Drones souterrains, inspection et imagerie 3D : contraintes et potentialités d’un nouvel outil de documentation des grottes et du karst
Les drones ont connu, au cours des dernières années, une forte diversification de leurs usages. La réduction du poids des engins et la diminution des coûts concourent à ces développements. En grotte, l’usage des drones est limité par l’altération des capteurs d’assistance au télépilotage : GNSS, vision, capteurs d’évitement, centrale inertielle. Le télépilote doit alors conduire la mission avec le double objectif de maintenir l’intégrité de la machine, de la grotte et des personnels, tout en assurant une captation correcte des données. Un test de photogrammétrie 3D, conduit dans la grotte Sainte-Catherine (Ariège) montre un résultat satisfaisant et confirme l’intérêt des drones dans les constructions de modèles 3D en grotte. Les conditions du pilotage, les conditions d’acquisition des données et les potentialités futures sont discutées.
(Karstologia, n° 0751-7688, pp. 1-8, 19/06/2026)
EDYTEM, USMB [Université de Savoie] [Université de Chambéry], CNRS, Fédération OSUG, ISTerre, IRD, INSU - CNRS, USMB [Université de Savoie] [Université de Chambéry], CNRS, Fédération OSUG, UGA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, INSU - CNRS, CNRS, UA, UM, IDEES, UNICAEN, NU, ULH, NU, UNIROUEN, NU, CNRS, IRIHS, UNIROUEN, NU
Paleoflora y Paleovegetación Ibérica III: Holoceno
(pp. 1095, 30/12/2022)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UMR ISEM, Cirad, IRD, EPHE, PSL, CNRS, UM, IMBE, AU, AMU, CNRS
Development of a Model to Estimate the Risk of Emission of Greenhouse Gases from Forest Fires
While the Mediterranean basin is foreseen to be highly affected by climate change (CC) and severe forest fires are expected to be more frequent, international efforts to fight against CC do not consider forest fires' greenhouse gas (GHG) emissions risk and the possibility of its mitigation. This is partly due to a lack of a methodology for GHG risk spatial assessment and consideration of the high value of carbon stocks in forest ecosystems and their intrinsic risk. To revert this, an innovative GHG emission risk model has been developed and implemented in a pilot forest area. This model considers geospatial variables to build up emission vulnerability based on potential fire severity and resistance of a landscape, value at risk and the hazard of a fire occurrence. The results classify low, moderate and high emission risks in the analysed areas. This identification of hotspots allows the prioritisation of fire prevention measures in a region to maximise the reduction of GHG emissions in the case of a fire event. This constitutes the first step in a holistic and consistent CC mitigation that not only considers anthropic GHG sources but also possible GHG emissions by forest fires that can be actively prevented, managed and reduced.
(Fire. vol. 6, n° 2571-6255, pp. 8, 29/12/2022)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Volcanism and tectonics unveiled in the Comoros Archipelago between Africa and Madagascar
Geophysical and geological data from the North Mozambique Channel acquired during the 2020–2021 SISMAORE oceanographic cruise reveal a corridor of recent volcanic and tectonic features 200 km wide and 600 km long within and north of Comoros Archipelago. Here we identify and describe two major submarine tectono-volcanic fields: the N’Droundé province oriented N160°E north of Grande-Comore Island, and the Mwezi province oriented N130°E north of Anjouan and Mayotte Islands. The presence of popping basaltic rocks sampled in the Mwezi province suggests post-Pleistocene volcanic activity. The geometry and distribution of recent structures observed on the seafloor are consistent with a current regional dextral transtensional context. Their orientations change progressively from west to east (»N160°E, »N130°E, »EW). The volcanism in the western part appears to be influenced by the pre-existing structural fabric of the Mesozoic crust. The 200 km wide and 600 km-long tectono-volcanic corridor underlines the incipient Somalia–Lwandle dextral lithospheric plate boundary between the East-African Rift System andMadagascar.
(Comptes Rendus. Géoscience. vol. 354, n° 1631-0713, pp. 1-28, 19/12/2022)
BRGM, iSTeP, INSU - CNRS, SU, CNRS, LMV, IRD, INSU - CNRS, CNRS, UCA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LGSR, UR, IPG Paris, IPGP, INSU - CNRS, UPD7, UR, IPG Paris, CNRS, IPGP - UMR_7154, INSU - CNRS, IGN, UR, IPG Paris, CNRS, UPCité, ITES, ENGEES, UNISTRA, INSU - CNRS, CNRS, GEO-OCEAN, UBS, IFREMER, INSU - CNRS, UBO EPE, CNRS, GM, IFREMER, GET, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, IPGS, UNISTRA, INSU - CNRS, CNRS, IPGP, INSU - CNRS, UPD7, UR, IPG Paris, CNRS, LGENS, INSU - CNRS, CNRS, ENS-PSL, PSL, BGR, LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France], EOST, UNISTRA, INSU - CNRS, CNRS, GEOAZUR 7329, INSU - CNRS, UniCA, CNRS, IRD [Occitanie], IRD, UniCA
PHANGS-JWST first results: spurring on star formation: JWST reveals localized star formation in a spiral arm spur of NGC 628
We combine JWST observations with Atacama Large Millimeter/submillimeter Array CO and Very Large Telescope MUSE Hα data to examine off-spiral arm star formation in the face-on, grand-design spiral galaxy NGC 628. We focus on the northern spiral arm, around a galactocentric radius of 3–4 kpc, and study two spurs. These form an interesting contrast, as one is CO-rich and one CO-poor, and they have a maximum azimuthal offset in MIRI 21 μm and MUSE Hα of around 40° (CO-rich) and 55° (CO-poor) from the spiral arm. The star formation rate is higher in the regions of the spurs near spiral arms, but the star formation efficiency appears relatively constant. Given the spiral pattern speed and rotation curve of this galaxy and assuming material exiting the arms undergoes purely circular motion, these offsets would be reached in 100–150 Myr, significantly longer than the 21 μm and Hα star formation timescales (both < 10 Myr). The invariance of the star formation efficiency in the spurs versus the spiral arms indicates massive star formation is not only triggered in spiral arms, and cannot simply occur in the arms and then drift away from the wave pattern. These early JWST results show that in situ star formation likely occurs in the spurs, and that the observed young stars are not simply the "leftovers" of stellar birth in the spiral arms. The excellent physical resolution and sensitivity that JWST can attain in nearby galaxies will well resolve individual star-forming regions and help us to better understand the earliest phases of star formation.
(The Astrophysical Journal Letters. vol. 941, n° 2041-8205, pp. L27, 16/12/2022)
UAB, OSU, MPIA, ESO, AlfA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UniCA, LAGRANGE, UNS, INSU - CNRS, UniCA, CNRS, UniCA, LAM, AMU, INSU - CNRS, CNES, CNRS, CRAL, ENS de Lyon, UCBL, INSU - CNRS, CNRS, ANU, CALTECH, Larefi, UB, IRAM, INSU - CNRS, CNRS, LERMA (UMR_8112), INSU - CNRS, CNRS, PSL, UCP, SU, CNRS, UC San Diego, UC
Etude de l’évolution de particules atmosphériques uniques en lévitation : application à la qualité de l’air et au changement climatique
L’objectif de la thèse était d’étudier le vieillissement des aérosols organiques secondaires (AOS) à l’échelle de la particule individuelle. Cet objectif s’inscrit pleinement dans le besoin urgent de combler notre manque de connaissances sur les voies de formation et de devenir atmosphérique des AOS. La lévitation acoustique est une technique expérimentale qui permet de s’affranchir de l’influence du support pour l’étude des propriétés physico-chimiques d’une particule atmosphérique. Le couplage d’un dispositif de lévitation acoustique avec la spectroscopie vibrationnelle nous a permis d’obtenir des informations sur la composition et les états de mélange chimiques des particules. Enfin, le développement d’un couplage de la spectrométrie de masse (PTR-TOF-MS) au dispositif de lévitation acoustique a permis l’analyse de la phase gazeuse dans la cellule de lévitation. In fine, ces développements instrumentaux nous permettent de suivre les modifications des phases particulaire et gazeuse en temps réel afin d’avoir une meilleure compréhension des mécanismes de vieillissement des aérosols. Nous nous sommes notamment intéressés dans cette thèse aux processus d’évaporation et aux propriétés d’hygroscopicité de particules de mélanges AOS/sels. L’influence de la composition chimique et de l’état de mélange de la particule sur ces processus a été mise en évidence. Les résultats obtenus confirment la complexité des propriétés chimiques des aérosols qui influent directement et indirectement sur le changement climatique au niveau global.
(14/12/2022)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
New insights into eDNA sorption onto environmental carbonaceous materials
A recommendation – based on reviews by Jérôme Duval and one anonymous reviewer – of the article: Jelavic S, Thygesen LG, Magnin V, Findling N, Müller S, Meklesh V, Sand KK (2022) Soot and charcoal as reservoirs of extracellular DNA. ChemRxiv, ver. 5 peer-reviewed and recommended by Peer Community in Ecotoxicology and Environmental Chemistry. https://doi.org/10.26434/chemrxiv-2021-9pz8c-v5
(Peer Community In Ecotoxicology and Environmental Chemistry, n° 2779-9948, pp. 100003, 09/12/2022)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
High sensitivity detection of nanoparticles permeation through polymer membranes: A physico-chemical and nuclear imaging measurement approach
Diffusion cells are devices made of donor and acceptor compartments (DC and AC), separated by a membrane. They are widely used in pharmaceutical, cosmetic, toxicology, and protective equipment tests (e.g., gloves) to measure the kinetics of permeants (molecules and nanoparticles) across biological membranes as the skin. However, rarely is the concentration of permeants in the AC measured in continuous or in real-time, and this limitation leads to significant discrepancies in the calculations of kinetic parameters that define the permeation mechanisms. In this study, a diffusion cell compatible with positron emission tomography was used to measure the permeation kinetics of nanoparticles across glove membranes. The technology allows for the measurement of nanoparticle concentration in real-time in the two compartments (DC and AC) and at a detection sensitivity several orders of magnitude higher compared with conventional spectroscopies, thus allowing a much more precise extraction of kinetic parameters. Ultra-small (<10 nm) gold nanoparticles were used as a model nanoparticle contaminant. They were radiolabeled, and their diffusion kinetics was measured in continuous through latex and nitrile polymer membranes. Permeation profiles were recorded at sub-nanomolar sensitivity and in real-time, thus allowing the high precision extraction of kinetic permeation parameters. The technology, methodology, and data extraction process developed in this work could be applied to measure in real-time the kinetics of diffusion of a whole range of potentially toxic molecules and nanoparticles across polymer membranes, including glove membranes.
(Review of Scientific Instruments. vol. 93, n° 0034-6748, 06/12/2022)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Clarifying the Role of ENSO on Easter Island Precipitation Changes: Potential Environmental Implications for the Last Millennium
El Niño Southern Oscillation (ENSO) events yield precipitation deficits and ensuing droughts, often damaging regional forests, in many parts of the world. The relative roles of ENSO, other natural climate changes, and anthropogenic factors on the forest clearing of Easter Island over the last millennium are still debated. Here, we analyze Easter Island precipitation changes using in situ, satellite-derived and reanalysis products spanning the last 4–7 decades, and 46 monthly 156-year-long (1850–2014) simulations derived from 25 CMIP5 and 21 CMIP6 (Coupled Model Intercomparison Project phases 5 and 6) General Circulation Models. Our analysis shows that La Niña events, the cold phases of ENSO, cause precipitation deficits of −0.2 to −0.3 standard deviation (relative to long-term mean) in all analyzed data types. ENSO-like events are further examined over the last millennium (850–1981). A new multiproxy reconstruction of the NINO3.4 index based on proxy records from the Past Global Changes 2k database and Random Forest method is produced. Our reconstruction reveals unusual high recurrences of La Niña-like situations during the fifteenth to seventeenth centuries, which likely induced significant precipitation deficits on the island. These situations are compared to published vegetation reconstructions based on pollen analyses derived from sedimentary cores collected in three island sites. We conclude the environmental consequences of cumulative precipitation deficits over long-lasting La Niña-like situations reconstructed here over the fifteenth to seventeenth centuries were likely favoring drought and forest flammability. La Niña events should be better accounted for among the causes of forest clearing on Easter Island.
(Paleoceanography and Paleoclimatology. vol. 37, n° 2572-4525, 05/12/2022)
LEGOS, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UdeC, HNHP, MNHN, UPVD, CNRS
The Rance tidal power station: Toward a better understanding of sediment dynamics in response to power generation
A three-dimensional coupled hydrodynamic and morphodynamic numerical model was developed to analyze sediment dynamics in the Rance estuary, in response to the tidal power station (TPS) built near the mouth in the 1960s. The Rance estuary is a relatively small low-discharge steep-sided ria, located along the Brittany coast in northern France, with a maximum spring tidal range of 13.5m. Taking advantage of this significant tidal regime, the first and currently the second largest operational tidal power station in the world was built at the estuary’s mouth, with peak output capacity of 240MW. After calibration and validation of the model for present-day conditions, suspended sediment concentration (SSC) and bed level evolution were evaluated at tidal and fortnightly scales for different scenarios, with and without TPS. Peak SSC are reached during spring tides and specifically during the estuary’s infilling (flood) stage where both turbines and sluice gates are open. Unbalanced with sediment transport during ebb, sediments are accumulated in the main channel of the upper estuary. Under natural tidal forcing (i.e., without TPS), simulations show that an estuarine turbidity maximum forms in the upper estuary, and sediment deposition is significant. However, sedimentation rates are two times lower than those observed in the presence of the TPS. A possible alternative for reducing sediment accumulation in the upper estuary would be the opening of sluice gates simultaneously with the turbines during falling tide, to enhance ebb currents that would allow particles transport towards the estuary’s downstream.
(Renewable Energy. vol. 201, n° 0960-1481, pp. 323-343, 01/12/2022)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS