Dissertations / Theses on the topic 'Redox condition'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Redox condition.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
Igboamalu, Tony E. "Kinetic studies of Cr(VI) reduction in an indigenous mixed culture of bacteria in the presence of As(III)." Diss., University of Pretoria, 2014. http://hdl.handle.net/2263/46240.
Full textDissertation (MEng)--University of Pretoria, 2014.
tm2015
Chemical Engineering
MEng
Unrestricted
Pham, Thu Ha. "Modifications de la physiologie de la levure Saccharomyces cerevisiae par des changements d’environnements redox et gazeux en condition de brasserie." Dijon, 2008. http://www.theses.fr/2008DIJOS001.
Full textModifying metabolic fluxes in Saccharomyces cerevisiae presents an interest both for cellular metabolism studies and the development of new technologies in alcohol beverage-related industries. This will permit to improve the production performances, to lower the alcohol level and to develop by-products of interest. During brewing fermentation, the use of gases modified the redox environment of S. Cerevisiae. The gaseous environments and extreme redox conditions altered partially the growth as well as the cellular morphology. However, the fermentation performances were improved up to 13-15% in gaseous environments (hydrogen and helium). Fermentation metabolite profiles including aroma compounds were modified differently by the effect of gas and redox (increasing in the production of glycerol, succinate and some higher alcohols important for the flavour of beer; decrease in the levels of some flavour-active esters). During storage at 4°C under limited nutritive condition, the survival of S. Cerevisiae cultivated with gas was improved up to 55%. This is due to its high intracellular glycogen content and its morphological adaptation. These results provide new information on the physiological behaviour of S. Cerevisiae in gaseous and redox environments. They also offer perspectives for the studying of gas and redox applications in S. Cerevisiae-related industries
Sansotta, Stefano [Verfasser], Dirk [Akademischer Betreuer] Zahn, Dirk [Gutachter] Zahn, and Bernd [Gutachter] Meyer. "Molecular Simulations Study of Silver Precipitation from Aqueous Solution and on Silica Substrate. Control of Shape and Charge via Redox Condition / Stefano Sansotta ; Gutachter: Dirk Zahn, Bernd Meyer ; Betreuer: Dirk Zahn." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2020. http://d-nb.info/1219303453/34.
Full textXiong, Yijun. "Phosphorus cycling under different redox conditions." Thesis, University of Leeds, 2018. http://etheses.whiterose.ac.uk/22045/.
Full textMasters-Waage, Nicholas. "Redox cycling under nuclear legacy conditions." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/redox-cycling-under-nuclear-legacy-conditions(abb173ad-0a8c-47b9-a2e7-99ea2048d2c2).html.
Full textBrown, Kevin Robert. "Cytochrome c₄ : characterisation, location and effect of growth conditions." Thesis, University of Edinburgh, 1988. http://hdl.handle.net/1842/30037.
Full textRupp, Erik C. "Catalytic Dechlorination of Volatile Organic Carbons under Redox Conditions." Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/194518.
Full textMarkelova, Ekaterina. "Interprétation du potentiel redox et évaluation de la mobilité des oxyanions contaminants (As, Sb,Cr) au cours de cycles redox successifs." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAU028/document.
Full textThis thesis demonstrates that a systematic experimental approach of increasing complexity allows reassessing the meaning of the redox potential (EH), and provides an update on the interpretation of its value in complex assemblages of mineral matrices, microbial consortiums, nutrients, and contaminants under dynamic, redox-oscillating conditions. To study the usefulness of EH measurements in water-saturated environmental systems a full redox cascade from +500 to -350 mV (pH ∼7.4) was reproduced in the laboratory. The experiments revealed that conventional Pt redox electrode responds to physical, chemical, and microbial processes to a different extent depending on oxygenation and on the presence of a redox buffer. The measurements of EH in argillaceous matrices depleted in the redox buffer, such as the electroactive Fe3+/Fe2+ couple, thus, are shown to have limited usefulness. In such environments, the abundant redox-sensitive couples, yet non-electroactive, such as O2/H2O, CrO42-/Cr(OH)3, NO3-/NO2-/NH4+, Sb(OH)6-/Sb2O3, and HAsO42-/H3AsO3 do not impact measured EH. To quantify the effect of oxidizing perturbations on the mobility of oxyanions in the argillaceous matrix, I performed batch experiments under controlled redox oscillations. Successive cycles of oxic and anoxic conditions were imposed on the argillaceous suspensions amended with a mixture of oxidized As(V), Sb(V), Cr(VI), and N(V). Oxyanion mobility was investigated under sterile conditions, with the addition of labile organic carbon (ethanol), and with the addition of soil microbial inoculum. Speciation analyses revealed irreversible reduction reactions with and without ethanol additions. Freshly reduced As(III), Sb(III), Cr(III), and N(III) were not re-oxidized during subsequent oxic periods demonstrating non-oscillating behavior. Microbially induced reduction transformations decreased aqueous concentrations of Sb and Cr via precipitation, removed N via volatilization, while preserved As in the solution. Depending on microbial diversity, altered by the addition of soil inoculum, two types of contaminant interplays are characterized as inhibitory and non-inhibitory reductions. These data, the representative of saturated subsurface environment (subsoil > 20 m), is further compared to oxyanion mobility in the near-surface environment (topsoil < 0.15 m). The key differences between the topsoil and subsoil systems are in the fraction of oxyhydroxide Fe-, Mn-, and Al- minerals, microbial diversity, pCO2, and the range of EH values developed during redox cycles. For example, the EH range over 900 mV (from +500 to -300 mV) in the topsoil suspension is contrasted to the EH range of 100 mV (from +350 to +250 mV) in the subsoil suspension. Furthermore, in the topsoil suspension, strong redox cycling of Fe and Mn is coincident with the oscillating mobility of As and Sb. This correlation suggests the crucial role of oxyhydroxide minerals acting not only as major sorbents, but also as catalysts for oxidation reactions eventually controlling the reversibility of contaminant sequestration. Therefore, depleted in oxyhydroxide minerals, argillaceous matrix is shown to be suitable environment for contaminant retention, as it can stand periodical redox oscillations without releasing contaminants back to the aqueous phase on the experimental time scale
Gaborieau, Marion. "Caractérisation des conditions redox du manteau terrestre dans différents contextes géodynamiques." Thesis, Université Clermont Auvergne (2017-2020), 2019. http://www.theses.fr/2019CLFAC084.
Full textMany studies have demonstrated that arc basalts are more oxidized (~ ∆QFM+1.5 ± 1) than mid-ocean ridge basalts (MORB; ∆QFM-1.2 à ~ ∆QFM). However, the oxidation state of the sub-arc mantle is still debated. The use of various proxies on the same set of samples aims to determine the oxidation state of magmas, the effects of secondary processes on their oxidation state and to better constrain the fO2 of primary magmas from different geodynamic settings and that of their mantle source. For that purpose, Fe3+/ΣFe ratios, V partition coefficients between silicate melts and olivines (DvOl/Melt) as well as V/Sc and V/Yb ratios were measured in melt inclusions from high-Mg olivines (Fo > 80 %) from subduction zones, mid-oceanic ridges and hot spots. The analysis of Fe3+/ΣFe ratios by XANES spectroscopy using analytical conditions that prevent beam damage during analysis of hydrous glasses and by Mössbauer spectroscopy confirmed that arc magmas are more oxidized than those from hot spots and mid-ocean ridges. A positive correlation between Fe3+/ΣFe ratios and water contents in melt inclusions suggests that the oxidation state recorded in primitive arc magmas is likely to be due to changes in the oxidation state of the mantle beneath arcs because of subduction processes. The calculation of the fO2 from Fe3+/ΣFe ratios also indicates that the range of oxidation state recorded in arc melt inclusions varies from one subduction zone to another. An evaluation of the effects of volatile degassing and differentiation processes on the magmatic fO2 was carried out on each melt inclusion population. fO2 values were then estimated for reconstructed primary melt compositions using the different redox proxies. Results obtained from Fe3+/ΣFe ratios, DvOl/Melt partition coefficients and V/Yb ratios suggest that arc primary magmas are more oxidized than those from hot spots and mid-ocean ridges. However, fO2 values differ from one proxy to another. Furthermore, the positive correlation between the Fe3+/ΣFe ratios, the fO2 calculated from these ratios and the water contents of primary magmas suggests that the difference in the oxidation state of magmas is not due to secondary processes. However, the comparison between the Fe3+/ΣFe ratios, the fO2 values calculated from these ratios and Th/La and Ba/La ratios of primary magmas does not confirm that the observed changes in redox state can be simply linked to the influence of silicate melt or aqueous fluids coming from the slab to the mantle wedge. On the opposite, fO2 values calculated from V/Sc ratios suggest that primary arc magmas are comparable to those from mid-ocean ridges and hot spots
Smedborn, Pausson Eva. "Chemical Stabilization of Arsenic in Contaminated Soil under Low Redox Conditions." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-72340.
Full textEfterbehandlingsmetoder för arsenikförorenad jord har tidigare fokuserat på ytliga jordlager där syre finns tillgängligt och förhållandena är oxiska. I denna masteruppsats har kemisk stabilisering av arsenik under anoxiska förhållanden i en förorenad jord studerats. I perkolationsförsök över två månader har effekten av två olika kemiska tillsatser, nollvärt järn (Fe(0)) och kalciumoxid (CaO), på utlakningen av halvmetaller och metaller som As, Zn, Cd, Cu och Cr samt påverkan på pH, konduktivitet och redoxpotential undersökts under både fluktuerande och konstanta flöden. Resultaten visar att CaO är en lovande tillsats att använda för kemisk stabilisering av As i jordar som har anoxiska förhållanden. 98% av As immobiliserades jämfört med den obehandlade jorden. Behandlingen med CaO resulterade även i ett stabilt basiskt pH på 13. Konduktiviteten hölls också på en stabil nivå på 6,5 mS cm-1 medans redoxpotentialen varierade en del men var negativ under hela experimentet. Den utlakade koncentrationen av As låg mellan 0.059 och 0.021 mg L-1. CaO immobiliserade även Zn, Cd och Cr med en effektivitet som låg mellan 50-65%, jämfört med den obehandlade jorden. Koppar däremot mobiliserades och lakades ut i större utsträckning; men då Cu-koncentrationen i jorden var låg från början utgör detta inget större problem. Geokemisk modellering indikerade att immobiliseringen av As kontrolleras av pH, men förblev opåverkad av redoxpotentialen. Då alkaliniteten i den CaO-behandlade jorden var hög förväntas de basiska förhållandena som kontrollerar den kemiska stabiliseringen av As att kvarstå under flera hundra år. Tidigare studier har visat att Fe(0) till stor del stabiliserar As under oxiska förhållanden, men under de anoxiska förhållandena i denna studie hade den Fe(0)-behandlade jorden liknande resultat som den obehandlade jorden, både vad gäller utlakning av metaller, pH, konduktivitet och redoxpotential. Detta markerar vikten av att aktivera Fe(0) genom att låta den reagera med syre och vatten i jorden för att bilda amorfa Fe-oxider som (halv)metallerna kan adsorbera till. I detta fall tillsattes inget vatten i förväg, vilket ledde till att det mesta av järnet lakades ut direkt, utan att bilda fler ytor som speciellt As kan binda till. För båda dessa jordar var utlakningen av As två storleksordnar större jämfört med den CaO-behandlade jorden. Studien visade också att en fluktuerande grundvattennivå kan ha en effekt på utlakningen av grundämnen både behandlad och obehandlad jord, då cykler av anoxiska och oxiska förhållanden påverkade koncentrationerna i utlakningsvattnet. Mer As lakades ut under de dagar som hade mer anoxiska förhållanden jämfört med oxiska dagar för den Fe(0)-behandlade jorden och den obehandlade jorden, medans det motsatta var sant för den CaO-behandlade jorden. Resultaten indikerar att CaO har en potential till att användas för att kemiskt stabilisera As i jordar som har låga redox-förhållanden, exempelvis i jordar som är under grundvattenytan och i deponier, men att försiktighet ska användas i jordar som har en mer komplex föroreningssituation, speciellt i jordar som är förorenat av både As och Cu.
Giles, Hamilton. "Biotransformation potential of phytosterols in biological treatment systems under various redox conditions." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/48993.
Full textRitter, Daniel James. "Relationship Between Recharge, Redox Conditions, and Microbial Methane Generation in Coal Beds." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/577493.
Full textSpain, Jackson M. "Characterization of redox conditions in a petroleum contaminated aquifer: Implications for bioremediation potential." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/35250.
Full textMaster of Science
Wilkes, Austin. "Phosphorus Mobility and Speciation Under Dynamic Redox Conditions in Shallow Eutrophic Freshwater Systems." ScholarWorks @ UVM, 2019. https://scholarworks.uvm.edu/graddis/1145.
Full textSmith, Dean A. "The demonstration of electron-transfer reactions and their effect on model lignin condensation reactions under alkaline pulping conditions." Diss., Georgia Institute of Technology, 1986. http://hdl.handle.net/1853/5700.
Full textDias, Gilberto Pereira. "Avaliação das condições redox das águas intermediárias do Oceano Atlântico Sudoeste nos últimos 40 mil anos." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/21/21137/tde-29012019-163323/.
Full textThe interest in the paleoceanographic history of the South Atlantic Ocean has increased in the last decades, however there are still few studies regarding the redox conditions of the intermediate water masses of the Southwest Atlantic and their relationship to the climatic changes during the upper Pleistocene and Holocene. Within this context, this work aims to evaluate the redox conditions of the intermediate waters of the Southwest Atlantic in the last 40 ka. For this, geochemical proxies - of redox conditions (V/ Sc, V/ Cr, V/ Al, Mn/ Al and Ni/ Co), of terrigenous sediments supply (Fe/ Ca and Ti/ Ca), of productive (COT, CaCO3), and organic matter source (δ13C and C / N) - were applied to marine sediments from a core collected on the continental slope of the Brazilian Southeastern margin and then related it to changes in the Atlantic Meridional Overturning Circulation (AMOC) and with the main cold climatic events of North Atlantic, such as the Last Glacial Maximum and millennial scale, such as events type the Heinrich Stadials, Younger Dryas and 8.2. Our results show that, over the last 40,000 years, the redox conditions of the intermediate waters of the Brazilian Southeast margin present oxic levels, which classifies the environment as oxidant, however, variations was noticed in the amount of oxygen dissolved in these waters influenced by certain climatic events, as well as changes in the input of terrigenous sediments and in the productivity. In orbital scale, the summer insolation of the Southern Hemisphere and the variation of sea level, leaded by the cycle of precession, are presented as the main mechanisms that influence these variations. On the other hand, at millennia scale, the AMOC variability is the main mechanism responsible of these variations. Among the climate events at millennia scale, the event 8.2 demonstrated a complex variability of the redox conditions of the intermediate waters of the Southwest Atlantic, once during its occurrence we observed increase concentrations of oxygen in these waters and a decrease of productivity.
Kabbes, Jason E. "Diamond Formation under Lower Mantle Redox Conditions: Experimental Constraints on the Mineralogical Host of Carbon in Earth’s Mantle." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1282152005.
Full textErbs, Marianne. "Formation and redox reactions of green rusts under geochemical conditions found in natural soils and sediments /." Zürich, 2004. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=15492.
Full textSchaller, Tobias Lukas. "Redox-sensitive metals in recent lake sediments proxy-indicators of deep-water oxygen and climate conditions /." [S.l.] : [s.n.], 1996. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=11901.
Full textGennaro, Mimma Emanuela. "Sulfur behavior and redox conditions in Etnean hydrous basalts inferred from melt inclusions and experimental glasses." Thesis, Orléans, 2017. http://www.theses.fr/2017ORLE2005/document.
Full textSulfur is an important volatile component of magmas that presents different oxidation states, depending on the redox conditions and on the phase of occurrence: in silicate melts it is typically dissolved as S⁶⁺ and/or S²⁻ , in the gas phase it occurs principally as SO₂ (S⁴⁺ ) and H₂S (S²⁻). Mount Etna, in which magmatic redox conditions are poorly constrained, is used as a case study to investigate sulfur behavior in hydrous basaltic magmas during magma differentiation and degassing. This research integrates the study of natural olivine-hosted melt inclusions with an experimental study on S solubility in hydrous alkali basalts at magmatic conditions.Experimental results suggest the important control of ƒO₂ on the S abundance in Etnean hydrous magma and its partitioning between fluid and melt phases. Melt inclusions were entrapped at different depths inside the magmatic system (up to ~ 18 km, below crater level). They delineate a continuous differentiation trend, marked by fractional crystallization, from the picritic basalt (FS) toward the most evolved and degassed (2013) basalt. S content in Etnean melt is extremely variable and reaches 4150 ppm in the primitive melt inclusions. XANES Fe³⁺/ΣFe spectra in some glass inclusions, resulted in the generally decreasing of Fe³⁺/ΣFe ratios from the most primitive (FS) to the most evolved (2013) melts. MELTS software confirms that the Fe³⁺/ΣFe decrease is due principally to the melt differentiation process, enhanced to the S degassing at ƒO₂ < NNO+1. Magma reduction, in turn, induces the decrease of the sulfur solubility in the hydrous Etnean basalt, as well as of the sulfide saturation, and may constitute a possible enhancer of S exsolution, triggering the important S degassing observed in the last decades in Mt. Etna
Merrett, Greg Lee. "Groundwater redox conditions at a petroleum contaminated site, Kuils River, South Africa : pathways for BTEX biodegradation." Master's thesis, University of Cape Town, 2003. http://hdl.handle.net/11427/8588.
Full textA shallow sandy aquifer, contaminated by petrol from an underground storage tank, was studied to determine if intrinsic bioremediation of the hydrocarbons is taking place. Groundwater samples taken from 32 monitoring wells were analysed for NO₃-,NH₄+, Mn²+, Fe²+, SO₄²-, and ΣH₂S. Portable electrodes were used to make field measurements of electrical conductivity, redox potential, and pH. The variation and distribution of these redox-sensitive groundwater constituents show that bioremediation via NO₃- reduction, Fe³+ reduction, and SO₄²- reduction (and possibly methanogenesis in the most reduced part of the plume) is occurring. In some cases redox processes are taking place simultaneously resulting in redox zones that overlap. Iron and sulphate reduction are the dominant processes taking place.
Goncharov, Aleksey. "Redox - pressure - temperature conditions in the continental upper mantle in relation to C-O-H fluid speciation." Phd thesis, Université Jean Monnet - Saint-Etienne, 2012. http://tel.archives-ouvertes.fr/tel-00974462.
Full textGronowski, Adrian. "Effects of uranium mining on groundwater - Geochemical modeling of aqueous uranium speciation due to changing redox conditions." Thesis, KTH, Mark- och vattenteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-161064.
Full textBarbieri, Manuela. "Effect of redox conditions on the fate of emergin organic micropollutants during artificial recharge of groundwater: batch experiment." Doctoral thesis, Universitat Politècnica de Catalunya, 2011. http://hdl.handle.net/10803/109161.
Full textLa recarga artificial de acuíferos, que consiste en la infiltración de agua subterránea en instalaciones diseñadas para tal fin, constituye una importante herramienta en la gestión de recursos hídricos. Más allá de aumentar los recursos de aguas subterráneas, suscita gran interés la capacidad de tratamiento natural que confiere el tránsito sub-superficial a las aguas. Los procesos que tienen lugar en el sistema suelo-acuífero (filtración, adsorción, mezcla, reacciones redox, biodegradación, etc.) permiten una mejora general de la calidad del agua, eliminando incluso diversos contaminantes orgánicos. En la actualidad, el reto es entender si los microcontaminantes orgánicos emergentes, es decir farmacéuticos, productos de cuidado personal, hormonas, drogas ilícitas, plaguicidas y tensioactivos, puedan también ser atenuados. Muchos de ellos no son completamente eliminados en tratamientos de agua convencionales, siendo introducidos constantemente en aguas superficiales por los efluentes de las plantas de tratamiento de aguas residuales. A pesar de sus baja concentraciones (ng/L and μg/L), su omnipresencia en el medioambiente es actualmente causa de preocupación para la vida acuática y la salud humana. En este contexto, la recarga artificial puede representar un tratamiento alternativo o complementario para la eliminación de microcontaminantes orgánicos de las aguas. Hay evidencias de que las condiciones redox dominantes pueden influenciar el comportamiento de contaminantes orgánicos convencionales en los acuíferos. Sin embargo, en el caso de los microcontaminantes emergentes los conocimientos sobre este tema es todavía limitado. El principal objetivo de esta tesis, motivada por proyectos de recarga artificial con aguas del río Llobregat (Barcelona, España), es investigar el efecto potencial de las condiciones redox sobre el comportamiento de microcontaminantes orgánicos seleccionados (la mayoría de los cuales son contaminantes emergentes) durante la recarga artificial. El estudio se basa en experimentos batch de laboratorio usando material natural del acuífero, microcontaminantes en concentraciones ambientales (1 μg/L cada compuesto), y condiciones verosímiles en enclaves de recarga artificial. Añadiendo cantidades adecuadas de aceptadores y donadores de electrones, fueron establecidas y se mantuvieron diferentes condiciones redox anaeróbicas (condiciones nitrato-, manganeso-, hierro- y sulfato-reductoras) en cada grupo de microcosmos. Se llevaron a cabo series bióticas y abióticas para separar la biodegradación de los contaminantes (mineralización biótica o transformación) de los procesos de adsorción y de otros procesos abióticos. También fue realizado un experimento para alta concentración de contaminantes (1 mg/L cada compuesto), para comprobar la representatividad de los estudios convencionales. El objetivo final de este trabajo es identificar 1) las condiciones redox más favorables para la eliminación del agua de los contaminantes seleccionados, para su posterior simulación en el sitio piloto, y 2) las tasas de eliminación de esos contaminantes, para predecir sus comportamientos en el acuífero.
Artificial recharge of groundwater, consisting in infiltrating water into aquifers by means of properly designed facilities, represents an important tool in water resources management. Beside its quantitative benefits (augmentation of groundwater resources, long term underground storage, etc.), a great interest for this technique is related to the natural treatment provided to water by subsurface passage. The processes occurring in the soil-aquifer system (filtration, sorption, mixing, redox reactions, biodegradation, etc.) have indeed proven to yield an overall improvement of water quality, removing effectively also a number of organic contaminants. At present time, the issue is to understand whether emerging organic micropollutants, i.e. pharmaceuticals, personal care products, hormones, illicit drugs, pesticides and surfactants, can also be removed. A number of these compounds are not completely removed by conventional water treatments, being thus introduced continuously into surface water bodies by the discharge of wastewater treatment plants effluents. In spite of their low concentration (ng/L and μg/L), their ubiquitous presence in the environment is currently a cause of concern for aquatic life and human health. In this context, artificial recharge may represent a potential alternative or complementary treatment for the removal of organic micropollutants from water. Evidences showed that, among the factors influencing the fate of conventional organic contaminants in the aquifer, the predominant redox conditions could play an important role. Yet, in the case of emerging micropollutants the knowledge on this topic is still limited. The main objective of this thesis, motivated by artificial recharge practices using Llobregat river water (Barcelona, Spain), is to investigate on the potential effect of redox conditions on the fate of selected organic micropollutants, most of them being emerging contaminants, during artificial recharge of groundwater. The study is based on batch experiments involving natural aquifer material, micropollutants at environmental concentrations (1 μg/L each compound), and settings feasible at artificial recharge sites. Different anaerobic redox conditions (namely, nitrate-, manganese-, iron- and sulphate-reducing conditions) were promoted and sustained in each set of microcosms by adding adequate quantities of electron donors and acceptors. The experiments included biotic and abiotic series to separate contaminant’s biodegradation (i.e. biotic mineralization or transformation) from sorption and other abiotic processes. An experiment at higher pollutants concentration (1mg/L each compound) was also carried out, to check the representativeness of studies at concentrations easier to be tested and analysed. The ultimate aim of the work is to identify 1) the most favourable redox conditions for the removal of the target compounds from water, for their following stimulation in the field test site, and 2) pollutants’ removal rates, to predict their behaviour in the aquifer.
Glock, Nicolaas [Verfasser]. "Benthic foraminifera as geochemical and micropaleontological proxies for redox conditions in the Peruvian oxygen minimum zone / Nicolaas Glock." Kiel : Universitätsbibliothek Kiel, 2011. http://d-nb.info/1020245891/34.
Full textBarton, John Leonard. "Method development for the analysis of electrochemical and transport processes in redox flow batteries at practical operating conditions." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/121901.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (pages 113-134).
The focus of this thesis is the development and assessment of techniques for the analysis of electrochemical and transport processes in redox flow batteries (RFBs) at moderate to high active species concentrations under direct current conditions. RFBs hold promise as an energy-intensive storage technology suitable for supporting the integration of intermittent renewable energy sources into the grid, but further improvements in technical performance and reductions in system cost are needed for broad deployment. At their core, all thesis projects are aimed at enabling the development of system descriptors that correlate material properties (e.g., viscosity, conductivity), cell geometry (e.g., flow field design), and operating parameters (e.g., flow rate, current density) to system performance metrics, such as cycle efficiencies and area-specific resistance.
More specifically, the investigation is divided into three primary projects: the development and assessment of a research-scale flow cell; measurements of mass-transfer coefficients; and integration of a polarization model into a standalone application useful for assessing system performance. The differential flow cell is engineered leveraging validation material from industrial collaborators. Not only is the performance is consistent with that of a ten-fold larger cell, but its smaller modular design enables rapid assessment of new chemistries and cell components with minimal materials requirements. Mass-transfer coefficients are then measured using this cell with a well-behaved redox active electrolyte (RAE), in which glucose is added in various amounts to modify the system viscosity with minimal changes to other properties.
The results or methodology developed could be extended other similar RAE systems either as preliminary estimates of mass-transfer performance or as a protocol for carefully evaluating the impact of new system parameters on mass-transfer. Finally, results of this mass-transfer analysis are incorporated into a simple flexible stack model, which can be used to estimate system performance as a function of key materials properties with limited empiricism.
by John Leonard Barton.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Chemical Engineering
Struckhoff, Garrett Cletus. "Plant-assisted bioremediation of perchlorate and the effect of plants on redox conditions and biodiversity in low and high organic carbon soil." Diss., University of Iowa, 2009. https://ir.uiowa.edu/etd/441.
Full textEberhard, Lisa [Verfasser], and Daniel [Akademischer Betreuer] Frost. "Serpentinite phase relations - An experimental study on redox conditions and fluid migration in subduction zones / Lisa Eberhard ; Betreuer: Daniel Frost." Bayreuth : Universität Bayreuth, 2021. http://d-nb.info/1227444621/34.
Full textTrincal, Vincent. "Interactions fluide-roche, conditions physico-chimiques et transferts de matière dans des zones de failles en milieux sédimentaires : exemple de failles chevauchantes pyrénéennes." Thesis, Besançon, 2015. http://www.theses.fr/2015BESA2006/document.
Full textThis work aims to study the physical and chemical parameters that control the mass-transfer and the clays formation and evolution in sedimentary environment thrust faults. Two Pyrenean thrust faults in low metamorphic grade were studied: the Millaris fault (related to Mont Perdu) and the Pic-de-Port-Vieux thrust (related to Gavarnie). In the Millaris fault, the deformation is accompanied mainly by dissolution of the matrix calcite by pressure-solution which induces a volume change of the rock from 20 to 40%. The Pic-de-Port-Vieux thrust records significant changes in the fault core-zone, but in the damaged zone also. In the footwall limestone, a mylonitisation is associated with a partial dissolution of dolomite in the presence of not exceeding 320-340°C fluids. In the hanging-wall pelites, the hematite dissolution by a reducing fluid causes a redox state change of the rock (confirmed by Mössbauer spectroscopy) and chlorite precipitation in synkinematic veins. Oscillatory zoning pattern chlorites located in some shearing veins revealed, by combining chemical mapping microprobe, redox state measurements with μ-XANES and thermometry, cyclic temperature variations of at least 50°C during the crystallization. A seismic valves process could be associated to Pic-de-Port-Vieux thrusting
Kretz, Carole. "Induction du LTR de VIH-1 dans des conditions de stress cellulaire : rôles de NF-κB et de l'état redox intracellulaire." Lyon 1, 1997. http://www.theses.fr/1997LYO10076.
Full textLlaguno, Jose R. "Paleoenvironments, origin, and relative maturity of organic matter in Barremian-Aptian limestones of the eastern Prada Quarry, Organyà Basin, NE Spain." FIU Digital Commons, 2017. https://digitalcommons.fiu.edu/etd/3510.
Full textStruckhoff, Garrett Cletus Parkin Gene F. "Plant-assisted bioremediation of perchlorate and the effect of plants on redox conditions and biodiversity in low and high organic carbon soil." [Iowa City, Iowa] : University of Iowa, 2009. http://ir.uiowa.edu/etd/441.
Full textMuhammad, Yuzir Muhamad Ali. "Effect of redox conditions in the degradation of (RS)-MCPP during biological treatment of synthetic wastewater in an anaerobic membrane bioreactor (AMBr)." Thesis, University of Newcastle Upon Tyne, 2008. http://hdl.handle.net/10443/528.
Full textBeckers, Felix [Verfasser]. "Mobilization, Methylation, and Ethylation of Mercury in Contaminated Floodplain Soils under Controlled Laboratory Redox Conditions as Influenced by Potential Immobilizing Agents as well as Mobilization of Mercury under Field Conditions / Felix Beckers." Wuppertal : Universitätsbibliothek Wuppertal, 2019. http://d-nb.info/1206122870/34.
Full textRice, Constance Elizabeth. "Examining the effects of plant diversity and community composition on reducing conditions in the soil of experimental wetlands." Columbus, Ohio : Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1243880360.
Full textHindersmann, Iris [Verfasser], and Tim [Akademischer Betreuer] Mansfeldt. "Trace elements in floodplain soils - effects of redox conditions on the mobility of trace elements and volatilization of mercury / Iris Hindersmann. Gutachter: Tim Mansfeldt." Köln : Universitäts- und Stadtbibliothek Köln, 2014. http://d-nb.info/1060190427/34.
Full textCACHOIR, CHRISTELLE. "Etude du comportement d'un dioxyde d'uranium en presence d'une eau granitique : role des conditions redox, du rapport s/v et de la concentration en carbonates." Paris 11, 1997. http://www.theses.fr/1997PA112295.
Full textTasi, Agost Gyula [Verfasser], and H. [Akademischer Betreuer] Geckeis. "Solubility, redox and sorption behavior of plutonium in the presence of α-D-isosaccharinic acid and cement under reducing conditions / Agost Gyula Tasi ; Betreuer: H. Geckeis." Karlsruhe : KIT-Bibliothek, 2018. http://d-nb.info/1164080857/34.
Full textEstop, Aragonés Cristian Verfasser], and Christian [Akademischer Betreuer] [Blodau. "Impact of extreme hydrological conditions on belowground carbon cycling and redox dynamics in peat soils from a northern temperate fen / Cristian Estop Aragonés. Betreuer: Christian Blodau." Bayreuth : Universität Bayreuth, 2012. http://d-nb.info/1059412691/34.
Full textGormley, Mark D. "The Influence of Hydrogeomorphology, Soil Redox Conditions, and Salinity on the Spatial Zoning of Saltgrass, Salt Rush, and Cattails in Scotts Creek Marsh, Swanton Pacific Ranch, CA." DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/1167.
Full textBates, Brittney Lynette. "The Influence of Groundwater Flowpaths, Nutrients, and Redox Conditions on the Extent of Microbial Methanogenesis in Coal Beds Using Solute and Isotope Chemistry: Powder River Basin, USA." Thesis, The University of Arizona, 2010. http://hdl.handle.net/10150/193411.
Full textNifuku, Ko. "Oceanic redox conditions during the Early Aptian Oceanic Anoxic Event (OAEla) in the Vocontian Basin, SE France: A high-resolution reconstruction from a combination of ichnological and geochemical approaches." 京都大学 (Kyoto University), 2010. http://hdl.handle.net/2433/120669.
Full textMaillard, Elodie. "Transport and degradation of pesticides in wetland systems : a downscaling approach." Phd thesis, Université de Strasbourg, 2014. http://tel.archives-ouvertes.fr/tel-01019664.
Full textBernhard, Gert, Katja Schmeide, Susanne Sachs, Karl-Heinz Heise, Gerhard Geipel, Jens Mibus, Adela Krepelova, and Vinzenz Brendler. "Investigation of the Complexation and the Migration Behavior of Actinides and Non-Radioactive Substances with Humic Acids under Geogenic Conditions - Complexation of Humic Acids with Actindies in the Oxidation State IV Th, U, Np." Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-28981.
Full textBernhard, Gert, Katja Schmeide, Susanne Sachs, Karl-Heinz Heise, Gerhard Geipel, Jens Mibus, Adela Krepelova, and Vinzenz Brendler. "Investigation of the Complexation and the Migration Behavior of Actinides and Non-Radioactive Substances with Humic Acids under Geogenic Conditions - Complexation of Humic Acids with Actindies in the Oxidation State IV Th, U, Np." Forschungszentrum Rossendorf, 2004. https://hzdr.qucosa.de/id/qucosa%3A21725.
Full textStåhlberg, Carina. "Mineralisation rates of natural organic matter in surface sediments affected by physical forces : a study of fresh- and brackish-water sediments subjected to changed redox conditions, resuspension, and advective pore water flow /." Linköping : Department of Water and Environmental Studies, [The Tema Institute], Linköping University, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-8332.
Full textDíaz, Ramos Rut Amelia. "Geoquímica do enxofre e morfologia da pirita em sedimentos do sistema de ressurgência de Cabo Frio (RJ)." Niterói, 2017. https://app.uff.br/riuff/handle/1/3021.
Full textMade available in DSpace on 2017-03-10T16:04:52Z (GMT). No. of bitstreams: 1 Dissertação Rut Díaz.pdf: 5376355 bytes, checksum: 1871a7342c4a6ea883cf39428d4b8c22 (MD5)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Universidade Federal Fluminense. Instituto de Química. Programa de Pós-Graduação em Geociências- Geoquímica Ambiental. Niterói, RJ
A região de Cabo Frio (RJ) é uma área de ressurgência que favorece a produtividade primária e promove elevado acúmulo de matéria orgânica (MO) nos sedimentos, a qual afeta as condições redox do ambiente de sedimentação e na interface água-sedimento, promovendo efeitos sobre a especiação inorgânica do enxofre (S). O presente estudo utiliza a geoquímica inorgânica das espécies reduzidas do S, operacionalmente definidas como acid-volatile sulfufide (AVS) e chromium-reducible sulfur (CRS), a composição isotópica (δ34S) do sulfato da água intersticial e do CRS, e a razão COT/CRS (carbono orgânico total/CRS) para avaliar a diagênese recente do S e a condição redox nos sedimentos. Adicionalmente foi estudada a morfologia da pirita e a distribuição de tamanho dos frambóides através de microscopia eletrônica de varredura (MEV) para inferir o estado de oxidação do ambiente de formação. Foram coletados quatro box-cores na plataforma continental do Sistema de Ressurgência de Cabo Frio (SRCF) para este estudo. Os conteúdos de COT variam entre 0,8 e 2,3%, as maiores concentrações foram observadas nas estações da porção média da plataforma. Baixos valores de enxofre total (ST) (< 0,2%) e CRS (< 0,05%) foram encontrados nas camadas superficiais, ocorrendo incremento com a profundidade, indicando o aumento da sulfato redução (SR). As estações com o maior conteúdo de ST foram as localizadas na porção média da plataforma, sendo este padrão de acumulação favorecido pela presença dos vórtices sob a plataforma. A razão COT/CRS indica que o fator limitante para a formação da pirita é o enxofre. Até 50% do S pode estar associado a MO, caracterizando o processo de sulfidização da MO. A composição isotópica do sulfato ao longo dos perfis é mantida constante entre +18,7 e +23‰ e sem fracionamento com respeito ao sulfato da água do mar (+ 21‰), indicando baixas taxas de SR. No entanto, a composição isotópica do CRS apresentou sinais altamente empobrecidos em 34S (-25,6 até -40,8 ‰), indicando reações de oxidação no ciclo do S, promovidas pela intensa bioturbaçao na área e/ou pelo regime hidrodinâmico regional. As diferentes características morfológicas, como as superfícies de oxidação nos microcristais, os processos de crescimento secundário e os poliframboides encontrados nas análises morfológicas da pirita, assim como também a variabilidade na distribuição dos diâmetros dos frambóides evidenciaram uma formação sob condição redox altamente dinâmica. Estes resultados confirmam a complexidade hidrodinâmica do SRCF, o qual afeta inúmeros processos sobre a plataforma, dentre os quais a diagênese no ciclo do enxofre
The Cabo Frio region (RJ) is an upwelling area, which favors the high primary productivity and promotes accumulation of organic matter (OM) in sediments, affecting the redox conditions of the sedimentation environment, the sediment-water interface and mainly the speciation of inorganic sulfur (S). Therefore, this study uses the inorganic geochemistry of reduced S species operationally defined as acid-volatile sulfufide (AVS) and chromium-reducible sulfur (CRS), the isotopic composition (δ34S) of pore water sulfate and CRS, and the COT / CRS ratio (total organic carbon / CRS), to evaluate the recent S diagenesis and redox conditions in sediments. Additionally, was study the pyrite morphology and size distribution of framboids by scanning electron microscopy (SEM) to infer the oxidation state of the environment. In this sense, were collected four box-cores on the continental shelf of the upwelling system of Cabo Frio (SRCF). The TOC contents range from 0.8 to 2.3%, the highest concentrations were observed at stations in the middle shelf. Low values of total sulfur (TS) (<0.2%) and CRS (<0.05%) were found in the superficial layers occurring an increase with depth, indicating an increase in sulfate reduction. The stations with the highest content of ST were located in the middle shelf, this pattern of accumulation is favored by the presence of cyclonic eddy under the platform. The COT/CRS ratio indicates that the limiting factor for the pyrite formation is the sulfur. The isotopic composition of sulfate did not vary much with the sediment depths and is kept constant between +18.7 and +23 ‰ and without fractionation of sulfate with respect to sea water (21 + ‰) indicating low net sulfate reductions, but the isotopic composition of the CRS is highly depleted (-25.6 to -40.8 ‰), indicating oxidation reactions in the cycle of S, promoted by the intense bioturbation in the area and the regional hydrodynamic regime. The different morphological characteristics observed, such as surface oxidation in the microcrystals, the processes of secondary growth and poliframboides found, as well as the variability in the framboids diameters distribution, show the formation under highly dynamic redox condition. These results confirm the complexity of SRCF due to the occurrence of different hydrodynamic conditions over the shelf
Shumskykh, Mykyta. "Release of trace elements from contaminated sediments into surface waters during sediments dynamics : an experimental study." Thesis, Tours, 2019. http://www.theses.fr/2019TOUR4008.
Full textIn aquatic systems, most of trace metals (TM) are buried in sediments and then can be released according to chemical conditions and microbial activity occurring at the sediment-water interface. The aim of this study was to assess the impact of resuspension events (flood or maintenance operations for dam reservoir) on the mobility of some TM. Different batch experiment conditions were chosen to mimic those events: under oxic and anoxic conditions on raw sediments and on gamma-irradiated ones (“sterilized” one). The use of deionized water allowed maximizing the release process. Two sediment types issued from different contexts were selected: the Villerest dam reservoir (France) and the Xiang River (China). Long term experiments (30-day long) allowed identifying that organic matter degradation, microbial activity and alteration/dissolution of trace metal bearing phases were the main controlling factors. The gamma-irradiation did not sterilize sediments but only limited aerobic bacteria and enhanced anaerobic activity. The impact of such 24h resuspension event on reservoir waters and downstream biota is very limited as less than 1% of trace elements was released
Fleurance, Stéphanie. "Métallogenèse de l'uranium associée à des processus superficiels : l'exemple de la Jordanie centrale." Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0312/document.
Full textThe different lithologies of the Belqa Group present an enrichment in P and various redox sensitive elements. The U, Cu, Co, Mo, V enrichment results from synsedimentary deposition in suboxic conditions. However, the higher Cr, Ni, Cd, Zn enrichment requires an exogenic metal flux probably related to the terrestrial leaching of ultrabasic rocks obducted during the collision between African-Arabian and Eurasian plates to the north of the study region, at the same time. Phosphates are the main host lithology for uranium and rare earth elements. The analysis of the apatites by laser ablation ICP-MS shows their evolution along the sedimentary-diagenetic and pyrometamorphic stages, up to the supergene weathering. The uranium liberation from the apatite structure during the pyrometamorphism and surficial weathering led to its availability as supergene ore mineralization. Pyrometamorphism resulted from the combustion of organic-rich layers and caused the destabilization of the apatites, and the formation of rocks which have compositions similar to clinker/Portland cements. Uranium has been also released from the structure of the apatite by supergene alteration. Meteoric weathering and the evaporitic groundwater resulted in the leaching and the transport of the elements (U, V) from the metamorphic carbonated hills, and from the surrounding permeable limestone which has undergone dissolution in the near surface zone
Schulze, Susanne. "Mikrobieller Abbau und Redoxzonierung im Abstrom einer teerölkontaminierten Altablagerung." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2004. http://nbn-resolving.de/urn:nbn:de:swb:14-1093000985218-62401.
Full text