Na região dos Andes Patagônicos entre os 41 a 44° S estão expostos amplos e contínuos afloramentos de rochas graníticas do segmento norte do Batólito Norte-Patagônico (BNP). Durante sua evolução a maior parte das rochas graníticas foram colocadas em rochas metamórficas, e outras partes foram colocadas em rochas vulcânicas do Jurássico-Berriasano, sedimentares e vulcânicas do Cretáceo Inferior, vulcânicas do Cretáceo Superior e sedimentares do Mioceno. Parte desta atividade magmática está associada à gênese de depósitos de minério. As rochas plutônicas expostas apresentam uma gradação desde dioritos até granitos e leucogranitos, apesar de que a área é largamente dominada por variedades intermediárias a ácidas. Determinações K-Ar permitiram identificar extensos e volumosos eventos plutônicos que descrevem duas faixas de orientação N-S durante o Cretáceo Inferior (ca. 120-100 Ma) e Mioceno (ca. 20-7 Ma), discretos durante o Jurássico Superior (ca. 155 Ma) e o Cretáceo Superior (ca. 95-70 Ma), restritos durante o Plioceno (ca. 5-3 Ma), e um provável evento plutônico no Eoceno (ca. 54-34 Ma), ao passo que experimentos Ar/Ar confirmam os eventos magmáticos do Cretáceo Inferior (ca. 126-100 Ma) e Mioceno (ca. 19-9 Ma). Determinações U-Pb convencionais indicam a provável perda e herança de Pb, apesar de confirmar os eventos magmáticos do Cretáceo Inferior (ca.129-114 Ma) e Mioceno (ca. 22-13 Ma). Além disso, as determinações U-Pb convencionais em zircões revelam a presença de rochas magmáticas pré-Andinas do Devoniano Inferior (ca. 400 Ma) provavelmente relacionadas com rochas do Maciço Norte-Patagônico. Determinações U-Pb SHRIMP em zircões indicam 110,0±9,6 Ma para um monzogranito e de 126,3±6,7 Ma para um piroxênio dioritio, 8,4±0,3 Ma para um tonalito e 13,26±0,19 Ma para um andesito porfirítico, e de 385,9±7,4 Ma para um corpo de microdiorito tectonizado. Estes dados indicam que o início da atividade plutônica é representada em ambos das faixas por pequenos corpos de colocação superficial, e a idade U-Pb SHRIMP do Devoniano confirma o evento magmático inferido das idades U-Pb convencionais. A distribuição de idades mostra um padrão complexo, mas, permite definir eventos magmáticos do Cretáceo, preferencialmente localizados, a E da Zona de Falha Liquiñe-Ofqui (ZFLO), do Mioceno no interior e a O desta estrutura, e do Plioceno no traço principal da ZFLO. A atividade plutônica do Mioceno, em direção a trincheira é diferente que o padrão definido para a região centro-norte dos Andes chilenos, onde é verificada a migração do arco magmático para a E com a conseqüente diminuição de idades neste sentido. Composições isotópicas de Sr e Nd mostram baixos e positivos teores de Nd com Sr entre -4 e +7 sugerindo que o BNP no segmento estudado, foi composto a partir de mistura de matérias do manto com fusão de crosta inferior, como é demonstrado pelos trabalhos anteriores, em áreas vizinhas. As composições isotópicas de Pb em feldspato, das mesmas amostras datadas por U-Pb convencional, variou com a idade, plútons com 206Pb/204Pb >18,62 são do Mioceno, enquanto que aqueles plútons com 206Pb/204Pb <18,57 são do Cretáceo, com uma relação inversa entre os plútons do Mioceno, o que é atribuído à variável interação com o embasamento metamórfico. Mineralizações de metais base com Au e Ag estão hospedadas em rochas vulcânicas do Cretáceo e limitadas à faixa magmática do Cretáceo Inferior e mineralizações de Au-As estão hospedadas no Microdiorito do Devoniano e em rochas metamórficas do Paleozóico e limitadas à faixa magmática do Mioceno. Além disso, em ambos as faixas, ocorrências de Cu-Mo são relatadas associadas com monzogranitos e tonalitios. Mineralizações de metais preciosos e de base no prospecto Las Juntas estão relacionados com alteração silíca-adularia e quartzo-sericita e deposição de pirita, esfalerita, galena com conteúdos de Ag e Bi, e calcopirita, e menor hematita, tetraedrite, arsenopirita, bornita e calcocita, em veios, vênulas, brechas e escassa disseminação. Os teores são variáveis, mas em veios mineralizados em Cu os teores podem atingir até 15% Cu, e em brechas mineralizadas em Cu-Pb-Zn os teores podem atingir até 32% Pb, 23% Zn e 0,28% Cu, com 1,4 para 1.300 ppm de Ag e 0,02 para 3,9 ppm de Au. Dados de inclusões fluidas indicam temperaturas de homogeneização variando entre 140 a 230º C, salinidades entre 3 a 6% em peso de NaCl equiv., e de deposição de metais base durante ebulição e mistura. Mineralizações de Au-As no prospecto Pichicolo estão relacionadas com alteração silíca e quartzo-sericita e deposição de arsenopirita e pirita, e menor pirrotita, calcopirita e bornita, em vênulas, stockwork e disseminação. Os teores variam entre 0,02 a 2,0 ppm de Au. Dados de inclusões fluidas indicam temperaturas de homogeneização entre 180 a 270º C, salinidades entre de 3 a 5% em peso de NaCl equiv., e deposição metálica durante ebulição e mistura. A mineralização, alteração e as características químicas e físicas de fluidos sugerem para ambos os prospectos características de epitermais de baixa sulfetação. O método Re-Os foi utilizado em molibdenitas hospedadas em plútons de monzogranito e tonalito para determinar a idade da mineralização de Cu-Mo. As idades obtidas (ca. 119 e 9,1 a 8,2 Ma) sugerem que a mineralização ocorreu em sistemas hidrotermais intimamente associada com os eventos magmáticos de Cretáceo Inferior e Mioceno, o que confirma a interpretação acerca da existência das faixas metalogéneticas polimetálicas do Cretáceo Inferior e aurífera do Mioceno propostas para a Cordilheira Norte-Patagônica. Biotita do monzogranito hospedeiro de mineralizaçao de Cu-Mo na aldeia Palena foi datada por Ar/Ar em 114,7 Ma, e outra datação, próxima da ocorrência, em 114,2 Ma. Biotita do tonalito hospedeiro da mineralização de Cu-Mo no estuário Reloncaví foi datada por Ar/Ar em 8,53 Ma, e outra datação, próxima da ocorrência, em 8,64 Ma. A proximidade e a superposição, dentro do erro analítico, entre as idades Ar/Ar em biotita, em ambas as áreas, sugerem que a alteração hidrotemal não foi estendida. Uma idade isocrônica Rb-Sr de 126±8 Ma obtida de rochas hidrotermalmente alteradas com mineralização polimetálica é interpretada como a idade do evento hidrotermal. Experimentos Ar/Ar em sericita hidrotemal de granulação muito fina com mineralização de Au-As mostra redistribuição de Ar por \'recoil\' e a idade integrada de 142±2 Ma sugere que a associação mineralização- magmatismo félsico do Jurássico não deve ser descartada. Composições isotópicas de Sr e Nd de rochas hospedeiras e ígneas associadas indicam que os magmas são principalmente derivados do manto com contaminação de crosta continental variável. Composições isotópicas de Pb em minerais de minério, rochas hospedeiras e ígneas associadas, em ambos os prospectos, se agrupam próximos da curva do orógeno no modelo da \'plumbotectonica\'. Em um diagrama 206Pb/204Pb-207Pb/204Pb, os minerais de minério e as rochas ígneas associados do prospecto Las Juntas são menos radiogênicos (206Pb/204Pb <18.6) que o prospecto Pichicolo (206Pb/204Pb >18.6). Este modelo é compatível com a idade absoluta cretácea da mineralização para Las Juntas e com a idade miocena assumida para Pichicolo. As tendências alongadas da composição de Pb nos minerais de minério indicam, principalmente, um modelo orogênico, sugerindo mistura variável de chumbo a partir de diferentes fontes, sobretudo de crosta superior. / In the Patagonian Andes region between 41 and 44° S extensive and continuous plutonic rocks of the North-Patagonian Batholith north segment are exposed. During their evolution most of the granitic rocks were emplaced in metamorphic rocks and other parts were emplaced in Late Jurassic-Berriasan volcanic rocks, Early Cretaceous sedimentary and volcanic rocks, Late Cretaceous volcanic rocks and Miocene sedimentary rocks. Part of this magmatic activity is associated with ore deposit genesis. The exposed plutonic rocks range mainly from diorites to granites and leucogranites, although the area is extensively dominated by intermediate to acid varieties. K-Ar determinations have allowed identification of extensive and voluminous plutonic events which describe two N-S oriented belts during the late Lower Cretaceous (ca. 120-100 Ma) and Miocene (ca. 20-7 Ma), discreet during the Upper Jurassic (ca. 155 Ma) and the Upper Cretaceous (ca. 95-70 Ma), restricted during the early Pliocene (ca. 5-3 Ma) and a probable plutonism in Eocene times (ca. 54-34 Ma), while Ar/Ar experiments confirm the late Lower Cretaceous (ca. 126-100 Ma) and Miocene (ca. 19-9 Ma) magmatic events. Conventional U-Pb determinations indicate the probable inheritance and loss of Pb, although they confirm the late Lower Cretaceous (ca. 129-114 Ma) and Miocene (ca. 22-13 Ma) magmatic events. In addition, the zircons conventional U-Pb determinations show the presence of pre-Andean Lower Devonian magmatic rocks (ca. 400 Ma) probably linked with rocks of the North- Patagonian Massif. Zircon U-Pb SHRIMP determinations indicate 110.0±9.6 Ma for a monzogranitic pluton and 126.3±6.7 Ma for a pyroxene dioritic stock, 8.4±0.3 Ma for a tonalitic pluton and 13.26±0.19 Ma for hornblende andesitic porphyry, and 385.9±7.4 Ma for a tectonized microdioritic body. These data indicate that the early plutonic activity is represented, in Mesozoic and Cenozoic belts, by basic to intermediate small bodies of shallow emplacement, and the SHRIMP U-Pb Devonian age confirms a magmatic event previously inferred by conventional U-Pb ages. The age distribution shows a complex pattern, which nevertheless allows, magmatic Cretaceous events to be located, preferably, to the E of the Liquiñe-Ofqui Fault Zone, magmatic Miocene events located in and to the W of this structure, and magmatic Pliocene events located in the main branch of the Liquiñe-Ofqui Fault Zone to be defined. The Miocene plutonic activity towards the trench is different to the defined pattern for the north-central Chilean Andes, where the magmatic arc migration to the E and the consequent age diminution in this same direction is verified. Nd and Sr isotopic compositions show low and positive Nd values together with Sr between -4 and +7 suggesting that the North-Patagonian Batholith in the studied segment, has been composed from mixing of mantle derived or mafic lithospheric material with melting of lower continental crust, as is shown by previous work in neighboring areas. The Pb isotopic compositions in feldspar, of the same dating samples by U-Pb conventional method, varied with the age, plutons with 206Pb/204Pb greater than 18.62 are Miocene, whereas those plutons with 206Pb/204Pb less than 18.57 are Cretaceous, with an inverse relation between Miocene plutons, which is attributed to varying interaction grade with the metamorphic basement. Metal base-mineralization with Au and Ag contains are hosted in Cretaceous volcanic rocks and restricted to the Lower Cretaceous magmatic belt and Au-As mineralization are hosted in Devonian microdiorite and Paleozoic metamorphic rocks and restricted to the Miocene magmatic belt. Also, in both belts Cu-Mo occurrences are reported in associated with monzogranites and tonalities, respectively. Metal base and precious mineralizations in the Las Juntas Prospect are related to silicicadularia and quartz-sericite alteration and deposition of pyrite, sphalerite, Ag-bearing and Bi-bearing galena, and chalcopyrite, and minor hematite, tetrahedrite, arsenopyrite, bornite and chalcocite, in vein, veinlets and minor breccia bodies, and scarce dissemination. Ore grades are variable, but in mineralized Cu-veins the values reach up 15% Cu, and in Pb-Zn-Cu breccias the values reach up 32% Pb, 23% Zn and 0.28% Cu, 1.4 to 1,300 ppm Ag and 0.02 to 3.9 ppm Au. Fluid inclusion data indicate homogenization temperatures varying between 140 to 230 ºC, salinities ranging from 3 to 6 weight % NaCl equivalent, and metal base deposition during boiling and mixing events. Asmineralizations with gold contain in the Pichicolo Prospect are related to silicic and quartz-sericite alterations and deposition of arsenopyrite and pyrite, and minor pyrrotite, chalcopyrite and bornite, in veinlets, stockwork and dissemination. Grades vary between 0.02 to 2.0 ppm Au. Fluid inclusion data indicate homogenization temperatures varying between 180 to 270 ºC, salinities ranging from 3 to 5 weight % NaCl equivalent, and metallic deposition during boiling and mixing events. The mineralization, alteration and the chemical and physical fluid characteristics suggest for both studied prospects epithermal low-sulphidation features. Re-Os method in molybdenites hosted in monzogranitic and tonalitic plutons have been used to determine timing of Cu-Mo mineralizations. The obtained ages (ca. 119 and 9.1 to 8.2 Ma) suggest that the mineralization occurred in hydrothermal systems closely associated with late Lower Cretaceous and Miocene plutonic events, which confirm the interpretation about the existence of Lower Cretaceous and Miocene metallogenic belts proposed for the North-Patagonian Cordillera. Biotite of the monzogranitic host rock directly related with the Palena village molybdenite mineralization was dated by Ar/Ar in 114.7 Ma, and near of the occurrence in 114.2 Ma. Biotite of the tonalite host rock directly related with the Reloncaví estuary molybdenite mineralization was dated by Ar/Ar in 8.53 Ma and near of the occurrence in 8.64 Ma. The proximity, and superposition within the analytical error, between the Ar/Ar biotite ages, in both areas, suggests non extended hydrothermal alteration. Rb-Sr isochron age of 126±8 Ma obtained from hydrothermally alterated rocks in a polymetallic prospect is interpreted as the age of the hydrothermal event. Ar/Ar step-heating experiments in hydrothermal very fine grain sericite from Au-As mineralization shown Ar-redistribution by recoil effect and the integrated age of 142±2 Ma suggest that the association mineralization-Jurassic volcanic felsic magmatism should not be discarded. Sr and Nd isotopic compositions of the host and igneous-related mineralization rocks indicate that magmas are mainly mantle derived with variable little crustal contamination. Pb isotopic compositions of the ore minerals, host and igneous-related mineralization rocks in both prospect clusters near of the orogene curve within a plumbotectonic model. On 206Pb/204 versus 207Pb/204Pb plot, the ore minerals and the associated igneous units of the Las Juntas prospect are less radiogenic (206Pb/204Pb <18.6) that the Pichicolo prospect (206Pb/204Pb >18.6). This model is compatible with the absolute Cretaceous mineralization-age determined for the Las Juntas prospect and with the constraint Miocene mineralization-age for the Pichicolo prospect. The elongate trends of the ore minerals in the general clusters indicate mainly an orogenic model fit, suggesting variable mixing of lead from different sources, mainly from upper crust.

Ce travail de thèse avait pour objectif de développer une méthode basée sur l’étude de la composition isotopique du soufre (δ 34S) permettant de déterminer l’origine, biotique/abiotique, des sulfures de fer au sein des couches de produits de corrosion (CPC). Puis, il s’agissait d’appliquer la méthodologie développée à des systèmes réels afin de déterminer les mécanismes de formation de ces sulfures de fer. Des méthodes d’analyse isotopique du soufre adaptées aux liserés de sulfures de fer micrométriques observés dans les systèmes réels ont été développées en nanoSIMS et ToF-SIMS. L’étude de sulfures de fer formés en milieu carbonaté anoxique en présence, ou non, de bactéries sulfato-réductrice a permis de valider l’emploi de ces méthodes pour la détermination de l’origine des sulfures de fer. L’application de ces méthodes isotopiques couplées à la caractérisation des sulfures de fer dans les systèmes réels a mis en évidence 2 faciès. Le faciès 1 pour lequel les sulfures de fer sont situés en externe de la CPC. Ils résultent de la migration des ions Fe2+ produits au niveau du métal jusqu’aux zones riches en ions S2- d’origine biotique. Les vitesses de corrosion y sont inférieures à 20 μm/an pour les systèmes de laboratoire et à 5 µm/an pour les objets archéologiques. Et le faciès 2 pour lequel la forte présence de phases conductrices dans la CPC entraîne une délocalisation des électrons, conduisant à la migration des ions S2- d’origine biotique vers le métal où ils précipitent sous forme de sulfures de fer. Ce faciès présente de fortes avancées de corrosion locales (200 µm) qui seraient dues à l’accumulation de phénomènes de corrosion par les chlorures et de biocorrosion. / The first goal of this project was to develop a methodology based on the study of the sulfur isotopic composition enabling the determination of iron sulfides origin, biotic or abiotic, within the corrosion products layers (CPL). Then, the aim was to apply this methodology to real corrosion systems in order to determine the mechanisms of iron sulfides formation. Sulfur isotopic analyses methodologies, adapted to micrometric iron sulfides layers observed in real corrosion systems, were developed in nanoSIMS and ToF-SIMS. The study of iron sulfides formed in anoxic carbonated medium with or without sulphate-reducing bacteria validated the use of these methods for the determination of iron sulfides origin. The application of these methods coupled with the precise characterization of irons sulfides formed in the real corrosion systems show two kind of corrosion pattern. In pattern 1, the iron sulfides are localized in the external part of the CPL. They result from the Fe2+ migration from the metal surface to areas rich in biotic S2-. In this pattern, corrosion rates are lower than 20 μm/year for laboratory systems, and lower than 5 μm/year for archaeological objects. In pattern 2, the large presence of conductive phases in the CPL results in the delocalization of electrons, and so a disequilibrium of the charges at the metal’s surface. That leads to the migration of biotic S2- in the CPL till the metal where they precipitate in iron sulphides. This pattern shows high corrosion rates (~100 μm/an) that might be resulting from the accumulation of biocorrosion and chloride corrosion mechanisms.

La dilution isotopique, SID pour « Stable Isotope Dilution », est une méthode largement utilisée pour la quantification de peptides et protéines en spectrométrie de masse, généralement associée aux techniques d’ionisation ambiante. Les travaux de cette thèse sont donc consacrés à l’application de la méthodologie de la dilution isotopique (SID) en spectrométrie de masse par désorption/ionisation laser assistée par une matrice (MALDI) pour la mesure d’interaction récepteur/ligand en pharmacologie. En effet, un nombre important de pathologies mettent en jeu des récepteurs membranaires tels que les récepteurs couplés aux protéines G (RCPG) en interaction avec différents ligands, souvent peptidiques. En particulier, le récepteur V1A est impliqué dans l’activité vasoconstrictrice de l’hormone peptidique AVP (Arginine VasoPressine) et la contraction de cellules musculaires ainsi que dans certains comportements sociaux. Ce récepteur a été choisi comme modèle d’étude nécessitant le marquage par voie chimique du ligand Homo-HO-LVA (pour « Hydroxy Linear Vasopressin Antagonist »), sélectionné pour sa forte affinité envers le récepteur V1A afin d’introduire l’entité permettant le dosage en SID/MALDI. Cette méthodologie est mise en œuvre via la génération d’une liaison covalente de la matrice HCCA (4-hydroxy-α-cyanocinnamic acid), couramment utilisée pour l’analyse peptidique pour obtenir le peptide modifié (JMV4854) par acylation en position N-terminale. Le but est alors de tirer profit de l’utilisation conjointe de ce marquage et de la matrice neutre HCCE (4-hydroxy-α-cyanocinnamate de méthyle) pour la détection spécifique et sensible de composés jusqu’à des concentrations picomolaires. L’étape stratégique de quantification par dilution isotopique nécessite un étalonnage et une validation statistique avant de pouvoir passer à l’application pharmacologique. Celle-ci consiste à mesurer l’affinité du JMV4854 pour le récepteur V1A par des expériences thermodynamiques de mesure de constantes de dissociation (Kd) afin de déterminer par la suite des constantes de dissociation de molécules non marquées via des expériences de compétition. Un second modèle de récepteur, le CCKB-R (cholecystokinine B receptor), a ensuite été étudié pour valider la méthodologie de quantification. Devant le regain d’intérêt des laboratoires pharmaceutiques pour les expériences cinétiques de mesure de constantes de dissociation, il serait intéressant d’y appliquer cette méthodologie. Celle-ci présente un potentiel intéressant en tant qu’alternative aux méthodologies actuellement incontournables que sont la radioactivité et la fluorescence. Un second d’axe d’étude a été initié avec un marquage conçu pour diriger la fragmentation de peptides pour des mesures en spectrométrie de masse en tandem par ionisation Electrospray (ESI-MS/MS). Des modifications par introduction en position N-terminale des peptides d’une charge fixe ont été envisagées. Des études préliminaires (synthèse d’ions préformés par incorporation d’une entité pyridinium) ont montré un comportement prometteur en fragmentation ouvrant de nouvelles perspectives de quantification. / The SID methodology, for Stable Isotope Dilution, is a widely applied methodology for peptides and proteins analysis in mass spectrometry, usually associated with atmospheric pressure ionisation techniques. This thesis is consequently devoted to the application of SID methodology in matrix assisted laser desorption/ionisation (MALDI) mass spectrometry to quantify receptor/ligand interaction in pharmacology. Indeed, a great number of pathologies involve membrane receptors like G protein coupled receptors (GPCR) in interaction with several ligands, frequently peptides. Particularly, the V1A receptor, is related to vasoconstriction activity of the peptide hormone AVP (arginine vasopressine) and contraction of muscular cells as well as many social behaviors. This receptor was chosen as model, requiring the chemical labelling of the ligand Homo-HO-LVA (Hydroxy Linear Vasopressin Antagonist), selected for its high affinity towards the V1A receptor in order to introduce the entity on which relies the quantification in SID/MALDI. This methodology is applied through the covalent binding of HCCA (4-hydroxy-α-cyanocinnamic acid) matrix, usually encountered in peptide analysis, to obtain the modified peptide (JMV4854) through N-terminal acylation. The objective is to take advantage of the use of both HCCA tagging and HCCE (4-hydroxy-α-cinnamic methyl ester) matrix for the specific and sensitive detection of compounds down to picomolar concentrations. Importantly, quantification with SID requires a calibration protocol and a statistical validation before pharmacological assays. This consists in the measurement of JMV4854 affinity towards V1A-R through thermodynamic experiments in order to quantify the dissociation constant (Kd) and determine afterwards constants for untagged molecules by competitive binding assays. Furthermore, a second receptor model, CCKB-R (cholecystokinine B receptor), was then studied to validate the quantification methodology. Facing the renewed interest in pharmaceutic industry of kinetic experiments for dissociation constant measurement, it would be interesting to apply this new methodology to drug discovery, representing a relevant alternative to current “gold-standard” methodologies such as radioactivity and fluorescence. A second field of research has been initiated with a covalent labelling designed to enhance peptide fragmentation for electrospray-based (ESI-MS/MS) tandem mass spectrometry measurements. Preliminary studies with the synthesis of pre-formed ions like N-terminal substitution with pyridinium entities gave very promising results opening the way of other quantification strategies.

Magister Scientiae - MSc / This research investigated the nature, source and the spatial variation of the salinity of the water used for irrigation in the urban farming area of Philippi, which lies in the Cape Flats region of the Cape Town Metropolitan Area, South Africa. The irrigation water is mainly drawn from the Cape Flats aquifer, and pumped into ponds for eventual crop irrigation. Water samples were collected in summer and in winter from fifteen selected sites using standard water sampling procedures. Each site consisted of one borehole and one pond. The samples were routinely analyzed for salinity levels, and concentrations of major and minor ions. From the same boreholes and ponds, water was sampled in summer for isotope analysis to assess effects of evaporation on the water quality and salinity. Descriptive statistics were used to display the variation in range of specific ions in order to compare them with the recommended ranges. Geographical Information Systems analysis described the spatial distribution of the salinity across the study area, and hydrogeochemical analysis characterized the various waters and detected similarities between the water samples in the study area and other waters found in the Cape Flats region. In addition, the US salinity diagram classification of irrigation water developed by Richards (1954) was used to assess the current suitability of groundwater and pond water samples collected during the entire sampling period for irrigation activities. The research indicated that the concentrations of some ions such as chloride, nitrate, potassium and sodium exceeded in places in the study area, the target range values set by the Department of Water Affairs and Forestry (DWAF, 1996) and the Food and Agriculture Organization (Ayers and Westcot, 1985). It revealed that borehole and pond water were mostly brackish across the area regarding their total dissolved salts content, and fresh water was only found in the middle part of the study area. The research found that sea water does not intrude into the aquifer of the study area, and the accumulation of salts in groundwater and soil in the study area is mainly due to the agricultural activities and partially due to the natural movement of water through the geological formation of the Cape Flats region. The conceptual model of the occurrence of the salinization process supported these findings. From this investigation it is understood that the groundwater and pond water in the study area were generally suitable for irrigation purposes but they have to be used with caution as the vegetables are classified as sensitive and moderately sensitive to salt according to DWAF Irrigation water guidelines (1996). The quality of these waters was mainly affected by the land use activities. / South Africa

Les plantes hyperaccumulatrices peuvent accumuler des concentrations extraordinaires de métaux dans leurs parties aériennes (e.g. Ni, Zn et Cd). Cette thèse a été entreprise afin d’élucider : 1) comment le Ni est absorbé par les racines des hyperaccumulateurs, et 2) comment il circule dans les différents organes via le xylème et le phloème. Les travaux ont utilisé des cultures hydroponiques avec l’hyperaccumulateur de Ni et Zn Noccaea caerulescens en présence de concentrations faibles et élevées de Ni et Zn et en interaction avec Fe et Co ; des analyses isotopiques et d’expression de gènes ont été conduites. Les résultats ont montré que l’hyperaccumulateur N. caerulescens possède un système de transport du Ni à faible affinité et à haute efficacité. L’absorption du Ni semble impliquer principalement les transporteurs de Zn et Fe. Le transport par le xylème est la principale voie d'accumulation du Ni dans les jeunes feuilles et les feuilles âgées. Mais la translocation par le phloème est aussi une source importante de Ni pour les jeunes feuilles. Dans le phloème, le Ni est principalement chélaté par des acides organiques, de type malate. La thèse ouvre des perspectives pour l’optimisation des procédés de phytoextraction et d’agromine des sols contaminés. / Hyperaccumulating plants are capable of accumulating extraordinary concentrations of heavy metals, e.g. Ni, Zn and Cd, in their shoots. This thesis was conducted to assess: 1) how roots of hyperaccumulators absorb Ni, and 2) how Ni circulates in different organs via xylem and phloem. Methods used were hydroponic cultures with the Ni/Zn hyperaccumulator Noccaea caerulescens in the presence of low and high Ni and Zn solutions, and in competition with Fe, Co, and Rb and Sr. Isotope fractionation in the plant, and gene expression of the Zn transporter ZIP10 and the Fe transporter IRT1 were studied. Results showed that the hyperaccumulator N. caerulescens takes up Ni mainly via low-affinity transport system, which seemed to be Zn and Fe transporters. Xylem transport is the main source for Ni accumulation in both young and old leaves, while phloem translocation also acts as an important source for young leaves. Ni is enriched in phloem sap and mainly chelated by organic acids especially malate during phloem translocation.

Abstract Dissimilatory microbial sulfate reduction (MSR) The specific objectives of the study were to provide the first measurements of sulfur isotope fractionation associated with acidophilic sulfate reducing-microorganisms, and to examine whether pH influences sulfur fractionation during MSR. The fractionation associated with the strains investigated was comparable to that of neutrophilic strains with similar metabolisms (4-12‰), but varied with pH. Two fractionation regimes were identified: one regime is consistent with fractionation during exponential growth, while the other – not identified previously - is not linked to active sulfate reduction and may result from internal sulfate accumulation. This would represent the first measurement of sulfur fractionation during sulfate uptake, the first step of MSR. Geological processes at the Cretaceous-Paleogene (KPg) boundary The KPg boundary is associated with one of the largest biological extinctions in the history of our planet. Two major geologic events - the Chicxulub bolide impact with evaporite terrane and the eruption of the Deccan continental flood basalts - coincide with the KPg boundary and have been identified as possible triggers for the extinctions, but their relative timing remains unresolved. The objectives of this study were to identify the contribution of these processes to the sulfur burden in the sedimentary environment of two freshwater KPg sections, and to determine their relative timing. The results demonstrate that the peak of Deccan volcanism post-dates the Chicxulub impact and the associated abrupt KPg mass extinction, thus precluding a direct volcanic causal mechanism, but shedding light on the underlying causes for the delayed recovery of ecosystems in the early Paleogene.

Cette thèse est consacrée à l'étude du conditionnement des parois des réacteurs de fusion, en particulier ITER. Le conditionnement est nécessaire pour contrôler l'état de surface de l'enceinte à vide et donc les performances des plasmas d'ITER.Le conditionnement du tokamak JET, ayant une paroi représentative de celle d'ITER, et son impact sur l'opération est étudié de manière approfondie.Un modèle 2D des décharges luminescentes de conditionnement est validé par des données expérimentales. Il prédit des décharges raisonnablement uniformes dans ITER.Des expériences de conditionnement sur JET montrent que l'échange isotopique est un moyen efficace pour contrôler l'inventaire de tritium dans ITER, l'efficacité d'élimination étant potentiellement comparable à la rétention prédite dans un plasma nominal.Un modèle 1D de l'hydrogène échange isotopique en béryllium est élaboré et validé. Il montre que la fluence et la température de surface déterminent l'efficacité de l'échange isotopique. / Thesis is devoted to studies of performance and efficiency of wall conditioning techniques in fusion reactors, such as ITER. Conditioning is necessary to control the state of the surface of plasma facing components to ensure plasma initiation and performance. Conditioning and operation of the JET tokamak with ITER-relevant material mix is extensively studied. A 2D model of glow conditioning discharges is developed and validated; it predicts reasonably uniform discharges in ITER. In the nuclear phase of ITER operation conditioning will be needed to control tritium inventory. It is shown here that isotopic exchange is an efficient mean to eliminate tritium from the walls by replacing it with deuterium. Extrapolations for tritium removal are comparable with expected retention per a nominal plasma pulse in ITER.A 1D model of hydrogen isotopic exchange in beryllium is developed and validated. It shows that fluence and temperature of the surface influence efficiency of the isotopic exchange.

Orientadores: Elson Paiva de Oliveira, Elton Luis Dantas / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Geociencias / Made available in DSpace on 2018-08-07T09:32:09Z (GMT). No. of bitstreams: 1 Carvalho_MarceloJuliano_D.pdf: 10664209 bytes, checksum: 0a433fc7eec27e438242f51755d9cd54 (MD5) Previous issue date: 2005 / Resumo: O presente trabalho procurou avançar nos conhecimentos sobre a evolução tectônica da Faixa Sergipana, um cinturão de rochas dobradas que ocorre na porção sul da Província Borborema bordejando o Cráton do São Francisco (CSF), com base na estudo da evolução tectônica de dois de seus domínios: os domínios Marancó e Poço Redondo. Para atingir esse objetivo foi realizado trabalho de campo detalhado que teve como base quatro cartas geológ icas em escala 1:100.000 e imagens de satélite (LANDSAT- TM), buscando observar as relações estruturais entre os diferentes Iitotipos. Sobre essa base geológica foram realizados estudos petrográficos, análises geoquímicas em rocha total (elementos maiores e traços), análises de isótopos de Nd e geocronologia U-Pb (SHRIMP e TIMS) nos principais Iitotipos. Os dados obtidos mostram que os domínios Marancó e Poço Redondo são intimamente correlacionados. Propõe-se aqui a denominação Domínio Marancó¿Poço Redondo para o conjunto de rochas que ocorre a norte da Zona de Cisalhamento Belo Monte-Jeremoabo e a sul da seqüência vulcanossedimentar de Canindé do São Francisco. A geologia de campo mostrou que o domínio é caracterizado por um bloco de rochas migmatíticas intrudido por diversos corpos granitóides e por uma seqüência vulcanossedimentar adjacente. Os migmatitos são orto-derivados, em sua maioria, e são intrudidos por pelo menos três gerações de granitos distintos. A seqüência vulcanossedimentar é dominada pela ocorrência de rochas metassedimentares imaturas. Metagrauvacas, metarritmitos, metapelitos, quartzitos e metaconglomerados ocorrem com freqüência. As rochas sedimentares têm forte contribuição de rochas vulcânicas intermediárias a acidas em sua gênese e são intercaladas a rocha piroclásticas. Lascas de rochas ultramáficas foram tectonicamente colocadas junto as supracrustais, principalmente na porção norte da seqüência. A geoquímica revelou que o paleossoma dos migmatitos Poço Redondo é granodiorítico e apresenta afinidade geoquímica com plútons de arco magmático. Duas idades U-Pb (SHRIMP) obtidas mostram que esses plútons foram gerados entre 980 e 960 Ma, portanto ligados a Orogênese Cariris Velhos. Os isótopos de Nd permitem considerá-los como gerados em arco de margem continental, onde magmas juvenis interagiram com crosta pré-existente. O augen gnaisse Serra Negra intrude os migmatitos e a seqüência vulcanossedimentar. A geoquímica desses granitos é característica de granitos pós-tectônicos ou associados a zonas de cisalhamento transcorrentes profundas. Uma idade obtida posiciona sua geração logo apôs a geração do granodiorito Poço Redondo, também ligada a Orogênese Cariris Velhos. Na seqüência vulcanossedimentar as rochas sedimentares apresentam características geoquímicas semelhantes às rochas geradas em ambientes de arcos modernos. O estudo de proveniência de sedimentos, realizado por datação de zircão detrítico e de análises Sm-Nd, mostra que a seqüência tem fontes muito restritas e predominantemente ligadas a Orogênese Cariris Velhos, provavelmente ao arco continental adjacente. Além desse conjunto de rochas ligadas ao ciclo Cariris Velhos, rochas associadas à Orogênese Brasiliana também ocorrem. O granodiorito Sítios Novos íntrude as demais unidades. Tratam-se de corpos granodioríticos ísotrópicos ricos em enclaves máficos. Esses granitos apresentam afinidade com granitos de arco magmático. Análise U-Pb mostrou idade de 650 Ma e os isótopos de Nd mostram que sofreram forte contaminação em sua gênese. Rochas vulcânicas andesíticas e dacíticas com afinidade com arco continental intrudem a seqüência vulcanossedimentar de Marancó. Idades de 602 Ma (U-Pb, SHRIMP) foram obtidas nessas rochas. Os isótopos de Nd mostram características semelhantes às dos granitos Sítio Novos. Esse conjunto foi provavelmente gerado em arco de margem continental durante a Orogênese Brasiliana. A deformação foi dividida em dois principais ciclos. O primeiro ciclo evoluiu de tectônica compressiva com vergência para SSW para uma fase transcorrente sinistrai. Três fases foram individualizadas. As relações de campo, sobretudo a das estruturas com os corpos graníticos datados, sugerem que essa deformação pode estar ligada a Orogênese Cariris Velhos. Um segundo ciclo deformacional, representado por zonas de cisalhamento transcorrentes que cortam toda a Faixa Sergipana, afeta as rochas do Domínio Marancó-Poço Redondo, porém em menor intensidade que o ciclo anterior. Esse segundo ciclo é relacionado à Orogênese Brasiliana. O Domínio Marancó Poço Redondo deve, portanto, configurar um arco continental e bacia adjacente gerados na margem sul do Maciço PEAL durante a Orogênese Cariris Velho. Esse bloco foi posteriormente descolado de seu local de origem e mais tarde acrescido à margem norte do Cráton do São Francisco durante a Orogênese Brasiliana. O domínio registra evidências dos dois ciclos orogenéticos em questão e o entendimento da relação entre eles pode contribuir para o entendimento das faixas de dobramento pré-cambrianas e, sobretudo, da Faixa Sergipana. / Abstract: This Thesis aims to advance in the geological knowledge of the Sergipano Belt, by studying the tectonic evolution for two within seven lithotectonic domains: the Marancó -Poço Redondo Domain. To reach the objective a detailed field work, that used four geological maps (1:100.000) from the Carira Project (PLGB, DNPM-CPRM, 1988) as base maps and a Landsat image, was carried out, with the aim to determinate the structural relationships between the main lithologies. Petrographic and geochemical analyses were performed and Sm-Nd isotopic and U-Pb (SHRIMP) data were acquired for the main rock types. The data show that the Marancó and Poço Redondo domains are closely related. We propose the denomination of Marancó - Poço Redondo Domain for the group of rocks that occurs to the north of the Belo Monte-Jeremoabo Shear Zone and to the south of the Canindé do São Francisco sequence. Field geology showed that the domain is composed by a migmatitic unit, which is intruded by several granitic bodies, and by a meta-volcano sedimentary sequence. The migmatites are orto-derived and intruded by at least three distinct granitic suites. The meta-volcano sedimentary sequence is characterized by immature sedimentary rocks. The main rock types include meta-greywacke, meta-pelites, quartzites and meta-conglomerades. Intermediate volcanics were probably the main source for the sedimentary sequence. Ultramafic rocks occur as tectonic slices intercalated to the sedimentary rocks. The geochemistry shows that the migmatites paleossome are granodioritic in composition and have geochemical affinities with magmatic arc plutonism. Two U-Pb (SHRIMP) ages of 980 and 960 were obtained for the migmatites. Theses ages link the migmatites to the Greenvile/ Cariris Velho Orogeny. The Nd isotopic data allow us to consider them as continental margin arc plutons, were juvenile magmas interacted with continental crust. The Serra Negra augen gneiss intrudes the migmatites and the meta-volcano sedimentary sequence. Its geochemical data shows that it is probably late tectonic and associated with major transcurrent shear zones. A SHRIMP age of 951 Ma. was acquired for this granites, which means that they were generated soon after the migmatites. In the meta-volcano sedimentary sequence, the sedimentary rocks show geochemical affinities with those generated in continental margin arc basins. A provenance study was carried out by dating detrital zircons and by Sm-Nd analyses in the sedimentary rocks. This study showed that the sequence has a very restrict source, strongly dominated by Cariris Velho-aged rocks, probably related to the continental arc. Besides the rocks closely related to the Cariris Velho Orogeny, Brasiliano/Pan-African aged rocks also occur. The Sítios Novos granite occurs as several intrusive, enclave-rich granodioritic bodies, which crosscut all the other rocks. Its geochemistry showed that it is calco-alkalic, metaluminous arc-related granite. A U-Pb (TIMS) analysis yields an age of 650 Ma and the Nd isotopic data shows strong contamination with older continental crust. Volcanic andesitic and dacitic arc- related rocks occur as dikes and sills cutting the metassedimentary sequence. Two samples were analyzed and yield U-Pb (SHRIMP) ages of 602 Ma. The Nd isotopic composition is very similar to that for the Sítios Novos granites. The deformational history for the Marancó - Poço Redondo Domain can be divided in two major cycles. The first one evolved form a compressional tectonics that developed SSW thrust faults, to dominantly sinistral transcurrent within three deformational fazes. Field relationships, chiefly those between the dated granites and structures, allow the interpretation of that this first cycle is related to the Cariris Velhos Orogeny. The second one is represented by regional scale transcurrent shear zones, which affect only the borders the Marancó Poço Redondo Domain. This second cycle is related to the Brasiliano/Pan-African Orogeny. Therefore, the Marancó Poço Redondo Domain represents a fragment of a continental margin arc and its related basin formed during the Greenvile/Cariris Velhos Orogeny at the southern margin of the Pernambuco - Alagoas Massif. The domain was detached from its original tectonic setting and accreted to the northern margin of the São Francisco Craton during the Pan-African / Brasiliano Orogeny. It records features of these two major tectonic cycles and the understanding of their relationships can be very helpful on the understanding of the Precambrian fold belts, in special the Sergipano Belt. / Doutorado / Metalogenese e Geoquimica / Doutor em Geociências

Chloroperoxidase (CPO) is a heme-containing glycoprotein secreted by the marine fungus Caldariomyces fumago. Chloroperoxidase contains one ferriprotoporphyrin IX prosthetic group per molecule and catalyzes a variety of reactions, such as halogenation, peroxidation and epoxidation. The versatile catalytic activities of CPO coupled with the increasing demands for chiral synthesis have attracted an escalating interest in understanding the mechanistic and structural properties of this enzyme. In order to better understand the mechanisms of CPO-catalyzed enantioselective reactions and to fine-tune the catalytic properties of chloroperoxidase, asparagine 74 (N74) located in the narrow substrate access channel of CPO was replaced by a bulky, nonpolar valine and a polar glutamine using site-directed mutagenesis. The CPO N74 mutants displayed significantly enhanced activity toward nonpolar substrates compared to wild-type CPO as a result of changes in space and polarity of the heme distal environment. More interestingly, N74 mutants showed dramatically decreased chlorination and catalase activity but significantly enhanced epoxidation activity as a consequence of improved kinetic perfection introduced by the mutation as reflected by the favorable changes in kcat and kcat/KM of these reactions. It is also noted that the N74V mutant is capable of decomposing cyanide, the most notorious poison for many hemoproteins, as judged by the unique binding behavior of N74V with potassium cyanide. Histidine 105 (H105) was replaced by a nonpolar amino acid alanine using site-directed mutagenesis. The CPO H105 mutant (H105A) displayed dramatically decreased chlorination and catalase activity possibly because of the decreased polarity in the heme distal environment and loss of the hydrogen bonds between histidine 105 and glutamic acid 183. However, significantly increased enantioselectivity was observed for the epoxidation of bulky styrene derivatives. Furthermore, my study provides strong evidence for the proposed histidine/cysteine ligand switch in chloroperoxidase, providing experimental support for the structure of the 420-nm absorption maximum for a number of carbon monoxide complexes of heme-thiolate proteins. For the NMR study, [dCPO(heme)] was produced using 90% deuterated growth medium with excess heme precursors and [dCPO(Phe)] was grown in the same highly deuterated medium that had been supplemented with excess natural phenylalanine. To make complete heme proton assignments, NMR spectroscopy has been performed for high-resolution structural characterization of [dCPO(heme)] and [dCPO(Phe)] to achieve unambiguous and complete heme proton assignments, which also allows important amino acids close to the heme active center to be determined.

Cette thèse vise à développer de nouvelles méthodes efficaces pour incorporer des isotopes de l’hydrogène dans les molécules organiques complexes, après une introduction portant sur les applications et la synthèse des molécules marquées par le deutérium et tritium. Les méthodes permettant le marquage, par échange isotopique direct, d’hétérocycles azotés par des isotopes de l’hydrogène restent perfectibles, voire inexistantes dans certains cas, malgré la récurrence de ce type de sous-structures dans les molécules d’intérêt pharmacologique. Pour cette raison, la majeure partie de ce travail a consisté au développement de nouvelles méthodes d’incorporation d’atomes de deutérium et de tritium sur des hétérocycles azotés catalysées par des nanoparticules métalliques. Dans un premier chapitre, la mise au point, le champ d’application d’une méthode de marquage mettant en jeu l’utilisation de nanocatalyseurs de ruthénium seront discutés. Dans ce cadre, des calculs théoriques ont permis de rationaliser les regiosélectivités obtenues expérimentalement et d’identifier notamment des intermédiaires clefs inédits. D’un point de vue applicatif, cette méthode a permis de synthétiser des étalons internes deutérés pour la quantification LC-MS mais aussi des molécules complexes tritiées ayant des activités spécifiques élevées en une étape de synthèse. Dans un autre chapitre, la synthèse et la réactivité de nouveaux nanocatalyseurs de nickel permettant de réaliser des échanges isotopiques sélectifs seront discutés. / This PhD thesis deals with the development of new efficient methods for the incorporation of hydrogen isotopes into organic molecules, which represents a serious issue especially for drug discovery and drug development processes. After giving an introduction about hydrogen isotopes and their applications in organic molecules, the course will proceed to an overview of different chemical transformations for establishing deuterium or tritium labels on molecular frameworks. The possibilities to label N-heterocycles by hydrogen isotopes through hydrogen isotope exchange (HIE) are still very restricted and even impossible for some representatives despite the strong recurrence of these substructures in numerous biologically active molecules. For this reason, the emphasis of the practical part will lie on the development of new methods for the incorporation of deuterium and tritium on N-heterocycles through metal nanoparticle catalysis. In the first chapter, HIE through ruthenium nanocatalysts will be optimized and the application range will be demonstrated. In this context, DFT-based calculations allowed to explain experimental regioselectivities and to identify new keyintermediates. In terms of application, it was shown that the ruthenium-catalyzed method is useful for the synthesis of deuterium labelled internal standards for LC-MS quantifications and for the tritiation of complex molecules displaying satisfying specific activities. In the next chapter, the synthesis of new nickel nanoparticles and their potential to catalyze selective HIE on N-heterocyclic derivatives will be discussed.