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Academic literature on the topic 'Multi-Traçage'
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Journal articles on the topic "Multi-Traçage"
Marechal, Jean-Christophe, Nathalie Courtois, Gilbert Jouanen, and Philippe Meus. "Multi-traçage de la Fontaine de Nîmes." Karstologia : revue de karstologie et de spéléologie physique 56, no. 1 (2010): 1–8. http://dx.doi.org/10.3406/karst.2010.2677.
Full textDissertations / Theses on the topic "Multi-Traçage"
Humez, Pauline. "Traçage des intrusions de CO2 dans les aquifères d'eau douce par les méthodes multi-isotopiques." Phd thesis, Ecole Nationale Supérieure des Mines de Paris, 2012. http://pastel.archives-ouvertes.fr/pastel-00797525.
Full textHumez, Pauline. "Traçage des intrusions de CO2 dans les aquifères d'eau douce par les méthodes multi-isotopiques." Electronic Thesis or Diss., Paris, ENMP, 2012. http://www.theses.fr/2012ENMP0049.
Full textThis study deals with the impact of CO2 leakages out of geological storage into overlying freshwater aquifers. Compared to other existing studies, the major added value of this study lies, on the one hand, in the research of new monitoring tools and isotopic approach in the context of CCS aiming at early and sensitive detection of CO2 leakage and, on the other hand, in the application of these tools at the (limited) laboratory scale as well as at field scale. In order to test these tools, solid and liquid materials were sampled out of the major strategic drinking water Albian aquifer in the Paris Basin (France). We have then precisely characterized and used them within a batch experiment. This experiment yields interesting results which help understanding and constraining precisely the water-rock-CO2 interactions as well as the isotopic responses. A real scale application of the method was then performed in Norway. It was an opportunity to develop this isotopic program and to track the isotopic evolution composition, while differentiating the natural processes and the system response tothe CO2 injection. When applied to the detection of CO2 leakage context, the two case studies open the way for choosing the “best” isotopic tools as indirect indicators of CO2 presence in these specific systems. The efficiency of these isotopic tools comes from the recording of the CO2 footprint all along the water-rock-CO2 interactions. Using such tools imposes a rigorous methodology, which is tackled inthis manuscript. Furthermore, future application will require adapting to the specifics of a proposed site
Froger, Claire. "Sources et dynamiques spatiales et temporelles des contaminations en éléments traces et hydrocarbures aromatiques polycycliques du continuum atmosphère - sol - rivière d'un bassin versant contrasté." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS394/document.
Full textThe development of human societies since the 19th century has led to deleterious impacts on the Critical Zone (from atmosphere to river, including biosphere and soils). Despite the decrease of pollutions since the late 1960’s, contaminations remain especially in urban environment, concentrating human activities. To better manage this pollution, it is necessary to understand the dynamics and pathways of contaminants through the atmosphere – soil – river continuum. The goal of this study in thus to evaluate the temporal and spatial variations of two contaminants (polycyclic aromatic hydrocarbons (PAH) and trace elements (TE)) in the Orge River catchment (900 km2, France) being under increasing urban pressure from up to downstream. Several fingerprinting approaches were used to trace sediment dynamics in the river (radionuclides: ⁷Be, ²¹⁰Pb, ¹³⁷Cs), to identify lead sources (lead isotopes) and PAH sources (PAH molecular ratios). The results demonstrated the strong influence of downstream urban areas on the river quality, with an increasing contamination for Cu, Zn, Sb, Pb and PAH in the particulate phase, and for SO42⁻, Na⁺ et Cl⁻, Cu, Zn and Pb in the dissolved phase. The sediment fingerprinting using radionuclides revealed a significant input of particles originating from urban areas and transferred through urban runoff, and identified road deposited sediments as the major source of contaminated particles downstream. Source tracking of Pb and PAH confirmed urban runoff as the main pathway of river contamination. In addition, annual and seasonal PAH and TE fluxes were estimated respectively for the atmospheric inputs, and riverine exports and revealed a global accumulation of contaminant over the catchment, already containing a significant stock of pollutants in its soils. Finally, this study highlights the need to integrate the Critical Zone and the potential of coupling multiples tracking approaches to properly evaluate the contaminant dynamics. These results may be used to establish a model of contaminants transfer in urban catchments
Van, der Heijden Gregory. "Apport du multi-traçage isotopique (26Mg, 44Ca et 2H) à la connaissance des flux d'éléments minéraux dans les écosystèmes forestiers." Phd thesis, AgroParisTech, 2013. http://pastel.archives-ouvertes.fr/pastel-01058253.
Full textFévotte, François. "Techniques de traçage pour la méthode des caractéristiques appliquée à la résolution de l'équation du transport des neutrons en domaines multi-dimensionnels." Phd thesis, Université Paris Sud - Paris XI, 2008. http://tel.archives-ouvertes.fr/tel-00468118.
Full textBonnière, Antoine. "L'approche par multi-traçage géochimique, isotopique et organique comme outil d'étude de l'origine et du transfert des contaminants dans les eaux souterraines : Application à la nappe de la Vistrenque." Electronic Thesis or Diss., Nîmes, 2024. http://www.theses.fr/2024NIME0004.
Full textIn France, groundwater supports 65% of the drinking water supply. The increasing pressures of human activities lead to water pollution and the closure of water supply wells. The diversity of existing pollutants and the emergence of new contaminants require a comprehensive understanding of the functioning of groundwater bodies. The implementation of action plans by local authorities and resource managers requires identifying the origins of contaminants and defining vulnerable areas with precision. The objective of this work is to establish a multi-tracer approach on the Vistrenque aquifer (France, Gard), to study the origin and transfer of contaminants. Analyses include natural tracers of water origin (major, minor, and trace elements), stable isotopes of water molecules (δ18O/δ2H-H2O), stable nitrogen isotopes of nitrates δ15N/δ18O-NO3-, boron isotope δ11B, gadolinium (Gd), as well as a range of organic molecules including pesticides and pharmaceutical residues, serving as tracers themselves. Using this multi-tracer approach, it was possible to identify the origin of nitrates in water catchment areas where agricultural and urban nitrate sources overlap. Analysis of the isotopic signature in δ15N/δ18O-NO3- of easily mobilized nitrates in soils has proved to be an effective tool for characterizing nitrogen pollution in an agricultural context. The land parcels responsible for contamination were identified, based on the comparison of the isotopic signatures of soils and groundwater. In addition to agricultural contamination, the infiltration of an urban effluent plume from a wastewater treatment plant into the aquifer highlighted the importance of studying the occurrence of pharmaceutical residues and the vulnerability of aquifers to emerging contaminants. All these observations have laid the groundwork for extending this approach to other study areas, focusing on the operability of the geochemical, isotopic, and organic multi-tracer approach
Lebreton, Benoît. "Analyse de la structure et du fonctionnement du réseau trophique d'un herbier par approche multi-traceurs : traçage isotopique naturel et profils acides gras : cas de l'herbier intertidal de Zostera noltii du bassin de Marennes-Oléron, France." La Rochelle, 2009. http://www.theses.fr/2009LAROS266.
Full textThe littoral zone contains ecosystems featuring high and diversified primary production which constitute the base for complex food webs. Among the producers, seagrass beds produce matter which in general is poorly consumed, thus contributing to the detritus food web. Furthermore, seagrasses form a support for high epiphyte production. This work was carried out to verify these general patterns for the functioning of an intertidal Zostera noltii seagrass bed. Biomasses of different producer and of consumer compartments were estimated and their spatial and temporal variations assessed. The fate of the produced matter was studied by a multi-tracer method using natural isotope tracing and fatty acid profiling. It is shown that epiphyte biomass was low, thus comprising a negligible resource for consumers. Among the macrofaunal consumers, grazers dominated (73% of macrofaunal biomass). Conversely, the meiofauna represented 30% of the total biomass of benthic consumers. When epiphytes were lacking, microphytobenthos was the principal food resource for most of the macrobenthic species (deposit feeders, grazers). The seagrass itself is not much used by the invertebrate consumers and its fate in the food web remains poorly understood. In conclusion, the results demonstrate the minor role of epiphytes in the trophic web of this intertidal seagrass bed. The benthic invertebrates exploit another algal resource: the microphyobenthos
Sciannandrone, Daniele. "Acceleration and higher order schemes of a characteristic solver for the solution of the neutron transport equation in 3D axial geometries." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112171/document.
Full textThe topic of our research is the application of the Method of Long Characteristics (MOC) to solve the Neutron Transport Equation in three-dimensional axial geometries. The strength of the MOC is in its precision and versatility. As a drawback, it requires a large amount of computational resources. This problem is even more severe in three-dimensional geometries, for which unknowns reach the order of tens of billions for assembly-level calculations.The first part of the research has dealt with the development of optimized tracking and reconstruction techniques which take advantage of the regularities of three-dimensional axial geometries. These methods have allowed a strong reduction of the memory requirements and a reduction of the execution time of the MOC calculation.The convergence of the iterative scheme has been accelerated with a lower-order transport operator (DPN) which is used for the initialization of the solution and for solving the synthetic problem during MOC iterations.The algorithms for the construction and solution of the MOC and DPN operators have been accelerated by using shared-memory parallel paradigms which are more suitable for standard desktop working stations. An important part of this research has been devoted to the implementation of scheduling techniques to improve the parallel efficiency.The convergence of the angular quadrature formula for three-dimensional cases is also studied. Some of these formulas take advantage of the reduced computational costs of the treatment of planar directions and the vertical direction to speed up the algorithm.The verification of the MOC solver has been done by comparing results with continuous-in-energy Monte Carlo calculations. For this purpose a coupling of the 3D MOC solver with the Subgroup method is proposed to take into account the effects of cross sections resonances. The full calculation of a FBR assembly requires about 2 hours of execution time with differences of few PCM with respect to the reference results.We also propose a higher order scheme of the MOC solver based on an axial polynomial expansion of the unknown within each mesh. This method allows the reduction of the meshes (and unknowns) by keeping the same precision.All the methods developed in this thesis have been implemented in the APOLLO3 version of the neutron transport solver TDT
Dausse, Amélie. "Facteurs d'échelle dans la hiérarchisation des écoulements au sein d'un aquifère karstique : Analyse multi-échelles des propriétés hydrodynamiques et de transport de l'aquifère du Lez." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS073/document.
Full textCharacterizing groundwater flows in karst aquifers at different scales of space and time, is not an easy task due to the high level of heterogeneity of these aquifers. Because the limited testing radius of classical hydraulic methods (slug tests, pumping tests), the regional hydraulic parameters of karst systems are generally estimated using the flow recession analysis method. But this integrative method generally does not give a differentiation into regionally varying parameters. Also, it is generally difficult to gather enough data to characterize aquifer heterogeneities at regional scale. For this reason, most of studies about hydrodynamic characterization of karst aquifer focus on local scales, i.e experimental field site scale or borehole scale; measurements at small scale could then be upscaled to obtain hydrodynamic parameters at regional scale. Consequently, understanding scale dependence of groundwater flows organization in such a context is of prime importance for the development of regional scale model.In this study, the monitoring of groundwater flow and transport is performed at several scales of time and space, within a single Mediterranean karstic carbonate aquifer, the Lez karst aquifer, located South of France. Groundwater is intensely pumped in a karst conduit upstream of the main karst outlet (Lez spring), for regional water supply. At regional scale, the relatively dense groundwater monitoring network permits to determine the hydrodynamic properties of the aquifer inferred from the hydrodynamic response to pumping at the Lez spring. At the scale of the experimental field site (Terrieu site), that comprises 22 boreholes, several experiments (i.e. pumping tests, packer tests, slug and injection tests) were performed to determine the hydrodynamic properties at experimental field site scale and borehole scale. Tracer experiments were also performed to provide an estimation of transport properties both at the scale of the experimental field site and at regional scale.The hydrodynamic properties estimated at different scale of space and time (for different hydrological conditions) were compared with flow paths organization linked to the geological structure of the reservoir. At regional scale both the hydrological conditions (i.e. high or low water level) and geological compartmentalization that impact the hydraulic connectivity, control the hydrodynamic properties. Tracer experiments revealed short time transfer and high connectivity between injection points and the spring. At the experimental field site scale, pumping and tracer test highlighted heterogeneous flow pattern that can be linked to the position of boreholes and the main geological features. At borehole scale, hydraulic tests revealed a high range of hydrodynamic properties (transmissivity from 10-11 m²/s to 10-2 m²/s) depending on the investigated part of the aquifer (matrix, fracture or drain).Depending on the water level conditions, the aquifer presents variable organization of flows that modify the hydrodynamic parameters. As expected, variability of hydrodynamic parameters depends on the scale of investigation: a difference of 10 to 105 has been quantified for a same parameter characterized at borehole scale and at regional scale. This hydrogeological parameters quantification of karst system provides important constrain about multiscale modeling using conceptual models to represent the characteristics of the main flow paths
Séraphin, Pierre. "Contribution du traçage isotopique (δ 18O et δ D) à la compréhension et à la modélisation hydrogéologique de la nappe de la Crau." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4353.
Full textThe Crau plain (Southern France) contains an alluvial aquifer described as a regional "heritage resource". Started nearly 500 years ago by creating a network of canals, the cultivation of grasslands is even today performed using a traditional technique of irrigation by flooding. Derived from another watershed, irrigation water has a major impact on the recharge of the aquifer. Nevertheless, urbanization of the territory, increase of uptakes, and climate change threaten the existing balance of the Crau aquifer. The preservation of this resource therefore requires the production of an efficient management tool accounting for the whole hydro-system in its hydrological and geometric complexity. This thesis presents an original approach of hydrogeological modeling by independently estimating, for each step, the necessary variables and parameters, reducing a recurring problem of equifinality. Providing a reliable forecasting tool, this new model is implemented by realistic scenarios to observe the impacts of climate change, the evolution of the planned land-use, and occasional reductions of irrigation input in 2030. Under the combined effects of these recharge reductions (up to -19%) the water table could be subjected to local decreases up to 2 m, leading to the drying up of rare and protected wetlands