Platinum and Rare Earth Elements distribution in costal sediments from French western Mediterranean Sea

International audienceThis study presents the first assessment of Technological Critical Elements (TCE), specifically platinum (Pt) and rare earth elements (REE), in coastal sediments along the French western Mediterranean Sea. These trace elements, increasingly used in advanced technologies, raise particular concerns due to their potential environmental impact. Surface sediment samples were collected from 21 stations along the French Mediterranean coast (from Spain border to Italy including Corsica Island) to evaluate TCE concentrations and identify potential sources. Most of the REE concentrations fell within expected natural levels and were mainly influenced by the geological characteristics of local watersheds, indicating a dominant geogenic origin. When normalized to European Shale, REE distribution patterns exhibited convex shapes, typical of coastal environments. In contrast, localized Pt enrichment were detected at specific sites, particularly in port areas, which could be linked to anthropogenic emissions from vehicular catalytic converters. These results highlight platinum as a relevant emerging contaminant in urban coastal environments. However, unexpected REE and Pt concentrations at the mouth of the Hérault river call for further investigation. This study highlights the importance of integrating geological background and anthropogenic pressures in coastal sediment quality assessments and supports the inclusion of TCE in long -term environmental monitoring programs in the Mediterranean Sea

Opportunities from energy-loss near-edge fine structure analysis to track chemical and structural damage in zircon

International audienceZircon (ZrSiO4) is the oldest-known mineral of Earth and an ubiquitous silicate in geochronology. More specifically, the accumulation of alpha decay damage in zircon over time significantly affects its physical and chemical properties, and can lead to a disturbance of the ages measured in this mineral. Therefore, analytical tools that enable comprehensive structural and chemical information at the nanoscale in this compound are highly sought after. In this context, we explore the electron energy-loss fine structures resulting from the excitation of O1s and Si2p core electrons in zircon, which are interpreted from ab initio calculations in a single-particle framework. An excellent agreement is obtained between the experimental and calculated fine structures, emphasizing the large distortion of the final electronic states induced by the core-hole potential. The O-K edge is particularly rich in information, with intense peaks dominated by O2p - Zr4d and O2p - Si3sp hybrids. This work suggests that the near-edge structures from the O1s and Si2p excitations accessible from electron energy-loss spectroscopy or X-ray absorption spectroscopy could be used as tools to follow, interpret and understand structural and chemical modifications in zircon subject to natural radiation damage. We illustrate the potential of this approach through the evolution of near-edge fine structures in a zircon sample that exhibits a locally amorphized zone formed by ultrafast laser excitation

Combining LIDAR, all-sky camera, and ECMWF-ERA5 reanalysis to investigate contrail formation and evolution over Clermont-Ferrand, France on June 2, 2023

International audienceContrails formed by aircraft in the upper troposphere contribute to anthropogenic climate forcing. However, the conditions driving their formation and persistence remain incompletely understood. This study combines a ACTRIS/EARLINET ground-based LIDAR, all-sky camera imagery, ADS-B aircraft tracking, and ECMWF-ERA5 reanalysis to analyse contrails formation and evolution over Clermont-Ferrand, France, on June 2, 2023. Twelve contrails are documented throughout the day, including five persistent and seven non-persistent contrails. Persistent contrails formed at 10.36 km altitude or lower are observed under ice-supersaturated conditions (relative humidity with respect to ice, RHi > 105 %) and at temperatures between 217 and 223 K. Non-persistent contrails produced by higher altitudes aircrafts, are associated with lower RHi mostly below 100 % and colder temperatures (214-217 K). The horizontal persistent contrail widths range from 0.53 ± 0.10 to 1.60 ± 0.44 km (all-sky camera estimation) and 0.35 ± 0.14 to 1.90 ± 0.32 km (LIDAR estimation), and vertical extents varied from 340 ± 10 to 440 ± 20 m. The optical properties of these contrails have also been estimated by LIDAR. Aerosol backscatter coefficient vary from 0.02 to 0.05 km-1 sr-1, scattering ratios from 8 to 20, volume linear depolarization from 0.13 to 0.24 and particle linear depolarization from 0.17 to 0.45. The maximum contrail observation duration by camera is 180 min. The study highlights the potential of ground-based remote sensing for contrail monitoring

The influence of the 3D Galactic gas structure on cosmic-ray transport and gamma-ray emission

International audienceCosmic rays (CRs) play a major role in the dynamics of the interstellar medium (ISM). Their interactions and transport ionize, heat, and push the ISM thereby coupling different regions of it. The spatial distribution of CRs depends on the distribution of their sources as well as the ISM constituents they interact with, such as gas, starlight, and magnetic fields. Particularly, gas interacts closely with CRs, influencing CR fluxes and gamma -ray emission. We illustrate the influence of 3D gas structures on CR transport and gamma -ray emission. We use the PICARD code and multiple samples of recent 3D reconstructions of the HI and H$_2$ Galactic gas constituents to investigate the impact on the transport of CRs and emission of gamma -rays. We find the necessary transport parameters to reproduce local measurements of CR fluxes, and see that they depend on the local distribution of gas density and structure. The distribution of CR fluxes exhibits energy-dependent structures that vary for all CR species due to their corresponding loss processes. Regions of enhanced secondary (primary) species are spatially correlated (anti-correlated) with the gas density. We observe a high sensitivity of the gamma -ray emission on the contrast of gas structures, as those determine the 3D spatial distributions of hadronic interactions and bremsstrahlung. We find that corresponding gas-induced structures in the distribution of CR electrons are also visible in Inverse Compton (IC) emission. Due to the aforementioned sensitivity, the analysis of CR data for CR sources and transport parameters requires the usage of accurate 3D gas maps

Search for Magnetic Monopoles with the Complete ANTARES Dataset

International audienceThis study presents a novel search for magnetic monopoles using data collected over a 14 year period (2008-2022) by the ANTARES neutrino telescope. The interaction of magnetic monopoles with matter was modeled according to Kazama, Yang, and Goldhaber cross-section. Upper limits on the flux of magnetic monopoles are obtained for velocities both above and below the Cherenkov threshold. No events consistent with the passage of magnetic monopoles were detected, enabling the setting of an upper flux limit for relativistic magnetic monopoles of the order of $10^{-18} \mathrm{cm}^{-2} \mathrm{s}^{-1} \mathrm{sr}^{-1}$

Long-term monitoring of coastal boulder deposits on Banneg Island: A good proxy for detection of extreme oceanic storms off West Brittany (France)

International audienceCoastal boulder deposits (CBD) provide relevant information on coast-erosion wave events, -defined here as extreme events combining energetic storm wave and high spring tide level-, and are crucial for understanding giant storm wave impacts on coastal geomorphology. Banneg Island, located off the coast of Brittany (France), faces Atlantic storm waves that are not attenuated in this highly exposed area. This island is characterised by CBD resulting from the erosion of western cliffs, that have accumulated at the top of the island as a result of storm wave/inudation processes. These accumulations have been subjected to topo-morphological survey for the last two decades (using GNSS measurements from 2005-2012, and using UAV-based measurements since 2012). Hydrodynamic conditions (wave and water levels) were also analyzed. We used these data to analyse the frequency of extreme events over the last 20 years. The results show a good relationship between boulder transport (measured as volume of boulder displacement) and the frequency of extreme events inundating the island. Over the survey period, we found significant interannual variability in the occurrence of these extreme events, depending on winter weather conditions. This storminess variability is significantly correlated with the WEPA climatic index, calculated on the 3 winter months (December to February). Finally, the results from Banneg Island were compared with long-term monitoring carried out in other sectors along the coast of Brittany, to build a comprehensive picture of storminess and its impact on coastal change in Brittany over the last 20 years

Surface albedo and thermal radiation dynamics under conservation and conventional agriculture in subhumid Zimbabwe

Source Agritrop Cirad (https://agritrop.cirad.fr/614360/) * Autres projets (id;sigle;titre): 101138269;ACCURATE;(EU) Albedo, Conservation agriCUltuRe and climATe bEnefit// FOOD/2021/424–933;RAIZ;(EU) Promoting agroecological intensification for resilience building in Zimbabwe//International audienceWhile conservation agriculture (CA) has been widely evaluated for its biogeochemical effects (e.g soil organic carbon sequestration and greenhouse gas emissions) for climate mitigation, its biogeophysical impacts related to changes in surface albedo remain understudied. This study assessed the biogeophysical effects of CA cropping systems with maize (Zea mays L.) in Zimbabwe. Measurements were conducted continuously over two cropping years at two long-term experiments with contrasting soil characteristics, on an abruptic Lixisol and on a xanthic Ferralsol. The dynamics of surface albedo, longwave radiation, leaf area index, soil moisture and temperature were monitored under three different treatments: conventional tillage (CT, tilled to ~15 cm), no-tillage (NT) and no-tillage with mulch (NTM, 2.5 t DM ha⁻¹). Our results revealed that, on the Ferralsol, NT and NTM significantly (p < 0.05) increased mean annual albedo (0.17) relative to CT (0.16), resulting in a negative instantaneous radiative forcing (iRF) and indicating a net cooling effect. iRF was stronger in 2021/22 (NT: -0.83 ± 0.17 W m-2; NTM: -1.43 ± 0.7 W m-2) than in 2022/23 (NT: -0.43 ± 0.09 W m-2; NTM: -1.03 ± 0.21 W m-2). Conversely, on the Lixisol, while NT increased surface albedo (0.27 vs. CT: 0.24), NTM significantly reduced albedo (0.23), causing positive iRF (warming). iRF was -3.34 ± 0.69 W m-2 and -2.78 ± 0.77 W m-2 for NT in the first and second cropping year, respectively, and increased from 1.14 ± 0.21 W -2 (2021/22) to 2.77 ± 0.41 W m-2 (2022/ 23) under NTM. Overall, our results suggest that the soil background albedo is an important site characteristic that needs to be considered and demonstrates the importance of considering biogeophysical effects when promoting practices of CA for climate change mitigation

Hybodont shark remains from Campanian (Upper Cretaceous) continental deposits of southern France

International audienceThe hybodont shark (Elasmobranchii, Hybodontiformes) material from the Campanian of two non-marine localities in southern France are described. Some teeth and a dorsal fin spine from the upper Campanian of Velaux are assigned to the genus Meristodonoides (Hybodontidae), whereas a single tooth from the lower Campanian of Villeveyrac is referred to Parvodus (Lonchidiidae), a genus hitherto unknown in the Upper Cretaceous. Among the latest Cretaceous continental ichthyofaunas of the European archipelago, hybodont sharks may have been minor relictual components with spatially restricted distributions, as suggested by their scarcity in the fossil assemblages from France and Romania combined with their apparent absence in other areas (Iberian Peninsula, Hungary)

Aetheras: Characterising exoplanetary atmospheric escape with NIR and UV spectroscopy

International audienceTo date, many exoplanets have been discovered which exhibit distinct characteristics not observed within our own Solar System, raising numerous unresolved questions regarding their compositions, atmospheres, formation processes, and evolutionary pathways.Several missions have been dedicated to enhance the understanding of the exoplanets like James Webb and Hubble Space Telescopes. However, they have a limited spectral range and resolution to allow for a complete characterisation of atmospheric dynamics. The Aetheras mission proposal was developed at the Summer School Alpbach 2023 and presents a satellite mission to overcome these limitations to better understand the formation, evolution and characteristics of exoplanets. This mission aims to unravel key enigmas in contemporary</p

Spatiotemporal changes and drivers of net greenhouse gas emissions from major cropping systems in China during 1984–2018

International audienc