sp. nov., a novel bacterium from uranium mill tailings repository sites with selenium bioremediation capabilities.

A Gram-stain-negative bacterial strain designated Be4, belonging to the genus , was isolated from mining porewaters sampled in uranium mill tailings repository sites, located in Bellezane, near Bessines-sur-Gartempe (Limousin, France). Cells were facultative anaerobic, rod-shaped, non-endospore-forming and motile with flagella. The mean cell size was 1.

Reactive transport modelling as a toolbox to compare remediation strategies for aquifers impacted by uranium in situ recovery.

More than 60% of worldwide uranium production is based on the In Situ Recovery mining technique. This exploitation method directly falls within the scope of the applications of reactive transport modelling to optimize uranium production and limit its associated environmental impact. We propose a modelling approach which is able to represent the natural evolution of an aquifer impacted by an ISR test performed using sulfuric acid.

Modeling subsurface contaminant transport from a former open-pit uranium mine in fractured granites (La Ribière, France): Reducing uncertainties with geophysics.

The long-term management of tailings from former uranium (U) mines requires an in-depth understanding of the hydrogeological processes and water flow paths. In France, most of the legacy U mines are located in fractured crystalline (plutonic) rocks, where the intrinsic subsurface heterogeneity adds to the uncertainties about the former extraction and milling activities and the state of the mine when production was ceased. U ores were mainly processed by sulfuric acid leaching, leading to high-sulfate-content mill tailings now contained in several tailing storage facilities (TSFs).

Role of zeolite content on the sorption properties of analcime-rich rocks from the Abinky Formation (Niger).

The Abinky formation, composed of analcimolites (i.e., rocks with <70 wt% analcime), underlies Tchirezrine II, which hosts the Imouraren (Niger) uranium deposit.

Using spectroscopic autoradiography of alpha particles for the quantitative mapping of Ra ultra-traces in geo-materials.

The measurement of Ra and the identification of Ra-bearing minerals are important for studying the behavior of radium in the environment. Various instruments for measuring Ra are currently used: among the radiometric techniques that measure in bulk (no spatialization), there are gamma spectrometers and alpha spectrometers. Other instruments such as SEM-EDS can map the chemical elements thus providing information on the distribution of Ra, but are limited for ultra-trace analyses on natural geomaterials.

Lateral river erosion impacts the preservation of Neolithic enclosures in alluvial plains.

Situating prehistoric sites in their past environment helps us to understand their functionality and the organization of early sedentary human societies. However, this is a challenge as the natural environment constantly evolves through time and erases these constructions, especially along riverbanks, thus biasing the archaeological record. This study introduces a reassessment of the paleo-landscape evolution around the Neolithic enclosures at the Noyen-sur-Seine site based on new field observations as well as the synthesis of (un)published and new radiocarbon dating.

Evaluating the impact of muon-induced cosmogenic Ar and Ar underground production on groundwater dating with field observations and numerical modeling.

Groundwater dating by radioactive cosmogenic tracers such as Ar relies on the decay rate from a known initial atmospheric activity (100%modern). Thereby, it is assumed that cosmogenic Ar production in the subsurface is negligible at depths below the water table and that contributions from natural rock radioactivity are minor or missing. Here we present Ar data from aquifers located in quaternary glacial sediments and tertiary limestones in Denmark, which unequivocally demonstrate that cosmogenic production can induce considerable age biases.

Assessment of Ra and U colloidal transport in a mining environment.

The colloidal transport of trace (Fe, Al, Ba, Pb, Sr, U) and ultra-trace (Ra) elements was studied in a mining environment. An original approach combining 0.45 μm filtered water sampling, the Diffusive Gradient in Thin films (DGT) technique, mineralogical characterization, and geochemical modelling was developed and tested at 17 sampling points.

Sediment delivery to sustain the Ganges-Brahmaputra delta under climate change and anthropogenic impacts.

The principal nature-based solution for offsetting relative sea-level rise in the Ganges-Brahmaputra delta is the unabated delivery, dispersal, and deposition of the rivers' ~1 billion-tonne annual sediment load. Recent hydrological transport modeling suggests that strengthening monsoon precipitation in the 21st century could increase this sediment delivery 34-60%; yet other studies demonstrate that sediment could decline 15-80% if planned dams and river diversions are fully implemented. We validate these modeled ranges by developing a comprehensive field-based sediment budget that quantifies the supply of Ganges-Brahmaputra river sediment under varying Holocene climate conditions.

Time-resolved laser-induced fluorescence spectroscopy and chemometrics for fast identification of U(VI)-bearing minerals in a mining context.

We evaluated the potential of time-resolved laser-induced fluorescence spectroscopy (TRLFS) combined with chemometric methods for fast identification of U(VI)-bearing minerals in a mining context. We analyzed a sample set which was representative of several environmental conditions. The set consisted of 80 uranium-bearing samples related to mining operations, including natural minerals, minerals with uranium sorbed on the surface, and synthetic phases prepared and characterized specifically for this study.

Effect of different phosphate sources on uranium biomineralization by the sp. Be9 strain: A multidisciplinary approach study.

Introduction: Industrial activities related with the uranium industry are known to generate hazardous waste which must be managed adequately. Amongst the remediation activities available, eco-friendly strategies based on microbial activity have been investigated in depth in the last decades and biomineralization-based methods, mediated by microbial enzymes (e.g.

A reactive transport model designed to predict the environmental footprint of an 'in-situ recovery' uranium exploitation.

Worldwide, most uranium production relies on the 'in situ recovery' (ISR) extraction technique. This consists of dissolving the ore using a leaching solution (acid or alkaline) directly within the deposit through a series of injection and extraction wells. Due to the nature of the injected ISR solutions, the water quality of the aquifer could be affected.

Evidence of microbial activity in a uranium roll-front deposit: Unlocking their potential role as bioenhancers of the ore genesis.

Uranium (U) roll-front deposits constitute a valuable source for an economical extraction by in situ recovery (ISR) mining. Such technology may induce changes in the subsurface microbiota, raising questions about the way their activities could build a functional ecosystem in such extreme environments (i.e.

Competitive ion-exchange reactions of Pb(II) (Pb/PbCl) and Ra(II) (Ra) on smectites: Experiments, modeling, and implication for Ra(II)/Pb(II) disequilibrium in the environment.

In this study, new experimental data for the adsorption of lead onto a swelling clay mineral with a tetrahedral charge (beidellite) at the ultratrace level (<10 M) are presented. The data were interpreted using an ion-exchange multisite model that considers the sorption of major cations (including H), which always compete with trace elements for sorption onto mineral surfaces in natural environments. The ability of the proposed model to predict experimental K values under various conditions of ionic strength (fixed by NaCl solutions) and aqueous cation compositions (including Pb and PbCl) was tested.

Implications of recently derived thermodynamic data and specific ionic interaction theory parameters for (Mg/Ca)UO(CO) complexes on the predominance of the Mg-Ca-UO-OH-CO systems, and application to natural and legacy-mine waters.

The formation of alkaline earth(II)triscarbonatouranyl(VI) (AeUO(CO)) species that have been evidenced both in laboratory and in-field studies, is important from slightly acidic pH up to near degraded cementitious in carbonated waters. They are also showing distinctive luminescence properties with a hypsochromic shift relative to UO. The conditions of pH, activities of alkaline earth(II) free ions (mostly Mg and Ca) and carbonate ions (HCO) can be predicted from the thermodynamic functions and constants.

Quantifying Ra activity in a complex assemblage of Ra-bearing minerals using alpha autoradiography and SEM/EDS.

Ra is an ultra-trace element with important environmental implications for many industries (including water treatment and oil and mineral extraction). Its extremely low concentrations in natural environments do not allow for direct observation and measurement of the Ra-bearing minerals governing Ra mobility. To better understand the retention processes for Ra in rocks and soil, a synthesized assemblage of Ra-doped minerals was made, combining montmorillonite, ferrihydrite and barite.

Identification of chlorohydrocarbon degradation pathways in aquitards using dual element compound-specific isotope measurements in aquifers.

Compound-specific isotope analysis (CSIA) has been increasingly used to understand and quantify the (bio)degradation processes affecting chlorohydrocarbons in aquifer-aquitard systems. In this study, we aimed at investigating through reactive transport simulations if dual element (C, Cl) CSIA in aquifer samples can provide information about the occurring (bio)degradation pathways in the underlying aquitard. To that end, we modeled the continous dissolution of a 1,1,2,2-tetrachloroethane (TeCA) dense nonaqueous phase liquid (DNAPL) source in an aquifer as well as the resulting TeCA groundwater plume formation and diffusion into the underlying aquitard.

Defining Local Chemical Conditions in Magnetosomes of Magnetotactic Bacteria.

Defining chemical properties of intracellular organelles is necessary to determine their function(s) as well as understand and mimic the reactions they host. However, the small size of bacterial and archaeal microorganisms often prevents defining local intracellular chemical conditions in a similar way to what has been established for eukaryotic organelles. This work proposes to use magnetite (FeO) nanocrystals contained in magnetosome organelles of magnetotactic bacteria as reporters of elemental composition, pH, and redox potential of a hypothetical environment at the site of formation of intracellular magnetite.

Biostimulation as a sustainable solution for acid neutralization and uranium immobilization post acidic in-situ recovery.

Major uranium (U) deposits worldwide are exploited by acid leaching, known as 'in-situ recovery' (ISR). ISR involves the injection of an acid fluid into ore-bearing aquifers and the pumping of the resulting metal-containing solution through cation exchange columns for the recovery of dissolved U. Rehabilitation of ISR-impacted aquifers could be achieved through natural attenuation, or via biostimulation of autochthonous heterotrophic microorganisms due to the associated acid neutralization and trace metal immobilization.

Uranium speciation control by uranyl sulfate and phosphate in tailings subject to a Sahelian climate, Cominak, Niger.

Long-term uranium mobility in tailings is an environmental management issue. The present study focuses on two U-enriched layers, surficial and buried 14.5 m, of the tailings pile of Cominak, Niger.

Discussion on "Competition on Spatial Statistics for Large Datasets".

Unlabelled: We discuss the methods and results of the RESSTE team in the competition on spatial statistics for large datasets. In the first sub-competition, we implemented block approaches both for the estimation of the covariance parameters and for prediction using ordinary kriging. In the second sub-competition, a two-stage procedure was adopted.

Barite precipitation in porous media: Impact of pore structure and surface charge on ionic diffusion.

Several scientific fields such as global carbon sequestration, deep geological radioactive waste disposal, and oil recovery/fracking encounter safety assessment issues originating from pore-scale processes such as mineral precipitation and dissolution. These processes occur in situations where the pore solution contains chemical complexity (such as pH, ionic strength, redox chemistry, etc.…) and the porous matrix contains physical complexity (such as pore size distribution, surface charge, surface roughness, etc.

Reactive transport modelling to investigate multi-scale waste rock weathering processes.

Prediction of drainage quantity and quality is critical to reduce the environmental risks associated with weathering mine waste rock. Reactive transport models can be effective tools to understand and disentangle the processes underlying waste-rock weathering and drainage, but their validity and applicability can be impaired by poor parametrization and the non-uniqueness conundrum. Here, a process-based multicomponent reactive transport model is presented to interpret and quantify the processes affecting drainage quantity and quality from 15 waste- rock experiments from the Antamina mine, Peru.

Modeling of microbial kinetics and mass transfer in bioreactors simulating the natural attenuation of arsenic and iron in acid mine drainage.

Natural attenuation in acid mine drainage (AMD) due to biological iron and arsenic oxidation offers a promising strategy to treat As-rich AMD in passive bioreactors. A reactive transport model is developed in order to identify the main controlling factors. It simulates batch and flow-through experiments that reproduce natural attenuation in a high-As AMD.

Initial effective stress controls the nature of earthquakes.

Modern geophysics highlights that the slip behaviour response of faults is variable in space and time and can result in slow or fast ruptures. However, the origin of this variation of the rupture velocity in nature as well as the physics behind it is still debated. Here, we first highlight how the different types of fault slip observed in nature appear to stem from the same physical mechanism.