Nutrient dynamics in a lodgepole pine forest at Bootleg Mountain, B.C., were investigated through the sampling of soil, snow and groundwater in six one-ha blocks. Nitrogen (NO3-, NH4+, TIN, TDN, TN), phosphorus (PO43-, TDP, TP), and DOC were analyzed in addition to N mineralization and nitrification. Position and dispersion statistics were computed for each variable and correlations (Pearson and Spearman) were computed for each pair of variables. The overall heterogeneities of soil, snow, and groundwater were generally lower between 1-ha blocks than between plots. Productivity in the soil was generally N-limited with low input from snow precipitation. Very little N leached from soil to groundwater. Phosphorus contents were highly variable and were the limiting nutrient in the groundwater. Rates of net and gross N mineralization and nitrification were determined using buried bags and 15N isotope dilutions. Gross rates were greater than net rates and nitrification was low relative to high immobilization rates. The N cycle appears to be tightly regulated, thus further study will be needed to monitor the impact of harvesting on N cycling.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv. / Härtill 4 uppsatser.

Nutrient dynamics in a lodgepole pine forest at Bootleg Mountain, B.C., were investigated through the sampling of soil, snow and groundwater in six one-ha blocks. Nitrogen (NO3-, NH4+, TIN, TDN, TN), phosphorus (PO43-, TDP, TP), and DOC were analyzed in addition to N mineralization and nitrification. Position and dispersion statistics were computed for each variable and correlations (Pearson and Spearman) were computed for each pair of variables. The overall heterogeneities of soil, snow, and groundwater were generally lower between 1-ha blocks than between plots. Productivity in the soil was generally N-limited with low input from snow precipitation. Very little N leached from soil to groundwater. Phosphorus contents were highly variable and were the limiting nutrient in the groundwater. Rates of net and gross N mineralization and nitrification were determined using buried bags and 15N isotope dilutions. Gross rates were greater than net rates and nitrification was low relative to high immobilization rates. The N cycle appears to be tightly regulated, thus further study will be needed to monitor the impact of harvesting on N cycling.

The proposed thesis concerns in the study of tribosphenic molar, the key apomorphy of mammalian clade, mainly in structure and development of its enamel coat. As the main model species served us European vespertilionid bat Myotis myotis. The aims of this thesis are: (1) to describe structure and microstructure of enamel in tribosphenic molars in detail; (2) to compare it with unicuspid teeth of the same dentition; (3) to describe mineralization process and enamel maturation in insectivorous dentition; (4) to describe late odontogenesis in molars of insectivorous dentition and its interlacing with enamel maturation, and how they come to occlusion.

La formation des gisements métallogéniques en général et uranifères en particulier, dans les bassins paléoprotérozoïques, dépend de la migration des fluides riches en divers éléments (U, Cu, Fe, etc.). L’objet de cette thèse a été de définir le contexte tectonique, sédimentologique et diagénétique associées aux gisements bitume--‐uranium du bassin de Franceville. L’étude tectonique réalisée met en évidence des failles de transfert N180--‐170, héritées de la tectonique archéenne et des failles normales longitudinales N110--‐120. Ces deux familles de failles compartimentent le bassin de Franceville en plusieurs sous--‐bassins de subsidence variable. Les failles longitudinales N110--‐120° contrôlent la mise en place d’anticlinaux de mur et des synclinaux de toit synsédimentaires (i.e. discordances progressives). Les gisements d’uranium du bassin de Franceville, se localisent au niveau des anticlinaux de mur des failles normales. L’étude sédimentologique du bassin caractérise la distribution spatiale des paléoenvironnements de dépôt. Quatre grands environnements de dépôts sont respectivement mis en évidence : fluviatile (formation FA inferieur), deltaïque (formation FA moyen), tidal (formation FA Supérieur) et marin profond (formation FB). La distribution des facies sédimentaires à la transition FA--‐FB est responsable de la mise en place de barrières de perméabilité. Les barrières de perméabilité sont responsables de l’augmentation de la pression fluide, qui favorise la mise en place des structures de surpression fluide (dykes, stylolites, veines de quartz), au voisinage des anticlinaux de mur contrôlés par les failles normales. Les différences de pression dans le bassin favorisent la migration des fluides uranifères et des hydrocarbures, des zones profondes du bassin vers les anticlinaux de mur. Les structures de fracturation hydraulique vont contrôler la mise en place des bitumes et des minéralisations d’uranium associées. / Metallogenic deposits within paleproterozoic basins depend on generation and migration of fluids. The aim of this study is to provide a better understanding of tectonic, sedimentological and diagenetic setting of the uranium deposits in the Franceville basin and to characterize hydraulic fracturing impact on fluid migration processes in sandstone reservoirs.Tectonic study define the N180-170° transfer faults, associated with Archean tectonic and the N110-120° longitudinal normal faults. These two fault directions split the Franceville basin into small sub-basins. The longitudinal normal faults are associated with footwall anticlines and hanging wall synclines. The uranium deposits of Franceville basin are located in footwall anticlines of longitudinal normal faults.Sedimentological analysis allows to describe four depositional environments: Fluvial (lower FA), deltaic (middle FA), tidal (upper FA), and open marine environments (FB). Facies distribution in the FA-FB transition promotes the establishment of permeability barriers. These latter are responsible of the increase in fluid pressure and of the formation of fluid pressure structures (dykes, stylolites, quartz veins), in footwall anticlines of longitudinal normal faults. Increase in fluid pressure allows the migration of uranium-fluids, and hydrocarbon from the deep basin to the footwall anticline. Hydraulic fracturing processes lead the precipitation of uranium mineralization, associated with bitumen, in microfractures.

Nitrogen availability and transformation in acidified and N saturated soils of Czech (The Bohemian Forest, Ore Mountains) and Ukraine (Pop Ivan massif) mountain forest ecosystems were investigated. The study was primarily focused on the role of microbial immobilization in soil N retention. The study was based on field measurements (ion exchange resins), analyses of selected soil biochemical and microbial characteristics, and on laboratory experiments (15N labelling).

A compostagem é uma solução inteligente para a destinação final de resíduos orgânicos. O presente trabalho baseou-se na hipótese de que é possível, por meio da aplicação de compostos orgânicos ao solo, alcançar patamares de produção agrícola equivalentes aos obtidos pela adubação nitrogenada mineral. O experimento foi realizado em vasos com Brachiaria brizantha cv. Marandu em dois solos, um de textura argilosa e outro de textura média. Objetivou-se avaliar a dose de nitrogênio (N) proveniente de composto de lixo, composto de lodo de esgoto e composto de lodo de dejetos suínos que fosse equivalente à dose de 150 mg dm-3 de N proveniente da adubação nitrogenada mineral. Para isso, as doses de composto orgânico foram determinadas com base nas frações de mineralização de N, estimadas em 30, 15 e 7%. Assim, para a obtenção de 150 mg dm-3 de N mineralizado, foram aplicadas doses de, respectivamente, 500, 1.000 e 2.143 mg dm-3 de N total, provenientes dos compostos orgânicos. Foram realizados três cortes no capim Marandu, sendo mensurados, a cada corte, o teor de clorofila, o número de folhas e de perfilhos, a área foliar, a biomassa e o teor de N total da parte aérea das plantas. Os resultados foram submetidos à análise de variância, teste de médias e análise de regressão. Foi possível, por meio dos compostos orgânicos, obter resultados de adubação nitrogenada equivalentes, e até superiores, aos obtidos pela adubação mineral, dependendo do tipo de composto, a dose aplicada e a escala temporal. De modo geral, os tratamentos com composto de lodo de esgoto, a partir da dose 1.000 mg dm-3 de N, foram superiores ao com adubação mineral no primeiro corte, equivalentes no segundo corte, e superiores no terceiro corte do capim Marandu. A quantidade de N liberada ao sistema por meio dos compostos de lixo e de lodo de dejetos suínos chegou aos patamares dos tratamentos com adubação mineral no segundo corte, na dose 2.143 mg dm-3 e no terceiro corte, na dose 1.000 mg dm-3 de N. As frações de mineralização de N que geraram resultados mais próximos aos da adubação nitrogenada mineral foram, em média, de 15% para o composto de lodo de esgoto e de 7% para os compostos de lixo e de lodo de dejetos suínos / Composting is a smart final destination for organic residues. The present work was based in the hypothesis that it is possible to obtain similar agricultural productivity levels applying organic compounds on soil in comparison with mineral nitrogen application. The experiment was conducted in pots with Brachiaria brizantha cv. Marandu in two soil types, with clay and sandy clay loam texture. The objective was to evaluate if estimated doses of nitrogen (N) from waste compost, sewage sludge compost and and pig manure compost, when applied on the soil, was equivalent to 150 mg dm-3 of mineral Nitrogen fertilizer. The doses of organic composts applied were based in estimations of N mineralized of 30, 15 and 7%, correspondent, respectively, to doses of 500, 1000 and 2143 mg dm-3 of total N. The grass was harvested three times, on each time the chlorophyll level, the number of leaves, number of branches, leaf area, biomass and total N were measured in the aerial part of the plants. The results were submitted to variance analysis, and regression analysis. It was possible, trough the N fertilization by organic composts, to obtain similar and even superior results, in comparison to the mineral N, depending on type of compost, the applied dose and the time frame. The treatment with sewage sludge compost in the dose of 1000 mg dm-3 of N was superior to the mineral N in the first harvest, similar in the second and superior in the third harvest of the grass. The waste and pig manure composts reached similarity with the mineral fertilization in the second harvest, in the dose of 2143 mg dm-3, and in the third harvest, in the dose of 1000 mg dm-3 of N. The mineralization fractions of N found for the composts that were the most similar the mineral fertilization were, in average, of 15% for the sewage sludge compost and 7% for the waste and pig manure compost

Submitted by Biblioteca de Pós-Graduação em Geoquímica BGQ (bgq@ndc.uff.br) on 2017-06-27T16:54:18Z No. of bitstreams: 1 Dissertação Lívia Cosme.pdf: 2494579 bytes, checksum: 91a88c82399caf6542accc460ff4d256 (MD5) / Made available in DSpace on 2017-06-27T16:54:18Z (GMT). No. of bitstreams: 1 Dissertação Lívia Cosme.pdf: 2494579 bytes, checksum: 91a88c82399caf6542accc460ff4d256 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / Universidade Federal Fluminense. Instituto de Química. Programa de Pós-Graduação em Geoquímica, Niterói, RJ / Metano (CH 4 ) e dióxido de carbono (CO 2 ) são considerados importantes gases do Efeito Estufa por sua propriedade de reter radiação infravermelha na atmosfera e contribuir ao aquecimento global . Ambien tes deposicion ais marinhos como baías, estuários e mares costeiros são o destino preferencial de aportes orgânicos advindos da bacia de drenagem e podem apresentar elevadas taxas de produção e degradação de matéria orgânica (MO) , as quais podem ainda ser altamente vari áveis nas escalas temporal e espacial . A quantidade e qualidade da MO, bem como o aumento da temperatura, podem intensificar os processos de mineralização anaeróbia de estoques orgânicos nos sedimentos costeiros. Neste sentido, o presente estudo se propô s a a valiar a heterogeneidade da produção anaeróbia de CO 2 e CH 4 , associada à presença de reservatórios e escapes de gás em sedimentos subsuperficiais da porção Nordeste da Baía de Guanabara, aliando a biogeoquímica com a sísmica de reflexão. Adicionalment e, o efeito do aumento médio de temperatura de 4°C previsto pelo cenário RCP 8.5 do IPCC para a região Sul do continente sulamericano até 2100 foi testado experimentalmente sobre as taxas de produção anaeróbia de CO 2 e CH 4 . Os resultados de biogeoquímica e sísmica no sedimento revelaram intensos processos de mineralização orgânica, os quais foram altamente variáveis tanto no perfil vertical quanto entre curtas distâncias dentro do ecossistema. Sendo a produção subsuperficial de gases de carbono (C) expressi va nesta área, contribuindo para a formação de sedimentos carregados de gás, escapes destes reservatórios nos sedimentos podem representar importantes fluxos ainda pouco estudados no ciclo de C. Os resultados também sugerem que o incremento do lançamento d e dejetos orgânicos e o aquecimento potencialmente favorecem uma maior liberação de gases de C desde os estoques orgânicos de CO 2 , gás que contribui, por sua vez , ao pró prio aquecimento em retroalimentação positiva. / Methane (CH 4 ) and carbon dioxide (CO 2 ) are considered important greenhouse gases for their property of retaining infrared radiation in the atmo sphere and contributing to global warming. Marine depositional environments such as bays, estuaries and coastal oceans are the preferred destination of organic inputs from the drainage basin and may present high rates of organic matter (OM) production and degradation, which may still be highly variable at the temporal and spatial scales . The quantity and quality of OM, as well as the temperature increase, can intensify the anaerobic mineralization processes of organic stocks in the coastal sediments. In thi s sense, the present study aimed to evaluate the heterogeneity of anaerobic CO 2 and CH 4 production, associated with the presence of reservoirs and gas leaks in subsurface sediments of the Northeast portion of Guanabara Bay, combining biogeochemistry with s eismic reflection. Additionally, the effect of the average temperature increase of 4 ° C predicted by the IPCC RCP 8.5 scenari o for the southern region of South American up to 2100 was experimentally tested on the anaerobic CO 2 and CH 4 production rates. Th e results of biogeochemistry and seismic reflection revealed intense organic mineralization processes, which were highly variable both in the vertical profile and between short distances within the ecosystem. As the subsurface carbon (C) gas production is significant in this area, contributing to the formation of gas charged sediments, leaks from these reservoirs in the sedimen ts can represent important fluxes that are still poorly studied in the C cycle. The results als o suggest that the increasing dischar ge of organic waste and warming potentially favor a greater release of C gases from organic CO 2 stocks, which in turn contribute to warming in a positive feedback

Dans le rachitisme hypophosphatémique lié à l’X (XLH), MEPE (Matrix Extracellular PhosphoglycoprotEin), une protéine non collagénique impliquée dans la biominéralisation, subit un clivage pathologique de son extrémité C-terminale. Les peptides ainsi libérés sont porteurs d’un domaine ASARM (acidic serine- and aspartate- rich motif) très conservé dans l’évolution. ASARM inhibe la réabsorption tubulaire du phosphate et la minéralisation de la matrice extracellulaire osseuse. Précédemment, notre équipe a identifié des taux élevés de ce peptide ASARM dérivé de MEPE dans la dentine issue de patients XLH. Ce travail a pour objectif principal d’étudier l’effet d’ASARM sur la minéralisation dentinaire afin de mieux comprendre son implication dans les anomalies dentaires observées chez les malades. Des lattis de collagène ensemencés avec des cellules souches pulpaires SHEDs (Dental pulp stem cells derived from deciduous teeth) englobés dans une tranche de dent humaine ont été cultivés dans des conditions d’induction odontoblastique avec et sans 20 µM de chacune des formes phosphorylé (p-ASARM) ou non phosphorylé (np-ASARM) du peptide recombinant. La minéralisation a été appréciée par microscopie électronique à balayage et colorations de von Kossa. L’expression des marqueurs odontogéniques (DSPP, ostéocalcine, MEPE) a été évaluée par immunohistochimie, qPCR et Western-blot. Parallèlement, des billes d’agarose imprégnées p-ASARM et np-ASARM ont été implantées dans un modèle d’effraction pulpaire chez le rat, dans lequel un pont de dentine de réparation se forme spontanément. La minéralisation dans la chambre pulpaire a été évaluée par micro-CT et immunohistochimie. Dans le modèle in vitro 3D, p-ASARM a inhibé la différenciation des SHEDs, ce qui s’est traduit par 1) l’absence de formation de nodule de minéralisation, 2) la diminution des marqueurs odontogéniques, 3) la surexpression de MEPE, comparativement au contrôle ou au traitement du milieu par np-ASARM. In vivo, p-ASARM a perturbé le processus de réparation dentinaire et a entrainé une surexpression de MEPE. Ces résultats confirment notre hypothèse selon laquelle p-ASARM inhibe la différenciation odonblastique et la minéralisation de la dentine. De plus, l’effet inducteur de p-ASARM sur l’expression de MEPE suggère l’existence d’une boucle de rétrocontrôle positif impliquée dans l’étiopathogénie du XLH. Ainsi, les défauts de minéralisation de la dentine hypophosphatémique sont probablement une conséquence de la libération du peptide ASARM dans la matrice extracellulaire. / In X-linked familial hypophosphatemic rickets (XLH), MEPE (Matrix Extracellular PhosphoglycoprotEin) is cleaved, releasing phosphorylated ASARM (acidic serine- and aspartate- rich motif) peptides that inhibit mineralization of bone extracellular matrix (ECM), and renal tubular phosphate reabsorption. We recently identified high levels of MEPE-derived ASARM peptides in human XLH dentin. The present study was aimed to investigate their effects on dentin mineralization in order to better understand their role in the etiology of tooth abnormalities observed in XLH patients. Dental pulp stem cells derived from deciduous teeth (SHEDs) were seeded in a collagen scaffold, cultured in human tooth slices under mineralizing conditions as a control, and with 20 µM of either phosphorylated (p-ASARM) or non-phosphorylated (np-ASARM) MEPE-derived ASARM peptides. Mineralization was assessed by scanning electron microscopy and von Kossa staining. Odontogenic markers (DSPP, osteocalcin, MEPE) were assessed by immunohistochemistry, RT-PCR and Western blot. In parallel, agarose beads soaked with recombinant ASARM peptides were implanted in a rat pulp injury model where a reparative dentin bridge is spontaneously formed; the repair process was evaluated by micro-CT and IHC. In the tooth slice culture model, p-ASARM inhibited SHED differentiation, with 1) no formation of mineralization nodule, 2) decreased odontogenic marker expression, and 3) up-regulation of MEPE expression, in contrast with np-ASARM and control. In the rat pulp injury model, p-ASARM impaired the formation of the reparative dentin bridge and increased MEPE expression. The present data support our hypothesis that p-ASARM impairs odontogenic differentiation process and the resulting mineralization of dentin. Moreover, the identification of a stimulating effect of p-ASARM on MEPE expression suggests a positive feedback loop in the pathogenicity of XLH disease. Accordingly, the mineralized defects in XLH tooth dentin may be a direct consequence of the release of ASARM peptides in the ECM.

Afin de mieux comprendre le comportement mécanique de l’os trabéculaire et d’améliorer la prédiction du risque de fracture, l’objectif de cette thèse est de développer un modèle numérique « bio-fidèle » prenant en compte l’hétérogénéité tissulaire, et de déterminer les contraintes mécaniques au sein des travées osseuses, dans le domaine de déformation élastique. À l’échelle tissulaire, une étude par nanoindentation a permis de dissocier les comportements élastiques et plastiques de l’os en fonction de sa composition (minéral/collagène). Ainsi, le comportement élastique du tissu osseux serait principalement lié à sa quantité de minéral alors que ses propriétés plastiques seraient davantage liées à la phase organique. Une loi reliant le degré de minéralisation de l’os (DMB) au module élastique a été déterminée dans l’os humain. La création d’un modèle numérique reproduisant de manière rigoureuse le comportement élastique de l’os trabéculaire, nécessite la prise en compte de l’hétérogénéité de la quantité de minéral (DMB) et donc son acquisition en 3D. Grâce à une méthode de recalage d’image 2D/3D, les acquisitions de microtomographie ont été comparées aux valeurs obtenues par microradiographie quantitative, méthode de référence de mesure du DMB. Sous certaines conditions, la microtomographie permet une évaluation correcte de l’hétérogénéité minérale. La création et l’analyse d’un modèle numérique par éléments finis de l’os trabéculaire, à partir des images de tomographie, a montré l’importance des paramètres du modèle (taille et formulation des éléments) ainsi que le rôle de l’hétérogénéité minérale sur l’évaluation des contraintes locales appliquées aux travées osseuses. / Finite element modeling has become more and more suitable to estimate the mechanical properties of trabecular bone. Such models tend to be used to evaluate bone fracture risk. The main goal of this study was to create a bio-faithful model of trabecular bone to evaluate elastic stresses fields in trabeculae. In a first part, a nanoindentation study lead to a dissociation of elastic and plastic behavior of bone tissue, depending of its composition (mineral/collagen). At osteon level, bone elastic behavior mainly depends on mineral quantity whereas its plastic behavior mainly depends on collagen maturity. The relation between degree of mineralization of bone (DMB) and elastic modulus have been determined for human bone. The purpose of second part of the study was to evaluate DMB heterogeneity inside a 3D model of trabecular bone. Using 2D/3D registration, we compare the results obtain with high resolution microtomography to those from quantitative microradiography, the goldstandard method used to measure DMB. We prove that it was possible to obtain a good evaluation of mineral heterogeneity in trabecular bone by tomography. The last part of this study, is dedicated to the creation of a finite element model of trabecular bone. After analyzing the influence of finite element modeling parameter on the assessment of mechanical response (size and element formulation), we showed that the integration of mineral heterogeneity at the tissue level lead to strong modifications of stress fields in bone trabeculae. The results of this study prove that bone mineral heterogeneity is an important parameter and should be taken into account when evaluating trabecular bone mechanical properties.