Nous avons choisi d’étudier la conversion catalytique des nitrates dissous qui sont une cause majeure de contamination des eaux. C’est un procédé complexe en plusieurs étapes qui suit la réaction : NO3- → NO2- → [NO] → N2 + NH4+ + OH-Le but scientifique de cette thèse a été de déterminer une relation entre la structure physico-chimique des catalyseurs supportés et leur activité et leur sélectivité dans la réduction des nitrates. Les cinétiques de réaction ont également été étudiées en relation avec la structure des catalyseurs supportés Les travaux réalisés ont été axés autour des points suivants : 1. Elaboration des supports de catalyseurs : Deux groupes principaux de matériaux ont été étudiés : des matériaux carbonés et des matériaux inorganiques qui ont été modifiés par un traitement acide ou basique ou par dépôt des oxydes (Al2O3, ZrO2 seuls ou en mélange). 2. Synthèse du catalyseur : Les oxydes de métaux nobles et de transition ont été fixés sur les supports. Des systèmes monométalliques avec Pt et Pd et bimétalliques Pd-Cu ont été étudiés puis caractérisés par de nombreuses techniques. L’efficacité des ces supports a été déterminée en fonction de leur activité catalytique. 3. Détermination des propriétés catalytiques : Le rôle et l’effet des paramètres tels que nature du support, composition de la phase active, présence de sels inorganiques dans le milieu réactionnel, nature du réducteur sur la vitesse de réduction des nitrates et sélectivité des réactions ont été largement étudiés La discussion générale fait ressortir les combinaisons support/catalyseur les plus efficaces pour la dénitrification des eaux de consommation / We chose to study the catalytic conversion of dissolved nitrate, which are a major cause of water contamination. It is a complex process into several steps following the reaction: NO3- → NO2-→ [NO] → N2 + NH4+ + + OH- The scientific goal of this thesis was to determine a relationship between the physico-chemical structure of catalysts and their activity and selectivity in the reduction of nitrates. The reaction kinetics were also studied in relation to the structure of catalysts. The work focused around the following points: 1. Preparation of catalyst supports: Two main groups of materials were studied: carbon materials and inorganic materials that have been modified by acid or base treatment or by deposit oxides (Al2O3, ZrO2 alone or in mixture). 2. Synthesis of catalyst: oxides of noble and transition metals have been established on the supports. Systems with monometallic Pt and Pd and bimetallic Pd-Cu have been studied and characterized by many techniques. The effectiveness of these materials was determined depending on their catalytic activity. 3. Determination of the catalytic properties: The role and effect of parameters such as support, type of medium, active phase composition, the presence of inorganic salts in the reaction medium, nature of reducing on the rate of nitrate reduction and selectivity of the reactions were widely studied. The debate highlights the combination support / most effective catalyst for denitrification of drinking water

Water protection proves to be a difficult task, whether it is dealt with through legislation or the implementation of a process to reduce further pollution. This study considers how the issue of water pollution from nitrates in agricultural practices has become better understood through the reforms of the common agriculture policy (CAP) and the enactment of various regulations and directives by EU. The implementation of the EC Nitrate Directive is a main focus of this study because it was a major movement towards protecting water against pollution from agriculture, and an important step in implementing the Water Framework Directive. The implementation process is analyzed from both a formal and practical perspective, along with a discussion of the difficulties that arose in the implementation phase. There is a focus on the implementation of the Nitrate Directive in UK, with an emphasis on England as a case study. The study finds that if the distribution of responsibilities (planning, regulating, implementing, and reporting) is shared between national, regional and local bodies, the compliance with political regulations becomes easier. It is also concluded that rearrangements of the existing institutions are necessary to reduce costs, exchange new ideas that could translate to regulative ideas, and create an atmosphere of trust between regulators and implementers. It can be concluded from this study that, despite the traditional centralization of governments, England has taken several steps towards integrating institutions and has tried to be open and responsive to the local communities. Finally, there are several lessons that can be learned from the UK’s approach to control nitrate pollution, which are discussed and outlined in the conclusion of this study. / Water protection proves to be a difficult task, whether it is dealt with through legislation or the implementation of a process to reduce further pollution. This study considers how the issue of water pollution from nitrates in agricultural practices has become better understood through the reforms of the common agriculture policy (CAP) and the enactment of various regulations and directives by EU. The implementation of the EC Nitrate Directive is a main focus of this study because it was a major movement towards protecting water against pollution from agriculture, and an important step in implementing the Water Framework Directive. The implementation process is analyzed from both a formal and practical perspective, along with a discussion of the difficulties that arose in the implementation phase. There is a focus on the implementation of the Nitrate Directive in UK, with an emphasis on England as a case study. The study finds that if the distribution of responsibilities (planning, regulating, implementing, and reporting) is shared between national, regional and local bodies, the compliance with political regulations becomes easier. It is also concluded that rearrangements of the existing institutions are necessary to reduce costs, exchange new ideas that could translate to regulative ideas, and create an atmosphere of trust between regulators and implementers. It can be concluded from this study that, despite the traditional centralization of governments, England has taken several steps towards integrating institutions and has tried to be open and responsive to the local communities. Finally, there are several lessons that can be learned from the UK’s approach to control nitrate pollution, which are discussed and outlined in the conclusion of this study. / kungsmarksv'gen 105 371 44 karlskrona sweden

Perchlorate contamination is widespread. Perchlorate, a water contaminant, disrupts iodide uptake to the thyroid, inhibiting growth and mental development. Recent studies have demonstrated autohydrogenotrophic perchlorate reduction to chloride. Hydrogen gas can be produced in-situ via the corrosion of zero-valent iron (ZVI), thereby avoiding problems related to the low aqueous solubility of hydrogen gas. The presence of nitrate has been shown inhibit autohydrogenotrophic perchlorate reduction. However, no studies have modeled the effects of nitrate on autohydrogenotrophic perchlorate biokinetics or developed a model to function as a design tool to predict long-term performance of ZVI/biotic perchlorate treatment systems in the presence of nitrate. Batch experiments demonstrated the presence of nitrate significantly inhibited perchlorate degradation by an autohydrogenotrophic microbial consortium. However, the consortium was capable of significant perchlorate reduction while the bulk of the nitrate was still present. A modified competitive inhibition model successfully predicted autohydrogenotrophic perchlorate degradation in the presence of nitrate. The model describes perchlorate degradation as a function of the biomass, perchlorate, hydrogen, and nitrate concentrations, as well as the single-component perchlorate, hydrogen, and nitrate half-saturation coefficients and perchlorate maximum substrate utilization rate. To obtain the single-component parameters, a series of batch experiments were performed under perchlorate-, nitrate-, and hydrogen-limiting conditions. The single-component biokinetic parameters and model predictions indicate the consortium could treat perchlorate-contaminated water with concentrations in the low hundreds of μg/L and in states with perchlorate treatment goals in the low μg/L range. The consortium biokinetic parameters and modified competitive inhibition model were used in the development of an AQUASIM based biofilm model. The model also integrated physical parameters, ZVI hydrogen production, and abiotic nitrate reduction. The model was calibrated using the long-term performance results of a laboratory-scale ZVI/biotic column. Both laboratory and modeling results showed when the column becomes hydrogen-limited, the presence of nitrate decreases perchlorate removal efficiency. Full-scale simulations demonstrated the model could prove useful as a predictive design tool. Simulations suggest that a permeable reactive barrier that includes 10% ZVI and additional media capable of pH buffering could remove typical contaminated ground water concentrations of perchlorate in the presence of typical oxygen and nitrate concentrations. / text

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This study was undertaken to determine the effects of beryllium nitrate on regeneration in the tail of Rana Pipiens larvae. The tails were amputated approximately 3 rom from the tips. Some were then treated with different concentrations of beryllium nitrate (0.5 N, 0.7 N, and 1.0 N). Normal regeneration of untreated amputated tails was fulfilled in an orderly manner. In the animals treated with beryllium nitrate, general tissue regeneration was inhibited. Considerable degeneration was observed in all tissues of the tail stumps. Holfever, the elastic lamella of the notochordal sheath was stimulated to stretch, oftentimes breaking the continuity of the fibrous lamella. The elastic layer appeared highly ravelled within the degenerated tissues of the tail, and, in some cases, extended for 3 to 4 inches from the tail stump due to a break in the covering epithelium.

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Master of Science / Department of Kinesiology / Carl Ade / Background: Cancer survivors treated with anthracycline-based chemotherapy have a high risk of developing anthracycline-induced cardiotoxicities, including cardiac abnormalities, endothelial dysfunction, and dilated cardiomyopathy. Notably, the imbalance of decreased nitric oxide (NO) production and increased reactive oxygen species has been shown to cause significant damage to cardiac tissue and mitochondria. Therefore, the aim of the current investigation was to determine if an inorganic dietary nitrate (NO3-) supplementation period could restore normal cardiac function in cancer survivors with a history of anthracycline chemotherapy. Methods: Ten cancer survivors, 9 with breast cancer and 1 with lymphoma, completed the experiment. Standard and Tissue Doppler echocardiography were used to assess LV and carotid artery function during systole and diastole at rest. Results: There were no differences in ventricular-arterial coupling (p=0.10), arterial stiffness (p=0.38) or strain of the LV (p=0.49). However, NO₃- supplementation improved strain rate in early filling, early mitral septal wall annular velocity, and mitral A-wave velocity or late diastolic filling. Conclusion: Following NO₃- supplementation, cancer survivors with a history of anthracycline chemotherapy showed significant improvements in diastolic function compared to placebo treatments. These findings add support to the literature of the therapeutic benefits of inorganic dietary NO₃- supplementation on cardiovascular function in clinical populations.