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This work correlates surface and ground water composition to the substrata, and traces how water chemistry evolves at Brazil’s largest coal mine, the Candiota Mine. The water is dominated by SO4, Fe, Ca, and Mg. A pH range of 2.7–3 in the pit lakes is attributed through chemical models to concomitant pyrite oxidation and carbonate dissolution along with slow hydrolysis of aluminosilicate minerals and buffering provided by several iron oxy-hydroxide species. The Fe deficit of the surface water relative to the expected values is mainly due to precipitation of Fe sulfate salts, hydroxysulfates, and oxyhydroxides in the waste piles and their runoff. A progressive decrease in oxygen partial pressure with increased lake depth leads to destabilization of the iron oxyhydroxides/hydroxysulfates formed near the surface, which explains their absence from the lake sediment. Although interacting with similar rock types, the groundwater has a significantly different composition than the surface water, with less salinity and a pH of 5–6.5, due to limited oxygen and its evolution in a nearly closed system that stabilizes at higher pH values, which is controlled by carbonate/bicarbonate buffering.

Introduction La lepre est rare en metropole, avec moins de 20 nouveaux cas diagnostiques par an. Nous rapportons une observation de lepre multibacillaire (MB) lepromateuse polaire (LP) avec erytheme noueux lepreux (ENL). Observations Une femme de 23 ans, originaire des Philippines, en France depuis 2015, sans antecedent notable etait adressee a la consultation de dermatologie pour des lesions cutanees d’extension progressive depuis 2015. L’examen mettait en evidence plus de 200 lesions papuleuses et nodulaires de petite taille, erythemateuses, violines ou discretement cuivrees. L’eruption, bilaterale et symetrique, touchait le visage avec confluence des lesions sur les oreilles et les levres ainsi que le tronc et les 4 membres. Il existait un œdeme brillant et tendu des 2 jambes. L’examen neurologique etait normal. Une premiere histologie realisee en externe mettait en evidence une infiltration cellulaire dermique constituee d’histiocytes clairs de grande taille, se disposant en nappe, avec un marquage CD 163+, facteur XIIIa + CD1a − faisant suspecter une histiocytose non langerhansienne. La presentation clinique et l’origine geographique faisant evoquer une lepre, une coloration de Ziehl sur biopsie cutanee etait demandee en urgence et revenait positive. Le frottis bacillaire realise sur le lobe de l’oreille etait positif +++, la PCR Mycobacterium leprae etait positive sur la biopsie cutanee. La NF, l’ionogramme sanguin, la CRP, les fonctions renale et hepatique etait normaux. Il existait une hypergammaglobulinemie polyclonale, des anticorps (Ac) anti-nucleaires mouchetes au 1/160 ; les Ac anti-Beta-2-GP1 et cardiolipines etaient faiblement positifs, une cryoglobulinemie de type III etait presente. L’electromyogramme montrait une polyneuropathie sensitivo-motrice axonale asymetrique touchant les membres inferieurs, evocatrice de multinevrite. Le diagnostic retenu etait une lepre MB dans une forme LP associee a un probable ENL (aspect nodulaire et œdemateux des membres inferieurs et auto-immunite biologique). La reprise de l’interrogatoire mettait en evidence un contage avec le pere traite pour une lepre 10 ans auparavant. Une polychimiotherapie anti-bacillaire associant Rifampicine®, Lamprene® et Disulone® etait instauree ( Fig. 1 et 2 ). Discussion Nous presentons ici un cas atypique de lepre LP avec ENL. La presentation clinique et histologique peut etre parfois trompeuse et mimer une histiocytose (dans les formes lepromateuses). La coloration de Ziehl (realisee sur biopsie cutanee) est un examen simple permettant de redresser facilement le diagnostic dans les formes lepromateuses multi-bacillaires. Conclusion Bien que rares, de nouveaux cas de lepre non autochtones sont diagnostiques chaque annee en France metropolitaine. Il faut savoir evoquer le diagnostic notamment chez des personnes originaires et/ou de retour de pays d’endemie.

Metal contents were measured in the main rivers of the Garonne basin (SW France). Metal concentrations are shown to be slightly lower but nevertheless comparable to those of other Western European rivers such as the Seine river. As these rivers, the bulk river load show typical metal enrichments (estimated through the enrichment factor, EF=(Cx/CAT)river/(Cx/CAT)cc) by factors of 10 and even 100 for some metals, relatively to the mean continental crust composition. A set of arguments is presented assigning the origin of this metal enrichment for most metals to a general non point contamination of anthropogenic origin through atmospheric inputs and soils transfer.

International audience; The aqueous interfacial chemistry of kaolinite and Na-montmorillonite samples was investigated by potentiometric measurements using acid/base continuous titrations and batch experiments at 25 and 60 °C. Using the batch experimental method, a continuous drift of pH was observed reflecting the mineral dissolution. Consequently, the continuous titration method appears to be the best way of studying solid surface reactions. For each clay mineral, the net proton surface excess/consumption was calculated as a function of pH and ionic strength (0.025, 0.1 and 0.5 M). At 25 °C, and according to the literature data, the pH corresponding to zero net proton consumption for montmorillonite appears to depend on ionic strength, whereas the value for kaolinite is constant and close to 5. Similar results are obtained at 60 °C, which suggests that the point of zero net proton consumption for clay minerals does not depend on temperature, at least up to 60 °C. On the other hand, the temperature rise induces a slight increase of the net proton surface excess. Finally, the diffuse double layer formalism (DDLM) is used to model the experimental data. The model involves two processes: the protonation/deprotonation of two types of edge sites (aluminol and silanol) and H+/Na+ exchange reactions on basal surfaces, while a tiny proportion of the negative structural charge remains uncompensated. This last process maintains a negative surface potential whatever the pH of the solution, which is in agreement with electrokinetic data.

The aim of this study is to model downward migration of lead from the plow layer of an experimental site located in Versailles (about 15 km southwest of Paris, France). Since 1928, samples have been collected annually from the topsoil of three control plots maintained in bare fallow. Thirty samples from 10 different years were analyzed for their lead and scandium contents and lead isotopic compositions. The fluxes are simple because of the well-controlled experimental conditions in Versailles: only one output flux, described as a first-order differential function of the anthropogenic lead pool, was taken into account; the inputs were exclusively ascribed to atmospheric deposition. The combination of concentration and isotopic data allows the rate of migration from the plowed topsoil to the underlying horizon and, to a lesser extent, the atmospheric fluxes to be assessed. Both results are in good agreement with the sparse data available. Indeed, the post-depositional migration of lead appears negligible at the human time scale: less than 0.1% of the potentially mobile lead pool migrates downward, out of the first 25 cm of the soil, each year. Assuming future lead inputs equal to 0, at least 700 yr would be required to halve the amount of accumulated lead pollution. Such a low migration rate is compatible with the persistence of a major anthropogenic lead pool deposited before 1928. Knowledge of pollution history seems therefore to be of primary importance.

International audience; The streamflow components were determined in a small catchment located in Eastern France for a 40 mm rain event using isotopic and chemical tracing with particular focus on the spatial and temporal variations of catchment sources. Precipitation, soil solution, springwater and streamwaters were sampled and analysed for stable water isotopes (18O and 2H), major chemical parameters (SO42−, NO3−, Cl−, Na+, K+, Ca2+, Mg2+, NH4+, H+, H4SiO4, alkalinity and conductivity), dissolved organic carbon (DOC) and trace elements (Al, Rb, Sr, Ba, Pb and U). 18O, Si, DOC, Ba and U were finally selected to assess the different contributing sources using mass balance equations and end-member mixing diagrams. Isotopic hydrograph separation shows that the pre-event water only contributes to 2% at the beginning of the stormflow to 13% at the main peak flow. DOC associated to Si and U to Ba allow to identify the different contributing areas (upper layers of the saturated areas, deep layers of the hillslope and rainwater). The streamflow (70%) originates from the deep layers of the hillslope, the remaining being supplied by the small saturated areas. The combination of chemical (both trace and major elements) and isotopic tracers allows to identify the origin of water pathways. During the first stage of the storm event, a significant part of the runoff (30-39%) comes from the small extended saturated areas located down part of the basin (overland runoff then groundwater ridging). During the second stage, the contribution of waters from the deep layers of the hillslope in the upper subcatchment becomes more significant. The final state is characterised by a balanced contribution between aquifers located in moraine and downslopes. Indeed, this study demonstrates the interest of combining a variety of hydrometric data, geochemical and isotopic tracers to identify the components of the streamwater in such conditions

Three successive stages of crystallization (magmatic, late-magmatic and hydrothermal) were petrographically, mineralogically and chemically distinguished in the Juquia carbonatite (southern Brazil). The first stage corresponds to crystallization of magmatic Fe-dolomite and hydroxy-fluorapatite, with phlogopite micas and magnetite as accessories. The second stage is characterized by the formation of late-magmatic Na-rich carbonate-fluorapatite, followed by the crystallization of Sr-rich fluorapatite. Veins of barite represent the hydrothermal third stage of crystallization. Post-magmatic mineralizations induced re-equilibration processes which also influenced the geochemical characteristics of the carbonatite. The greatest changes are observed for trace elements (Na, Sr, Ba), REE, and 87Sr86Sr ratios. Isotopic ratios δ18O, δ13C and 143Nd44Nd values clearly support the magmatic origin of the two first mineralization stages. Evolution of 143Nd144Nd and 87Sr86Sr isotopic ratios during the post-magmatic processes indicates the possible participation of either some exogenic fluid, or batches of magma, with distinct compositions or more evolved fluids during crystallization of late-magmatic minerals. REE distributions show a progressive MREE to HREE enrichment, compared to LREE, along the three stages of mineralization. This evolution is explained as the result of preferential complexation of HREE in the last fluids in the form of carbonate, fluoride, phosphate or multiple complexes.

International audience

The geochemical composition of oceanic basalts should represent a very interesting tool to discuss this problem (Hofmann, 1997). It can actually be thought that distinct geochemical characteristics should characterize oceanic basalts derived from mantle reservoirs evolving either through a layered or a whole mantle convective mode. In the large scale mantle convective mode for example, the time span from one convective turn to another would be rather large. According to present day plate velocities, and taking into account the generally admitted increase of mantle viscosity with depth, time span should be quite elevated and could reach half a billion year. Consecutively, in this convective mode, mixing of mantle materials within each convective cell and between convective cells will be minimized, allowing large scale mantle heterogeneities to persist. Mantle materials magmatically differentiated along the convective turns, such as the oceanic crust and complementary residual mantle could remain close one to another along several periods. If mid oceanic ridge basalts (MORB) and oceanic island basalts (OIB) form in the same convective cell from such magmatically differentiated sources, relationships between MORB and OIB compositions can be expected. The differentiation ages of the mantle sources indicated by the basalts compositions could be significantly old reaching possibly several billion years for differentiated sources which realized several convective turns without being involved in new differentiation processes. The geochemical approach, however, presents difficulties. Interpretations of the oceanic basalts data can be numerous depending on the assumed nature of their sources. Furthermore within a model frame, expected compositions can extend on a large range, depending, for example, on melt tapping processes and more generally mantle geodynamics. These factors remain nowadays a matter of debate. To check the plausibility of a model, an interesting work is ultimately to discuss the geodynamical constrains used in the modelling or obtained from it. Oceanic basalts database and whole convective mantle modelling

Combined with isotopes, the use of incompatible element ratios in the framework of ( C/ x C z , C/ y C z ) representations is a promising way of investigating the problem of mantle heterogeneity. This trace element approach is tested and validated: an extensive analysis of literature data shows that isotopically distinct OIB are characterized among other factors also by distinct incompatible trace element ratios. Good correlations are found between some incompatible trace element ratios and the 87 Sr/ 86 Sr isotopic composition of oceanic mantle materials. These correlations agree with the expected relations inferred from reservoir fractionation processes. The source reservoirs of low- 87 Sr/ 86 Sr oceanic basalts (MORB and OIB) appear depleted with respect to trace elements as a result of continental crust extraction. The question of the presence of recycled continental crust material in the source of high- 87 Sr/ 86 Sr oceanic basalts is then explored. The analysis developed on the basis of the proposed approach supports the existence of such material in some of these basalts.

The samples from alpine peridotite massifs (Beni Bouchera, Lherz and the Alps) have been analyzed for rare earth elements. The peridotites as a whole are characterized by various degrees of light REE depletion (Ce varies from 1.2 to 0.02 times chondrite) and a small variation in heavy REE (Yb varies about a factor of 2, from 1.3 to 2.2 times chondrite). They show a restricted and regular distribution in a Ce-Yb diagram, giving two types of linear trends for individual massifs (trend A for the Alps and Lizard; trend B for Beni Bouchera and Lherz, branching from trend A). The model calculations of partial melting based on the partition relations of REE among silicate minerals and melts suggest that trend A could represent a series of residua left after partial melting of garnet peridotite despite the fact that there is no garnet observed in the peridotites studied here. It is suggested that trend A would represent a melting event which predated the emplacement of the massifs and occurred at higher pressure (in the presence of garnet) than expected from the present mineralogy. The calculations also suggest that trend B could represent a partial melting event at lower pressures than trend A after the massifs uplifted into spinel peridotite field. It is also suggested that the REE concentrations of the mantle could be estimated as 2–2.5 times chondrite.

IN many meteorites, the abundances of the heavy isotopes of Xe are enriched relative to solar Xe. In some cases, this enrichment results from the addition of fission products from U and Pu. In some carbonaceous chondrites, however, the isotopic enrichment pattern of the heavy Xe is inconsistent with the measured Xe yield patterns of U, Pu, Cm, and Cf fission. The lack of correlation between heavy Xe enrichment and U concentration in separated mineral phases also argues that the Xe is not due to fission of an element whose chemical properties are similar to U. It has been suggested that this enrichment resulted from the decay of a superheavy element1,2. An experimental test of this hypothesis is proposed here.

National audience

Réflexion de géographie historique à partir des énumérations de villes babyloniennes dont la tradition attribue la fondation à Nemrod (Gn 10, 10-12), personnage biblique, dans les sources syriaques, les exégètes chrétiens se faisant l'écho de commentaires talmudiques. Il s'agit essentiellement des principaux centres chrétiens de l'empire sassanide. Les liens d'évangélisation de ces villes avec le pôle édessénien conduit l'A. à proposer l'hypothèse de listes les étapes d'une route reliant les communautés de Mésopotamie et de Babylonie, particulièrement l'Osrhoène et la plaine assyrienne. Il pourrait y avoir là les éléments suggestifs d'une sorte de cartographie des missions édesséniennes