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8 results on '"L. Charlet"'

1. Speciation dynamics of oxyanion contaminants (As, Sb, Cr) in argillaceous suspensions during oxic-anoxic cycles

Author

L. Charlet, Christopher T. Parsons, Raoul-Marie Couture, Philippe Van Cappellen, Ekaterina Markelova, Igor Markelov, and Benoît Madé

Subjects
Total organic carbon, education.field_of_study, Aqueous solution, Population, Oxyanion, 010501 environmental sciences, 010502 geochemistry & geophysics, 01 natural sciences, Pollution, Anoxic waters, Redox, Matrix (geology), chemistry.chemical_compound, Adsorption, chemistry, Geochemistry and Petrology, Environmental chemistry, Environmental Chemistry, education, 0105 earth and related environmental sciences
Abstract

Argillaceous geological formations are considered promising repositories for waste containing inorganic contaminants. However, the sequestration capacity of an argillaceous natural barrier may change as a result of dynamic environmental conditions, in particular changes in redox state. Here, we imposed redox cycles to argillaceous suspensions amended with a mixture of the inorganic contaminants As(V), Sb(V), Cr(VI), by alternating 7-day cycles of sparging with either oxic or anoxic gas mixtures. During the redox cycles, we assessed the relative importance of different contaminant sequestration mechanisms under sterile and non-sterile conditions. The non-sterile experiments were carried out 1) with the argillaceous material as is, that is, containing the native microbial population, 2) with the addition of ethanol as a source of labile organic carbon, and 3) with the addition of both ethanol and a soil microbial inoculum. In order to capture the observed solid-solution partitioning trends, a series of mixed thermodynamic-kinetic models representing the dynamic conditions in the experiments were developed using PHREEQC. Parameter values for processes such as adsorption, which occurred in all experiments, were kept constant across all the simulations. Additional formulations were introduced as needed to account for the microbial detoxification and respiration of the contaminants in the increasing complexity experiments. Abiotic adsorption of As and abiotic reductive precipitation of Cr dominated sequestration of these two contaminants under all experimental conditions, whereas the presence of microorganisms was essential to decrease the aqueous Sb concentration. Once reduced, As(III), Sb(III), and Cr(III) were not re-oxidized upon exposure to dissolved O2 in any of the experiments. Neither the mineralogy nor the native microbiota catalysed contaminant oxidation processes. Thus, kinetically, the reduction of As(V), Sb(V), and Cr(VI) was irreversible over the experimental duration (49 days). The capacity of the argillaceous matrix to reduce and sequester the aqueous contaminants, without subsequent remobilization to the aqueous phase during the oxic periods, supports the use of argillaceous barriers for geologic waste storage.

Published
2018
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2. Deconstructing the redox cascade: what role do microbial exudates (flavins) play?

Author

Philippe Van Cappellen, Raoul-Marie Couture, C. M. Smeaton, Ekaterina Markelova, Benoît Madé, L. Charlet, and Christopher T. Parsons

Subjects
0301 basic medicine, biology, Chemistry, 030106 microbiology, Inorganic chemistry, Fluorescence spectrometry, Context (language use), Electrolyte, 010501 environmental sciences, biology.organism_classification, Electrochemistry, 01 natural sciences, Redox, 03 medical and health sciences, chemistry.chemical_compound, Electron transfer, Nitrate, Geochemistry and Petrology, Chemistry (miscellaneous), Environmental Chemistry, Shewanella oneidensis, 0105 earth and related environmental sciences
Abstract

Environmental contextRedox potential is a controlling variable in aquatic chemistry. Through time series data, we show that microbial exudates released by bacteria may control trends in redox potential observed in natural waters. In particular, electron transfer between these exudates and the electrode could explain the values measured in the presence of abundant oxidants such as oxygen and nitrate. AbstractRedox electrodes are commonly used to measure redox potentials (EH) of natural waters. The recorded EH values are usually interpreted in terms of the dominant inorganic redox couples. To further advance the interpretation of measured EH distributions along temporal and spatial redox gradients, we performed a series of reactor experiments in which oxidising and reducing conditions were alternated by switching between sparging with air and N2. Starting from a simple electrolyte solution and ending with a complex biogeochemical system, common groundwater solutes, metabolic substrates (NO3− and C3H5O3−), bacteria (Shewanella oneidensis MR-1) and goethite (α-FeOOH(s)) were tested by increasing the system complexity with each subsequent experiment. This systematic approach yielded a redox cascade ranging from +500 to −350 mV (pH ~7.4). The highest and lowest EH values registered by the platinum (Pt) electrode agreed with Nernstian redox potentials predicted for the O2/H2O2 and FeOOH/Fe2+(aq) couples respectively. Electrode poisoning by the organic pH buffer (MOPS) and addition of bacteria to the aerated solutions resulted in marked decreases in measured EH values. The latter effect is attributed to the release of flavins by Shewanella oneidensis MR-1 to the medium. As expected, equilibrium with the non-electroactive NO3−/NO2−/NH4+ redox couples could not account for the EH values recorded during dissimilatory nitrate reduction to ammonium (DNRA). However, the observed EH range for DNRA coincided with that bracketed by EH values measured in separate abiotic solutions containing either the oxidised (+324 ± 29 mV) or reduced (−229 ± 40 mV) forms of flavins. The results therefore suggest that the Pt electrode detected the presence of the electroactive flavins, even at submicromolar concentrations. In particular, flavins help explain the fairly low EH values measured in the presence of strong oxidants, such as O2 and NO3−.

Published
2017
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3. Early Palaeolithic bone diagenesis in the Arago cave at Tautavel, France

Author

L. Quattropani, M. Menu, H. de Lumley, and L. Charlet

Subjects
Calcite, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Mineralogy, Sediment, Hydroxylapatite, 010502 geochemistry & geophysics, 01 natural sciences, Apatite, Diagenesis, chemistry.chemical_compound, chemistry, Cave, Geochemistry and Petrology, visual_art, visual_art.visual_art_medium, Guano, Clay minerals, Geology, 0105 earth and related environmental sciences
Abstract

Bones from level G in the Arago cave (Tautavel, Southern France, 450 ky) were analysed using a combination of particle induced X-ray and gamma-ray emission (PIXE and PIGME) and X-ray diffraction (XRD). Human occupation and guano production by bats introduced a large amount of phosphate into the cave and as a result a decarbonated pocket was formed in the sediment, characterized by the dissolution of clay minerals, calcite and bones, and by the precipitation of phosphate secondary minerals. The Al released by clay minerals was reprecipitated as crandallite in the few remaining bones, and as montgomeryite with traces of crandallite in the surrounding sediments. Bones within the pocket have very high levels of Al, Fe, F and Zn and often have ‘diffusive’ type U-shaped concentration profiles. These profiles show that post-mortem uptake of trace elements occurred, and thus that trace element composition has to be used with care in palaeonutritional studies but is indicative of local palaeoenvironment. This uptake is complicated by a large increase in hydroxylapatite crystallinity in Palaeolithic bones compared to modern or more recent ones, as a result of the large P influx which occurred in the Arago cave after the sediment deposition.

Published
1999
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5. I.2 Hydrogeolocial / sedimentological control on arsenic distribution / heterogeneity Arsenic binding onto phyllosilicates and glutathione: Soil immobilisation and human excretion mechanisms

Author

S. Chakraborty J. Gailer, J. He, L. Charlet, F. Bardelli, and C. Parsons

Subjects
Arsenic contamination of groundwater, Excretion, chemistry.chemical_compound, Geography, chemistry, Environmental chemistry, Environmental engineering, chemistry.chemical_element, Glutathione, Arsenic
Published
2012
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6. In Situ Characterization of Heavy Metal Surface Reactions: The Chromium Case

Author

A. Manceau and L. Charlet

Subjects
Birnessite, Chemistry, Coprecipitation, Health, Toxicology and Mutagenesis, Inorganic chemistry, Public Health, Environmental and Occupational Health, Oxide, Soil Science, chemistry.chemical_element, Sorption, Pollution, Chemical reaction, Analytical Chemistry, Metal, Chromium, chemistry.chemical_compound, Adsorption, visual_art, visual_art.visual_art_medium, Environmental Chemistry, Waste Management and Disposal, Water Science and Technology
Abstract

Mobility and toxicity of heavy metals are largely controlled by chemical reactions which take place at the oxide/water interface. Insights in the mechanisms involved in these reactions can be obtained from the recently developed synchrotron-based fluorescence-yield X-ray absorption spectroscopy. The phenomena investigated in the present study are: the precipitation of Cr(HI), its coprecipitation with Fe(III), its sorption onto goethite (αFeOOH), and its oxidation at the surface of a Mn(IV) oxide, birnessite. These examples are used to show how a combination of macroscopic and spectroscopic information provides a mechanistic picture of the mobilization and immobilization pathways of heavy metals in natural systems.

Published
1992
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7. Synthesis of a Se0/Calcite Composite Using Hydrothermal Carbonation of Ca(OH)2 Coupled to a Complex Selenocystine Fragmentation

Author

L. Charlet, A. C. Scheinost, A. Fernández-Martínez, F. Renard, G. Montes-Hernandez, Maïté Bueno, Laboratoire de Géophysique Interne et Tectonophysique (LGIT), Institut des Sciences de la Terre [2011-2015] (ISTerre [2011-2015]), Université Joseph Fourier - Grenoble 1 (UJF)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-PRES Université de Grenoble-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-PRES Université de Grenoble-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Laboratoire Central des Ponts et Chaussées (LCPC)-Observatoire des Sciences de l'Univers de Grenoble [1985-2015] (OSUG [1985-2015]), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology [2007-2019] (Grenoble INP [2007-2019])-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut polytechnique de Grenoble - Grenoble Institute of Technology [2007-2019] (Grenoble INP [2007-2019])-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Centre National de la Recherche Scientifique (CNRS), Physics of Geological Processes [Oslo] (PGP), Department of Physics [Oslo], Faculty of Mathematics and Natural Sciences [Oslo], University of Oslo (UiO)-University of Oslo (UiO)-Faculty of Mathematics and Natural Sciences [Oslo], University of Oslo (UiO)-University of Oslo (UiO)-Department of Geosciences [Oslo], University of Oslo (UiO)-University of Oslo (UiO), Laboratoire de Géodynamique des Chaines Alpines (LGCA), Observatoire des Sciences de l'Univers de Grenoble [1985-2015] (OSUG [1985-2015]), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology [2007-2019] (Grenoble INP [2007-2019])-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology [2007-2019] (Grenoble INP [2007-2019])-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut des Sciences de la Terre [2011-2015] (ISTerre [2011-2015]), Université Joseph Fourier - Grenoble 1 (UJF)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-PRES Université de Grenoble-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut de recherche pour le développement [IRD] : UR219-PRES Université de Grenoble-Centre National de la Recherche Scientifique (CNRS), Institute of Resource Ecology, Institute of Radiochemistry, European Synchrotron Radiation Facility (ESRF), Institut Pluridisciplinaire de Recherche sur l'Environnement et les Matériaux (IPREM), Université de Pau et des Pays de l'Adour (UPPA)-Centre National de la Recherche Scientifique (CNRS), Institut Laue-Langevin (ILL), ILL, Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Laboratoire Central des Ponts et Chaussées (LCPC)-Institut des Sciences de la Terre (ISTerre), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut des Sciences de la Terre (ISTerre), Laboratoire Central des Ponts et Chaussées (LCPC)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institute of Resource Ecology [Dresden], and Helmholtz-Zentrum Dresden-Rossendorf (HZDR)

Subjects
Calcite, Materials science, Carbonation, Mineralogy, chemistry.chemical_element, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, 02 engineering and technology, General Chemistry, 010501 environmental sciences, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Hydrothermal circulation, chemistry.chemical_compound, Calcium carbonate, chemistry, Carbonatation, Chemical engineering, Carbonate, General Materials Science, 0210 nano-technology, Selenium, 0105 earth and related environmental sciences, Biomineralization
Abstract

International audience; Elemental selenium (Se0)/calcite composites were synthesized in a batch system by hydrothermal carbonation of calcium hydroxide under high CO2−Ar pressure (90 bar) and high temperature (90 °C) coupled to a complex selenocystine fragmentation. Under O2-poor conditions, the composite consisted predominantly of spherical, amorphous nanoparticles of elemental red selenium (

Published
2008
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8. A dynamic study of the sorption and the transport processes of cadmium in calcareous sandy soils

Author

A Martin-Garin, L Charlet, X Vitart, and J.P Gaudet

Subjects
Calcite, Cadmium, Chromatography, Aqueous solution, Inorganic chemistry, chemistry.chemical_element, Sorption, Hydrogen-Ion Concentration, Silicon Dioxide, Calcium Carbonate, Chemical kinetics, chemistry.chemical_compound, Kinetics, Calcium carbonate, chemistry, Models, Chemical, Soil Pollutants, Adsorption, Waste Management and Disposal, Dissolution, Calcareous
Abstract

The interactions of Cd 2+ with silica and calcite were observed through laboratory dynamic experiments. Cd 2+ sorption processes were characterised as a function of reaction kinetics in aqueous solutions saturated or not with respect to calcite. Chromatographic column experiments show that Cd 2+ sorption on silica can be considered as a reversible equilibrate reaction which depends on water composition and pH. For a porous medium composed by a mixture of silica and calcite, the Cd 2+ migration behaviours are predominantly controlled by calcite. The amount and the reversibility of sorbed Cd on calcite are strongly affected by kinetic limitations. Stirred flow through reactor experiments provide an original method to separate and characterise the ‘fast’ and ‘slow’ Cd sorption on calcite processes. The ‘fast’ Cd reversible adsorption isotherms and the rate of Cd subsequent uptake by ‘slow’ reactions are determined. In addition, the inhibition of calcite dissolution is observed as a function of sorbed Cd in order to provide a complete mechanistic database for coupled transport-geochemistry models.

Published
2002

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