Le colza est une culture oléagineuse très exigeante en intrants azotés associée à une faible efficience d’usage de l’azote (EUA). Le défi majeur vise à améliorer le bilan agroenvironnemental du colza par une optimisation de l’EUA, notamment en condition où l’azote est limitant dans le sol. L’EUA est limitée par une faible efficience de remobilisation de l’azote (ERA) lors de la sénescence des feuilles. L’objectif de ce travail de thèse a consisté à rechercher, chez le colza, la topologie et l’orientation des attributs métaboliques associées à l’ERA pendant la sénescence foliaire.Les résultats montrent que le métabolome des feuilles évolue tout au long de leur développement végétatif, de leur croissance à leur chute. Il est spécifique à chaque étage foliaire et traduit des relations trophiques et environnementales particulières liées au positionnement des feuilles dans le couvert végétal. Ces spécificités sont associées à des variations de teneurs en glucides, d’acides aminés,de glucosinolates et de coumarines en lien étroit avec la régulation phytohormonale du développement foliaire et avec leur translocation dans le phloème. Le cas de la Proline a été plus particulièrement approfondi et l’activation de son catabolisme sous régulation circadienne dans les tissus sénescents a été mise en évidence. Une approche combinée de transcriptomique et de métabolomique a permis de démontrer une variabilité génotypique importante dans les processus de dégradation et de transport des protéines, glucides et acides aminés entre deux génotypes à forte ERA. De la même manière, des relati / Oilseed rape is a very demanding oleaginous crop for nitrogen inputs associated with a low nitrogen use efficiency (NUE). The main challenge to improve the agri-environmental balance of oilseed rape is to optimize the NUE, especially under nitrogen deprivation. The NUE is limited by a low nitrogen remobilization efficiency (NRE) during leaf senescence. The aim of this thesis was to define the metabolome topology and orientation associated with NRE during leaf senescence in oilseed rape.The results show that leaf metabolome dynamically evolves throughout their vegetative growth, until their fall. Metabolome was found specific to each leaf rank, reflecting the trophic and environmental relationships related to the leaf positioning in the canopy. These specificities are associated with variations in carbohydrates, amino acids, glucosinolates and coumarins contents in close connection with the phytohormonal regulation of leaf development and with their translocation in the phloem.In particular, the activation of Proline circadian-controlled catabolism in senescent tissues was demonstrated. Finally, significant variations in the degradation and transport of proteins, carbohydrates and amino acids between two highly efficient NRE genotypes were highlighted using a combined transcriptomic and metabolomic approach. Similarly, a close relationship has been described between the genes expression levels and the metabolic content involved to increase NRE under low nitrogen input.The results are discussed regarding nitrogen remobilization improvement and more generally nutrients i

O Bloco São Gabriel, localizado na zona central do embasamento cristalino do Rio Grande Sul, apresenta extensos registros do Neoproterozóico do Ciclo Brasiliano, contidos em complexos ígneos e metamórficos. Esses complexos também guardam registros sedimentares, com sequências carbonáticas metamorfisadas, cuja evolução tectônica é pouco conhecida. Essas sequências são observadas na Formação Passo Feio (Caçapava do Sul), no Complexo Cambaí (Vila Nova do Sul) e no Complexo Metavulcano-sedimentar Coxilha do Batovi (São Gabriel). As rochas carbonáticas da Formação Passo Feio compreendem dolomita mármores impuros. As amostras do Complexo Cambaí são classificadas como calcita mármores impuros. Os mármores do Complexo Coxilha do Batovi compreendem litotipos calcíticos e cálcio-silicáticos, cuja assembleia mineral é composta predominantemente por calcita em alguns exemplares e por grafita em outros, com percentuais de até 10% de quartzo, demonstrando contribuição siliciclástica no protólito. Idades de zircões de rochas associadas com os mármores, de trabalhos anteriores, indicam um intervalo entre 770 – 700 Ma para a deposição dos carbonatos do Bloco São Gabriel. Os carbonatos da Formação Passo Feio sofreram dolomitização durante ou logo após a deposição, enquanto os carbonatos do Complexo Cambaí não foram afetados pela dolomitização. A geoquímica dos elementos traços e terras raras indica que os mármores analisados preservaram as assinaturas originais do protólito nos diferentes graus metamórficos: Coxiha do Batovi (grau baixo), Formação Passo Feio e Complexo Cambaí (grau médio). A análise integrada dos isotópicos de Sr, 13C e 18O da Formação Passo Feio e do Complexo Cambaí revelou a preservação de assinaturas isotópicas primárias. Na Formação Passo Feio essas assinaturas são: 0,7074 (Sr87/Sr86), -0,26‰ e 2,44‰ (δ13CPDB) e -5,68‰ (δ18OPDB). Quando comparadas com a variação desses isótopos na água do mar ao longo do Neoproterozóico, verifica-se que os mármores da Formação Passo Feio e do Complexo Cambaí estão situados no intervalo entre 740 e 730 Ma. O período sugerido para a deposição das rochas carbonáticas da Formação Passo Feio é de 770 a 730 Ma, e entre 740-730 para o Complexo Cambaí. / The São Gabriel Block, located in the central zone of the crystalline basement of Rio Grande do Sul has extensive Neoproterozoic records of the Brasiliano Cycle, contained in igneous and metamorphic complexes. These complexes also keep sedimentary records with metamorphosed carbonate sequences whose tectonic evolution is poorly understood. These sequences are found in Passo Feio Formation, located in Caçapava do Sul region, in Complex Cambaí, at Vila Nova do Sul region and in Coxilha do Batovi metavolcanosedimentary Complex, in the São Gabriel region. The Passo Feio Formation carbonate rocks consist of impure dolomite marbles. The Cambaí Complex samples are classified as impure calcite marbles. Coxilha do Batovi Complex samples include calcite and calc-silicate marbles whose mineral assemblage are composed predominantly of calcite in some samples and graphite in others, with quartz rates up to 10% showing the siliciclastic contribution to the protolith. Zircon ages of associated rocks from previous works indicate an interval between 770-700 Ma for carbonate deposition in S. Gabriel Block. The carbonates from Passo Feio Formation were affected by dolomitization process during or early after its deposition, while the carbonates from Cambaí Complex were not affected by dolomitization. Trace elements and REE geochemistry of marbles indicate preservation of original signature of carbonate protoliths along different metamorphic grades; Coxilha do Batovi (low grade), Passo Feio Formation and Cambaí Complex (medium grade). The integrated analysis of Sr isotope, 13C and 18O from Passo Feio Formation and Cambaí Complex revealed the preservation of primary isotopic signatures. The Passo Feio Formation signatures are: 0,7074 (Sr87/Sr86), -0,26‰ and 2,44‰ (δ13CPDB) and -5,68 (δ18OPDB). In Cambaí Complex, the primary signatures are: 0,7069 (Sr87/Sr86), 5,75 (δ13CPDB) and -11,64 (δ18OPDB). When compared with the variation of these isotopes in seawater along the Neoproterozoic it appears that Passo Feio Formation and Cambaí Complex are situated in the range between 740 and 730 Ma. Based on these data it is suggested that the São Gabriel Block depositional event occurred between 770-700 Ma. The period suggested for the carbonate rocks depositional event of Passo Feio Formation is between 770-730 Ma, and specifically between 740-730 for Cambaí Complex.

This dissertation contains a study about plane curves and surfaces. The two most common way to define this elements are reviewed: the parametric and the implicit definition, with emphasis on the latter. An analysis of some methods to represent plane curves and surfaces is made. One notices that this job is relatively simple when the parametric definition is used, however with the implicit definition this requires a larger number of operations. This works also presents some methods to find approximations of curves and surfaces implicitly defined that preserves the topology and that generate objects smooth enough. This is achieved basically by a subdivision of the plane (respectivelly the space), which is used to find a piecewise linear approximation of the curve (respectivelly the surface), then this approximation is subdivided to make the result smooth. In the case of surfaces the output is a triangular mesh. Some treatments are also made to improve the quality of the mesh. / Fundação de Amparo a Pesquisa do Estado de Alagoas / Esta dissertação contém um estudo a respeito de curvas planas e superfícies. São vistas as duas formas mais usuais de se definirem estes elementos: a definição paramétrica e a implícita, com ênfase nesta última. São analisadas algumas formas de representação de curvas planas e superfícies, o que vem a ser uma tarefa relativamente simples ao se utilizar a definição paramétrica, porém com a definição implícita isto exige um maior número de operações. São apresentados alguns métodos para encontrar aproximações de curvas e superfícies definidas implicitamente que mantenham a sua topologia e que geram objetos suaves o suficiente. Isto é feito basicamente subdividindo-se o plano (respectivamente o espaço), que é utilizado para aproximar a curva (respectivamente a superfície) de forma linear por partes, e então subdivide-se essa aproximação para que o resultado seja suave. No caso das superfícies a saída é uma malha triangular. São realizados também tratamentos para aumentar a qualidade desta malha.

La biodégradation stimulée est une méthode de dépollution in situ utilisée pour dégrader des hydrocarbures. Son suivi se fait actuellement via des forages coûteux et trop peu nombreux. Ce travail de thèse propose d’améliorer le suivi d’une biodégradation en combinant des méthodes géophysiques électriques (polarisation provoquée) et des analyses de CO2 (flux en surface et isotopie du carbone). Ces outils ont été testés à l’échelle du laboratoire, puis mis en œuvre sur un site pilote en cours de dépollution. La dégradation aérobie du toluène en colonnes par une souche bactérienne connue (Rhodococcus wratislaviensis) a été caractérisée par une production de CO2, un fractionnement isotopique du carbone, et par une évolution de la résistivité électrique complexe du milieu poreux, en corrélation avec les analyses microbiologiques et géochimiques. Ces résultats ont permis de mettre en place un suivi à l’échelle du terrain. Le site est une station-service où des fuites d’essences et de gasoil ont eu lieu il y a une quinzaine d’années. Une tranchée apporte de l’oxygène à la nappe pour stimuler les processus bactériens aérobies. Des campagnes géophysiques ainsi que des analyses de CO 2ont été réalisées à partir de février 2014. Les premiers résultats montrent une zone plus conductrice et plus chargeable qui correspond à la zone polluée définie par les analyses géochimiques en forages. De plus, au niveau de cette zone, de fortes émissions de CO2 ont été mesurées avec une signature isotopique caractéristique d’une biodégradation d’hydrocarbures. Ces résultats montrent l’intérêt de combiner des méthodes géophysiques avec des analyses de gaz pour surveiller des zones de biodégradation et d’ores-et-déjà, permettent de fournir une méthodologie non destructrice et originale de monitoring in situ. / Stimulated biodegradation is a depollution technique used to degrade hydrocarbons. Its monitoring is currently done thanks to very few expensive wells. This PhD research work proposes to improve bioremediation monitoring by combining geophysical electrical methods (induced polarization) and CO2 analyses (surface emissions and carbon isotopic ratio). These tools were tested at laboratory scale and then implemented on a pilot site under decontamination. Aerobic degradation of toluene in columns by a known bacterial strain (Rhodococcus wratislaviensis) was characterized by CO2 production, carbon isotopic fractionation and by an evolution of electrical complex resistivity of porous media, in correlation with microbiological and geochemical analyses. These results allowed to implement a monitoring at the site scale. The site is a gas station where gasoline and diesel leaked fifteen years ago. A trench supply oxygen to the water table in order to stimulate aerobic bacterial processes. Geophysical campaigns and CO2 analyses have been carried out since February 2014. The first results show a more conductive and chargeable area which corresponds to the contaminated zone defined by geochemical analyses in wells. Moreover in this area CO2 emissions have been measured with an isotopic signature typical of hydrocarbon biodegradation. These results show the interest of combining geophysical methods with gas analyses to monitor biodegradation and they have already allowed to provide a non-destructive and new methodology for in situ monitoring.

Le milieu interstellaire (MIS) où se forment les étoiles est constitué de gaz très dilué dominé par l'hydrogène moléculaire, et de grains de poussière de taille submicrométrique. Ces poussières jouent un rôle crucial en atténuant la lumière des étoiles lointaines, protégeant ainsi les molécules du gaz des rayonnements ultra-violets, et en servant de catalyseurs à une chimie hétérogène à très basse température. Outre la synthèse de l'hydrogène moléculaire, la surface des grains permet de former des molécules organiques dites complexes comme le méthanol (CH3OH) à partir de l'hydrogénation (et la deutération) du monoxyde de carbone (CO). Les glaces ainsi formées participent à la complexification moléculaire du MIS et seront à terme intégrées au sein de disques de poussières, berceaux des astéroïdes, comètes et exo-planètes. L'objectif de cette thèse est l'étude des mécanismes d'échanges hydrogène-deuterium sur certains groupements fonctionnels de molécules organiques simples, méthanol par exemple, présentes à la surface ou dans les manteaux des grains interstellaires. La thèse est centrée sur une exploration expérimentale de ces processus en phase condensée, à l'aide d'une expérience de cryogénie synthétisant des glaces à très basse température (15K) couplée à un spectromètre infrarouge. Nous montrons que ces échanges se produisent avant la sublimation du manteau de glace sur des groupes fonctionnels capables d'établir des liaisons hydrogènes avec les molécules d'eau voisines. Le processus catalysant est vraisemblablement la cristallisation de la glace d'eau. Des études cinétiques nous permettent d'évaluer les énergies d'activation du transfert H/D (6745K) et de la transition amorphe-cristalline (8100K), et de déterminer la constante de vitesse d'échange dans le domaine de température 120-140~K. Cette constante de vitesse est, de plus, comparée à des calculs semi-classiques basés sur un traitement ab initio. En marge de ces expériences, des observations millimétriques de la molécule de méthanol en direction de proto-étoiles confirment une variabilité des abondances relatives des isotopologues simplement deutérés de cette molécule en fonction de la masse de la protoétoile. / The interstellar medium where stars are formed consists of a dilute gas which is dominated by molecular hydrogen and dust grains less than a few microm in size. The dust plays a crucial role in the attenuation of light from the stars. They also protect molecules within the gas from UV photons. Furthermore, they serve as heterogeneous catalysts for chemistry at low temperature. The surface of the grains also permit the formation of complex organic molecules such as methanol via the hydrogenation and/or deuteration of carbon monoxide. The ices are formed and subsequently participate in increasing the molecular complexity of the clouds. Finally, they are incorporated into debris disks, asteroids, comets, and exoplanets. The objective of this thesis is to study the mechanism of hydrogen/deuterium exchange within certain functionnal groups of simple organic molecules such as methanol, which are present on the surface of these grain mantles. The thesis is focused on the experimental determination of these processes in the condensed phase. This will be achieved with the aid of a cryogenic synthesis of the ices at very low temperatures coupled with infrared spectrometry. We observe that it is possible for the exchange to proceed before the sublimation of the ice mantles. However, this is only the case when the functional groups within the molecule may form hydrogen bonds with water. From our results we see that this process seems to be catalysed by the crystalization of the water ice. The kinetics study permits us to evalute the activation energy for the H/D exchange (6745 K) and for the transition from amorphous to crystaline ice (8100 K). In addition it also allows us to determine the rate constant for the exchange in the temperature range 120-140 K. In addition we have performed theoretical calulation in an attempt to elucidate the mechanism for the exchange. However, the experimental rate constant for the exchange is much larger in comparison to the one predicted by a semi- classical treatment based on the AB initio potential we have obtained. Further to this observations of methanol towards protostars have been conducted. These observations show that there is a variation in the relative abundance of the CH2DOH and CH3OD. This variation in relative abundance seems to have some dependence upon the mass of the protostar, with high mass stars showing (CH2DOH/CH3OD ≤ 1) and low/intermiediate mass stars showing (CH2DOH/CH3OD >> 3).

O conhecimento das preferências ecológicas de espécies de foraminíferos planctônicos tem sido muito utilizada em investigações paleoceanográficas obtendo bons resultados. O presente estudo realizou inferências sobre as condições oceanográficas das águas superficiais da porção sudoeste do Atlântico Sul nos últimos 450.000 anos através da variação da abundância de foraminíferos planctônicos em dois testemunhos da Bacia de Campos. A partir da Análise de Correspondência foram identificados os três principais fatores responsáveis pela variação dos foraminíferos planctônicos encontrados em cada um dos testemunhos. No testemunho KF-13 os três fatores principais foram interpretados como temperatura, espessura da camada de mistura e sazonalidade; enquanto para o testemunho KF-14 os fatores foram definidos como espessura da camada de mistura, produtividade e sazonalidade. Com esses fatores foram identificados os intervalos de maior intensidade de ventos e produtividade na região. As principais mudanças climáticas do Atlântico Sul encontram-se relacionadas às mudanças de intensidade de ventos e dos sistemas dependentes deles como o Giro Subtropical do Atlântico e a Zona de Convergência Subtropical. / Paleoceanographic investigations based on planktonic foraminifera ecologic preferences are widely and succesfully applied. The present study infered surface waters oceanographic conditions from the South Atlantic southwest margin in the past 450.000 years through the planktonic foramifera abundance variation in two cores from Campos Basin. Correspondence Analysis defined three principal factors responsible for the planktonic foraminifera abundance variation in each core. The three KF-13 main factors were interpreted as temperature, mixed layer thickness and sazonality; KF-14 principal factors were defined as mixed layer thickness, productivity and sazonality. These factors made it possible to identify higher wind stress and higher productivity intervals in this region. The main climatic variations in South Atlantic are due to changes in wind stress and the systems which depend on it such as the Atlantic Subtropical Gyre and the Subtropical Convergence Zone.

Made available in DSpace on 2014-10-09T12:30:19Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:06:22Z (GMT). No. of bitstreams: 1 01390.pdf: 3035700 bytes, checksum: a55cb0f7c61cf43e4a20a8c70f3a6833 (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Orientador: Carlos Ducatti / Banca: Marcelo Zacarias Moreira / Banca: Cyntia Ludovico Martins / Resumo: Este trabalho objetivou avaliar o turnover e a meia-vida do carbono nas fezes e sangue de ovelhas alimentadas com plantas C3 e C4, pela técnica dos isótopos estáveis. Oito ovelhas da raça Santa Inês, após um período de adaptação de 45 dias recebendo 50% de feno de alfafa e 50% de silagem de milho, foram distribuídas ao acaso em dois tratamentos: o primeiro consistiu de animais que receberam feno de alfafa (C3-FA) e o segundo, dos animais que receberam apenas silagem de milho (C4-SM). Para mensurar o turnover de carbono (substituição isotópica) nas fezes e sangue em determinado intervalo de tempo, foi utilizada a função exponencial do tempo. Apenas os valores isotópicos das fezes atingiram o patamar de equilíbrio, indicando valores de meia-vida de 1,2 e 1,0 dias para os tratamentos C3-FA e C4-SM, respectivamente. Já no sangue, o tempo de coleta dos dados (104 dias) foi insuficiente para encontrar o patamar de equilíbrio isotópico, indicando uma troca de carbono lenta. De acordo com os resultados deste estudo, pode-se concluir que o sangue apresenta turnover lento indicando o sinal isotópico de dietas antigas; e as fezes, turnover rápido, indicadas para refletir dietas recentes, próximas da fase de avaliação / Abstract: The aim of this work was to evaluate the carbon turnover and half-life on feces and blood sheep, fed on C3 and C4 plants, using the stable isotopes technique. Eight Santa Ines sheep, after 45 days as adjustment period receiving 50% of alfalfa hay and 50% of corn silage, were randomly assigned to two treatments: the first one the animals fed on alfalfa hay (C3-FA) and the second one the animals fed on only corn silage (C4-SM). The time exponential function was used to measure the carbon turnover (isotope substitution) on feces and blood in a certain period of time. Only the isotope feces values reached the plateau value, indicating half-life of 1.2 and 1.0 days for C3-FA and C4-SM treatment, respectively. The data collection time (104 days) for blood was not enough to find a plateau isotope, indicating a slow carbon exchange. So we can infer that the blood has a slow turnover, indicating isotopic signal of ancient diets; and the feces showed a fast turnover, being used to reflect recent diet, next to the evaluation period / Mestre

O Bloco São Gabriel, localizado na zona central do embasamento cristalino do Rio Grande Sul, apresenta extensos registros do Neoproterozóico do Ciclo Brasiliano, contidos em complexos ígneos e metamórficos. Esses complexos também guardam registros sedimentares, com sequências carbonáticas metamorfisadas, cuja evolução tectônica é pouco conhecida. Essas sequências são observadas na Formação Passo Feio (Caçapava do Sul), no Complexo Cambaí (Vila Nova do Sul) e no Complexo Metavulcano-sedimentar Coxilha do Batovi (São Gabriel). As rochas carbonáticas da Formação Passo Feio compreendem dolomita mármores impuros. As amostras do Complexo Cambaí são classificadas como calcita mármores impuros. Os mármores do Complexo Coxilha do Batovi compreendem litotipos calcíticos e cálcio-silicáticos, cuja assembleia mineral é composta predominantemente por calcita em alguns exemplares e por grafita em outros, com percentuais de até 10% de quartzo, demonstrando contribuição siliciclástica no protólito. Idades de zircões de rochas associadas com os mármores, de trabalhos anteriores, indicam um intervalo entre 770 – 700 Ma para a deposição dos carbonatos do Bloco São Gabriel. Os carbonatos da Formação Passo Feio sofreram dolomitização durante ou logo após a deposição, enquanto os carbonatos do Complexo Cambaí não foram afetados pela dolomitização. A geoquímica dos elementos traços e terras raras indica que os mármores analisados preservaram as assinaturas originais do protólito nos diferentes graus metamórficos: Coxiha do Batovi (grau baixo), Formação Passo Feio e Complexo Cambaí (grau médio). A análise integrada dos isotópicos de Sr, 13C e 18O da Formação Passo Feio e do Complexo Cambaí revelou a preservação de assinaturas isotópicas primárias. Na Formação Passo Feio essas assinaturas são: 0,7074 (Sr87/Sr86), -0,26‰ e 2,44‰ (δ13CPDB) e -5,68‰ (δ18OPDB). Quando comparadas com a variação desses isótopos na água do mar ao longo do Neoproterozóico, verifica-se que os mármores da Formação Passo Feio e do Complexo Cambaí estão situados no intervalo entre 740 e 730 Ma. O período sugerido para a deposição das rochas carbonáticas da Formação Passo Feio é de 770 a 730 Ma, e entre 740-730 para o Complexo Cambaí. / The São Gabriel Block, located in the central zone of the crystalline basement of Rio Grande do Sul has extensive Neoproterozoic records of the Brasiliano Cycle, contained in igneous and metamorphic complexes. These complexes also keep sedimentary records with metamorphosed carbonate sequences whose tectonic evolution is poorly understood. These sequences are found in Passo Feio Formation, located in Caçapava do Sul region, in Complex Cambaí, at Vila Nova do Sul region and in Coxilha do Batovi metavolcanosedimentary Complex, in the São Gabriel region. The Passo Feio Formation carbonate rocks consist of impure dolomite marbles. The Cambaí Complex samples are classified as impure calcite marbles. Coxilha do Batovi Complex samples include calcite and calc-silicate marbles whose mineral assemblage are composed predominantly of calcite in some samples and graphite in others, with quartz rates up to 10% showing the siliciclastic contribution to the protolith. Zircon ages of associated rocks from previous works indicate an interval between 770-700 Ma for carbonate deposition in S. Gabriel Block. The carbonates from Passo Feio Formation were affected by dolomitization process during or early after its deposition, while the carbonates from Cambaí Complex were not affected by dolomitization. Trace elements and REE geochemistry of marbles indicate preservation of original signature of carbonate protoliths along different metamorphic grades; Coxilha do Batovi (low grade), Passo Feio Formation and Cambaí Complex (medium grade). The integrated analysis of Sr isotope, 13C and 18O from Passo Feio Formation and Cambaí Complex revealed the preservation of primary isotopic signatures. The Passo Feio Formation signatures are: 0,7074 (Sr87/Sr86), -0,26‰ and 2,44‰ (δ13CPDB) and -5,68 (δ18OPDB). In Cambaí Complex, the primary signatures are: 0,7069 (Sr87/Sr86), 5,75 (δ13CPDB) and -11,64 (δ18OPDB). When compared with the variation of these isotopes in seawater along the Neoproterozoic it appears that Passo Feio Formation and Cambaí Complex are situated in the range between 740 and 730 Ma. Based on these data it is suggested that the São Gabriel Block depositional event occurred between 770-700 Ma. The period suggested for the carbonate rocks depositional event of Passo Feio Formation is between 770-730 Ma, and specifically between 740-730 for Cambaí Complex.

La mesure de composition isotopique est utilisée dans l'étude du cycle biogéochimique du zinc ; cycle largement impacté par les activités anthropiques. Toutefois, l'interprétation de ces mesures réalisées sur des échantillons naturels ou synthétiques requiert la connaissance des propriétés isotopiques du zinc en condition d'équilibre (qui servent de référence) et la compréhension des mécanismes à l'origine des variations de composition isotopique. Dans ce travail, nous avons déterminé en réalisant des calculs quantiques, les constantes d'équilibre de fractionnement isotopique du zinc dans des phases solides et liquides. Nous avons mis en évidence les paramètres cristallochimiques qui contrôlent les propriétés isotopiques : la constante de force interatomique du zinc, les longueurs de liaisons Zn-premiers voisins et la charge électronique de ces premiers voisins. Nous avons réalisé un développement méthodologique permettant de calculer les propriétés isotopiques dans les phases liquides à partir de trajectoires de dynamique moléculaire à un coût réduit en temps de calcul. Nous avons montré à travers la modélisation du zinc aqueux, qu'une description raisonnable des forces de van der Waals par une fonctionnelle d'échange et de corrélation non locale est nécessaire à la stabilisation à conditions ambiantes du complexe hexaaquo zinc par rapport à d'autres complexes, réconciliant ainsi calculs et expériences. Ce travail met à disposition des études expérimentales une base de données cohérente de constantes d'équilibres isotopiques. / Isotopic compositions are used to study the biogeochemical cycle of Zn, which is greatly impacted by anthropic activities. However, the interpretation of the measurements performed on natural or synthetic samples requires the knowledge of Zn isotope properties in equilibrium conditions (as reference) and the understanding of the mechanisms that are at the origin of the isotopic composition variations. In this work, we determined by performing quantum calculations, equilibrium Zn isotope fractionation constants in various phases including solids and liquids. We highlighted the crystal-chemical parameters controlling the isotopic properties : Zn interatomic force constant, Zn-first neighbours bond lengths and the electronic charge on atoms involved in the bonding. We carried out a methodological development in order to calculate isotopic properties in liquid phases from molecular dynamics trajectories at a reduced computational cost. We showed through the modelling of aqueous Zn that a reasonable description of van der Waals forces using a non-local exchange correlation functional is required to stabilise the experimentally observed hexaaquo zinc complex over other complexes at room temperature. This work provides a consistent database of equilibrium Zn isotope fractionation constants for experimental works.