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Les écosystèmes des eaux souterraines sont de plus en plus reconnus pour leur faune endémique, phylogénétiquement ancienne et écologiquement spécialisée. Avec plus de 425 espèces décrites, les amphipodes niphargidés constituent la famille des eaux souterraines la plus riche en espèces au monde et un système modèle intéressant pour la biologie de l'évolution. Cependant, les scientifiques doivent faire face à des données incomplètes et biaisées en raison de trois déficits majeurs: le déficit Linnéen pour la taxonomie, le déficit Darwinien pour la phylogénie, et le déficit Wallacien pour la biogéographie. La présente thèse vise à évaluer l'importance de ces déficits chez les niphargidés, ouvrant ainsi la voie pour y remédier. Le premier chapitre est une évaluation des effets de la découverte d'espèces cryptiques (une des causes du déficit Linnéen) sur notre compréhension des modèles de distribution à grande échelle de la diversité des niphargidés. Contrairement à ce que l'on attendait, les espèces cryptiques putatives sont réparties de manière homogène le long des gradients environnementaux, et leur découverte ne modifie donc pas notre compréhension des modèles de distribution. Le deuxième chapitre analyse l'importance de l'application des techniques moléculaires à la taxonomie des niphargidés. En étudiant le genre Microniphargus, la morphologie seule s'est avérée peu informative en raison de la pédomorphose et de l'homoplasie. L'utilisation de marqueurs ADN a permis d'attribuer le genre à une famille différente (Pseudoniphargidae), venant éclaircir les relations phylogénétiques au sein des Niphargidae (et contribuant ainsi à remédier au déficit Darwinien). Le troisième chapitre traite du rôle des régressions et transgressions marines sur la distribution des niphargidés en utilisant la biogéographie moléculaire et une modélisation biogéographique innovante (afin de remédier au déficit Wallacien). Les résultats soutiennent l'idée que la dispersion a joué un rôle essentiel dans la biogéographie historique des niphargidés, en montrant que leurs voies de dispersion sont corrélées à des événements paléogéographiques anciens. Enfin, le quatrième chapitre traite de la taxonomie, de la phylogénie et de la biogéographie d'un clade de niphargidés distribué dans la région des Alpes et des Carpates, et illustre un cas de discordance mitonucléaire dans la délimitation d'espèces vivant dans des zones affectées par les glaciations quaternaires. Une histoire complexe de divergence de lignées évolutives et de contacts secondaires pendant les fluctuations climatiques du Pléistocène explique la plus grande variabilité de l'ADN mitochondrial par rapport aux marqueurs nucléaires. Dans une telle situation, la description formelle d'espèces cryptiques basée sur le seul barcodage de l'ADN mitochondrial, comme dans certains articles récents sur les niphargidés, n'est pas recommandée. Cette thèse ouvre plusieurs perspectives pour des recherches futures basées sur la taxonomie intégrative et la modélisation biogéographique, permettant aux niphargidés très diversifiés de jouer un rôle majeur dans la surveillance des écosystèmes des eaux souterraines. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

<p> This is a study of the groundwaters and their associated rocks and minerals from the Lac du Bonnet batholith at the Underground Research Laboratory (URL), Pinawa, Manitoba, to assess the water-rock interaction in crystalline rocks by using Sr, O and U-series isotopes. Emphasis is also placed on the development of the analytical techniques.</p> <p> A high precision analytical technique of U-series isotopes has been developed in this study by using solid-source mass spectrometry. A precision of better than 1% (2σ) is achieved in determining the 234U/238U and 230Th/234U ratios using 10^-8 g of U and 10^-11 g of 230Th. The potential applications of this method is demonstrated by dating small speleothem samples and the results agree well with those of α-spectrometry. This method also applies well to precise determination of the 234U/238U ratios in groundwaters and igneous rocks and minerals using small quantities of samples. However, precise measurements of 230Th in igneous rocks and minerals are limited by the large 232Th tail in the Th mass spectrum. Even better precision is achievable if pure Th spike is used.</p> <p> An ICP-MS isotope dilution method is also developed for fast and precise determination of Sr concentrations in groundwater samples. A precision of 1% is routinely achieved by taking into account the dead-time effect of the Channel Electron Multiplier (CEM) and the sample-to-spike ratios.</p> <p> The isotope results of both the groundwaters and the host rocks and minerals have revealed the processes of water-rock interaction and water mixing through the history of the batholith. Strontium isotope systematics of the rocks and their constituent minerals have shown that Sr loss occurred on whole-rock scale during both the high-temperature alteration (about 2300 Ma ago) and the low-temperature alteration which lasted at least 450 Ma. The Sr loss is most pronounced in plagioclase of altered samples. Uranium-series results indicate the disequilibrium of both whole-rock samples and minerals, and migration of U on whole-rock scale in, at least, the last million years.</p> <p> The Sr and O isotopic results have shown that the groundwaters from the three sub-horizontal, successively deeper fracture zones (FZ) have distinct isotopic signature: 87Sr/86Sr= 0.715 to 0.719 and 𝛿18O=-13o/oo for FZ-3; 87Sr/86Sr= 0.720 to 0.729 and 𝛿18O=-13 to -20o/oo for FZ-2; 87Sr/86Sr= 0.730 to 0.738 and 𝛿18O=-13 to -17o/oo for FZ-1. Uranium-series results show that all the groundwaters are highly enriched in 234U and the 234U/238U activity ratios range from 2.6 to 7.7. Mixing of three groundwaters is indicated by the Sr and O isotopes and the elemental chemistry. The three end-members are fresh surface water, the deep fresh (possibly glacial melt) groundwater and the deep saline groundwater.</p> <p> Comparison between the rocks and associated groundwaters shows that Sr isotopic equilibrium exists between plagioclase of altered samples and the groundwaters. This similarity indicates the vulnerable mineral phase control, such as plagioclase in this case, of the isotopic signatures, hence, chemistry of the groundwaters.</p> / Thesis / Master of Science (MSc)

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Este trabalho foi realizado na regiÃo do Cariri, localizada no sul do Estado do Ceara, onde se encontra a maior e mais importante reserva de agua subterrÃnea do Estado, a Bacia Sedimentar do Araripe. Nessa regiÃo, a principal fonte de agua para o abastecimento publico e privado e o recurso hÃdrico subterrÃneo armazenado no Vale do Cariri, nos aquiÃferos, Rio da Batateira, MissÃo Velha e Mauriti. Dada a importÃncia desta reserva hÃdrica, diversos trabalhos, no decorrer dos anos, tÃm sido feitos para obter informaÃÃes relevantes sobre a Ãgua subterrÃnea da regiÃo. O objetivo deste trabalho foi estudar as aguas subterrÃneas dessa regiÃo e identicar mudanÃas ocorridas durante os Ãltimos 16 anos, utilizando medidas hidroquÃmicas e medidas dos isotopos ambientais oxigÃnio-18, deutÃrio, carbono-13 e carbono-14. Para isso, foram analisadas 17 amostras de Ãgua subterrÃnea coletadas nos municÃpios de Crato, Barbalha, Juazeiro do Norte, Milagres, MissÃo Velha e Nova Olinda. Os resultados isotÃpicos mostraram que na maioria das amostras houve contribuiÃÃo de recargas recentes, caracterizando Ãguas jovens, com valores de O-18 apresentando pequenas flutuaÃÃes em relaÃÃo aos de Ãguas de chuvas atuais e com valores de pMC elevados. Entretanto, 04 amostras apresentaram mistura de aguas modernas com Ãguas nÃo modernas, paleoaguas, devido aos baixos valores de O-18 (< -4 por mil). A idade aparente das amostras de Ãguas subterrÃneas foi calculado pelo metodo de radiocarbono, utilizando um software estatÃstico de tratamento de dados, desenvolvido nesse trabalho; e as idades foram corrigidas pelos modelos de Pearson, Tamers e Vogel. Quanto aos resultados dos parÃmetros hidroquÃmicos, predominam Ãguas do tipo bicarbonatada quanto aos Ãnions e mista quanto aos cÃtions, numa relaÃÃo: rHCO3- > rCl- > rSO4 2- e rCa2+ rMg2+ > rNa+. As Ãguas amostradas enquadram-se nos padrÃes de potabilidade do CONAMA, com exceÃÃo de duas amostras. / This work was performed in the Cariri, located in the south of the state of Ceara, where is found the largest and most important groundwater reserves of the state, the Araripe Sedimentary Basin. In this region, the main source of water for public and private supply is groundwater stored in the Cariri Valley, in the aquifers, Rio da Batateira, MissÃo Velha and Mauriti. Given the importance of these water reserves, several research projects have been made to obtain relevant information about the groundwater in the region. The objective of this work was to study groundwaters samples this region and to identify changes occurred during the last 16 years, using hydrochemical measures and measures of environmental isotopes oxygen-18, deuterium, carbon-13 and carbon-14. For this, we analyzed 17 samples of groundwater collected in the municipalities of Crato, Barbalha,Juazeiro, Milagres, MissÃo Velha and Nova Olinda. The isotope results showed that in most samples were found contributions of recent recharge, featuring young waters, with values of O-18 with minor fluctuations with respect to modern rain water and high values PMC. However, 04 samples showed a mixture of modern waters with paleowater, with low values of O-18 (<-4 permil). The apparent age of groundwater samples was calculated by the method of radiocarbon using software processing statistical data, developed in this work, and ages were corrected by the methods of Pearson, Tamers and Vogel. Regarding the results of hydrochemical parameters, bicarbonate type waters predominate for anions and the mixed type for cations: rHCO3- > rCl- > rSO4 2- e rCa2+ rMg2+ > rNa+. The waters comply with the standards of potability of CONAMA, regarding major ions, except two samples.

The isotopes 238 U, 234 U and 230 Th, as members of the uranium-radium decay chain, are fractionated in the environment by changes of geochemical conditions, and they can be used for dating of recent or past geochemical processes in the Quaternary. Samples of water with uranium and of water-activated solids were taken of radioactive mineral water springs at two study sites in the area of Krkonoše-Jizera crystalline complex: Svatý Vojtěch (St. Adalbert) in Horní Malá Úpa, and Bukový Pramen in the Těsný důl valley in Janské Lázně. Uranium was co-precipitated in field conditions with hydroxides of FeIII+ in 50-liter water samples of the radioactive springs. In the lab, uranium and thorium were separated from water precipitates, as well as from solid samples after their chemical decomposition, using chromatographic extraction agent UTEVA. All the three isotopes of interest emit alpha particles, and so their activities were measured by alpha spectrometry and expressed as 234 U/238 U and 230 Th/234 U ratios. As an internal standard, 232 U/228 Th was used. The resulting 234 U/238 U activity ratios of four water samples measured ranged from 1.0747 to 1.423. In twelve samples of solid phases activity ratios 234 U/238 U from 0.861 to 1.129 were determined. The 230 Th/234 U activity ratios form two distinct...

In the years 2014-2015 a radiohydrogeochemical survey was carried out in the Tanvald granite body. Tanvald granite is a two-mica granite body located on the southern edge of the Krkonoše-Jizera Pluton, in the Lusatian part of the Saxony and Thuringian zone of the Variscan orogenic belt. The aim of the survey was to find radioactive water, the 222 Rn volume activity of which exceeds 1500 Bq/l. Such water is - under the Act no. 164/2001 Coll. - considered as radioactive mineral water. The result was a found of 20 water sources meeting this condition and many other sources approaching this value. In terms of the findings, the most important area is Dlouhý Most, where 8 of the radioactive water resources exceeding 1500 Bq/l were found. The most important of these is probably the source TGR/11 with the 222 Rn volume activity 2449 Bq/l. A cluster of water sources with a slightly higher conductivity (exceeding 300 µS/cm) appears in the Dlouhý Most area. Chemical analysis of the most important of them (TG1/15) showed that it is water of the Na-Ca-Cl type, probably contaminated by a run-off from the motorway, which is salted in winter. Another important site is the Kokonín fault area. At this important geological structure a total of four springs of radioactive water with the 222 Rn volume activity greater...

Radiohydrochemical exploration took place in east part of the "smrčinský" pluton between "Skalná-Plesná-Bad Brambach in years 2016-2018. The main aim of the exploration was location and thorough research of possible occurrence of waters with radioactive concretation higher than 1500 Bq/l. That is a value for radioactive mineral waters given by the "lázeňským" law number 164/2001 Sb. Most important area is Plesná-south where was discovered several springs with values exceeding 5000 Bq/l. Eminent spring is called "Břetislav-Radonka" and lies one kilometre southwest from the train station Plesná-Šneky with an activity of about 12.5 kBq / l 222 Rn and a flow rate of about 2.5 l / min. It is the most active surface discharge of radon mineral water in the Czech Republic Another significant source area is north of Skalna - north. These springs were discovered almost 60 years ago, Dr. Marie Zukriegelová. The main source of this area was named after its discoverer - the "Marie Z" spring with an activity of 5800 Bq / l 222 Rn.Further the research focused on historical radioactive conduit which were used to supply village Skalné with water. The conduit was separated on two "branches" and the younger one was built ten years after the first one. In both pipes were found radioactive waters and the most important...

Les aquifères de socle fracturés très répandus en Bretagne, constituent des formations géologiques hétérogènes renfermant des ressources en eau. Ces structures sont souvent constituées d'une zone altérée et d'une zone fracturée. La zone altérée est peu épaisse et proche de la surface, elle est constituée de roches altérées envahies par l'eau souterraine qui y circule rapidement des hauts topographiques du bassin versant vers l'exutoire. L'eau y présente des temps de résidence courts (<20 ans) et est souvent polluée par les nitrates. La zone altérée située plus en profondeur et plus épaisse est constituée de roches dures traversées par des fractures. L'eau circule exclusivement au travers de fractures et lentement, le temps de résidence de l'eau y est donc long (>40 ans). Dans cette zone, l'eau est plus minéralisée et souvent riche en fer en Bretagne. Ces différentes circulations d'eau, induisent des conditions chimiques contrastées dans les zones altérée et fracturée, mais leur effet sur l'écosystème microbien des eaux souterraines n'a jamais été exploré. Cette étude montre que les circulations hydrologiques influencent à l'échelle régionale et locale la structuration des communautés microbiennes au sein des eaux souterraines d'aquifères de socle. La position d'une eau souterraine le long des voies de circulations des eaux souterraines dites « boucles hydrologiques » contrôle directement la structure des communautés microbiennes via le contrôle de la succession des donneurs et accepteurs d'électrons disponibles. Les communautés microbiennes analysées montrent une prédominance de Nitrobacter. Dans l'eau souterraine récente (<20 ans) donc principalement dans la zone altérée, les Nitrobacter. sont surtout des Comamonadaceae et Oxalobacteraceae, microorganismes versatiles et capables de dénitrifier. Dans l'eau souterraine ancienne (>40 ans) et isolée donc dans la zone fracturée, ce sont en grande majorité des Gallionellaceae, microorganismes microaérophiles spécialisés dans l'oxydation du fer(II). La prédominance des Gallionellaceae dans la zone fracturée suggère un écosystème profond basé sur l'oxydation du fer(II). Cependant, ce processus suppose une arrivée minimale d'oxygène dans la partie profonde, via par exemple un mélange avec une masse d'eau récente oxygénée. La proportion de Gallionellaceae dans les différentes eaux analysées montre une corrélation positive avec le degré de mélange des eaux anciennes avec des eaux récentes, jusqu'à une limite de 20% d'eau récente. Le suivi temporel de la dynamique des communautés d'un aquifère avant et au début de la recharge a montré dans la zone altérée des conditions chimiques très fluctuantes et une communauté microbienne très changeante mais toujours constituée de nombreux potentiels dénitrifiants. Dans la zone fracturée, la communauté dominée par les Gallionellaceae est relativement stable, malgré des changements chimiques ponctuels substantiels et un degré de mélange transitoire important (jusqu'à 60% d'eau récente) au début de la recharge. Les Gallionellaceae semblent donc capables de résister à des changements ponctuels et importants des conditions chimiques. Les eaux souterraines de la partie profonde des aquifères, bien qu'isolées, restent relativement connectées à la surface ce qui permet probablement le maintien de l'écosystème microbien profond. / Hard-rock aquifers are heterogeneous geological structure very widespread in Britany that have the property to store groundwater. These aquifers are often made of a weathered zone and a fractured zone. The weathered zone is a rather thin layer close to the surface and is constituted of weathered rocks submerged in groundwater. In this zone, groundwater circulates rapidly from the upper parts of the watershed to the aquifer outlet, thus shows short groundwater residence time (< 20y) and is often polluted by nitrates. The fractured zone is located deeper and is thicker. It is composed of fresh rocks crossed by fractures in which groundwater exclusively flows with a very slow velocity, thus groundwater residence time in this zone is rather long (>40 y). In the fractured zone, groundwater is much more mineralized and often rich in iron, in Britany. The differences of flow velocities in the weathered and the fractured zones are responsible for contrasted chemical conditions in these two zones, but the influence of groundwater flow velocity on the microbial ecosystem in groundwater remains largely unexplored. This work shows hydrologic circulations influence the microbial community structuration in hard-rock aquifer groundwater at regional and local scales. Position of a groundwater along a hydrologic flowpath or a “hydrological loop” directly controls microbial community structure through the control of the successively available electron donors and acceptors. The analyzed microbial communities show a predominance of Betaproteobacteria. In recent groundwater (< 20y) thus particularly in the weathered zone, Betaproteobacteria are mainly Comamonadaceae and Oxalobacteraceae, which are generalists able to do denitrification. In old and isolated groundwater (> 40y) thus particularly in the fractured zone, Betaproteobacteria are mainly Gallionellaceae, which are microaerophilic iron-oxidizer. The predominance of Gallionellaceae in the fractured zone suggests a deep ecosystem based on iron oxidation. However, this process implies a minimal input of oxygen in the deeper part, for instance via mixing with recent oxygenated groundwater. Proportion of Gallionellaceae in the different analyzed groundwater shows a positive correlation with the degree of mixing between old and recent groundwater, up to a limit of 20% of recent groundwater. The temporal microbial community dynamics in a single aquifer, before and during the beginning of recharge, demonstrated in the weathered part very fluctuant chemical conditions and a shifting microbial community that remains always composed of numerous potential denitrifiers. In the fractured part, microbial community is dominated by Gallionellaceae and remains rather stable, despite the punctual but substantial changing of the chemical conditions and degree of mixing (up to 60% of recent groundwater) at the beginning of the recharge. Gallionellaceae seem thus able to resist to important and punctual chemical conditions changings. Groundwater in the deeper part of aquifers, even isolated, remains relatively connected to surface, likely allowing the deep microbial ecosystem to maintain.

Les systèmes aquatiques continentaux sont des vecteurs majeurs du cycle global du carbone, recevant une quantité importante de carbone qu’ils émettent vers l’atmosphère et exportent aux océans. Nous caractérisons les concentrations et les transferts de toutes les formes carbonées à l’interface eau souterraine-ruisseau-atmosphère, dans un bassin versant de plaine, tempéré, forestier et sablonneux, où l’hydrologie se produit majoritairement au travers du drainage des eaux souterraines. Nous suivons différentes stations couvrant l’ensemble de la variabilité du bassin, depuis les eaux souterraines jusqu’à l’exutoire, avec des proportions variables d’occupation du sol. Le DOC est exporté majoritairement en périodes de crues alors que la même quantité de DIC est exportée entre périodes de crues et d’étiages. Le carbone terrestre dérivé des sols forestiers est la source principale de carbone dans les eaux superficielles et seulement 3% de la NEE est exportée. L’occupation du sol modifie localement les formes de carbone dans les ruisseaux mais à l’échelle du bassin la forêt prédomine. Nous quantifions le dégazage de CO2 en s’appuyant sur un bilan de masse isotopique. Environ 75% du dégazage total se produit dans les ruisseaux de premiers et de seconds ordres, qui se comportent comme des points chauds pour l’émission de CO2. Ce travail de thèse contribue à une meilleure définition du rôle des ruisseaux et des rivières dans le cycle global du carbone. De manière plus précise, il améliore les connaissances sur la proportion du pompage biologique de CO2 atmosphérique d’un écosystème qui est exportée vers le réseau hydrographique, ainsi que le devenir de ce carbone en aval. / Inland waters are a major component of the global carbon cycle. These systems receive a significant amount of carbon from aquatic and terrestrial sources. A part of this carbon is degassed in the atmosphere while another is exported to the oceans. We characterize the concentrations and transfers of all carbon forms at the groundwater-stream-atmosphere interface, in a temperate, forested and sandy lowland watershed, where hydrology occurs in majority through drainage of groundwater. We monitored contrasting study site representative of the diversity of the ecosystem, from groundwater to river mouth, with different proportion of land use. DOC is exported in majority during high flow periods whereas the same amount of DIC is exported between high and base flow periods.Terrestrial carbon that originates from soils forests is the major source of carbon in surface waters but only 3% of the NEE is exported. Land use modifies locally the different forms of carbon in streams but at the basin scale forests predominate. We quantify the degassing ofCO2 based on fairly well balanced isotopic mass balance. About 75% of the total degassing occurs in first and second order streams, which behave as hotspots for CO2 degassing. This work contributes to a better definition of the role of streams and rivers in the global carboncycle. Specifically, this work enhances understanding on the proportion of CO2 pumped byan ecosystem and then exported to the river system, as well as the fate of this carbon downstream.