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Brief Communication: Sensitivity analysis of peak water to ice thickness and temperature: A case study in the Western Kunlun Mountains of the Tibetan plateau
No full textInternational audienceThis study investigates the sensitivity of peak water in the western Kunlun Mountains of the Tibetan Plateau. Using the Open Global Glacier Model, we analyze how variations in inverted ice volume and temperature bias under different climate scenarios affect peak water timing and magnitude. We compare two global ice thickness datasets, revealing substantial differences in the predicted peak water timing and magnitude. The results highlight that smaller initial ice volumes lead to earlier peak water occurrences, particularly under the SSP5-8.5 scenario. Temperature bias also significantly influences runoff magnitude and the timing of peak water, especially under high-emission scenarios. These findings underscore the importance of accurate ice thickness estimates and climate projections for predicting future water availability and informing water management strategies in glacier-dependent regions. IntroductionModeling the future evolution of glaciers is essential due to their significant impact on sea level rise (0.61 ± 0.08 mm Sea Level Equivalent -SLEyr -1 for the 2006-2015 period) and freshwater resources (Nauels et al., 2017). Consequently, the projected changes in runoff will also impact downstream water management (Hock et al., 2019). With increasing air temperatures, glacier ablation and therefore glacier runoff is expected to rise and reach a maximum, defined as "peak-water," after which glacial freshwater outputs will decline due to the shrinking glacier area (Huss and Hock, 2018). Determining precisely the timing and magnitude of maximum runoff is therefore of prime importance for freshwater management, likely affecting ecosystems, drinking water resources as well as other sectors as agriculture or hydro-power production (Arias et al., 2021).The indirect inversion of ice thicknesses is a critical step which can have a substantial impact on the peak water (Huss and Farinotti, 2012). However, existing glacier thickness estimations are uncertain and exhibit notable differences in both the spatial distribution and the overall volume of glaciers (Farinotti et al., 2019; Millan et al., 2022). Advances in satellite remote sensing have allowed the emergence of new global data products, such as the first global estimate of glacier mass change (Hugonnet et al., 2021) or global mapping of thicknesses based on surface flow velocities (Millan et al., 2022). Among available largescale glacier models, flowline models like the Open Global Glacier Model (OGGM, Maussion et al., 2019) or the Global
Desorption of rare earth elements (REEs) from schwertmannite under acid mine drainage (AMD) and AMD-seawater conditions
No full textInternational audienceSchwertmannite as a sink for rare earth elements (REEs) in environments affected by acid mine drainage (AMD) plays a significant role in the fate of these elements. The conditions to precipitate schwertmannite (i.e., sulfate-rich water and pH between 2.5 and 3.5) are not suitable for this Fe-oxyhydroxysulfate (Fe 8 O 8 (OH) 6 SO 4 ) to adsorb REEs. In estuaries where AMD-impacted rivers meet (e.g. the Odiel and the Tinto rivers in the Ría de Huelva estuary in SW Spain), AMD mixes with seawater raising the pH between 4.5 and 8, thereby enabling REE adsorption on schwertmannite at circumneutral pH. However, the estuarine tidal dynamics exposes REE-enriched schwertmannite to more acidic water, inducing REE desorption, which has yet to be studied.In the present work, batch experiments were performed to study the REE desorption from a REE-enriched schwertmannite within the pH range 4.5 -7 in the presence of sulfate at room temperature. Solution-chemistry data were used to obtain the REE desorption surface constants from different surface complexation. Desorption of a Lu-enriched schwertmannite at different pH was investigated with High Energy X-Ray Diffraction (HEXD) and Extended X-ray Adsorption Fine Structure (EXAFS) to characterize the changes in the surface complexes during desorption. The results indicate that (1) REEs desorb from schwertmannite at pH < 6 and desorption is pH dependent, (2) desorption of light REEs is higher than that of heavy REEs, (3) REE sorption onto schwertmannite surface is not a totally reversible reaction, and that (4) both monodentate and bidentate surface complexes are involved in the Lu-desorption reaction. These observations indicate that (1) REE-enriched schwertmannite remains stable in the areas of the estuary nearer the sea and that (2) tidal fluctuations displace schwertmannite colloids towards areas that are more affected by AMD, inducing REE desorption from schwertmannite
Orbital and sea-level controls on long-term sediment deposition in the Amazon Fan
No full textInternational audienceThe Amazon Fan, one of the largest deep-sea fans on Earth, is a vital archive of the Amazon Basin's long-term climate and tectonic evolution. However, the factors driving sediment deposition patterns during the Neogene remain poorly understood. Here, we present an astronomical age model for a 4800 m-long sedimentary record (BP-3 well), spanning the past ~24 million years, a key interval encompassing the Amazon River's evolution into a transcontinental system. Gamma-ray (GR) data reveal strong Milankovitch cyclicity, highlighting the fan's sensitivity to orbital climate variability and enabling correlations with global mean sea level (GMSL). Our analysis shows persistently low sedimentation rates (~5–13 cm/kyr) during the late Miocene, despite Andean uplift and increased precipitation, likely due to sediment trapping by mega-wetlands in Western Amazonia. A marked increase in sedimentation (~50 cm/kyr) during the Early Pliocene (5.1–4.8 ± 1.78 Ma) reflects the collapse of these barriers, facilitating sediment transport to the Atlantic despite high GMSL. The GR record also captures the transition from obliquity- to eccentricity-dominated glacial-interglacial cycles during the mid-Pleistocene Transition (~1.3 Ma). These findings align with GMSL and benthic δ18O data, supporting a minimal tuning approach and emphasizing the Amazon Fan's sensitivity to global climate changes. Our revised chronology provides a robust framework for understanding the Neogene evolution of the Amazon River and its links to Andean tectonics and climate variability
Description of a male Zimirina corsica sp. nov. (Arachnida, Araneae)-the first Prodidomidae species reported on the European territory of France
No full textInternational audienceA new Prodidomidae species (genus Zimirina Dalmas) is proposed based on the description of a male specimen caught in Corsica. The specimen can be distinguished from other Zimirina males by the shape of its tegulum and cymbium. Considering that it differs in a number of characters from all other male Zimirina we propose to name this new species Zimirina corsica sp. nov., referring to the type locality
Mono‐ IrIII versus heterobimetallic IrIII‐AuI complexes for circularly polarized luminescence
No full textInternational audienceFundamental rationalization of the structural–circularly polarized luminescence (CPL) activity relationship is a challenging task. Herein, a pair of enantiopure, heterobimetallic IrIII–AuI complexes IrAu‐4 featuring chirality‐at‐metal is thoroughly investigated by means of spectroscopical and computational techniques, also including spin‐orbital coupling (SOC) effects. Upon resolution of the racemic mixture of the starting chloro‐bridged dimer via a chiral auxiliary ligand, the complexes IrIII–AuI are straightforwardly prepared in a stepwise procedure with retention of configuration in good yields. The IrAu‐4 complexes display moderate orange phosphorescence arising from an admixed metal‐to‐ligand and ligand‐to‐ligand charge transfer (3MLCT/3LLCT) excited state and good chiroptical activity, as shown by both electronic circular dichroism (ECD) and CPL spectroscopy. A comparison between the parental mononuclear pairs Δ‐Ir(ppy)2(acac) and Λ‐Ir(ppy)2(acac) and the binuclear IrAu‐4 counterparts also provides interesting insights. The latter possess higher dissymmetry factor (glum) values despite the very similar ECD activity of the lower‐lying 1MLCT band with enantiospecific polarization bias of the light dictated by the chiral‐at‐metal configuration. The different nature of the emissive excited state between the two families of complexes and its implication onto the radiative rate constant and the dipolar force is tentatively accounted for the increased CPL‐activity observed in IrAu‐4
Improved behavioral inferencing from biologging tags through magnetometry
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Agronomie des territoires: Spécificités pour la recherche dans ses finalités, objets et démarches, postulats et postures de recherche, implications épistémologiques.
No full textInternational audienceCe diaporama explore les fondements et évolutions de l’agronomie des territoires, en mettant l’accent sur ses implications conceptuelles, méthodologiques et épistémologiques. S’inscrivant dans les travaux du chantier de l'Association Française d'Agronomie « Épistémologie et temporalités de l’agronomie », la présentation synthétise un corpus de littérature scientifique interdisciplinaire associant agronomie, géographie, sciences du paysage et sciences sociales. La synthèse retrace l’évolution des modes de raisonnement — du champ au paysage — et présente les concepts clés : unités locales de gestion, faits techniques, systèmes agro-sylvo-pastoraux, objets intermédiaires et démarches de géo-prospective. Il montre comment les interactions entre milieu, paysage, pratiques, réseaux et acteurs redéfinissent les objets de recherche en demandant l'explicitation des dimensions spatiales en agronomie. En conclusion, l'exposé souligne les implications épistémologiques majeures : nécessité de conjuguer échelles et niveaux d'analyse, de croiser savoirs experts et savoirs-faire locaux, et de conceptualiser le paysage comme médiateur entre pratiques agricoles et stratégies de gestion collective. Il appelle à une science paysagère de la durabilité résolument inter- et transdisciplinaire
Diagnosing plague in 17th century camelids from Romania along historical Silk Routes
No full textInternational audienceSix camels exhumed from a 17th-century Silk Route site in Romania, along with negative controls, were blindly investigated via dental pulp paleometagenomics and paleoproteomics for traces of Yersinia pseudotuberculosis complex including the plague agent Yersinia pestis. Specific reads were detected in sample R04 (one read) and R05 (two reads) which also yielded a 16S rRNA guanine transferase specific for Y. pestis and one other Y. pseudotuberculosis complex peptide. Taken together, these validated data diagnosed plague in these ancient camels which likely participated in plague dissemination along ancient Silk Routes during the large Medieval and Modern Times pandemic in Europe.</div
Antibacterial activity of fungus comb extracts from Senegalese fungus-farming termites
No full textInternational audienceFungus-farming termites (Macrotermitinae), predominantly found in Africa, are eusocial insects with significant ecological roles. Historically, they have been valued in traditional medicine, human diets, and livestock feed. These termites share a long-standing symbiotic relationship with Termitomyces fungi, which has evolved over millions of years and is critical to their survival and ecological impact. This mutualism promotes a unique monoculture of Termitomyces in the fungus comb while suppressing fungal and bacterial antagonists, likely due to the comb's structural or chemical properties, sparking interest among researchers. In this study, we conducted an extensive examination of 11 fungus combs associated with five termite species collected in Senegal. Our analysis revealed significant antibacterial properties in the crude extracts of the combs, notably against multidrug-resistant strains. Chemical analyses led to the identification of dicrotalic acid (Meglutol) in the active fractions of two combs from agricultural areas. This compound, likely of plant origin, suggests a link between termite feeding habits and the antimicrobial potential of the combs. Although the exact bioactive compounds responsible for the antimicrobial activity have not yet been fully identified, the presence of various metabolites may explain the maintenance of Termitomyces monocultures and the suppression of pathogens. This also illustrates the complex ecological relationship between Termitomyces and termites, which may work together to produce natural bioactive compounds that suppress pathogens.</div
Deciphering the nature of secondary Ag S species in soils polluted with Ag nanoparticles
No full textInternational audienceSilver nanoparticles Soil X-ray absorption near edge structure (XANES) spectroscopy Nano X-ray fluorescence (nXRF) A B S T R A C T Ag₂S nanoparticles (Ag₂S-NPs) are the main silver species in sewage sludge and soils polluted with silver nanoparticles (AgNPs). Uncertainties about Ag + release and nano-Ag₂S toxicity prompted us to further investigate Ag speciation and distribution under realistic conditions. In a previous study we found by bulk X-ray absorption spectroscopy (XAS) that besides Ag 2 S, a secondary Ag -S species was present in sewage sludge and soils. This species accounted for 24-36 % of total silver. The objective of the present work was to investigate the nature of this Ag-S species. A combination of X-ray absorption near edge structure (XANES) spectroscopy at Ag K and L III edges at micro and nano resolutions and of S K-edge micro XANES were used. Nano X-ray Fluorescence (nXRF) was used to investigate the nanoparticle size distribution and to evaluate the presence of mixed metal sulfides. We identified the secondary Ag-S species as Ag bound to thiol groups of organic matter (Ag-thiolate). It was present around the Ag 2 S-NPs, and likely resulted from the complexation of Ag + by thiol groups of soil organic matter. Ag 2 S-NPs displayed a variety of sizes, with 10 % to 40 % of particles bellow 100 nm. Mixed metal sulfides were also present. This study improves our understanding of the fate of Ag-NPs in terrestrial environments, highlights the potential reactivity of Ag 2 S-NPs in soils, and shows the primary role of soil organic matter as a sink for released Ag + . This multi-scale, high-resolution approach represents a novel and powerful methodology for studying nanoparticle behavior in complex environmental matrices