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3D Structural Modelling and Restoration of a Deformed Alpine Karst Reservoir: Insights into the Groundwater Flows of the Dévoluy Massif (French Alpine Foreland)
No full textInternational audienceIn foreland fold-thrust belts, tectonically deformed aquifers remain underexplored, largely due to the complex architecture of their hydrogeological reservoirs. This limited understanding prevents the development of sustainable management policies to face the current decline in groundwater availability. In the southwestern Subalpine Chains, we characterised the structure of the folded Senonian karst aquifer of the Dévoluy Massif, which is transected by the Median Dévoluy Thrust. Using surface structural data, we performed an original 3D structural model of the massif. Quantitative analyses of this model indicate a total Senonian package volume of 114 km 3 , of which 25 km 3 lie below the elevation of Gillardes Spring, the main karst discharge. A structural restoration of the base of the Senonian indicates Alpine shortening of ~4.4 km in the southern part of the massif and ~1.2 km in the northern part. The deformation of the karst reservoir into two N-trending synclines, separated by the Median Dévoluy Thrust, is identified as a key control on the northward groundwater drainage pattern, culminating at Gillardes Spring. This 3D structural modelling approach also allowed for identification of suitable areas for the exploration of new deeper resources. Finally, this study highlights the potential of a hydrostructural approach and 3D structural modelling for assessing the hydroge-ology in tectonically deformed karst reservoirs
Caractérisation haute résolution des sites pollués: Tests d’outils innovants pour la mesure de flux et concentrations – projet HRSC
No full textInternational audienceLa caractérisation de la pollution du milieu souterrain d’un site est un enjeu essentiel pour définir les actions de remédiation et atteindre les objectifs associés. Or la caractérisation des pollutions, par l’intermédiaire d’un prélèvement classique (i.e. concentration moyenne) d’eau souterraine dans un piézomètre, ne permet pas de traduire la complexité des sites. Des prélèvements multiniveaux et l’acquisition de données complémentaires aux données de qualité chimique des eaux peuvent permettre de répondre à ce besoin de caractérisation détaillée des eaux souterraines. Les tests de déploiement d’outils multiniveaux sur 2 sites réels ont montré le caractère opérationnel de ces outils, leur capacité à mettre en évidence les hétérogénéités verticales des concentrations en HCT et COHV, des vitesses d’écoulement et des flux de polluants. Ces tests ont permis de montrer l’apport de ces outils et d’expliquer des différences observées entre les outils déployés et vis-à-vis des mesures classiques (concentration moyenne sur l’épaisseur de la lame d’eau dans le puits). Ce projet a ainsi permis de porter à connaissance de la communauté des sites et sols polluées au travers d’une vidéo et de fiches détaillant les périmètres d’utilisation de ces outils, les conditions opérationnelles de leur mise en oeuvre mais aussi leurs limites
Flow and thermal modeling of a geothermal doublet in a layered reservoir of Paris Basin
No full textInternational audienceThe Dogger carbonate formation of Paris Basin has been a target for geothermal exploitation since the late 1960's. The reservoir consists of a hot water aquifer of regional extent composed of pervious oolithic limestones and dolomites of Mid-Jurassic age. The depths and temperatures are ranging from 1450 to 2000 m and 56 to 80°C respectively. Based on flowmeter logs and seismic surveys the pervious units are conceptualized as layers of large extent, greater than the mean inter-well distance, 10 3 metres, a few metres thick and interbedded by aquitards. The geothermal performance of a doublet is measured by two indicators: the cold-water breakthrough time and the temperature reached in the producer well after thirty years. These indicators are assessed for each doublet by geomodelling and flow and thermal numerical simulation. Another modeling tool of interest for the layered geology of Paris Basin is the model proposed by Gringarten and Sauty in 1975. Their model gives the time evolution of the temperature in a producer well for a single pervious infinite layer embedded into an impervious host rock. This model is very valuable because it links analytically the thermal response of a doublet to the physical parameters of the system. However, it cannot be extended to the multilayered case and is of little help to tackle the connectivity issue raised when layers are of finite extent. In this paper we address these two heterogeneity issues by means of geostatistical simulations and upscaling approaches. We propose to keep the Gringarten and Sauty modeling framework and explore how to account for both vertical and lateral heterogeneities by using equivalent parameter
Strike-slip tectonic-driven peraluminous rare-metal magmatism: insights from the late-Variscan Blond granitic complex (French Massif Central)
No full textInternational audienceDuring the late Carboniferous to early Permian, major crustal magmatism in the internal domains of the European Variscan belt was locally associated with the emplacement of small volume of highly-fractionated peraluminous magmas strongly enriched in rare metals such as Li, Be, Nb, Ta, Sn, and W known as rare-metal granites and pegmatites. The northern part of the French Massif Central (FMC) is particularly well endowed with such deposits, and significant scientific research has focused on their formation conditions and magmatichydrothermal evolution. However, the tectonic context of rare-metal magmas emplacement, including the role of deformation in melt extraction, ascent and metal enrichment, remains poorly understood. The Blond peraluminous granitic complex, located in the NW FMC, represents an ideal natural laboratory for studying the relationship between late-Variscan tectonics and rare-metal magmatism. The main granitic intrusion consisting of two-mica and muscovite facies was syntectonically emplaced at 319 ± 7 Ma along the Oradour fault, a major late-Variscan N135-striking dextral strike-slip shear zone. Both facies are crosscut by several F-Sn-(Li)-rich topaz-cassiterite granitic dykes and stocks (”ongonite”) likely emplaced in relation to N60-striking sinistral shear zones. New structural measurements, petro-geochemical analyses, and U-Pb dating are currently in progress to investigate the magmatic and tectonic history of the Blond complex and its relationship with the emplacementof strongly evolved melts.In the northwest part of the complex (La Puelle quarry), the muscovite facies of the Blond granite shows a ~N100 oriented subvertical magmatic fabric and is affected by two sets of high-dipped strike-slip shear bands (mean: N033-77°E and N072-82°S) and one set of steep ongonite dykes (mean: N006-62°E). The shear bands are sinuous and show sinistral plastic to brittle-plastic deformation as protomylonitic zones with S-C fabrics and cores of (ultra)mylonite or ultracataclasite. They bear sub-horizontal lineations or striations, and are locally overprinted by extensional fractures developed along the shear band and filled by combquartz. The ongonite dykes (1 to 20-cm thick) are commonly sinuous, locally arranged in en échelon pattern, and become thinner in the propagation tip. The contacts between the dykes and the host rock are either sinuous or sharp. One ongonite dyke is plastically deformed within a sinistral shear zone, which supports a syntectonic emplacement. The reduced stress tensor calculated through inversion of structures (n=34) is consistent with reverse strike-slip deformation (sub-vertical ) with a sub-horizontal N010-oriented σ1. The structures in the quarry can be explained with the classical Riedel shear model, where the ongonite dykes represent tension gashes, and the N033 and N072-oriented families the R’ and P’ antithetic shear zones, respectively, linked at depth to the Oradour fault. In situ U-Pb dating of magmatic cassiterite constrains the emplacement of ongonites at 310 ± 6 Ma. The episode of tectonically-assisted rare-metal magmatism seems synchronous with the N-S-striking emplacement of the Richemont rare-metal rhyolitic dyke (313 ± 3 Ma) and wolframite-cassiterite-bearing quartz veins (310 ± 4 Ma). These observations underscore the significant role of late-Variscan strike-slip tectonics in creating structures of localized extension, which facilitated the vertical migration of rare-metal-rich melts and the focalization of mineralizing fluids at upper crustal levels.This work is funded by ANR-22-EXSS-0014
Agroécologie et eau : comment s'intègrent-elles dans le projet alimentaire territorial de l'agglomération de Carcassonne ?
No full textFiche de stag
Vers un outil web aidant les acteurs de l'aménagement du territoire (de la planification au design) à mieux intégrer les sols dans leurs processus et leurs pratiques.
No full textInternational audienceSoil is an essential part of the Earth continental surface, but it is submitted to a multitude of threats. The associated degradation is at risk for human being and ecosystems. That is why the integration of soil in spatial planning and design is essential. Spatial planners and designers however usually lack knowledge on soils. In addition, soils are not directly considered in current sectorial regulations. The European soil monitoring law should help increase awareness on soils and promote the use of the various tools and methods already developed to qualify soils. To fill the lack of tools to help planners and designers find out the right soil tools/methods to answer their needs along their process, the EU funded SPADES project is developing a webtool called Navigator. The objective of this abstract is to present the users’ need analysis to the soil community to get its feedback as a target group of the soil-planner Navigator. The users’ needs analysis is based on meetings with stakeholders from the pilots involved in the SPADES project, on a taskforce of stakeholders from the SPADES pilots and other volunteers. National and international events are also opportunities to interact directly with professionals and experts
Étude de l’impact de l’irrigation sur les services et dis services écosystémiques fournis par les plantes de service dans des systèmes en transition vers l’agriculture de conservation
No full textCette étude porte sur l’agriculture de conservation et la gestion durable de l’eau, dans un contexte de changement climatique où cette ressource devient limitée. L’objectif principal est de comparer l’impact de différentes modalités d’irrigation sur les services écosystémiques (SE) et les disservices écosystémiques (DSE) fournis par les couverts d’interculture. Ces plantes de service jouent un rôle clé dans la fertilité, la protection et la résilience des sols, mais leur performance dépend fortement de leur développement, donc de la disponibilité en eau. L’expérimentation a été conduite sur deux sites d’INRAE contrastés par leur climat : Toulouse-Auzeville (océanique altéré) et Montpellier-Lavalette (méditerranéen sec). Trois modalités hydriques ont été testées (pluvial, irrigation de levée, irrigation sans restriction) sur des couverts d’été (sorgho seul ou en mélange avec niébé et tournesol), suivis par des couverts d’hiver (féverole) et une culture de rente (sorgho grain). L’étude a porté sur la croissance et la biomasse des couverts, ainsi que sur plusieurs SE et DSE : restitution en azote et éléments minéraux, stockage de carbone, régulation des adventices, structuration et humidité du sol. Les résultats montrent que l’irrigation influence fortement la biomasse et donc les services rendus, surtout en climat sec. En revanche, l’impact sur la culture principale reste limité à court terme. Ces travaux montrent que l’irrigation peut renforcer les SE fournis par les couverts, mais aussi générer des DSE liés à la consommation d’eau. Elle doit donc être pensée comme un compromis, ajusté au climat et aux objectifs agronomiques, afin de concilier performance agricole et durabilité des agroécosystèmes
Simulation des conduits karstiques des Calcaires du Barrois avec KarstNSim
No full textInternational audienceIn this work, we show how, when applied to the Barrois Limestones, the KarstNSim approach allows for stochastic simulation of 3D karst networks. KarstNSim is a pseudo-genetic method, based on a simplified reproduction of the consequences of the physicochemical processes at the origin of karst. It relies on the definition of a cost function across the entire domain. This function is then used to compute least cumulative cost paths between pairs of input and output points of the network, thereby tracing the branches of the karst network skeleton. This approach constrains the network morphology according to speleogenetic concepts, through simple input parameters such as the position of inception horizons, the orientation of fracture sets, the presence and position of one or several water tables, and the intrinsic karstification potential of the geological domain.KarstNSim offers the possibility to reproduce polygenic karsts through sequential simulations, where each iteration influences the next. Thanks to its adaptable cost function, KarstNSim can also account for pre-karstification processes in the geological domain, such as ghost-rock weathering, which then influences the position and geometry of the simulated conduits.The approach is applied to the karstified Barrois plateau, a region located east of the Paris Basin, composed of widely outcropping Tithonian limestones. Karstification there began during an emersion phase and has continued to the present day through different processes: ghost-rock weathering, crypto-alteration, and epigenic karstification beneath cover (Jaillet, 2000). These processes are linked to a progressive lowering of the regional base level associated with the slow exhumation of carbonate formations.KarstNSim makes it possible to simulate karst networks by reconstructing this geological history: integrating a structuring pre-karstification and a progressive base-level lowering that induces conduit tiering. Finally, conduit dimensions are simulated on the skeletons generated by KarstNSim using a curvilinear Sequential Gaussian Simulation approach.Dans ce travail, nous montrons comment, en l'appliquant aux Calcaires du Barrois, l'approche KarstNSim permet de simuler de manière stochastique des réseaux karstiques 3D. KarstNSim est une méthode pseudo-génétique, dont le principe est la reproduction simplifiée des conséquences des processus physico-chimiques à l'origine du karst. Elle s'appuie sur la définition d'une fonction de coût dans l'ensemble du domaine. Cette fonction est ensuite utilisée pour calculer des chemins de moindre coût cumulé entre paires d'entrée et de sortie du réseau, traçant les branches du squelette du réseau karstique. Cette approche permet de contraindre la morphologie du réseau aux concepts spéléogénétiques associé, grâce à des paramètres d'entrée simples, comme la position d'horizons d'inception, l'orientation de familles de fractures, la présence et la position d'une ou plusieurs nappes phréatiques, et le potentiel de karstification intrinsèque du domaine géologique.KarstNSim offre la possibilité de reproduire des karsts polygéniques par des simulations séquentielles, chaque itération influençant les suivantes. Au travers de sa fonction de coût modulable, KarstNSim peut aussi prendre en compte des processus de pré-karstification du domaine géologique, comme la fantômisation, qui influence alors la position et la géométrie des conduits simulés.L'approche est appliquée au plateau karstifié du Barrois, une région située à l'est du Bassin parisien, constituée de calcaires tithoniens largement affleurants. La karstification y a débuté à la faveur d'une phase d'émersion et s'est poursuivie jusqu'à aujourd'hui sous différentes modalités : fantômisation, crypto-altération et karstification épigène sous couverture (Jaillet, 2000). Ces processus sont en lien avec une baisse progressive du niveau de base régional associé à l'exhumation lente des formations carbonatées.KarstNSim permet de simuler les réseaux karstiques en reconstituant cette histoire géologique : intégration d'une pré-karstification structurante et baisse progressive du niveau de base induisant un étagement des conduits. Enfin, les dimensions des conduits sont simulés sur les squelettes créés par KarstNSim à l'aide d'une approche par Simulation Gaussienne Séquentielle curvilinéaire
The European agro-economic model AROPAj
No full textThis publication presents the European agro-economic AROPAj model. Throughout recent years the model has been adapted to suit FADN data and the expansion of the European Union (EU ). The revised model, which is presented here, is based on the same principles,modularity, and generic conceptions of the previous renditions. The strength of the model lies in the evolution of computing capacities and facilities, especially when new scientific problems arise.The starting premise of the model resulted from the combination of different factors, namely new policy tools announced to be implemented by the changing Common Agricultural Policy (CAP), the need to account for a wide diversity of farming systems, and the changing geographical area following the EU enlargement. In complement of econometric approaches relying on past information, the model introduces new mathematical programming (MP) approaches using the most relevant data.The Farm Accountancy Data Network (FADN ) is considered as a permanent, robust and representative source of information, useful for MP models delineated at the farm level. The information in the FADN database consists of surveys of individual farm samples. The database provides individual information mainly accounting of accountancy and financial or economic variables. The AROPAj model is also capable of using data on physical variables such as livestock, production, and land. Nevertheless, a lot of AROPAj parameters are not directly sourced by raw FADN data. For example, the model makes use of other data sources, including expert reports and books, such as livestock feeding. Other sources utilized by some AROPAj modules are inter alia data concerning land use and land cover (Land Use/Cover Area frame Statistical Survey (LUCAS), CORINE Land Cover (CLC)), the European Soil Database provided by the European Joint Research Centre (JRC), the Digital Elevation Model (DEM ), and the Climate information provided by the European MARS JRC Unit. These variables are grouped by means of a clustering method to form a group of similar farms that present similar characteristics and thus can form a unit of modeling for the AROPAj model: the farm type (also denominated by farm group). The overall model is based on farm-groups, designed on a regional scale, for all of the EU.In large part, the AROPAj model originates from modeling tools aiming at CAP impact assessments. Mathematical programming models are effective in this way, especially when the implementation of new policy tools in economic models has to rely on non-time dependent data, unlike time-inferred econometric models. Due to the wide and complex diversity of CAP tools renewed throughout decades, the CAP block size quickly increased. The generic modeling approach embraces the wide variety of European farming systems which are subsumed by the continually-growing EU. It involves a multi-scale analysis from the farm type level to the EUlevel, accounting for realistic discontinuities at the farm level.The model is also designed to assess global change impacts and analyze policy while accounting for the complexity of interactions between agriculture and the environment. In this regard, it is a tool used for the analysis of a large range of economic and environmental domains, such as greenhouse gas (GHG) emissions and abatement, nitrogen sourced pollutions, biomass provision from perennial crops, ozone impacts and adaptation to climate change. Other collateral outputs may exist when providing farm-based estimates and data related to physical parameters.The interest of linking the AROPAj economic model with biophysical models relies on the possibility of accounting for environmental (physical impacts such as soil and climate) and technical variable impacts on the production functions, as well as on the agricultural system output relevant to environmental concerns. The general goal is to bring to light the relationship between crop production inputs (e.g. fertilizer applications) and crop production outputs (e.g. yields). The potential relation between the economic and biophysical models is to be found in the management practices of the farmer, such as irrigation, application of pesticides, and fertilizer.Some refinements are required when the farm group’s optimal solution is made of non-marketed crop output (or of non-marketed nitrogen input). In other words, this occurs when, at the optimum, the crop production is entirely re-used on-farm (e.g. for livestock feeding), or when no N -input comes from the market (e.g. manure sourced). In this case, market prices have to be replaced by relevant shadow prices, which are part of the optimal solution. In practice, the problem is solved by iterated AROPAj runs with shadow prices replacing the prices used at the previous iteration for the yield function derivative. This process of convergence is fast in most AROPAj LP’s, except for a few cases where solutions have periodic forms over iterations, with slight amplitudes.The model is running using the GNU software and applications, except for the marketed optimization solving tool (GAMS). Year after year, the choice has been made to promote the use of GNU software for AROPAj improvement, not only regarding the financial cost, butmainly to facilitate the maintenance and the evolution of our programs and applications. The model also produces some interesting spatially disaggregated outputs in line with multi-scale environmental problems. The computing and algorithm facilities embedded in the modeling process allow new improvements and new model exploitation exercises. The European agro-economic AROPAj model is built of a set of linear programming models, aiming at a good representation of European farming systems in term of geography and farm type diversity as well. As a result, the model aims at being a tool and a reference, which benefits a significant numbers of PhDs and MSc students, and contributes to many published peer-reviewed papers (to which this document refers)
Développement d'un outil intégré à base d'électrodes tout-solide pour la mesure in situ et en continu du pH des eaux d'une formation argileuse en conditions de stockage géologique.
No full textIn France, the Callovo-oxfordian (Cox) geological formation has been chosen as the future site for a deep geological repository dedicated to the isolation of nuclear waste, as part of an innovative reversible storage concept. The monitoring of this repository depends in particular on the monitoring of two key parameters: pH and redox potential, which reveal physical, chemical and electrochemical transformations (oxidation-reduction). In this context, the work carried out in this thesis focused on the design and optimization of robust all-solid-state pH-sensitive electrodes and reference electrodes, adapted to the extreme constraints of deep geological storage. This manuscript first presents the synthesis and preparation of all-solid-state metal oxide/metal (MOx/M) electrodes based on iridium (IrOx/Ir), ruthenium (RuOx/Ru) and molybdenum (MoOx/Mo), used for pH measurement. The IrOx/Ir and MoOx/Mo electrodes were synthesised by thermal oxidation, while the RuOx/Ru electrodes were prepared by electrodeposition. A hydration treatment was applied to all these electrodes in order to stabilize the potential drift, an essential point for guaranteeing the long-term reliability of the pH sensor. The IrOx/Ir electrodes show a near-nernstian response, while those based on molybdenum and ruthenium show a super-nernstian response. Using characterization techniques such as scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), the morphology, structure and chemical composition of the films present on the electrode surface were determined, and the main redox couples responsible for the response to pH variations were determined:Ir(IV)/Ir(III),Ru(IV)/Ru(III) and Mo(IV)/Mo(VI),present in the form of oxides and oxyhydroxides. In addition, electrochemical impedance spectroscopy (SIE) measurements were used to highlight the interface phenomena involved in the response of IrO₂/Ir₂O₃ and MoO3/MoO2 electrodes. These electrodes were potentiometrically tested in environments simulating real storage conditions and showed interesting performances. In a second phase, a specific perovskite was studied: lithium lanthanum titanium oxide (LLTO), to be used as a pH-sensitive electrode or as a reference electrode. LLTO has ionic properties fixed by its grains and grain boundaries. The synthesis of the powder was optimized using conventional solid-state chemistry method. A unique technique was used to manufacture electrodes based on polycrystalline LLTO: Spark Plasma Sintering (SPS). Depending on the sintering conditions, some electrodes (with a higher grain boundary conductivity σgb) showed a sub-nernstian response to pH, while others (lower σgb) behaved as a reference. σgb being two orders of magnitude lower than the grain conductivity σg. Crystal growth by the floating zone method was used to eliminate the contribution of grain boundaries. However, the response of LLTO single crystals to pH variation remains sub-nernstian. The polycrystalline reference electrodes have been tested under conditions simulating real environments, and have demonstrated promising performance, in particular insensitivity to redox species.En France, la formation géologique Callovo-oxfordienne (Cox) a été retenue pour accueillir le futur centre de stockage géologique profond dédié à l'isolement des déchets nucléaires, dans le cadre d'un concept innovant de stockage réversible. La surveillance de ce stockage repose notamment sur le suivi de deux paramètres clés : le pH et le potentiel redox, révélateurs des transformations physiques, chimiques et électrochimiques (oxydoréduction). Dans ce contexte, les travaux de cette thèse ont porté sur la conception et l'optimisation d'électrodes sensibles au pH et d'électrodes de référence tout-solide robustes, adaptées aux contraintes extrêmes du stockage profond. Ce manuscrit présente tout d'abord la synthèse et la mise en forme d'électrodes tout-solide oxyde de métal/ métal (MOx/M) à base d'iridium (IrOx/Ir), de ruthénium (RuOx/Ru) et de molybdène (MoOx/Mo), utilisées pour la mesure du pH. La synthèse des électrodes IrOx/Ir et MoOx /Mo a été réalisée par oxydation thermique, tandis que la préparation des électrodes RuOx /Ru été effectuée par électrodéposition. Un traitement d'hydratation a été appliqué à l'ensemble de ces électrodes afin de stabiliser la dérive de potentiel, un point essentiel pour garantir la fiabilité du capteur de pH sur le long terme. Les électrodes IrOx/Ir présentent une réponse proche de la nernstienne, tandis que celles à base de molybdène et de ruthénium présentent une réponse super-nernstienne. Grâce aux caractérisations par microscopie électronique à balayage couplée à la spectroscopie dispersive en énergie des rayons X (MEB-EDS), la diffraction des rayons X (DRX) et la spectroscopie photoélectronique à rayons X (XPS), la morphologie, la structure et la composition chimique des films présents à la surface de l'électrode ont été déterminées, et les principaux couples redox responsables de la réponse aux variations de pH ont été déterminés :Ir(IV)/Ir(III), Ru(IV)/Ru(III) et Mo(IV)/Mo(VI), présents sous forme d'oxydes et d'oxyhydroxydes. De plus, des mesures de spectroscopie d'impédance électrochimique (SIE) ont permis de mettre en évidence les phénomènes d'interface impliqués dans la réponse des électrodes IrO₂/Ir₂O₃ et MoO3/MoO2. Ces électrodes ont été testées en potentiométrie dans des environnements simulant les conditions réelles du stockage, et ont montré des performances intéressantes. Dans un second temps, une pérovskite spécifique a été étudiée : l'oxyde de titane et de lanthane de lithium (LLTO), envisagée comme électrode sensible au pH ou comme électrode de référence. En effet, le LLTO possède des propriétés ioniques fixées par ses grains ainsi que ses joints de grain. La synthèse de la poudre a été optimisée à l'aide de la chimie du solide classique. Une technique inédite a été mise en œuvre pour la fabrication des électrodes à base de LLTO polycristallin : le Spark Plasma Sintering (SPS). En fonction des conditions de frittage, certaines électrodes (ayant une conductivité des joints de grain σgb plus élevée) ont donné une réponse sub-nernstienne au pH, tandis que d'autres (σgb plus faible) se sont comportées comme référence. σgb étant deux ordres de grandeur plus faible que la conductivité des grains σg. La croissance cristalline par la méthode de zone flottante a été utilisée afin d'éliminer la contribution des joints de grain. La réponse des monocristaux de LLTO aux variaition de pH reste toutefois sub-nernstienne. Les électrodes de références polycristallines ont été testées dans des conditions simulant les environnements réels, et ont démontrées des performances prometteuses, notamment une insensibilité aux espèces redox