Natural remobilization and historical evolution of a modern coastal transgressive dunefield
The vast majority of coastal dunes in Europe have been stabilized by increasing vegetation cover since the mid‐20th century. However, some systems may experience a remobilization phase, generally occurring locally and further propagating alongshore, the drivers of which remain poorly documented. This study investigates the evolutionary paths (stabilization/destabilization/remobilization) from 1945 to 2020 of a 2 km‐long modern coastal transgressive dunefield located in southwest France with a holistic approach (GPR profiles, aerial photographs and LiDAR topographic data). Results show a landward migration of the transgressive dune by approximately 233 ± 7.5 m, through two distinct stages of rapid landward migration from 10 to 23 m/yr (Stage I: 1949–1959 and Stage III: 2000–2021) separated by an approximately 40‐year stage of slow to no migration, but with substantial windward slope deflation (Stage II). The onset of Stage II is due to the fixation of vegetation by human action between 1950 and 1959. The onset of Stage III is hypothesized to be driven by long and sustained upper backshore/dune toe erosion beginning in 1968 due to a massive shoal welding that locally disturbed the longshore drift. It induced a destabilization of the dune and erosion of the vegetation cover over some decades. A non‐synchronization is therefore observed between the start of the perturbation (1968), then the migration (2000), in line with the hysteresis concept of Tsoar (2005). This study shows that almost all of the sedimentary volume of the 1945 dune has been remobilized by translation to shape the dune system in its current form. The 2.2 km dunefield has grown by approximately 673 000 ± 190 000 m 3 during the 2005–2020 period. Among this volume, there is a new foredune that was built from 2005 between the upper beach and the transgressive dune (volume in 2020 of about 394 000 ± 68 000 m 3 ).
(Earth Surface Processes and Landforms. vol. 48, n° 0197-9337, pp. 1064 - 1083, 02/09/2026)
CEFREM, UPVD, INSU - CNRS, CNRS, BRGM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ONF
Simulation of organic aerosol, its precursors, and related oxidants in the Landes pine forest in southwestern France: accounting for domain-specific land use and physical conditions
Organic aerosol (OA) still remains one of the most difficult components of the atmospheric aerosols to simulate, given the multitude of its precursors, the uncertainty in its formation pathways, and the lack of measurements of its detailed composition. The LANDEX (LANDes Experiment) project, during its intensive field campaign in summer 2017, gives us the opportunity to compare biogenic secondary OA (BSOA) and its precursors and oxidants obtained within and above the Landes forest canopy to simulations performed with CHIMERE, a state-of-the-art regional chemistry transport model. The Landes forest is situated in the southwestern part of France and is one of the largest anthropized forests in Europe (1×106 ha). The majority of the forest is comprised of maritime pine trees, which are strong terpenoid emitters, providing a large potential for BSOA formation. In order to simulate OA buildup in this area, a specific model configuration setup adapted to the local peculiarities was necessary. As the forest is nonhomogeneous, with interstitial agricultural fields, high-resolution 1 km simulations over the forest area were performed. Biogenic volatile organic compound (BVOC) emissions were predicted by MEGAN, but specific land cover information needed to be used and was thus chosen from the comparison of several high-resolution land cover databases. Moreover, the tree species distribution needed to be updated for the specific conditions of the Landes forest. In order to understand the canopy effect in the forest, canopy effects on vertical diffusivity, winds, and radiation were implemented in the model in a simplified way. The refined simulations show a redistribution of BVOCs with a decrease in isoprene and an increase in terpenoid emissions with respect to the standard case, both of which are in line with observations. Corresponding changes to simulated BSOA sources are tracked. Very low nighttime ozone, sometimes near zero, remains overestimated in all simulations. This has implications for the nighttime oxidant budget, including NO3. Despite careful treatment of physical conditions, simulated BSOA is overestimated in the most refined simulation. Simulations are also compared to air quality sites surrounding the Landes forest, reporting a more realistic simulation in these stations in the most refined test case. Finally, the importance of the sea breeze system, which also impacts species concentrations inside the forest, is made evident.
(Atmospheric Chemistry and Physics. vol. 23, n° 1680-7316, pp. 3679-3706, 02/09/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LISA (UMR_7583), INSU - CNRS, UPEC UP12, CNRS, UPCité, LMD, INSU - CNRS, X, IP Paris, ENPC, SU, CNRS, ENS-PSL, PSL, IMBE, AU, AMU, CNRS
Clogging detection and productive layers identification along boreholes using Active Distributed Temperature Sensing
Fiber-Optic Active Distributed Temperature Sensing (FO-ADTS) experiments were performed on an Aquifer Thermal Energy Storage system (ATES) site located on the university campus of Bordeaux, France. The experiments consisted in heating the steel core of the FO cable while monitoring the rate of temperature increase during the heating periods. The changes in temperature, that were monitored through time at every depth under various hydraulic conditions and in different boreholes, were used to evaluate both aquifer properties and wells conditions. A first ADTS experiment was conducted under cross borehole configuration using a pumping well and a monitoring well separated by a distance of 8.5 meters. Then, to check the reciprocity of the results, a second experiment was conducted by switching the monitoring and the pumping well. The results obtained through the use of analytical solutions for reproducing and interpreting the data lead to the following conclusions: (i) ADTS can be used to estimate both thermal conductivity and Darcy velocity distribution along boreholes, crucial properties for ATES performance. (ii) The proposed method is a promising tool to detect clogging locations in the boreholes when it occurs. This can be of great practical interest to maintain systems performance, since, once FO cables deployed, experiments could be easily repeated without opening boreholes and stop the system operation.
(Journal of Hydrology. vol. 617, n° 0022-1694, pp. 129113, 02/09/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GR, UR, INSU - CNRS, CNRS
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