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Agronomic and water quality impacts of urea particle size were evaluated through field and laboratory experiments and mathematical modeling. In a two-year field study, corn silage yield, corn nitrogen (N) removal, and nitrate-N (NO₃⁻-N) leaching from urea pellets (1.5 g each) and granules (0.01-0.02 g each) applied at 184 kg-N/ha were compared. A control treatment (no N) and two other N application rates (110 and 258 kg-N/ha) were also included. Urea particle size impact on dissolution rate, dissolved urea movement, mineralization, and N0³-N leaching were evaluated in the laboratory. A two-dimensional (2-D) mathematical model was developed to simulate the fate of subsurface-banded urea and its transformation products, ammonium (NH₄⁺)and NO₃⁻. With 184 kg-N/ha, corn silage yield was 15% higher (p = 0.02) and corn N removal was 19% higher (p = 0.07) with pellets than granules in the second year of the field study. In the absence of yield response at 110 kg-N/ha, reason for higher yield at 184 kg-N/ha with pellets was unclear. Greater N removal reduced NO₃⁻-N leaching potential from pellets compared to granules during the over-winter period. No urea form response to yield or corn N removal was observed in the first year. In 23 of 27 sampling events, granules had higher NO₃⁻-N concentration in the root zone than pellets, with average nitrate-N concentrations of 2.6 and 2.2 mg-N/L, respectively. However, statistically, NO₃⁻-N leaching from the root zone was unaffected by urea form, probably due to high variability within treatments masking the treatment effects. In October 1997, pellets retained 16% more (p = 0.04) inorganic-N in the top half of the root zone than granules, due to slower nitrification in pellets as was determined in the mineralization study. Slower NO₃⁻-N leaching allowed for greater N extraction by plants. Pellets had lower dissolution, urea hydrolysis, and nitrification rates than granules; however, nitrification inhibition was the dominant mechanism controlling N fate. The model took into account high substrate concentration effects on N transformations, important for simulating the fate of band-applied N. The model exhibited good mass conservative properties, robustness, and expected moisture and N distribution profiles. Differences in measured field data and model outputs were likely due to uncertainties and errors in measured data and input parameters. Model calibration results indicated that moisture-related parameters greatly affected N fate simulation. Sensitivity analyses indicated the importance of nitrification-related parameters in N simulation, particularly, their possible multiplicative effects. Need for extensive model testing and validation was recognized. The validated 2-D N model could be incorporated into a management model for better management of subsurface-banded granular N. However, the 2-D model is not appropriate for simulating the three dimensional N movement from pellets. / Ph. D.

The location of utilities buried beneath the built environment has always been a concern for those conducting work that involves excavation or the placement of items into the ground. Whether physically removing material or driving piles, posts, and more, the potential for accidental utility strikes is increasing with the movement of more traditional utilities from above ground to below. Also, the addition of utilities and new technology in underground spaces that hasn't existed in the past, such as fiber optics and more highspeed telecommunication lines, is occupying more space. Traditional methods of surveying, in combination with surface geophysics and the development and improvement of processes and technologies to track the location of buried assets led to the engineering services category termed Subsurface Utility Engineering (SUE). In order to aid utility engineers and consultants who are responsible for the collection of utility data this research aimed to help identify a way to compare the various technologies and incorporate information about the individual project in order to choose the most appropriate locating method for a project with a defined set of parameters. The result was the development of standard evaluation forms that can be sent to technology vendors and consultants to evaluate the performance and limitations of a technology. This data can then be compiled into a database located within an Excel-based program created to compare the technologies. The program, VT PALMS (Virginia Tech Program for Asset Locating Method Selection), consists of the performance and economic databases, a project information Page sheet, and the results of the comparison of each technology in the database to the information on the project information sheet. The results are presented in three ways; 1) a speedometer chart with a needle that indicates the percentage of the parameters used in the database that are compatible - also referred to as the Reliability Factor, 2) a matrix view that indicates the parameters where a potential conflict may exist, and 3) an economic indicator that shows the comparable cost of using each technology listed in the database. / Master of Science

Field tests were conducted and historical operating data were evaluated to assess the performance of the Monterey WWTP utilizing subsurface flow (SF) constructed wetlands. Previous work with SF wetlands has demonstrated adequate, but variable removal of organic matter, suspended solids, and nitrogen. Few research studies have observed the generation of compounds in the wetlands that affect other treatment processes, specifically reduced compounds that contribute to the chlorine demand. This study attempts not only to distinguish the factors leading to the inadequate performance of the SF wetlands in removing organic matter and nitrogen, but also to identify the cause of the frequent occurrences of a nondetectable chlorine residual in the chlorine contact tank at the Monterey WWTP. Collection and analysis of historical operating data from January 1998 to May 2000 revealed a constantly decreasing removal of carbonaceous biochemical oxygen demand (CBOD5) by the SF wetlands and a poor removal of ammonia-N throughout the system. The decreasing removal of CBOD5 appeared to be caused by clogging of the wetland bed media by accumulated solids. The inability to remove the accumulated solids by pumping was shown. Analysis of field data also showed that the SF wetlands removed 88% of the influent TSS and 71% of the influent CBOD5, while experiencing a 18% increase in ammonia-N. Bisulfide produced in the anaerobic wetland beds accounted for 95% of the chlorine lost in contact tank. The variable production of sulfide is the cause of the frequent nondetectable chlorine concentrations observed. The results of this study suggest that chemical costs of chlorine and sulfur dioxide may be greatly reduced if bisulfide can be removed before chlorination. Also, the use of large rocks as media in SF wetland beds may significantly reduce the physical and biological removal of organic matter. / Master of Science

This Ph.D. thesis presents advancements in the analysis of radar sounder data. Radar sounders (RSs) are remote sensors that transmit an electromagnetic (EM) wave at the nadir direction that penetrates the subsurface. The backscattered echoes captured by the RS antenna are coherently summed to generate an image of the subsurface profile known as a radargram. The first focus of this work is to automate the segmentation of radargrams using deep learning methodologies while minimizing the need for labeled training data. The surge in radar sounding data volume necessitates efficient automated methods. However, the amount of training labeled data in this field is strongly limited. This first work introduces a transfer learning framework based on deep learning tailored for radar sounder data that minimizes the training data requirements. This method automatically identifies and segments geological units within radargrams acquired in the cryosphere. With the cryosphere being a critical indicator of climate change, understanding its dynamics is paramount. Geological details within radargrams, such as the basal interface or the inland and floating ice, are key to this understanding. Our work shifts the focus to uncharted territory: the coastal areas of Antarctica. Novel targets such as floating ice and crevasses add complexity to the data, but the transfer learning framework minimizes the need for extensive labeled training data. The results, based on data from Antarctica, confirm the effectiveness of the approach, promising adaptability to other targets and radar data from existing and future planetary missions like RIME and SRS. The second focus of this thesis explores the generation of novel and improved geological data products by harnessing the unique characteristics of radar sounder data, including subsurface information and so-called “unwanted” clutter. The thesis introduces two methods that use RS data to generate geological products. The first contribution proposes a global high-frequency radar image of Mars. This product delivers a novel, comprehensive global radar image of Mars, capturing both surface and shallow subsurface structures. The method unlocks the potential to explore concealed Martian geology and further understand Martian geological features like dust, revealing possible candidate large dust deposits that were unknown until now. Furthermore, this method can potentially offer insights into celestial bodies beyond Mars, such as the detection of new lunar facets and Venusian geological formations. The third contribution aims to generate Digital Elevation Models (DEM) from single swath radargrams. The activity addresses the challenge of precise bed DEM estimations in Antarctica. Bed topography is critical in ice modeling and mass balance calculations, yet existing methods face limitations. To overcome these, we employ a generative adversarial network (GAN) approach that utilizes clutter information from single radargrams. This innovative technique promises to refine bed DEMs and enhance our understanding of glacier erosion and ice dynamics. The proposed methodologies were validated with data acquired on both Earth and Mars, showing promising results and confirming their effectiveness.

L'imagerie de la proche surface est essentielle en géotechnique car la caractérisation et l'identification des premiers mètres du sol interviennent dans de nombreuses applications de l'aménagement du territoire. Les méthodes classiques d'imagerie sismique sont appréciées car elles sont simples de mise en oeuvre et d'interprétation. Utilisés en génie civil, ces outils ont généralement été développés initialement en prospection pétrolière. La problématique que nous abordons dans ce travail intéresse réseau de transport d'électricité (RTE) ; il s'agit d'identifier la géométrie des fondations de pylônes électriques très haute tension en utilisant des méthodes d'imagerie sismique qui ont fait leurs preuves dans le contexte de la géophysique de gisement. En particulier, nous évaluons les performances de l'inversion de la forme d'onde (FWI) et de la migration par retournement temporel. Nous présentons le principe de ces méthodes que nous mettons ensuite en oeuvre avec un outil basé sur une modélisation de la propagation d'ondes en milieu élastique 2D ; dans ce cadre, le temps de calcul de l'inversion est aujourd'hui raisonnable, ce qui est loin d'être le cas lorsqu'on considère un milieu élastique 3D. Ensuite, nous présentons les résultats d'imagerie sur données synthétiques puis réelles. Concernant les données synthétiques 2D, l'inversion permet d'identifier les dimensions de la fondation à condition que le rapport de vitesse entre la fondation et l'encaissant ne dépasse pas 3. La migration permet quant à elle d'imager de façon satisfaisante des contrastes beaucoup plus élevés. Sur données réelles, les tests que nous avons faits ne permettent pas d'identifier la géométrie de la fondation avec ces méthodes ; en réalisant l'inversion de données synthétiques 3D avec notre outil 2D, nous montrons que le caractère 3D des données est un obstacle important à l'utilisation de notre outil sur des données réelles contenant une forte signature 3D de la structure à imager. / Near surface imaging is essential for geotechnics purpose. Characterization and identification of the first layers - between 0 and 10m - of the ground is necessary for many applications of national and regional development. Classical methods of imagery arouse a great interest as they are easy to use. In general, these numerical tools used in civil engineering have been first developped by seismic petroleum companies. The issue we are tackling comes to identifying the geometry of the foundations of very high voltage electric pylons using seismic imagery methods for french electricity transport and network. In particular, we assess the performances of the full waveform inversion and the reverse time migration. First, we explain the principle of these methods and then we implement them with a tool based on 2D modelisation which involves a reasonable computing time, contrary to 3D inversion carried out with today's means. Next, we show imagery results on synthetic and real data. Concerning, synthetic data, inversion makes it possible to identify the dimensions of the foundation as long as the velocity ratio between the foundation and the bedrock does not exceed 3. As to migration, it has good results with even much higher contrasts. Concerning real data, these two methods don't succeed in identifying the geometry of the foundation ; we inverted 3D synthetical data with our tool and show that the 3D property of data is prohibitive to 2D-inversion of real data with such an important 3D signature as the one we get on the foundation data.

Les communautés microbiennes de sédiments de subsurface ont été décrites jusqu’à 1922 mbsf (meters below the seafloor) et pourraient représenter 0,6% de la biomasse totale. Largement incultivées, ces communautés comprennent des groupes endémiques aux environnements de subsurface et des généralistes retrouvés dans des environnements contrastés, appartenant aux 3 domaines du vivant (Bacteria, Eukarya and Archaea). Bien que jouant un rôle majeur dans les grands cycles géochimiques, l’écologie microbienne des sédiments de subsurface reste peu connue. Les conditions hostiles de ces sédiments contrastent avec la présence d’activité et de viabilité microbiennes. Dans ce contexte, de nombreuses questions sur les modes de vie et les métabolismes des microorganismes enfouis demeurent. L’objectif de cette thèse était de mieux comprendre quelles stratégies adaptatives pouvaient être mises en place par les communautés microbiennes de subsurface et de caractériser leur potentiel physiologique. Pour cela, 3 approches ont été utilisées.(1) Une approche culturale a permis de décrire 2 nouvelles espèces bactériennes sédimentaires (Halomonas lionensis, ungénéraliste versatile, et Phaeobacter leonis, une bactérie marine typique). L’étude de la résistance aux conditions de subsurface de ces deux espèces et de la bactérie Sunxiuqinia faeciviva, isolée à 247 mbsf, a ensuite été étudiée. (2) Par une étude de génomique comparée et structurale, la plasticité physiologique de H. lionensis a été analysée. (3) Enfin, le potentiel fonctionnel de communautés microbiennes enfouies à 31 et 136 mbsf dans le bassin de Canterbury a été étudié, en analysant les 2métagénomes correspondants. Les résultats culturaux et génomiques montrent que H. lionensis et S. faeciviva résistent mieux aux stress de subsurface que P. leonis et, dans le cas de H. lionensis, ceci impliquerait des propriétés physiologiques variées pouvant expliquer le succès écologique du genre Halomonas. Les données de métagénomique indiquent que les diversités phylogénétique et fonctionnelle de subsurface du bassin de Canterbury sont distinctes de celles d’environnements de surface et suggèrent que des métabolismes comme la fermentation, la méthanogenèse ou la β-oxydation pourraient être importants. La présence de gènes d’importance écologique et évolutive a permis d’émettre des hypothèses sur les modes de vie de ces microorganismes et des évènements de recombinaison génomique de groupes toujours incultivés ont aussi pu être décrits / Microbial communities inhabiting marine subsurface sediments were described up to 1922 mbsf (meters below the sea floor) andcould represent 0.6% of the total biomass. This microbial diversity, remaining elusive to cultivation, comprises groups specific to subsurface environments and groups of generalists found in contrasted habitats, all belonging to the 3 domains of life (Bacteria,Eukarya and Archaea). Although playing a major role in global geochemical cycles, the microbial ecology of the subseafloor remains largely unknown. The hostile conditions of subsurface sediments contrast with the descriptions of microbial activity andviability in the subseafloor. In this context, many questions related to the microbial physiology and the lifestyles of buried communities remain to be answered. The objective of this thesis was to better understand which adaptive strategies could be deployed by subseafloor microbial communities and to characterize their physiological potential. In that aim, 3 approaches were used.(1) A cultural approach enabled describing 2 novel sedimentary bacterial species (Halomonas lionensis, a versatile generalist and Phaeobacter leonis a typical marine bacterium). The survival of these 2 species to subseafloor conditions and of the subsurface bacteria Sunxiuqinia faeciviva, isolated at 247 mbsf, was then studied. (2) Using a structural and comparative genomic approach, the physiological plasticity of H. lionensis was investigated. (3) Finally, the functional potential of the microbial communities buried at 31 and 136 mbsf in the Canterbury Basin was analyzed, by studying the 2 corresponding metagenomes. Cultural and genomics results showed that H. lionensis and S. faeciviva are more resistant to subsurface constrains than P. leonis and, in the case of H. lionensis, this may involve various physiological properties, maybe explaining thee cological success of the genus Halomonas. Metagenomic data showed that the functional and the phylogenetic diversity of the subseafloor are distinct from the ones from surface environments and highlighted the importance of metabolic pathways like fermentation, methanogenesis and β-oxidation. Genes of ecological and evolutionary interests enabled speculating about lifestyles of buried microorganisms and analyses of genomic fragments highlighted recombination events of still uncultivated microbial groups

A partir d'un ensemble de données d'observation ainsi qu'un modèle couplé physiquebiogéochimique à haute résolution (CROCO-PISCES), cette thèse explore les processus biophysiques associés à l’une des plus grandes floraisons phytoplanctoniques de l’océan global, au Sud-Est de Madagascar, et le possible rôle des tourbillons sur ces blooms. L’étude montre que ce phénomène se produit dans une région caractérisée par une couche de mélange peu profonde, avec des eaux de surface moins salées probablement associées au courant Sud-Est de Madagascar (SEMC), et avec une structure dipolaire dans la circulation moyenne. Les observations ont révélé une diminution des remontées d’eaux froides (upwelling) le long des côtes sud-est de Madagascar pendant les mois de bloom. Dans le modèle, les nitrates provenant des niveaux de subsurface (advection verticale ; upwelling) ainsi que de la côte malgache (advection horizontale) favorisent la production phytoplanctonique simulée. Une expérience lagrangienne de particules montre une plus forte advection de ces dernières dans la zone de floraison pendant les périodes de bloom alors qu’elles sont déviées vers le sud de Madagascar vers le continent Africain pendant les années sans floraison. Une étude est réalisée à partir d’un jeu de données de suivi des tourbillons co-localisés avec des flotteurs de profilage Argo, pour mieux comprendre des tourbillons intensifiés en surface et subsurface. Une méthode d’identification des structures tourbillonnaires de subsurface a été mise en place en se basant sur l’anomalie de la hauteur dynamique stérique. Ces tourbillons, appelés ‘SIDDIES’ (South Indian ocean eDDIES), se produisent en tant que tourbillon intensifié en surface (surfSIDDIES) et en subsurface (subSIDDIES). Ils se déplacent le long d’une bande de latitude située entre 15°S et 35°S appelée « couloir SIDDIES ». Au cours de leurs déplacements, les subSIDDIES cycloniques (anticycloniques) transportent via les processus d’advection, des masses d’eaux chaudes et peu salées de l’Est vers l’Ouest de l’Océan Indien, contribuant ainsi à environ 58% (32%) du flux total de chaleur par tourbillons dans le sud de l'océan Indien. / Using observational datasets and a high resolution coupled biophysical model (CROCOPISCES), the main aims of this thesis is to study the biophysical processes associated with one of the largest phytoplankton blooms in global ocean, southeast of Madagascar, and the possible role of mesoscale eddies.The study has shown that the bloom occurs in a region of shallow-stratified mixed layer water, with low-salinity waters at the surface possibly associated with the South-East Madagasacar Current (SEMC), and dipole structure in the mean circulation. Observations show that curren-driven upwelling south of Madagascar is reduced during bloom months. It is shown in the model that nitrate from subsurface levels (upwelling) as well as from the Madagascan coast (advection) fertilize the simulated bloom. A Lagrangian analysis shows dispersion of higher percentages of particles in the bloom region during bloom years and south of Madagascar during non-bloom years.Using co-located Argo profiles and an eddy detected algorithm dataset, surface and subsurface-intensified eddies are studied. Subsurface eddies are identified using a detection method based on their steric dynamic height anomaly. Referred to as `SIDDIES’ (South Indian ocean eDDIES), they occur as surface (surfSIDDIES) or subsurface (subSIDDIES) and propagate along a latitudinal band (15°S-35°S) termed as `SIDDIES Corridor’. Advecting warm and fresh water during their propagation, cyclonic (anticyclonic) subSIDDIES contribute about 58% (32%) of the total eddy-heat flux in the South Indian Ocean.

L'utilisation de pesticides sur les surfaces agricoles conduit à une contamination généralisée des eaux de surface et de subsurface en France. Dans l'attente d'une évolution profonde des pratiques agricoles et d'une baisse durable de l'utilisation des pesticides, il est intéressant de chercher à limiter des transferts des zones agricoles aux zones aquatiques. Pour mieux agir sur les voies de transfert, il est nécessaire d'approfondir les connaissances des processus en jeu et de leurs interactions éventuelles et de tirer au mieux partie des observations du terrain.L'objectif de cette thèse est l'intégration de processus de transferts réactif dans le modèle hydrologique à base physique CATHY (CATchment HYdrology), capable de simuler en 3 dimensions les écoulements de l'eau de façon couplée surface-subsurface et le transport advectif dans des situations variablement saturées. En subsurface, les processus d'adsorption linéaire et de dégradation du premier ordre sont implémentés. Un module de mélange des solutés entre la lame ruisselante et la première couche de sol est ajouté, qui permet de simuler la remobilisation des solutés de la subsurface dans le ruissellement. Le couplage surface-subsurface des écoulement est très efficace dans ce modèle, et le couplage du transport de soluté adoptant la même stratégie a été amélioré pour mieux respecter la conservation de la masse.Le modèle est en premier lieu testé sur des données issues d'expérimentations de transfert de subsurface sur une maquette de laboratoire à petite échelle (2 m de long, o.5 m de large, 1 m de profondeur). Les résultats sont confrontés aux chroniques de flux massiques observées et une analyse de sensibilité de type Morris est menée. Le modèle est capable de reproduire de façon satisfaisante les observations, et très satisfaisante après une légère calibration. Les conductivités à saturation horizontale et verticale, la porosité et le paramètre $n$ de la courbe de rétention influencent de façon non négligeable les résultats hydrodynamiques et de transfert de soluté. Dans un second temps, le modèle est évalué sur les données issus d'un versant viticole réel (0.6 ha) dans un contexte orageux avec de fortes interactions surface-subsurface. Une analyse de sensibilité globale est menée, et met en valeur les mêmes paramètres que la méthode de Morris. Les interactions entre les paramètres influencent fortement la variabilité des sorties hydrodynamiques et de transfert. La conservation de la masse est très correctement assurée malgré la complexité de la simulation.Le modèle auquel on aboutit correspond bien aux objectifs de départ, sa validation est solide, même si elle n'est rigoureusement valable que dans les contextes précis où elle a été réalisée. On a montré que le modèle était robuste et capable de reproduire des données observées. D'autres processus manquent encore pour représenter toutes les voies de transfert à l'échelle du versant, notamment la représentation du transfert préférentiel en subsurface et du transport sédimentaire en surface. / Pesticide use on agricultural surfaces leads to a broad surface and subsurface water contamination in France. Awaiting a deep agricultural practices evolution and a sustained fall of the pesticide use, it is of interest to limit transfers form agricultural fields to rivers. In order to constrain those transfers, a deepen knowledge of processes at stake and their potential interactions is necessary, as well as taking full advantages of fields observations.The aim of this PhD is the reactive transfer processes integration in the Hydrological physically-based model CATHY (CATchment HYdrology) which simulates surface-subsurface coupled water flow and advectiv solute transport in three dimensions and in variably saturated situations. Linear adsorption and first order decay are implemented in subsurface. A mixing modules is added, and evens the concentration between surface runoff and subsurface first layer. This module simulates the solute mobilisation from soil to surface runoff. The water flow surface-subsurface coupling procedure is very accurate in CATHY, and the transport coupling procedure is improve in order to respect the mass conservation.The model is first evaluated on subsurface transfer laboratory experimentation data at a small scale (2 m long, o.5 m wide, 1 m deep). Results are compared to mass flux evolution in time and a Morris sensitivity analysis is conducted. The model is able to acceptably reproduce observation, and properly after a slight calibration. Horizontal and vertical saturated conductivities, porosity and the $n$ parameter of retention curve significantly influence hydrodynamics and solute transport. As a second step, the model is evaluated on data from a field wine hillslope on an intense rain event, therefore in a context with a lot of surface-subsurface interactions. A global sensitivity analysis is conducted and highlights same parameters as the Morris method. Interactions between parameters highly influence the variability of hydrodynamic and solute transfer outputs. Mass conservation is accurate despite the complexity of the context.The resulting model meets the objectives, its evaluation is strong even if its theoretically only valid in the precise context in which the evaluations where conducted. The model is robust and able to reproduce observed data. Some complementary processes are still missing in the model to properly represent transfer ways at the hillslope scale, such as subsurface preferential transfers and surface sedimentary transport.

Le présent travail a pour objectif d’étudier la synergie entre la déformation plastique et les processus d’adsorption et d’absorption de l’hydrogène en surface et en subsurface du nickel monocristallin. La Réaction d’Evolution de l’Hydrogène (REH) et l’absorption de l’hydrogène en subsurface (RAH)partagent le plus souvent l’intermédiaire commun : l’hydrogène adsorbé (Hads). Le chemin réactionnel de la REH sur des surfaces de nickel (100) en milieu acide sulfurique peut être présenté par un mécanisme de Volmer-Heyrovsky. Les paramètres cinétiques élémentaires correspondants comme les coefficients de symétrie, les enthalpies d'activation, le nombre de sites actifs, ont été simulés via un modèle thermocinétique en utilisant les données expérimentales. Ces paramètres peuvent être affectés par la déformation plastique. Cette dernière modifie la densité et la distribution des dislocations stockées affectant la rugosité de surface à l'échelle atomique et engendrant des sites actifs supplémentaires d'adsorption. En revanche, l’émergence de ligne de glissement à la surface conduit à un phénomène de désactivation associé la formation de plan plus compact (111). L’entrée d’atomes d’hydrogène associée à l’étape de transfert surface-Subsurface peut être mesurée à l’aide d’une méthode potentiostatique de type pulsé. Cette dernière a permis de caractériser la diffusion et le piégeage de l'hydrogène en subsurface. Deux zones peuvent être distinguées, l’une proche de la surface (subsurface) et l’autre au coeur de l'échantillon. Dans ce cas, le coefficient de diffusion associé à la subsurface semble être beaucoup plus élevé que celui obtenu au coeur du métal. En revanche,l’application d’une contrainte mécanique conduit à une augmentation de la densité de pièges. Cette dernière, développée au voisinage de la surface : « subsurface », est plus faible que celle à coeur du matériau, ce qui suggère un effet adoucissant en subsurface. / The present work has for objective to study the synergy between the plastic strain and the processes of adsorption and absorption of hydrogen on the surface and the subsurface of nickel single crystal.Hydrogen Evolution Reaction (HER) and Hydrogen Absorption in subsurface (HAR) share mostly the common intermediate: the adsorbed hydrogen (Hads). The HER pathway on nickel (100) single crystal surfaces in sulphuric acid medium can be related by a Volmer-Heyrovsky mechanism. The corresponding elementary kinetic parameters as symmetry coefficients, activation enthalpies, number of active sites, have been identified via a thermokinetic model using experimental data. These parameters can be affected by defects associted with plastic strain. Irreversible plastic strain modifies the density and the distribution of storage dislocations affecting the surface roughness at atomic scale and generating additional active adsorption sites. Further more, surface emergence of mobile dislocations induces the formation of slip bands, which modify the surface roughness and the electronic state of the surface and increases the (111) surface density. The entry of hydrogen atoms associated to the transfer step surface-Subsurface can be measured using a potentiostatic double-Steptechnique (pulse method). This last allowed to characterizing the diffusion and trapping of hydrogen in the subsurface. Two domains can be distinguished, that of the subsurface and that of the bulk of the sample. In this case, the diffusion coefficient near the surface (subsurface) seems to be much higher than that obtained in the bulk of the metal. On the other hand, the application of mechanical stressleads to an increase of traps density. This last, developed near the surface: « subsurface », is lower than that at the bulk of material, which suggest a softening effect in the subsurface.