Thesis (M.S.)--University of Tennessee, Knoxville, 2003. / Title from title page screen (viewed Mar. 22, 2004). Thesis advisor: Carol P. Harden. Document formatted into pages (x, 149 p. : col. ill., col. maps). Vita. Includes bibliographical references (p. 72-78).

Thesis (Ph. D.)--University of Tennessee, Knoxville, 2001. / Title from title page screen. Document formatted into manuscript-like pagination: vii, 98 leaves : ill. Vita. Includes bibliographical references (leaves 85-86).

The processes that control the reductive dissolution of Mn0₂ by Fe(II) under conditions simulating the effects of acid mine drainage on subsurface environments and the subsequent precipitation of Fe(III) has been investigated. Results from real-time, in situ X-ray absorption spectroscopy (XAS) flow-through reaction cell studies indicate that a mixed Fe/Mn solid phase with the local structure of the spinel mineral jacobsite (MnFe₂O₄) is formed after the Mn0₂ surfaces are coated with ferric precipitates. In the absence of previously precipitated Fe(III), no reduced manganese solid is formed. The ferric precipitates do not incorporate significant quantities of Mn(II) down gradient from the reactive Fe(II) front. The maximum amount of the original Mn0₂ incorporated into this jacobsite-like solid is 5%. Results from batch experiments showed similar results compared to the flow-through experiments, with an initially fast rate of Mn(II) release, followed by a much slower release after 5-10 min had elapsed. The reaction products, Fe(III)(aq) and Fe(III)(s) were found to decrease the initial reaction rate. A simple model was developed to describe the temporal concentrations of Mn(II)(aq), Fe(II)(aq), and Fe(III)(aq) that include a Langmurian blocking function to describe the effects of the ferric reaction products on the reaction rate. The model also allowed for a second order process to occur at long time that was dependent solely on the aqueous concentrations of Fe(II) and Mn02. The formation of the ferric reaction products were found to transform from aqueous sulfate complexes to (presumable) ternary surface complexes with sulfate. Within 10 h, these precipitates may have formed chains of edge-sharing octahedra on the order of 60 Å. The precipitates have large amount of sulfate associated with them, which may preclude the formation of ferrihydrite, and may indicate the formation of schwertmannite. The average Fe:SO₄ ratio was 4.4 ± 1.0, a value similar to that reported for schwertmannite. The presence of goethite was identified by X-ray diffraction as early as 50 d, indicating that sulfate is being excluded from the precipitates. The release of Mn(II), FeT, and sulfate was controlled by diffusion, which may also be the process that controls the rate of transformation.

Thesis (Ph. D.)--University of Missouri-Columbia, 1996. / Typescript. Vita. Includes bibliographical references (leaves 262-273). Also available on the Internet.

Thesis (M.S.)--Indiana University, 2007. / Title from screen (viewed on August 8, 2007) Includes vita. Department of Earth Sciences, Indiana University-Purdue University Indianapolis (IUPUI) Includes bibliographical references (leaves 145-149)

No description available.

A variety of conservation trends have gained and lost favor throughout the years in agriculture, with U.S. Farm Bills often influencing what conservation practices are implemented by farming communities throughout the U.S. This dissertation focuses on the unintended consequences of conservation management practices in the Fifteenmile Watershed of Wasco County, Oregon. Specifically, I seek to address how farmer enrollment in various conservation techniques, loosely defined as no-till agriculture, has affected soil and water quality through the increased use of herbicide, and subsequently rendered ecological and human health vulnerable. Using a critical physical geography framework, I address both the biophysical factors and social structures that have co-produced changes in soil and water quality in the study area of this research through intensive physical field data collection, spatial analysis, social surveys, and interviews. I also demonstrate how three neoliberal sets of processes: market-friendly reregulation; state rollback and deregulation; and the creation of self-sufficient individuals and communities, have transformed the human socio-environmental relationship to agriculture. These processes have had significant effects on the policies governing how soil and water quality are managed on both a state and national level, and have created a dependence on enrollment in conservation practices that may ultimately prove counterproductive for long term goals of environmental protection and sustainability.

This dissertation integrates a process-based hydrological investigation with an ongoing paired-catchment study to better understand how forest harvest impacts catchment function at multiple scales. We do this by addressing fundamental questions related to the stocks, flows and transit times of water. Isotope tracers are used within a top-down catchment intercomparison framework to investigate the role of geology in controlling streamwater mean transit time and their scaling relationships with the surrounding landscape. We found that streams draining catchments with permeable bedrock geology at the Drift Creek watershed in the Oregon Coast Range had longer mean transit times than catchments with poorly permeable bedrock at the HJ Andrews Experimental Forest in the Oregon Cascades. We also found that differences in permeability contrasts within the subsurface controlled whether mean transit time scaled with indices of catchment topography (for the poorly permeable bedrock) or with catchment area (for the permeable bedrock). We then investigated the process-reasons for the observed differences in mean transit time ranges and scaling behavior using a detailed, bottom-up approach to characterize subsurface water stores and fluxes. We found that the mean transit times in catchments underlain by permeable bedrock were influenced by multiple subsurface storage pools with different groundwater ages, whereas storage in the poorly permeable catchments was limited to the soil profile and that resulted in quick routing of excess water to the stream at the soil bedrock interface, leading to mean transit times that were closely related to flowpath lengths and gradients. Finally, we examined how and where forest trees interacted with subsurface storage during the growing season using a forest manipulation experiment, where we tested the null hypothesis that near-stream trees alone influenced daily fluctuations in streamflow. We felled trees within this zone for two 2.5 ha basins and combined this with isotopic tracing of tree xylem water to test if water sources utilized by trees actively contributed to summer streamflow. We rejected our null hypotheses and found that diel fluctuations in streamflow were not generated exclusively in the near-stream zone. We were unable to link, isotopically, the water sources trees were utilizing to water that was contributing to streamflow. Our results provide new process-insights to how water is stored, extracted, and discharged from our forested catchments in Western Oregon that will help better explain how forest removal influences streamflow across multiple scales and geological conditions. / Graduation date: 2012

A região de São Pedro (Estado de São Paulo) apresenta muitos problemas ambientais relacionados aos processos erosivos, sendo que uma das áreas mais afetadas é a bacia do córrego do Espraiado, alvo deste estudo. Este trabalho buscou a caracterização e identificação: dos elementos do terreno; dos materiais inconsolidados; da evolução espacial e temporal das feições erosivas, cadastradas a partir de fotografias aéreas nos anos de 1972, 1978, 1995, e em trabalhos de campo para as feições de 2002; das técnicas de controle e reabilitação empregadas em algumas áreas; e das condições geométricas atuais da drenagem. A partir destas informações foram elaborados os seus respectivos mapas em escala de detalhe (1:10.000), para servirem de suporte ao final para uma análise dos processos erosivos atuantes, e das técnicas de controle e reabilitação utilizadas, pois algumas delas não tiveram eficiência, tendo como conseqüência o aparecimento de novas feições nas áreas reabilitadas. / The São Pedro region (São Paulo state) presents many environments problems related to erosive process. The Espraiado creek watershed, is goal of this study is very affected. This work was developed according to several steps: the characterization and identification of terrain elements and unconsolidated materials; temporal and spatial evolution analyses of the erosive features, by aerial photographs of dates 1972, 1978 and 1995, and field works in 2002; assessment of the control and rehabilitation techniques used in the area; and present-day geometric condition of drainage channel. From the results, were elaborated maps, at a scale 1:10.000, that were used to support final analyses about erosive processes, control and rehabilitation techniques in the area.

In karst areas relationships between activities occurring on the surface and the overall health of the subsurface environment are often highly interconnected. However, the complex nature of karst flow systems can often make identification of these connections difficult. Carroll Cave, a large stream cave system located in the central Missouri Ozarks, is known for its biological and speleological significance. A dye tracing project to delineate a Carroll Cave recharge area through dye tracing has identified an area of 18.5 km2 which contributes water to the cave. The water from Thunder River within Carroll Cave was positively traced to eight springs of the thirteen springs at a distributary spring system known as Toronto Springs. Through examination of the geochemistry of the individual springs, differences in water chemistry between the various outlets has become evident. Additional work with YSI Sonde dataloggers and consideration of carbonate chemistry relationships has sought to further define the variations in hydrochemical behavior, thus aiding in the discrimination potential spring sources. Primary sources thought to contribute water to the spring system include Carroll Cave and Wet Glaize Creek, with some minor influence from other losing streams in the vicinity. Seepage runs along Wet Glaize Creek have also identified major losing reaches, in close proximity to structural features, which may contribute water to Toronto Springs. Examination of the measured parameters and derived have identified that Carroll Cave and Wet Glaize Creek are the primary end members for Ca2+, Mg2+, HCO3-, specific conductance, and temperature. Using these parameters a two end member mixing model has been developed which describes the mixing zone setting at Toronto Springs and calculates the average proportions of flow contributions by the end members. By using a multi-proxy approach of dye tracing, seepage runs, and geochemistry for the individual springs, the source waters and pathways for the springs at Toronto Springs have been identified.