Copper (Cu) and zinc (Zn) occur in distinct chemical forms in organic waste, yet their long-term behavior and fate in agricultural soils remain poorly understood. We used synchrotron-based X-ray absorption spectroscopy (XAS) to investigate Cu and Zn speciation in contrasting organic wastes derived from pig farming (pig slurry and pig deep litter) and to track their decade-long fate in amended soils. Pig slurry contained Cu(I) and Zn sulfides, whereas pig deep litter contained Cu(II) bound to organic matter and amorphous Zn phosphate. Over the long term, these initially contrasting metal species converged toward similar species and displayed comparable accumulation patterns in soil. Cu and Zn likely released from sulfide dissolution were complexed by organic matter and phosphate ligands in soil, resembling the species introduced via pig deep litter that persisted after application. Under the field-realistic conditions studied, Cu and Zn associated with soil minerals such as phyllosilicates and Fe/Mn (hydr)oxides did not increase in response to organic waste inputs. In addition, the long-term stability of amorphous Zn phosphate is highlighted. These findings provide new insight to address Cu and Zn contamination in an integrated manner in agroecosystems.

Nickel is generally found in trace amounts in the environment and can be beneficial to living organisms, but it is also an environmental contaminant of high concern, primarily due to anthropogenic releases. Fe oxides play a significant role in the behavior and fate of Ni in the environment, as they can interact with metal cations. However, the interactions between magnetite (Fe3O4) and Ni are not well described, and in particular the effect of magnetite stoichiometry (Fe(ii)/Fe(iii) = R) is not well considered. Ni sorption experiments were performed on stoichiometric (R0.5) and oxidized (R0.1) magnetite as a function of Ni concentration and pH under anaerobic conditions. Samples were analyzed by transmission electron microscopy, X-ray absorption spectroscopy (XAS) and magnetic circular dichroism at the Ni L2,3-edges and XAS at the Ni K-edge. At high Ni concentrations, Ni precipitates as Ni(OH)2 on the magnetite surface, but also as distinct sheet-like particles. At low Ni concentrations, high energy resolution fluorescence detection (HERFD) XAS analyses at the Ni K-edge revealed Ni incorporation into R0.5 magnetite and surface adsorption of Ni onto R0.1 magnetite. The present results were compared with those previously published for Co, which revealed an unexpected distinct behavior of Ni and Co. This element-specific binding mechanism highlights the unique properties of magnetite compared to other naturally occurring iron oxides (e.g. goethite, hematite), for which Ni and Co binding mechanisms are similar. Taken together, these results will help not only to predict the behavior and fate of Ni under environmental conditions in the presence of magnetite but also to synthesize magnetite nanoparticles doped by the addition of Ni with interesting magnetic properties.

We present a comprehensive study on the chemical reactivity in the gas phase, with amino acids and peptides, and in the cell, the anticancer activity and localization of a series of seven cationic biphenyl gold(III) complexes with aryl, alkyl, and chiral diphosphine ancillary ligands. Despite some structural differences, all the complexes similarly featured high stability toward reduction or ligand exchange in cell-free conditions. The biphenyl Au(III) complex including the 1,2-diphenylphosphinoethane (dppe) ligand manifested the same high stability in a cellular setting, as attested by a combination of cryo-Synchrotron Radiation-X-Ray Fluorescence (cryo-SR-XRF) nano-imaging and cryo-Synchrotron Radiation-X-ray Absorption Spectroscopy (cryo-SR-XAS) measurements. Tandem cryo-SR-XRF elemental mapping and confocal fluorescence microscopy demonstrated the selective accumulation of the dppe complex in mitochondria. This represents the first study of the speciation and distribution of an organogold(III) complex in cancer cells.

Hydrothermal conversion of uranyl oxalate into UO 2+ x unravelled by in situ XANES, opening a new avenue for nuclear fuel fabrication.

Iron-sulfur (Fe-S) clusters are essential inorganic cofactors dedicated to a wide range of biological functions, including electron transfer and catalysis. Specialized multiprotein machineries present in all types of organisms support their biosynthesis. These machineries encompass a scaffold protein, on which Fe-S clusters are assembled before being transferred to cellular targets. Here, we describe the first characterization of the native Fe-S cluster of the anaerobically purified SufBC(2)D scaffold from Escherichia coli by XAS and M & ouml;ssbauer, UV-visible absorption, and EPR spectroscopies. Interestingly, we propose that SufBC(2)D harbors two iron-sulfur-containing species, a [2Fe-2S] cluster and an as-yet unidentified species. Mutagenesis and biochemistry were used to propose amino acid ligands for the [2Fe-2S] cluster, supporting the hypothesis that both SufB and SufD are involved in the Fe-S cluster ligation. The [2Fe-2S] cluster can be transferred to ferredoxin in agreement with the SufBC(2)D scaffold function. These results are discussed in the context of Fe-S cluster biogenesis.

This paper presents the development of a novel high-pressure/high-temperature reactor cell dedicated to the characterization of catalysts using synchrotron x-ray absorption spectroscopy under operando conditions. The design of the vitreous carbon reactor allows its use as a plug-flow reactor, monitoring catalyst samples in a powder form with a continuous gas flow at high-temperature (up to 1000 °C) and under high pressure (up to 1000 bar) conditions, depending on the gas environment. The high-pressure/high-temperature reactor cell incorporates an automated gas distribution system and offers the capability to operate in both transmission and fluorescence detection modes. The operando x-ray absorption spectroscopy results obtained on a bimetallic InCo catalyst during CO2 hydrogenation reaction at 300 °C and 50 bar are presented, replicating the conditions of a conventional microreactor. The complete setup is available for users and permanently installed on the Collaborating Research Groups French Absorption spectroscopy beamline in Material and Environmental (CRG-FAME) sciences and French Absorption spectroscopy beamline in Material and Environmental sciences at ultra-high dilution (FAME-UHD) beamlines (BM30 and BM16) at the European Synchrotron Radiation Facility in Grenoble, France.

Bauxite residues (BRs) are highly alkaline wastes generated during alumina production from bauxite ore. Billions of tons have been accumulating worldwide for more than 100 years, they are stored in various forms, and pose environmental and societal issues. At the same time, BRs are promising secondary sources for the production of critical metals including rare earth elements (REEs). However, knowledge on REE speciation is lacking, and is consequently an obstacle to the development of large-scale extraction process. This study analyses the influence of origin of the bauxite ore (lateritic or karstic), the storage conditions and storage time on the properties of ten BR samples, with a particular focus on the speciation of yttrium, which is used as a proxy to identify the behaviour of heavy REE. A multi-scale approach linked yttrium speciation and the origin of the bauxite ore whereas no major variation was observed as a function of storage conditions or ageing of the BRs. Yttrium is mainly found in the form of xenotime phosphate particles in BRs of lateritic origin, while in karstic BRs, the majority of yttrium is probably adsorbed or incorporated into other minerals including iron oxyhydroxide and hydroxyapatite minerals.

This study probes the exposure route-dependent fate of silver nanoparticles by using a 3D cell model mimicking the liver. It reveals the cellular trafficking and transformation of silver species, up to their storage in vacuoles or biliary excretion.

In New Caledonia, a significant fraction of soils developed on the Peridotite Nappe are naturally enriched in trace metals, such as nickel and chromium, that can be remobilized upon wildfires (Thery et al., 2022). In this Pacific archipelago, the average annual burnt vegetation surface is estimated to be 30,000 ha, representing 2% of the total land surface (Dumas et al., 2013). However, much larger surfaces can burn during strong El Nino years. This was notably the case in 2016 at Ile des Pins, in the South part of the archipelago, where the burnt surface reached 1000 ha compared to an average annual value of 300 ha. Concomitantly, a dramatic increase in nickel concentrations could be observed in some water supply catchments, with some values reaching up to 4000 µg/L compared to the WHO and European guidelines of 70 µg/L and 20 µg/L, respectively. This situation led the authorities to order some investigations to better understand the link between these increased wildfires and the degradation of freshwater quality.In this presentation, we will discuss the results of these investigations performed for two years on the dynamics and biogeochemistry of nickel across a drinking water catchment supplied by both surface and groundwater. The surface water originates from a doline, which is a characteristic feature of karstic landscapes frequently observed in the lateritic landscapes on ultramafic rocks from New Caledonia (Jeanpert et al., 2016). Geochemical analyses of the surface water collected in the burnt doline showed very high nickel concentration (i.e. up to 300,000 µg/L) compared to groundwaters (i.e below 30 µg/L). These surface waters were also found enriched in sulfate (i.e. up to 3200 mg/L) compared to groundwaters (i.e. below 8 mg/L). Water isotopes analyses allowed to propose a simple mixing model between these two end-members to reconstitute the water supply at the drinking water catchment. In addition, mineralogical characterization of the doline sediments and XAS-derived analysis of nickel speciation allowed to evidence a mixed Mg/Ni-sulfate and Ni/Fe-sulfides as the two major Ni-bearing mineral species. Although the sulfides are common species in sedimentary settings, the occurrence of a mixed Mg/Ni sulfate was considered to result from the large 2016 wildfires that impacted the nickel biogeochemistry in the sediments. The high solubility of this latter mineral species is probably playing a major control on nickel concentration in the water that is supplied to the downstream drinking water catchment.This study brings further understanding on how wildfires can impact drinking water catchments quality by modifying the biogeochemical cycling of trace metals across their related watersheds. In the case of New Caledonia where most of drinking water catchments are supplied by surface water (a significant fraction of them being related to ultramafic watersheds), it spreads awareness to local policy-makers about the vulnerability of the water resource relative to wildfires. At a larger scale, it also put some warning on the possible impact of wildfires on drinking water catchments related to ultramafic watersheds worldwide.

Inorganic contaminant release resulting from mining activities can impact surrounding ecosystems. Ores formed by primary sulfide minerals produce sulfuric acid after mineral oxidation, which is the driving force of metal release. Yet secondary metal sulfates may form and play a crucial role in controlling the metal fate. In the case of thallium (Tl), it has been shown that in natural Tl-rich sulfide deposits and those found in mining areas, Tl can be trapped by Tl-jarosite (Tl-rich iron sulfate) and dorallcharite (TlFe3(SO4)2(OH)6). Our Tl speciation characterization results have generated novel insight into the long-term behavior of this metal derived from a unique natural hotspot: the Jas Roux site (France). The biogeochemical cycle of the soil ecosystems of Jas Roux dates back almost 15000 years ago and has now reached a steady state. A chemical gradient was found in soils across the toposequence underlying the Jas Roux outcrop. X-ray absorption spectroscopy revealed that Tl was mainly present in secondary minerals at the top of the studied zone. Oxidative dissolution of Tl-rich sulfide minerals and pyrite accounts for the presence of Tl-jarosite in soils, either by direct formation in soils or by gravity erosion from the outcrop. The Tl-jarosite quantity was found to decrease from the top to the bottom of the toposequence, probably due to sulfate leaching. Released Tl likely adsorbed on phyllosilicates such as Illite or muscovite, and a fraction of Tl was found to have oxidized into Tl(III) along the toposequence.

The dissipative translocation of the Zn2+ ion between two prototypical coordination complexes has been investigated by combining X-ray absorption and 1H NMR spectroscopy. An integrated experimental and theoretical approach, based on state-of-the-art Multivariate Curve Resolution and DFT based theoretical analyses, is presented as a means to understand the concentration time evolution of all relevant Zn and organic species in the investigated processes, and accurately characterize the solution structures of the key metal coordination complexes. Specifically, we investigate the dissipative translocation of the Zn2+ cation from hexaaza-18-crown-6 to two terpyridine moieties and back again to hexaaza-18-crown-6 using 2-cyano-2-phenylpropanoic acid and its para-chloro derivative as fuels. Our interdisciplinary approach has been proven to be a valuable tool to shed light on reactive systems containing metal ions that are silent to other spectroscopic methods. These combined experimental approaches will enable future applications to chemical and biological systems in a predictive manner.

Soil is a major receptor of manufactured nanomaterials (NMs) following unintentional releases or intentional uses. Ceria NMs have been shown to undergo biotransformation in plant and soil organisms with a partial Ce(IV) reduction into Ce(III), but the influence of environmentally widespread soil bacteria is poorly understood. We used high-energy resolution fluorescence-detected X-ray absorption spectroscopy (HERFD-XAS) with an unprecedented detection limit to assess Ce speciation in a model soil bacterium (Pseudomonas brassicacearum) exposed to CeO2 NMs of different sizes and shapes. The findings revealed that the CeO2 NM's size drives the biotransformation process. No biotransformation was observed for the 31 nm CeO2 NMs, contrary to 7 and 4 nm CeO2 NMs, with a Ce reduction of 64 ± 14% and 70 ± 15%, respectively. This major reduction appeared quickly, from the early exponential bacterial growth phase. Environmentally relevant organic acid metabolites secreted by Pseudomonas, especially in the rhizosphere, were investigated. The 2-keto-gluconic and citric acid metabolites alone were able to induce a significant reduction in 4 nm CeO2 NMs. The high biotransformation measured for <7 nm NMs would affect the fate of Ce in the soil and biota.

ABSTRACTIron-sulfur (Fe-S) clusters are essential inorganic cofactors dedicated to a wide range of biological functions including electron transfer and catalysis. Specialized multi-protein machineries present in all types of organisms support their biosynthesis. These machineries encompass a scaffold protein on which Fe-S clusters are assembled before being transferred to cellular targets. Here, we describe the first characterization of the native Fe-S cluster of the anaerobically purified SufBC2D scaffold from Escherichia coli by XAS, Mössbauer, UV-visible absorption and EPR spectroscopy. Interestingly, we propose that SufBC2D harbors two types of Fe-S cluster, a [2Fe-2S] cluster with an unprecedented usual coordination and a previously unreported [3Fe-3S] cluster. These data combined with mutagenesis and biochemistry allow to propose ligands for these clusters. These results support the hypothesis that both SufB and SufD are involved in Fe-S cluster ligation and are discussed in the context of Fe-S cluster biogenesis where both [2Fe-2S] and [4Fe-4S] clusters need to mature cellular Fe-S protein targets.

Acute exposure of A549 cells to Ag-NPs induces stronger effects on DNA integrity, ROS level, cell metabolism and cell cycle than repeated exposure. Ag-NPs dissolves in both exposure conditions and Ag ions recombine with thiolated proteins.

Ferralsols upon ultramafic rocks are among the most Cr-enriched soils at the Earth surface. Weathering and erosion of these soils represents a major source of Cr for coastal sediments downstream of ultramafic settings. Although Cr mainly occurs as Cr(III)-bearing chromite and Fe-(hydr)oxides in Ferralsols upon ultramafic rocks, several evidences of oxidized Cr(VI) in relation with Mn-oxides have been reported. Regarding the high solubility and toxicity of this latter Cr species, a thorough characterization of Cr and Mn crystal-chemistry in tropical sedimentary settings downstream of Ferralsols upon ultramafic rocks is needed to evaluate the potential threat towards the biodiversity of these coastal environments. In this study, we determined Cr and Mn speciation across a shore-to-reef gradient in lagoon sediments downstream of one of the largest lateritized ultramafic regolith in New Caledonia that contains up to 5 wt% Cr2O3. Chromium K-edge XANES data emphasized the absence of Cr (VI) and indicated a major hosting of Cr by chromite and clay minerals close to the shore, whereas Cr-bearing goethite dominated Cr speciation close to the reef. Manganese K-edge XANES data indicated a major hosting of Mn by clay minerals close to the shore, whereas Mn-carbonates dominated Mn speciation close to the reef. The lack of Mn-oxides detection was considered to explain the absence of Cr(VI) in the studied sediments. This result thus suggests that, despite their shallow character that can favor occasional re-oxidation of the top-layer sediments upon re-suspension events, lagoon sedimentary settings downstream of Cr-rich Ferralsols upon ultramafic rocks appear rather favorable to Cr sequestration as the less mobile and less toxic Cr(III) form. However, the reverse trends observed from the shore to the reef between the chromite and goethite contributions to Cr speciation, as well as the decrease of the Cr/Ti ratio, suggest that a fraction of Cr could have been released towards the water column upon partial weathering of chromite to goethite during sediments transport across the shore-to-reef gradient. This latter point emphasizes the potential hazard that could still represent Cr for the exceptional biodiversity of tropical lagoon ecosystems downstream of Cr-rich Ferralsols, despite the absence of detectable Cr(VI). It thus calls for further studies aimed at better evaluating the stability of Cr(III)-bearing mineral phases upon early diagenesis in these shallow sedimentary settings.

Hard magnetic nanocomposites are attractive materials for integration in various microsystems and for building of next-generation permanent magnets. However, exploiting their full potential requires control of their microstructure at the nanometer scale. Studying these materials in model systems synthesized by nanofabrication routes provides interesting insights into the interplay between the microstructure and the magnetic performances. Here, by using a combination of mass-selected low-energy cluster beam deposition and electron-beam evaporation, we prepare nanocomposite films where Co nanoinclusions are integrated in a hard magnetic FePt matrix. Local atomic structures and element-selective magnetic properties of such nanocomposites have been thoroughly investigated using polarization-dependent hard x-ray absorption spectroscopies. These results demonstrate that magnetically soft inclusions are stabilized at room temperature, emphasizing the role of interdiffusion in the preparation of nanocomposites.

Microorganisms are key players in the transformation of mercury into neurotoxic methylmercury (MeHg). Nevertheless, this mechanism and the opposite MeHg demethylation remain poorly understood. Here, we explored the impact of inorganic mercury (IHg) and MeHg concentrations from 0.05 to 50 μM on the production and degradation of MeHg in two sulfate-reducing bacteria, Pseudodesulfovibrio hydrargyri BerOc1 able to methylate and demethylate mercury and Desulfovibrio desulfuricans G200 only able to demethylate MeHg. MeHg produced by BerOc1 increased with increasing IHg concentration with a maximum attained for 5 μM, and suggested a saturation of the process. MeHg was mainly found in the supernatant suggesting its export from the cell. Hg L3-edge High- Energy-Resolution-Fluorescence-Detected-X-ray-Absorption-Near-Edge-Structure spectroscopy (HERFD-XANES) identified MeHg produced by BerOc1 as MeHg-cysteine2 form. A dominant tetracoordinated βHgS form was detected for BerOc1 exposed to the lowest IHg concentrations where methylation was detected. In contrast, at the highest exposure (50 μM) where Hg methylation was abolished, Hg species drastically changed suggesting a role of Hg speciation in the production of MeHg. The tetracoordinated βHgS was likely present as nano-particles as suggested by transmission electron microscopy combined to X-ray energy dispersive spectroscopy (TEM-X-EDS) and nano-X ray fluorescence (nano-XRF). When exposed to MeHg, the production of IHg, on the contrary, increased with the increase of MeHg exposure until 50 μM for both BerOc1 and G200 strains, suggesting that demethylation did not require intact biological activity. The formed IHg species were identified as various tetracoordinated Hg-S forms. These results highlight the important role of thiol ligands and Hg coordination in Hg methylation and demethylation processes.

The release of CeO2-bearing residues during the weathering of an acrylic stain enriched with CeO2 nanomaterial designed for wood protection (Nanobyk brand additive) was studied under two different scenarios: (i) a standard 12-weeks weathering protocol in climate chamber, that combined condensation, water spraying and UV–visible irradiation and (ii) an alternative accelerated 2-weeks leaching batch assay relying on the same weathering factors (water and UV), but with a higher intensity of radiation and immersion phases. Similar Ce released amounts were evidenced for both scenarios following two phases: one related to the removal of loosely bound material with a relatively limited release, and the other resulting from the degradation of the stain, where major release occurred. A non-linear evolution of the release with the UV dose was evidenced for the second phase. No stabilization of Ce emissions was reached at the end of the experiments. The two weathering tests led to different estimates of long-term Ce releases, and different degradations of the stain. Finally, the photo-degradations of the nanocomposite, the pure acrylic stains and the Nanobyk additive were compared. The incorporation of Nanobyk into the acrylic matrix significantly modified the response of the acrylic stain to weathering.

In this methodological study, we demonstrated the relevance of 3D imaging performed at various scales for the ex vivo detection and location of cerium oxide nanomaterials (CeO 2 -NMs) in mouse lung. X-ray micro-computed tomography (micro-CT) with a voxel size from 14 µm to 1 µm (micro-CT) was combined with X-ray nano-computed tomography with a voxel size of 63 nm (nano-CT). An optimized protocol was proposed to facilitate the sample preparation, to minimize the experimental artifacts and to optimize the contrast of soft tissues exposed to metal-based nanomaterials (NMs). 3D imaging of the NMs biodistribution in lung tissues was consolidated by combining a vast variety of techniques in a correlative approach: histological observations, 2D chemical mapping and speciation analysis were performed for an unambiguous detection of NMs. This original methodological approach was developed following a worst-case scenario of exposure, i.e. high dose of exposure with administration via intra-tracheal instillation. Results highlighted both (i) the non-uniform distribution of CeO 2 -NMs within the entire lung lobe (using large field-of-view micro-CT) and (ii) the detection of CeO 2 -NMs down to the individual cell scale, e.g. macrophage scale (using nano-CT with a voxel size of 63 nm).