Grain size distribution, porosity, and hydraulic conductivity from over 400 unlithified sediment samples were analized. The measured hydraulic conductivity values were then compared to values calculated using 20 different empirical equations commonly used to estimate hydraulic conductivity from grain size analyses. It was found that most of the hydraulic conductivity values estimated from the empirical equations correlated very poorly to the measured hydraulic conductivity values. Modifications of the empirical equations, including changes to special coefficients and statistical off sets, were made to produce modified equations that considerably improve the hydraulic conductivity estimates from grain size data for beach, dune, off shore marine, and wadi sediments. Expected hydraulic conductivity estimation errors were reduced. Correction factors were proposed for wadi sediments, taking mud percentage and the standard deviation (in phi units) into account.

Particle size distribution (PSD) of gypseous soils is important in the soil science community. When gypsum constitutes a major portion of the soil, its removal prior to PSD analysis distorts the results and may lead to textures that do not relate to conditions in the field. In order to understand the true characterization of the soil and the gypsum particles, the entire soil sample should be analyzed. Four different approaches to the BaCl2 method presented in the literature (Hesse, 1976, Matar and Douleimy, 1978, Viellefon, 1979) were used to evaluate the use of BaCl2 solution to reduce the solubility of gypsum by forming a protective coating of BaSO4 around gypsum particles. Results showed that the BaCl2 method was unsatisfactory, as dispersion of clays was not sufficient to allow particle size analysis using the pipette method. A procedure using a laser diffraction particle size analyzer (LPSA) was also evaluated. As gypsum is insoluble in methanol, methanol was selected as a possible solution, but it caused flocculation of clays and could not be used to analyze samples containing silicate clays. Gypsum saturated water containing Na hexametaphosphate was evaluated as a solution. First, 20 non-gypseous samples were analyzed on a sand-free basis using saturated gypsum water with Na hexametaphosphate. Results were used to establish a relationship comparing LPSA results and pipette results. An equation y = 1.37x + 2.03 was established relating LPSA clay percent by volume (x) to the pipette clay percent by weight (y). The equation had a R2 value of 0.84 and was significant at the 1% level. From this equation a comparison of 21 gypseous samples was made, between clay percentages of the pipette method and the LPSA method. Results indicate that LPSA can be used to give a satisfactory particle size distribution of gypseous soils when coupled with sand analysis by sieving.

Particle size distribution (PSD) of gypseous soils is important in the soil science community. When gypsum constitutes a major portion of the soil, its removal prior to PSD analysis distorts the results and may lead to textures that do not relate to conditions in the field. In order to understand the true characterization of the soil and the gypsum particles, the entire soil sample should be analyzed. Four different approaches to the BaCl2 method presented in the literature (Hesse, 1976, Matar and Douleimy, 1978, Viellefon, 1979) were used to evaluate the use of BaCl2 solution to reduce the solubility of gypsum by forming a protective coating of BaSO4 around gypsum particles. Results showed that the BaCl2 method was unsatisfactory, as dispersion of clays was not sufficient to allow particle size analysis using the pipette method. A procedure using a laser diffraction particle size analyzer (LPSA) was also evaluated. As gypsum is insoluble in methanol, methanol was selected as a possible solution, but it caused flocculation of clays and could not be used to analyze samples containing silicate clays. Gypsum saturated water containing Na hexametaphosphate was evaluated as a solution. First, 20 non-gypseous samples were analyzed on a sand-free basis using saturated gypsum water with Na hexametaphosphate. Results were used to establish a relationship comparing LPSA results and pipette results. An equation y = 1.37x + 2.03 was established relating LPSA clay percent by volume (x) to the pipette clay percent by weight (y). The equation had a R2 value of 0.84 and was significant at the 1% level. From this equation a comparison of 21 gypseous samples was made, between clay percentages of the pipette method and the LPSA method. Results indicate that LPSA can be used to give a satisfactory particle size distribution of gypseous soils when coupled with sand analysis by sieving.

Gold nanoparticles (AuNPs) have garnered considerable attention for their interesting size-dependent properties. These properties have fueled applications that span a continuum ranging from simple to sophisticated. Applications for these materials have grown more complex as syntheses for these materials have improved. For simple applications, current synthetic processes are sufficient. However, development of syntheses that generate well-defined particle sizes with specifically tailored surface functionalities is an on-going challenge for chemists. The aim of this dissertation is to improve upon current AuNP syntheses to produce sophisticated materials needed to discover new material properties, and provide efficient access to materials to develop new advanced applications. The research described in this dissertation improves upon current methods for AuNP production by using a microreactor to provide enhanced mixing and synthetic control, and small angle X-ray scattering (SAXS) as a precise, rapid, solution-based method for size distribution determination. Using four ligand-stabilized AuNP samples as reference materials, SAXS analysis was compared to traditional microscopic size determination. SAXS analysis provided similar average diameters while avoiding deposition artifacts, probing a larger number of particles, and reducing analysis time. Next, the limits of SAXS size analysis was evaluated, focusing on identifying multiple distributions in solution. Utilizing binary and ternary mixtures of well-defined AuNP reference samples, SAXS analysis was shown to be effective at identifying multiple distributions. While microscopy has limited ability to differentiate these modes, SAXS analysis is more rapid and introduces less researcher bias. Because AuNP size and ligand functionality are interdependent, accessing desired core sizes with varied functionality is challenging. To address this, a new microfluidic synthetic method was developed to produce thiolate-passivated AuNPs with targeted core sizes from 1.5 - 12 nm with tailored functionality. This ability to control size while independently varying surface functionality is unprecedented. Lastly, AuNP core formation was probed by simultaneous in situ SAXS and UV/visible spectroscopy. A coalescence mechanism for AuNP growth was observed when using Bunte salt ligands. This finding compares well to observed coalescence in other systems using weakly-passivating ligands, and supports the hypothesis that Bunte salts passivate ionically during particle growth while resulting in covalent linkages. / 2015-10-10

This research had two main objectives: quantify surface-water and groundwater interactions along a stream reach, and determine the hydraulic conductivity at the site where two reservoirs are proposed. The objectives of this research aim to help maintain stream ecology and increase surface water storage for recreational and industrial purposes. The stream reach, located in the Pascagoula River Basin of southeast Mississippi, begins at Lake Okatibbee and terminates at Pascagoula into the Gulf of Mexico. Four USGS continuous gauging stations provided more than forty years of stream discharge data for a hydrograph baselow-recession analysis, which determined the baseflow component within the stream. The analysis showed that baseflow decreases along the stream reach and increases again before reaching the Gulf of Mexico. Thirteen borehole samples were collected at the sites of the proposed reservoirs in George County, Mississippi to determine the hydraulic conductivity of the sediments, which showed high a hydraulic conductivity.

Pacific salmon has been a staple resource for residents of British Columbia for over seven thousand years. Archaeological evidence obtained from a shell midden at Namu, B.C., provides detailed information about the diets of the First Peoples living at Namu over the past seven thousand years. Pacific salmon was the most prevalent species of fish uncovered within the midden, excluding herring. Pink, chum and sockeye species were consumed in the greatest quantities. Pink was particularly favored because of its ability to store over winter months without spoiling. Evidence from the shell midden also reveals fluctuations within the pink salmon fishery from ~3800 until 1900 cal year BP. The paleoenvironmental conditions within Namu Lake during the time of the pink collapse have never before been explored. There is also little evidence pertaining to what may have contributed to the collapse of the pink fishery. Sediment cores collected from Namu Lake, B.C. provide evidence for paleoenvironmental conditions that may have contributed to fluctuations in the pink salmon population. Particle size analyses of lake sediment cores indicate changes in river discharge as well as erosional intensity within the Namu basin. Particle size, coupled with radiocarbon dating, reveal a transitional period within the basin from ~ 3200 to 2200 cal year BP. A decrease in elemental ratios/Al, particularly Ca, Na, Ba, and Sr, provides evidence for a decline in erosional intensity and a relatively drier period within the basin. The decrease in erosional intensity could be due to consistently drier conditions at Namu. A resulting reduction in the flow of the Namu River would have caused an increase in finer particles within the pink salmon spawning grounds. Average C/N ratios for NC1 are 26.28, indicating that organic matter within the lake is mainly terrestrial in origin. These results, combined with the particle size and trace metal analysis, reveal that river discharge and slope wash had declined during this period causing fine material to remain in the Namu River (outflowing), which is the spawning grounds for the pink salmon, rather than being transported out into the bay. The results of this study reveal that a shift in moisture, towards relatively dry conditions, negatively impacted spawning pink salmon at Namu Lake. This study provides insight into the sensitivity of Pacific salmon to climate and the effects future climate change may have on the species. The ability of environmental data to supplement and enhance archaeological information and interpretations of prehistoric conditions is illustrated throughout this study. The cores collected at Namu Lake also reveal the need for site specific climatic data in order to accurately interpret archaeological contexts and conditions. / Thesis / Master of Science (MSc)

No description available.

No description available.

Conservation tillage tobacco production has gained little producer acceptance since introduction in the late 1960's. Yield reductions, tobacco quality issues, unacceptable weed control, and inadequate planting equipment limited practice adoption and substantiated the need for continued research. The recent developments of a Subsurface Tiller-TransplanterTM and the herbicide SpartanTM renewed producer interest in conservation tillage and led to an investigation with both flue-cured and Virginia dark-fired tobacco. Flue-cured tobacco was transplanted into rye mulch on bedded rows and subsequently cultivated at various timings. Conservation tillage significantly reduced soil erosion approximately 92 percent and tobacco yield approximately 23 percent when row cultivation was not applied. Row cultivation significantly increased tobacco yield without increasing soil erosion. The yield of conservation tillage tobacco receiving a minimum of two cultivations was similar to conventional tobacco. The second study evaluated wheat, rye, crimson clover, and mixtures of crimson clover with either wheat or rye as cover crop mulches for conservation tillage production of Virginia dark-fired tobacco. Conservation tillage, regardless of cover crop, reduced dark-fired tobacco yields approximately 779 and 488 pounds per acre in 1996 and 1997, respectively. The removal of cover crop residue for hay did not lower tobacco yield compared to leaving residue on the soil surface. Row cultivation increased conservation tillage tobacco yield approximately 247 pounds in 1997 regardless of cover crop. The nitrogen contribution of crimson clover was minimal in both years of the study and did not affect tobacco performance. / Master of Science

The purpose of this study was to evaluate Lewis (2016) simple method to determine hydraulic conductivity in soil samples. This was conducted by comparing Lewis method to a slug-test, Guelph permeameter and calculations from grain size analysis in order to find out if the method is a reliable source for measuring hydraulic conductivity. Other parameters to compare is time consumption, cost effectiveness and area of use. Four different samples were used in the testing, a sand, two tills and pyrite ash (which is a rest product from manufacturing sulfite pulp). The results indicated that measurements in the homogenic sand all methods was in a good range of each other, while in the more heterogenic till the slug-test and Lewis method was close and the calculations from grainsize analysis was much lower. Only grainsize analysis was performed on the pyrite ash and the results was similar to Lewis method. This study shows that Lewis method works well as a reliable source for K measurements and is less time consuming than all the other methods. The material required for the method can be obtained in a hardware store.