Prior observations by Koch (2005) suggest the presence of soil water mixed with current rainfall in runoff samples at the Kendall subwatershed of the USDA-Agricultural Research Service Walnut Gulch Experimental Watershed (WGEW). However, previous observations elsewhere in the WGEW have shown runoff to consist mainly of current precipitation (Goodrich et al., 2004). The disparity between the two studies demonstrates a need for continued research; therefore, this study uses isotope and solute geochemical tracers to determine the sources contributing to runoff at the Lucky Hills subwatershed of the WGEW during the 2015 monsoon season. A comparison of the stable isotopes of water (2H and 18O) in runoff to those in precipitation and soil water, shows that runoff and precipitation are distinct (p < 0.05), while soil water cannot be differentiated from runoff (p > 0.05). However, graphical representations of chloride and sulfate concentrations in the three water sources (precipitation, soil water and runoff), conclusively reveal that there is negligible soil water present in the runoff at Lucky Hills. Therefore, it is likely that there is no soil water mixing into the runoff at the Lucky Hills subwatershed, but more research is necessary to confirm these results. Because no runoff or soil water data was generated at the Kendall subwatershed during the 2015 monsoon season, continued research is necessary to draw conclusions about the sources contributing to runoff in the Kendall subwatershed, and in other portions of the Walnut Gulch Experimental Watershed.

Thesis (Ph.D.)--University of Adelaide, Dept. of Geology and Geophysics 1999. / Bibliography: leaves 233-260.

Thesis (M.S.)--University of Wisconsin--Madison, 1968. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

The Late Devonian-Early Mississippian-age New Albany Shale is both a source rock and reservoir rock for hydrocarbons in the Illinois Basin. Previously suggested models for organic carbon enrichment consider productivity, anoxia, and the interdependent roles of sedimentation, primary production, and microbial metabolism. This study attempts to reconstruct paleoenvironmental conditions during deposition and re-evaluates these models using geochemical data from multiple cores across the eastern edge of the Illinois Basin in west-central Kentucky. Geochemical methods utilizing redox-sensitive major elements (C, S, Fe, P, K, Ti, and Si), trace elements (V and Mo), and ratios (Ni/Co, V/Cr, and V/(V+Ni) are used. Analysis of paleo-redox indicators suggests variable bottom-water conditions during accumulation of the New Albany Shale members including: anoxic to possibly euxinic conditions for the Clegg Creek Member, anoxic to periodically dysoxic conditions for the Camp Run, and dysoxic to oxic (normal marine) for the Morgan Trail and Blocher Members. Variability in redox proxy results suggests that multiple parameters should be utilized in such studies rather than relying on a single proxy. High C/P ratios observed in these members may be controlled by regeneration of P, enhanced productivity, and sequestration of organic carbon (the productivity-anoxia feedback (PAF) mechanism) under anoxic conditions. The lack of correlation between organic carbon content and clastic-influx proxies suggests that organic matter (OM) accumulation was not controlled by sedimentation rate or increased nutrient supply associated with increased sediment influx.

<p> The Proterozoic' Coldwell Alkaline Complex is the southernmost intrusion of a number of N -S trending igneous bodies occurring in the Midcontinental Rift system exposed in the Lake Superior area. The Coldwell complex is host to several Ni-Cu-PGEbearing intrusions two of which; the Two-Duck Lake intrusion (Marathon deposit) and the Geordie Lake gabbro (MacRae occurrence) have been investigated in some detail with respect to PGE mineralisation. Both of these have been suggested to have experienced crustal contamination in conjunction with mineralisation. As a test of this possibility, a detailed Sm-Nd, oxygen isotope, and whole-rock geochemical study of these mineralised occurrences as well as of the Dunlop occurrence and the Middleton occurrence, together with unmineralised rocks of the complex was undertaken. The primary objectives are to determine whether crustal contamination is indicated in mineralised rocks and to try and ascertain the nature of the magma which formed the complex. </p> <p> The Coldwell complex is thought to have been formed by emplacement of magma at three intrusive centres. Sm-Nd data for rocks from these three centres reveal similar isotopic values, with slight variations; samples taken from the western gabbros exhibit eNd values averaging -0.9 ranging from -2.9 to 0.9, whereas rocks from the eastern margin and centre of the complex have eNd values of about an average of 0.5 ranging from -0.5 to 1.2 suggesting that the magma that formed these rocks has undergone a lesser degree of crustal contamination. This data, supported by oxygen isotope and wholerock geochemical information indicates that crustal contamination seems to play a small, and varied role in the genesis of the Coldwell magmas. The Nd isotope data all clusters at values for CHUR, which indicates that it has been enriched relative to the depleted mantle. It has been postulated that an enriched mantle plume resided under the rift and promoted rift-related magmatism. The data from this study would seem to support this supposition. </p> <p> Geochemical parameters utilised to define fields to geochemically delineate possible end member contributors to this primarily plume-derived magma indicate, that in addition to small, variable amounts of assimilation of upper and lower crust, the plume magmas also interacted with the lithospheric upper mantle to a small degree. </p> / Thesis / Master of Science (MSc)

Information from soil geochemical mapping programmes is useful within a number of different fields including for example mineral exploration and environmental research. The purpose of this thesis was to investigate the relationship between soil metal concentrations and geological factors such as bedrock lithology, structural geology, mineralizations etc. The study used data acquired in association with a nationwide soil geochemical mapping programme conducted by the Geological Survey of Sweden, SGU. These data contained both total element concentrations measured via X-ray fluorescence spectroscopy and acid leached concentrations measured with plasma technique. Basic statistical compilations were made, including classification of element concentrations into percentiles according to SGU standards, calculation of leachability and correlation analyses. Spatial analyses were also done, using GIS-software. The results showed that all investigated elements except zinc had elevated median values for total concentrations in the project area compared to the natural median values. The strongest correlation for total element concentrations was that between iron and cobalt with Spearman ρ=0.88. Furthermore, the results of this study indicated that sampling sites superimposing volcanic rocks contained the highest total concentrations of manganese. The results also suggested that manganese content increased with increasing age of the underlying bedrock. The highest median concentration of 0.80 g/kg was found in Archean rocks. Known mineralizations were often reflected in the form of positive element anomalies in the till geochemistry. The obtained results were also consistent with the average composition of the bedrock. No clear connections with any of the other investigated geological factors could be made.

Le stockage des déchets ménagers et assimilés est devenu un enjeu important pour l’environnement. Les smectites, ayant une faible perméabilité et une forte capacité à retenir les polluants, sont fréquemment utilisées comme barrière de sécurité passive au fond des alvéoles de stockage. Ce travail consiste à simuler au laboratoire l’infiltration de solutions de polluants métalliques dans des smectites, d'analyser les mécanismes d'interaction et prévoir leur comportement hydraulique et physico-chimique. Pour cela, nous utilisons des smectites naturelles de référence (SWy2 échangée avec différents cations, Na+ et Ca2+), mais aussi une smectite synthétique et des solutions de polluants métalliques (contenant essentiellement Zn et Pb). Les interactions « en batch » ont permis de tester plusieurs paramètres : rapport solide/liquide, concentration du polluant, pH…Les analyses des lixiviats ont montré que l’argile sodique adsorbe mieux les polluants que l’argile calcique et que l’adsorption est meilleure en milieu neutre. Les résultats expérimentaux ont pu être modélisés à l’aide de PHREEQC en utilisant le modèle 2SPNE. A partir des constantes d’échange et de complexation de la littérature, les simulations montrent que le modèle est en très bon accord avec les données expérimentales pour le zinc. Ces résultats ont permis d’établir de nouvelles constantes pour le plomb, et de connaitre les mécanismes d’adsorption en fonction de la concentration en équilibre de la solution métallique et du pH. Pour simuler au laboratoire le fonctionnement d’une barrière argileuse, des expériences d’infiltration sous pression ont été réalisées en oedométrie sur les smectites. Que ce soit avec l’eau déminéralisée, les solutions de polluants métalliques (Cu, Pb, Zn), ou un lixiviat synthétique, à pH libre ou fixé à 5, ces argiles ont des conductivités hydrauliques inférieures à 10-12 m.s-1 qui prouvent leurs bonnes capacités d’étanchéité. / Storage of household and industrial wastes has become an important issue for the environment. Smectites, with a low permeability and a high capacity to retain pollutants, are frequently used as an engineered barrier at the bottom of landfills. The aim of this work was to simulate in the laboratory the infiltration of metallic pollutants solutions in smectites, to analyze the interaction mechanisms and to predict the hydraulic and physico-chemical behavior of these clays. Natural reference smectites (SWy2 exchanged with different cations, Na+ and Ca2+) but also a synthetic smectite were used together with metallic pollutant solutions (containing mainly Zn and Pb). Several parameters were tested in the "batch" experiments: solid/liquid ratio, pollutant concentration, pH ... Analyses of leachates showed that the sodic clay better adsorbs pollutants than the calcic clay, and the adsorption was better in the neutral medium than in acidic conditions (pH 5). The experimental results were then modeled using the PHREEQC code and the 2SPNE model. From the exchange and complexation constants of the literature, simulations showed that the model was in very good agreement with the experimental data for zinc. These results allowed to establish new thermodynamic constants for lead and to assess the adsorption mechanisms as a function of the equilibrium concentration of the metallic solution and the pH. To simulate a clay barrier at the laboratory scale, infiltration experiments under pressure were performed onto smectites within oedometer cells. Whether with deionised water, metallic pollutant solutions (Cu, Pb, Zn) or a synthetic leachate, at free pH or buffered at 5, these clays kept a hydraulic conductivity less than 10-12 ms-1 which proved their good sealing properties.

No description available.

Increasing salinity has been a growing concern for users of waters from the Pecos River and the reservoirs it feeds in the Texas portion of the River's watershed. Irrigation water diverted from the river in the northern reach of this watershed is often only suitable for a limited number of crops, reducing harvesting options for local farmers. In the south, the Pecos feeds into the International Amistad Reservoir along the border with Mexico. During the 1990s, total dissolved solids concentrations in the reservoir rose as much as 10 mg/L per year and often approached the drinking water standard for potable water (1000 mg/L). Since this time, control efforts have focused on reducing the river's salinity, requiring the identification of salt sources. Hydrologic trend analysis and geochemical identification methods were used to determine these sources for the reach of the river between Red Bluff Reservoir and Brotherton Ranch. Between Red Bluff Reservoir and Coyanosa, flow diversions remove much of the flow that carries the salts, resulting in decreased salt loads, but also making the river more sensitive to evapotranspirative concentration. This sensitivity is evident in the river between Coyanosa and Girvin, where salinity begins to increase to the highest levels within the study area. However, salt loads increase here as well, indicating external salt sources as a contributor. The most substantial increase in bromide ions and the Br-/Cl- ratio appears between Grandfalls and Imperial, although no conclusion could be drawn regarding the identity of the source. The ratio continues to increase up to Girvin, where it appears that evapotranspirative concentration again has a significant effect. Here, several points drifted to the right of the groundwater mixing zones, plotting at values that were uncharacteristic of these sources.

Fractured reservoirs, especially in low permeable carbonate rocks, are important target for hydrocarbon exploration and production because fractures can control fluid flow inside the reservoir. Hence, quantitative knowledge of fracture attributes is important for optimal hydrocarbon production. However, in some cases fractures can cause leakage of injected CO2 during enhanced oil recovery (EOR) or CO2 sequestration. Furthermore, CO2 can geochemically interact with reservoir fluids and host rock. Hence, time-lapse monitoring of the progress of CO2 in fractured reservoirs is also very important. In order to address these challenges, I have developed an integrated approach for studying fluid flow and seismic wave propagation in fractured media using Discrete Fracture Network (DFN) models. My seismic simulation study suggests that CO2 saturated reservoir shows approximately ten times more attenuation than brine saturated reservoir. Similarly, large P-wave velocity variation in CO2 saturated reservoir and amplitude variation with offset (AVO) results for our example model predicts that CO2 is easier to detect than brine in the fractured reservoirs. The effects of geochemical processes on seismics are simulated by time-lapse modeling for t = 1000 years. My modeling study suggests that intra-aqueous reactions are more significant during injection of CO2 for t = 6 years, while slower mineral reactions dominate after pressure equilibrium is achieved that is from t = 6 to 1000 years. Overall both types of geochemical reactions cause change in reflection coefficient of 2 to 5%, which may be difficult to detect in some cases. However, the significant change in the seismic properties at the boundary of the CO2 front can be used to detect the flow path of CO2 inside the reservoirs. Finally, a method for generating stochastic fracture models was extended and improved to more realistic field model for seismic and fluid modeling. My detail analysis suggests that fractures generated by isotropic stress field favor orthogonal sets of fractures in most subsurface rocks that can be converted to seismic model, similar to DFN study. The quality and validity of the models is assessed by comparisons to DFN models, including calculations of fractal dimension measures that can help to characterize fractured reservoirs.