/denitrifying bacteria, whereas in "slow" soils that metabolic group was inactive, absent, or susceptible to nitrite toxicity. / Ph. D.

Groundwater contaminated by organic chemicals from industrial spills, leaking underground gasoline storage tanks and landfills has caused concern about the future of a major source of drinking water. Compounds from industrial sources such as alcohols and phenols are frequently found as groundwater contaminants. These compounds are highly soluble in water and do not adsorb well to aquifer material. They also have the potential to migrate in the subsurface system achieving significant levels in drinking water supplies. In addition, they can serve as carriers for carcinogenic compounds such as benzene, toluene and xylene which are relatively insoluble in water, but are quite soluble in alcohol. A potential alternative to expensive groundwater reclamation projects is the use of the natural soil bacteria to degrade organic contaminants. Very little is known, however, about subsurface soil bacteria to man-made organic chemicals or the degradation rates of these compounds. Such information would be useful in planning cleanup or protection strategies for groundwater systems. This study was designed to measure the kinetic response of tertiary butyl alcohol (TBA), determine the biological degradation rates of methanol, ethanol, propanol, l-butanol, TBA, pentanol, phenol and 2,4-dichlorophenol; describe site specific conditions which enhance or inhibit degradation and compare biodegradation rates with thermodynamic predictions. Laboratory microcosms utilizing soil from two previously uncontaminated sites of widely varying conditions were constructed to simulate the subsurface environment. Nitrate was added to some microcosms to stimulate denitrification and metabolic inhibitors were added to others to define conditions at each site which favor biodegradation. Each of the test compounds except TBA was readily degraded in the Blacksburg soil. Inhibition of sulfate reduction by the addition of molybdate stimulated degradation of all compounds including TBA, whereas, inhibition of methanogenesis with BESA slowed the degradation rates. The addition of nitrate did not affect the biodegradation in Blacksburg soil. In the Newport News soil, all of the test compounds were biodegraded at substantially higher rates than was observed in the Blacksburg soil. The presence of the metabolic inhibitors did not affect degradation, however, the addition of nitrate increased the degradation rates of the alcohols but not the phenols. The degradation rates in each of the soils did not correlate with the bacterial population size or free energies of the reactions. / Ph. D.

京都大学 / 新制・課程博士 / 博士(地球環境学) / 甲第24955号 / 地環博第246号 / 新制||地環||49(附属図書館) / 京都大学大学院地球環境学舎環境マネジメント専攻 / (主査)教授 勝見 武, 准教授 高井 敦史, 教授 越後 信哉 / 学位規則第4条第1項該当 / Doctor of Global Environmental Studies / Kyoto University / DFAM

No / There is developing interest in the analytical use of human hair from archaeological contexts in key research areas such as DNA, trace elemental and isotopic analyses. Other human tissues, especially bone, that have been used for trace element, isotopic and DNA analyses have had extensive study concerning their diagenesis, but this has not been done for hair. Consideration must be given to the complex interaction of hair with its buried environment, thereby laying a firm basis for the use of hair in future research. Since human hair is known to survive under a diverse range of environmental conditions, a pilot study has investigated the basic processes of hair degradation, using samples from different climatic zones and burial types. Variation in the degree of preservation of archaeological hair was characterized by light microscopy, electron microscopy, and FT-Raman spectroscopy, relating morphological change of the surface and internal structure of hair to its biochemical integrity. The results demonstrate a breakdown of cortical cell boundaries and disruption of the cuticular layering, coupled with infiltration of material from the burial matrix that suggests a progressive loss of cohesion that is in part due to microbiological activity. Medullated hair is shown to be more susceptible to physical breakdown by providing two routes for microbial and environmental attack. At the molecular level the proteinaceous component undergoes alteration, and the S-S cystine linkages, responsible for the strength and resilience of hair in living individuals, are lost.

Groundwater related courses are offered through several colleges at Virginia Tech. These classes enroll a diverse group of students with varied academic backgrounds and educational levels. Though these classes emphasize different aspects of groundwater resources, they lack a unified approach in instructional materials and learning methodologies for knowledge they do share. The goals of this research are to lessen the impact of variable student backgrounds and to better integrate the courses to improve teaching and learning, through the development of a multi-tiered, interdisciplinary website, Groundwater Interactive (GWI). GWI, as an educational technology, employs a variety of interactive multimedia. The primary educational components of the website include interactive and graphical models and quizzes, and a student-authored primer. An implementation strategy based on experiential and cooperative learning models is developed for application of the GWI tool in the classroom. An assessment methodology to evaluate the effectiveness of these new learning methods and techniques was also developed, but was not implemented as part of this work. / Master of Science

Depuis la préhistoire, plusieurs matériaux ont été utilisés pour fabriquer des instruments et des appareils de santé. Au cours des dernières décennies, avec l’apparition du terme « biomatériau », les matériaux ont été conçus pour contrôler des réactions biologiques spécifiques, pour augmenter la durée de vie des biodispositifs et la qualité de vie des patients dans le monde. Cependant, indépendamment de la nature du matériau, ou au sens strict du biomatériau, et de la fonction remplie, ils sont susceptibles aux phénomènes de surface causés par son environnement. Certains phénomènes intéressants incluent l’action des protéines, des électrolytes et des cellules sur les surfaces métalliques. Ces interactions peuvent entraîner le développement de complications telles que la formation de thrombus, la corrosion et la calcification, qui affecteront le fonctionnement des dispositifs, et la contamination bactérienne qui peut transformer la surface en vecteur de propagation de maladies. Des recherches ont exploité des stratégies de modification de surface pour minimiser ou éviter ces complications. Ces approches demandent du temps et des efforts pour développer une surface efficace pour chaque cas. Sur cette base, l’objectif principal de ce travail était de concevoir et de développer des revêtements à base de chitosane à utiliser dans le revêtement de surfaces métalliques et de dispositifs utilisés dans le système de santé et de modifier ces surfaces pour moduler la réponse biologique. Pour atteindre cet objectif, le projet de recherche a été divisé en trois parties. La première était le greffage du chitosane utilisant de la dopamine comme ancre. La deuxième était le développement d’un greffage original en une étape remplaçant la dopamine par l’acide caféique. La dernière était la modification du revêtement de chitosane pour moduler la réponse biologique de la surface. À chaque étape, les surfaces revêtues ont été caractérisées par analyses biologiques et physico-chimiques. Les résultats ont démontré que la méthodologie développée produisait des revêtements de chitosane qui possédait des réponses biologiques et des performances physico-chimiques favorables et qui pouvait être modifiés pour améliorer ou conférer la propriété souhaitée. De plus, cette méthodologie permet de produire une plateforme capable d’être appliquée sur une large gamme de complications en raison de sa modulabilité. Cela représente une diminution de la consommation de temps pour créer une nouvelle surface à partir du zéro pour chaque situation. / Since prehistoric times, several materials have been used to make health instruments and devices. In recent decades, with the appearance of the term "biomaterial", materials have been designed to control specific biological reactions, to increase the lifespan of biodevices and the quality of life of patients around the world. However, regardless of the nature of the material, or in the strict sense of the biomaterial, and the function fulfilled, they are susceptible to the surface phenomena caused by its environment. These phenomena include the action of proteins, electrolytes, and cells on metal surfaces. These interactions can lead to the development of complications such as thrombus formation,corrosion, and calcification, which will affect the functioning of the devices, and bacterial contamination, which can transform the surface into a vector for the spread of disease. Researches were made on the use of surface modification strategies to minimize or avoid these complications. These approaches require time and effort to develop an effective surface for each case. On this basis, the main objective of this work was to design and develop chitosan-based coatings to coat metallic surfaces and devices used in the health care system and to modify these surfaces to modulate the biological response. To accomplish this objective, the research project was divided into three parts. The first was the grafting of chitosan using dopamine as an anchor. The second was the development of an original one step graft replacing dopamine with caffeic acid. The last was the modification of the chitosan coating to modulate the biological response of the surface. At each stage, the coated surfaces were characterized by biological and physicochemical analyzes. The results obtained showed that the developed methodology produced chitosan coatings that had favorable biological responses and physicochemical performances, and that it could be modified to improve or confer the desired property. Besides, this methodology makes it possible to produce a platform able to be applied to many complications due to its modularity. It represents a reduction in the consumption of time to create a new surface from scratch for each situation.