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 25 for “"Suboxic"”.
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Shelf biogeochemical interactions and feedback processes in the Benguela upwelling system
… to simulate nitrogen processes under oxic and suboxic conditions in upwelling systems with no option for other cycles. Intermediary nitrogen processes, nitrous oxide production and nitrogen loss mechanisms are studied using this model. Physical and advection processes that drive the oceanic …
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GEOCHEMICAL ANALYSIS OF THE EAGLE FORD SHALE IN WEBB AND DIMMIT COUNTIES, TX
… Redox proxies (Mo, U, V) indicate dominantly suboxic to anoxic conditions in the Lower Eagle Ford Shale, with possible abiotic anoxia driven by sediment stratification, while the Upper Eagle Ford Shale is characterized by more oxic to suboxic bottom-water conditions. These findings refine the …
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Isotopic evidence for the cycling of nitrate and nitrous oxide in aquifers beneath an irrigated agricultural district using established and emerging measurement techniques
… oxic basalt aquifer to the downgradient suboxic alluvial aquifer; and beneath leaking irrigation channels, where electron donor-rich suboxic hyporheic zones have manifested. Modifications to current land management practices have been proposed in view of these findings. The secondary aim …
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Geological and Geochemical Investigation of the Petroleum Systems of the Permian Basin of West Texas and Southeast New Mexico
… strongly suggests source-rock deposition under suboxic and anoxic-suboxic conditions for all but the Bone Spring and Simpson source beds, in which case the geochemical evidence suggests deposition under anoxic conditions. Geochemical thermal modeling indicates adequate to advanced maturity for …
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Controls on the accumulation of organic matter in the Eagle Ford Group, Central Texas, USA.
… associated with the Lower Eagle Ford Formation, suboxic conditions associated with most of the upper Eagle Fords, and then a return to normal marine conditions at the top of the Eagle Ford Formation. The high TOC content of the lower Eagle Ford was most likely caused by high productivity which in …
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Geobiology of marine magnetotactic bacteria
… or greigite (Fe3S4), and are abundant in the suboxic to anoxic zones of stratified marine environments worldwide. Their population densities (up to 105 cells ml-1) and high intracellular iron content suggest a potentially significant role in iron cycling, but very little is known about their …
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Trace element signatures of Peruvian and Chilean upwelling sediments
… extreme enrichments of e.g. Cd, Mo and Re. The suboxic conditions for sediments below the OMZ are indicated by moderate Cd, Mo contents but high Re contents. Cadmium, Cu, Zn, Ni, Cr, Ag, and Tl predominantly accumulate via biogenic pre-concentration in plankton remains whereas Re, Sb, As, V, U …
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Provenance, redox conditions, and diagenesis of shales in Chang 7 member of Upper Triassic Yanchang Formation, Ordos Basin, China
… in previous studies. Results show complete oxic-suboxic conditions in sections and wells on the north, while dominantly anoxic in sections on the south. Conflicting redox conditions of Chang 7 shales discovered both in this study and previous studies are caused by limited extent of anoxic water …
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Enhanced removal of emerging contaminants during managed aquifer recharge using optimized operating conditions
… to be optimal for CEC-removal performance. Under suboxic conditions, a low-BDOC environment is more efficient than a high-BDOC (>2 mg/L BDOC) environment. A low-end threshold has been observed, where too little dissolved organic carbon (<0.26 mg/L DOC) is present to promote effective CEC …
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An Outcrop Based Study of the Weches Formation in Sabine County, Texas: Investigating Its Unconventional Resource Potential through the Study of Stratigraphy, Sedimentology, Petrology, and Geochemistry
… generative potential and an intermittent suboxic to oxic environment. Rock-Eval pyrolysis analysis for the Therrill Member identified Type III kerogens (dry gas prone) but poor source rock quality based on S1 values < 0.5 and S2 values < 2.5.</p> <p>Results from this study indicate that …
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Rare metal resources in polymetallic nodules from the Eastern Equatorial Pacific Ocean
… and diagenetic (precipitation from oxic/suboxic sediment porewaters) processes. Bulk analysis revealed high contents of Mn (29%), Ni (1.3%), Cu (1.0%), Co (0.17%) and REY (700 – 800 ppm). Analysis of (micro-drilled) individual layers in two nodule samples using ICP-MS shows that REYs are …
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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
… the toe are a mix of runoff from oxic and suboxic/anoxic portions of the fill, highlighting the heterogeneous structure and varying redox conditions within valley fills.
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Geobiology of marine magnetotactic bacteria
… or greigite (Fe3S4), and are abundant in the suboxic to anoxic zones of stratified marine environments worldwide. Their population densities (up to 105 cells ml−1) and high intracellular iron content suggest a potentially significant role in iron cycling, but very little is known about their …
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DEPOSITIONAL SYSTEMS INTERPRETATION OF EARLY PERMIAN MIXED SILICICLASTICS AND CARBONATES, MIDLAND BASIN, TEXAS
… clay and silt rich facies suggests dysoxic to suboxic conditions within the basin during the time of deposition. An SEM investigation of pore types and their distribution led to the recognition of three pore types: phyllosilicate framework pores, organic matter pores, and dissolution pores. SEM …
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SOURCE AND MATURATION OF HYDROCARBONS IN THE FRIO FORMATION OF THE HUMBLE FIELD, SOUTHEAST-TEXAS GULF COAST BASIN
… genetic family and are sourced from a clay-rich, suboxic/oxic, marine-terrigenous transitional depositional environment. The oils were likely generated from mature source rocks which had already entered the main oils generation window with vitrinite reflectance ranging from 0.68% to 1.3% and …
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Holocene sedimentary and aquatic biogeochemical responses reflected in Ordy Pond, Oahʻu, Hawai'i, and, contemporary modeling of submarine groundwater discharge in Kahana Bay, Oahʻu, Hawaiʻi
… productivity fell, and surface waters became suboxic to anoxic. Primary productivity is believed to have been controlled by the availability of sunlight; the longer daily photoperiod during stratification resulted in greater organic matter production, while greater mixing in winter reduced the …
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Selenium Distribution and Cycling in the Eastern Equatorial Pacific Ocean
<p>Oxygen minimum zones in oceanic waters have become increasingly important to the marine environment and society. Low oxygen waters affect not only the distribution and abundance of marine organisms, but also impact the solubility and transport of trace elements that are of biological importance, …
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Constraining Respired Carbon Storage in the Eastern Tropical Pacific Over the Last 25 Thousand Years Using Benthic Foraminiferal Boron/Calcium Ratios
… uranium (aU) concentrations, a proxy for suboxic bottom-water conditions, increased significantly in the Eastern Equatorial Pacific (EEP) during the Last Glacial Maximum (LGM, 18 kyr – 23 kyr). If this is correct, the low-oxygen, CO<sub>2-</sub>rich waters would also have a lower pH and a …
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Genomic Diversity of Magnetotactic Bacteria from Underexplored Extreme Aquatic Habitats
… to global oceanic OMZs, which are regions of suboxic to anoxic water columns where microbial communities exert strong control over nutrient dynamics. A total of 88 publicly available metagenomic datasets from OMZs were retrieved and processed. Using a combination of assembly, binning, and …
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Genomic Diversity of Magnetotactic Bacteria from Underexplored Extreme Aquatic Habitats
… to global oceanic OMZs, which are regions of suboxic to anoxic water columns where microbial communities exert strong control over nutrient dynamics. A total of 88 publicly available metagenomic datasets from OMZs were retrieved and processed. Using a combination of assembly, binning, and …
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