Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 49 for “"Geochemical Processes"”.
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A study of some of the geochemical processes of rock weathering
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Geology and Geophysics, 1961.
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Laboratory and field-based investigations of subsurface geochemical processes in seafloor hydrothermal systems
… the results of four discrete investigations into processes governing the organic and inorganic chemical composition of seafloor hydrothermal fluids in a variety of geologic settings. Though Chapters 2 through 5 of this thesis are disparate in focus, each represents a novel investigation aimed at …
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Relationships of Watershed Climate and Geochemical Processes to Trophic Characteristics in Texas Reservoirs
… to investigate relationships between watershed geochemical climatic processes and trophic characteristics in 80 Texas reservoirs. Three classes of reservoirs were identified by using Gibbs' graph comparing total dissolved solids (TDS) with the ratio of sodium to calcium plus sodium. These …
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Laboratory and field-based investigations of subsurface geochemical processes in seafloor hydrothermal systems
… the results of four discrete investigations into processes governing the organic and inorganic chemical composition of seafloor hydrothermal fluids in a variety of geologic settings. Though Chapters 2 through 5 of this thesis are disparate in focus, each represents a novel investigation aimed at …
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Applications of PB-210/RA-226 and PO-210/PB-210 disequilibria in the study of marine geochemical processes
The distribution of Pb-210 and Po-210 in dissolved (<O.4 micron) and particulate (>0.4 micron) phases has been measured at ten stations in the tropical and eastern North Atlantic and at two stations in the Pacific. Both radionuclides occur principally in the dissolved phase. Unsupported Pb-210 …
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Applications of Pb-210/Ra-226 and Po-210/Pb-210 disequilibria in the study of marine geochemical processes.
Thesis. 1976. Ph.D.--Massachusetts Institute of Technology. Dept. of Earth and Planetary Sciences.
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Isotopes of selenium as redox tracers of geochemical processes influencing the export and behavior of selenium contamination in coal mine watersheds
… developed to measure the presence and extent of geochemical processes affecting the mobility and environmental impact of Se. Se isotope systematics are well defined through laboratory experiments but have seldom been applied to real environments. The leftover material from coal mines within the …
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Effect of geochemical processes and environment on the spatial pattern of selenium in soil, surface water, and groundwater at the Hovland Ranch, central South Dakota
… magnesium and sulfate minerals create a major geochemical sink for water soluble selenium. The solubility of these salts may be the principal factor controlling the mobility and transport of selenium in the soil-water environment. </p>
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Geochemical processes in the earth's mantle and the nature of crust-mantle interactions : evidence from studies of Nd and Sr isotope ratios in mantle-derived igneous rocks and lherzolite nodules
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1980.
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A stable isotope investigation of nitrate contamination at Many Devils Wash, Shiprock UMTRCA Site, Shiprock, NM
… is from naturally occurring sources released by geochemical processes similar to those in other areas that are underlain by Mancos. Other studies have found high concentrations of nitrate, selenium, sulfate, and uranium from decomposition and weathering of Mancos Shale. The goal of this research …
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Geochemical interpretation on groundwater flow in the Southern Great Basin
The study of geochemical processes and integrated water flow can help identify groundwater sources and improve predictions of contaminant fate and transport in groundwater systems. Understanding groundwater flow paths in and around the Nevada Test Site (NTS) is important due to the possible …
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Background groundwater concentrations of dissolved selenium in the Kamloops, BC Area - characterization, spatial distribution, and management
… are likely due to natural occurring geochemical processes and local geology, as the concentrations are widespread throughout the Kamloops area where anthropogenic sources were not identified. The higher selenium concentrations may be due to the leaching of subsurface soils in the …
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Geochemical Constraints of Porphyry Cu Deposits-Forming Magmas in Sonora, Mexico
… have been well-studied, the petrological and geochemical processes that govern magma fertility, essential prerequisites for PCD formation, remain less well constrained. Magma fertility is primarily controlled by variations in pressure-temperature (P–T) conditions, redox state, and volatile …
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Vliv fosforečnanů na mobilitu arzenu v kontaminovaných oblastech
… systems. To gain a better understanding of the geochemical processes that control the mobility and stability of arsenic and its phases exposed to low phosphate levels, a variety of environmental matrices was studied using different experimental approaches. Among the samples studied were …
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Lichen: the challenge for rock art conservation
… confirm from elemental chemical analyses that geochemical changes do take place in the presence of lichens. The combined mechanical and chemical processes contribute to the degradation and greater erodability of all the rock surfaces studied. Chemically, we have demonstrated that cements that …
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Geochemistry of cave pools in the Guadalupe Mountains, NM : implications for geomicrobiology
… variations in a geologic context, identify the processes that control cave pool hydrologic variations and determine geochemical controls on modern and paleo-bacterial communities. Structural studies indicate cave pools align along NE and NW structures in the karst system. The intersection of …
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The Relationship Between Salvinia molesta Infestation and the Microbial Ecology of Wetlands at Caddo Lake, TX, USA
<p>Wetlands are known to host many beneficial geochemical processes such as nutrient cycling and carbon sequestration. These processes are primarily driven by the microbial communities within a wetland. The establishment of non-native invasive species within wetlands has the potential to alter the …
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HYDROGEOLOGICAL CHARACTERIZATION OF A LEGACY WASTE STORAGE SITE AND THE CHALLENGE OF COMMUNICATING UNCERTAINTY
… ignores the stratigraphic heterogeneity and geochemical processes that would influence the rate and distance contaminants travel. The inherent uncertainty of modelling results prompted research into how people interpret and respond to scientific uncertainty. There is a need for the ongoing …
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3D Printing of Specialty Devices for Geochemical Investigations: Real-Time Studies of Goethite and Schwertmannite Formation
… are needed to investigate low-temperature geochemical processes. We recently showed that desktop 3D printing stereolithography (SLA) can be used to efficiently fabricate a mixed flow reactor (MFR) with high dimensional accuracy comparable to traditional machining methods (Michel et al., …
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Investigating the Transformations of Arsenic and Toxic Metal(Loid)S Speciation and the Impact on Arsenic Bioaccessibility in Particulate Matter from Mine Tailings Sites Distributed in Different Climates
… This study examines the solid-phase weathering, geochemical speciation, and bioaccessibility of arsenic (As), lead (Pb), zinc (Zn), and cadmium (Cd) in sulfidic mine tailings collected from 11 abandoned sites across a broad climatic gradient in the Western United States, ranging from arid to …
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