Observational constraints project a ~50% AMOC weakening by the end of this century
Climate models show considerable discrepancies in their future projections around the Atlantic, mainly due to uncertainties in the fate of the Atlantic Meridional Overturning Circulation (AMOC). Climate models suggest a reduction in AMOC strength of 32 ± 37% by 2100 (90% probability, Shared Socioeconomic Pathways 2-4.5 scenario, Coupled Model Intercomparison Project Phase 6). To refine this estimate and reduce its uncertainty, we use four different observational constraint methods. The best one, which provides the lowest leave-one-out error, integrates a large set of observable variables using ridge-regularized linear regression—a method unusual in climate science. It gives an estimate of the AMOC slowdown of 51 ± 8% (90% probability), i.e., a weakening ∼ 60% stronger than suggested by the multimodel mean. This refinement mainly results from correcting a bias in South Atlantic surface salinity, consistent with recent studies emphasizing its role in the proximity to an AMOC tipping point. This more substantial AMOC weakening has key implications for future adaptation strategies.
(Science Advances. vol. 12, n° 2375-2548, 17/04/2026)
ASTRAL, IMB, UB, Bordeaux INP, CNRS, Inria, UB, Bordeaux INP, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Assessing spatiotemporal changes in the benthic habitats of the West Gironde Mud Patch through the analyses of surface sediments, benthic macrofauna and sediment profile images
This work aims to refine the current assessment of spatiotemporal changes in the benthic habitats of the West Gironde Mud Patch. It follows a survey based on the analysis of surface sediment characteristics and benthic macrofauna composition at 5 stations located along a depth gradient, which was achieved between 2010 and 2018. The present work extends this observation period to 2021 and includes the indirect assessment of bioturbation through the analysis of sediment profile image characteristics. Temporal changes in surface sediment characteristics were essentially seasonal with strong increases in chloropigment concentrations in spring. Temporal changes in benthic macrofauna composition were mostly interannual with a major difference between 2010 and 2016-2021 currently attributed to the impact of a major physical disturbance during 2013-2014. In this study, extending the observation period shows that full recovery of benthic macrofauna composition had not yet been achieved by 2021. Sediment profile image characteristics (tube and organisms numbers, area of subsurface structures, oxic void depth and aRPD thickness) showed: (i) clear seasonal changes at the two deepest stations, mostly associated with a spring increase in tube numbers; and (ii) no significant difference between 2010 and 2016-2021, except at the deepest station. The discrepancy between benthic macrofauna composition and sediment profile image characteristics may result from differences in the recovery dynamics of benthic macrofauna composition and functionalities. Overall, results clearly call for a further extension of the WGMP observation period, which could consist in a yearly sampling at only two stations.
(Continental Shelf Research. vol. 298, n° 0278-4343, pp. 105637 (14p.), 01/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UA, CHROME, UNIMES, DYNECO, IFREMER
Deciphering copper and zinc leaching from antifouling paints with different operating modes: flux determination and toxicity evidence
Laboratory experiments were performed using 3 antifouling paints with different operating modes immersed in seawater for 7 days, to estimate copper and zinc fluxes and determine the scale of the related contamination. The toxicity of antifouling paints leachates was also assessed for natural bacterioplanktonic and phytoplanktonic communities. Given the increase in copper and zinc concentrations (4 to 1750-fold enrichment in dissolved Cu and to 7 to 200-fold enrichment in dissolved Zn), a systematic mortality upon phytoplankton was evidenced within 2 days of exposure to leachates produced from 1 hour to 2 days of immersion, whatever the paint. This went oppositely with the environmental risks calculated according to European guidelines, demonstrating an acceptable risk for the environment. Considering that 1 hour of leaching from a 7 cm² painted disk polluted 0.5L of seawater with Cu in our experimental conditions whatever the paint used, we estimated that a painted ship hull of 15 m² can pollute more than 10 m 3 of seawater within the same time. Leachates produced after only 20 minutes even yielded phytoplankton growth inhibition or mortality for insoluble and self-polishing paints, respectively, shortening the time needed for a freshly painted ship hull of 15 m² to pollute 10 m 3 . The bacterioplanktonic community appeared less sensitive than phytoplankton but demonstrated the same hierarchy: the highest toxicity was observed for the insoluble matrix and the lowest toxicity for the soluble one. This study therefore brings added value in terms of biocides flux determination, range of studied paints and concrete toxicity evaluation.
(Marine Pollution Bulletin. vol. 225, n° 0025-326X, pp. 119265, 01/04/2026)
MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Dominance of cellulosic and synthetic microfibers in upper layers of the Atlantic Ocean: evidence from the Vendée globe 2020 race
This study investigates the large-scale assessment of microplastic and anthropogenic microfiber pollution across the Atlantic Ocean, using continuous upper layer (0-5 m) sampling device aboard a sailing vessel during the Vendée Globe race 2020. Building on 53 samples and around 64 m 3 of filtered seawater, we applied three-stage size filtration 300 μm, 100 μm and 30 μm to capture small-size particles typically undersampled in large-scale oceanic surveys. Microplastic concentrations were inversely proportional to particle size, with the 30-100 μm fraction reaching mean values of 65.09 MP/m 3 -three times higher than the 100-300 μm range and over 60 times higher than for particles >300 μm. Smaller fractions exhibited higher polymeric and morphological diversity, dominated by polyethylene, polypropylene, and epoxy resins, while larger particles were mainly polyester and polyamide microfibers from textile sources. In addition, cellulosic fibers represented 87 % of the anthropogenic microfibers >100 μm, surpassing synthetic counterparts. These included cotton, viscose, and other regenerated or natural fibers, indicating diverse potential sources such as clothes, hygiene products, and cigarette butts. Geographically, high microplastic concentrations were observed in the North Atlantic (~106.2 MPs/m 3 on average) near European coastal regions, whereas lower levels in the South Atlantic subtropical region (~49.8 MPs/m 3 on average) suggest vertical redistribution and spatial heterogeneity mediated potentially by ocean dynamics. These results highlight the need to incorporate all anthropogenic particles across fine-scale size classes into marine pollution international assessments. Continuous, opportunistic sampling using leisure, commercial or race vessels is shown to be a valuable approach for capturing particle diversity in remote and open oceanic regions.
(Marine Pollution Bulletin. vol. 225, n° 0025-326X, pp. 119173, 01/04/2026)
RDT, IFREMER, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CBMN, UB, ENITAB, INC-CNRS, CNRS, LOPS, IRD, IFREMER, INSU - CNRS, UBO EPE, CNRS
Caractérisation multi-échelle, suivi innovant et optimisation des stratégies de remédiation des LNAPL en milieux poreux hétérogènes
Les liquides légers non aqueux (LNAPL), issus principalement des hydrocarbures pétroliers, constituent une source durable de contamination des sols et des eaux souterraines. Leur comportement dans les milieux poreux hétérogènes est contrôlé par des processus multiphasiques complexes impliquant forces capillaires, propriétés hydrodynamiques du milieu et fluctuations de la nappe phréatique. Ces mécanismes favorisent le piégeage résiduel des hydrocarbures et limitent fortement l’efficacité des techniques conventionnelles de remédiation, telles que le pompage ou l’extraction multi-phase. Dans ce contexte, cette thèse vise à améliorer la compréhension des mécanismes contrôlant la mobilité et la récupérabilité des LNAPL, ainsi qu’à développer des outils innovants de caractérisation et de suivi des traitements in situ. Une première partie du travail repose sur une analyse critique de plus de cinquante études de cas issues de la littérature scientifique afin d’évaluer les performances des principales techniques hydrauliques de récupération des LNAPL. Cette étude met en évidence l’existence d’une asymptote rapide de récupération, avec des rendements généralement limités à 30-60 % des volumes mobilisables, principalement en raison du piégeage capillaire et de l’hétérogénéité géologique. La thèse développe ensuite une approche de caractérisation multi-échelle combinant microtomographie 3D aux rayons X (μ-CT) et chromatographie en phase gazeuse (CPG) sur des sols contaminés prélevés in situ. Cette méthodologie permet de visualiser quantitativement la distribution des ganglions d’hydrocarbures dans la matrice poreuse, d’évaluer leur connectivité ainsi que les distributions de porosité et de perméabilité du milieu. Les résultats obtenus montrent que la connectivité des ganglions de LNAPL et les contrastes de granulométrie contrôlent fortement la transmissivité du produit et sa récupérabilité. Un second apport majeur de la thèse concerne le développement d’un outil de suivi in situ basé sur l’imagerie par fluorescence induite par ultraviolet (UVIF). Cette méthode permet un suivi rapide, non destructif et spatialement résolu des variations de saturation en hydrocarbures au cours des traitements. Les essais réalisés démontrent la capacité de l’UVIF à détecter et quantifier en quasi temps réel les modifications de distribution du LNAPL lors des opérations de pompage et d’injection. Enfin, des essais pilotes réalisés sur un site industriel contaminé ont permis d’évaluer une stratégie de remédiation innovante combinant injection de xanthane et de tensioactif sous confinement hydraulique. Le xanthane a été utilisé afin de limiter les écoulements préférentiels et de contrôler la propagation du tensioactif dans la zone ciblée, tandis que le tensioactif favorisait la mobilisation des hydrocarbures piégés par réduction de la tension interfaciale. Les résultats montrent une amélioration significative de la récupération du LNAPL ainsi qu’un meilleur contrôle hydraulique de la zone traitée. Les travaux réalisés apportent ainsi des contributions scientifiques, méthodologiques et opérationnelles importantes pour la gestion des sites contaminés par des LNAPL, en proposant à la fois une meilleure compréhension des mécanismes de piégeage et de mobilité des hydrocarbures et de nouveaux outils de caractérisation, de suivi et d’optimisation des stratégies de remédiation.
(18/03/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
An assessment of European and Atlantic sturgeons’ paleoniches during the Holocene
The use of species distribution models (SDMs) in paleoecology enhances its contribution to ecology and conservation biology, such as estimating climate change impacts and informing conservation efforts. Acipenser sturio and A. oxyrinchus are closely related sturgeon species currently arranged in two disjunct distributions across the Atlantic Ocean. However, paleogenetic findings highlighted that both species were present in European waters over at least five millennia. Their joint European history during the Holocene period might have been driven by the thermal hypothesis, with A. oxyrinchus being a cooler-water species than A. sturio . Given their current poor state of conservation, quantifying their environmental preferences at a time when the two species were more abundant could help shape future conservation/restoration measures. Paleo-species distribution models were built for each species based on paleoclimate variables and archeozoological remains, most of which were genetically identified at the species level. Response curves for air temperature and precipitation were then applied to estimate relative continental paleohabitat suitability (HSI) in watersheds across four regions (i.e., the Baltic Sea, the Northern Seas, the South European Atlantic shelf, and the Mediterranean Sea) throughout the Holocene. The estimated niches confirmed the thermal sensitivity difference between the two species, with A. oxyrinchus having a narrower thermal range towards colder annual temperatures. Comparing HSI suitability between the two species, the four regions were globally all suitable for A. sturio but not for A. oxyrinchus , which showed much greater variability. Catchments with outlets to the Mediterranean Sea and the South European Atlantic shelf were mainly suitable for A. sturio . In contrast, those with an outlet in the Baltic Sea were slightly more suitable for A. oxyrinchus than for A. sturio . Catchments with outlets to the Northern Seas showed comparable suitability for both species. This superposition in near-past suitable habitats implied that the two species can potentially exist under the same environmental conditions and as such suggested future risks of biotic interactions which should be further acknowledged in potential stocking practices.
(Frontiers in Ecology and Evolution. vol. 14, n° 2296-701X, 16/03/2026)
UR EABX, INRAE, BioArch, MNHN, CNRS, CRAVO, MNHN, CReAAH, UM, UR, UR2, CNRS, MC, Nantes Univ - UFR HHAA, Nantes Univ, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UB, MIZ PAN = MIZ PAS
Explosive volcaniclastic sedimentation in the Comoros Archipelago over the past 1.5 Myr (western Indian Ocean)
A new chronostratigraphic framework for deep-sea volcaniclastic sedimentation in the Somali Basin provides key constraints on the timing, magnitude, and recurrence of explosive volcanism associated with the Comoros Archipelago over the past ~1.5 Myr. Multibeam bathymetry, high-resolution seismic reflection data, and seven sediment cores recovered north of the archipelago are combined to establish basin-scale correlations of volcaniclastic turbidites. Temporal control is achieved through tuning of oxygen isotope stratigraphies.Seismic–core correlations reveal multiple regionally extensive event deposits, with individual layers covering minimum areas ranging from ~20 km² to more than 130,000 km². Petrographic observations and geochemical analyses show that the turbidites are dominated by basaltic to trachybasaltic glass fragments (sideromelane and tachylite), consistent with a Comorian volcanic provenance. The large volumes, widespread dispersal, and sharp basal contacts of these deposits support direct syn-eruptive emplacement by eruption-fed sediment gravity flows, rather than post-eruptive remobilization. Such deposits require highly energetic explosive activity, consistent with Surtseyan to (sub-)Plinian eruptions capable of generating large quantities of pyroclastic material and transporting it hundreds of kilometers into the deep basin.The resulting chronostratigraphy documents recurrent phases of intensified volcaniclastic sedimentation at ~1.63–1.35 Ma, ~1.03–0.72 Ma, and ~0.40–0.13 Ma, indicating episodic but long-lived explosive volcanism in the Comoros region during the Quaternary. These findings highlight the Comoros Archipelago as a major center of explosive basaltic volcanism in the western Indian Ocean and underscore the importance of deep-marine sedimentary records for assessing the frequency, magnitude, and hazard potential of large-scale submarine eruptions.
(14/03/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LGSR, UR, IPG Paris, IPGP - UMR_7154, INSU - CNRS, IGN, UR, IPG Paris, CNRS, UPCité, OPGC, INSU - CNRS, CNRS, UCA, BRGM, SHOM, CEREGE, IRD, AMU, CdF (institution), INSU - CNRS, CNRS, INRAE, ITES, ENGEES, UNISTRA, INSU - CNRS, CNRS
Challenges of monitoring contaminants in soils: insights from the French experience
Soil pollution is one of the major threats upon soil health. However, the main knowledge of the extent and the diversity of contaminants in soils has been obtained during the last years and there is still a big knowledge gap. If the most campaigns were focusing on trace elements or well-known organic contaminants such as PAH or PCB, the bigger challenge lies ahead when looking at emerging contaminants such as PFAS, pesticides or microplastics. The recent EU directive on soil monitoring might be an opportunity to tackle these knowledge gaps about diffuse soil contamination and the risk they may pose along with a better distribution of the knowledge across countries. This presentation aims to showcase what has been done the last 20 years in France regarding soil contaminants, and specifically since 2020 about trace elements, organic contaminants but also pesticides and microplastics and what are the challenges going-on. Major results and lessons from these monitoring in France could be used when building the European monitoring to ensure the most efficient choices to advice and answer policy questions and enlighten decisions regarding contaminants.
(14/03/2026)
Info&Sols, INRAE, LPTC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LAS, INRAE, ADEME
A second track of the Réunion hotspot in the Mascarene Basin
Hotspots are generally interpreted as the surface expression of lithospheric plates moving over mantle plumes, progressively forming volcanic chains aligned with plate motion. However, it is increasingly recognized that hotspots—such as Hawaii, Samoa, and Tristan–Gough— can exhibit two volcanic lineaments that are not necessarily parallel and display distinct geochemical characteristics. Here we report the discovery of a previously unrecognized volcanic chain related to the Réunion hotspot in the Mascarene Basin (western Indian Ocean), which we term the Mascarene Chain (MASC). This chain extends from the Seychelles across the seafloor through a series of seamounts and records a southward progression of volcanism from ca. 67 to 6 Ma. This age progression is constrained by multi-technique geochronology (⁴⁰Ar/³⁹Ar on biotite; U–Pb on zircon; (U–Th)/He on zircon and apatite) performed on dredged volcanic samples. Petrology, whole-rock major and trace elements and Sr–Nd–Pb isotopes, as well as zircon trace elements and δ¹⁸O–Hf isotopes, indicate that these volcanoes formed from extremely low (<1%) degrees of partial melting of a fertile, metasomatized mantle source with a clear enriched-mantle affinity, distinct from the Réunion plume signature. The MASC is synchronous with the main Réunion hotspot track, from the Deccan Traps (67–65 Ma) to Réunion Island (5–0 Ma), and converges toward the current apex of the Réunion plume. The chain also lies along the boundary of an uplifted region in the Mascarene Basin, interpreted as resulting from plume-related buoyancy forces. We therefore propose that the MASC represents a secondary track of the Réunion hotspot, generated by the indirect action of the plume uplifting the Mascarene lithosphere. The progressive convergence of volcanism is consistent with a decreasing radius of influence as the plume waned. Our results further suggest that secondary hotspot tracks are generated by plume-induced upper-mantle melting, rather than by compositional heterogeneities within the plume source.
(13/03/2026)
LGSR, UR, IPG Paris, ITES, ENGEES, UNISTRA, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CEREGE, IRD, AMU, CdF (institution), INSU - CNRS, CNRS, INRAE, NMT, NMC, GEOPS, INSU - CNRS, CNRS, IPGP - UMR_7154, INSU - CNRS, IGN, UR, IPG Paris, CNRS, UPCité, iSTeP, INSU - CNRS, SU, CNRS, CY, LMV, IRD, INSU - CNRS, CNRS, UCA
Observations and Modelling of Coastal Dune Dynamics Along the Gironde Coast, France
Considered as reservoirs of biodiversity, coastal dunes also represent natural barrier against coastal flooding and large source of sediment to mitigate coastal erosion. Dynamics of coastal dunes are forced and controlled by marine, aeolian and biological processes. A better understanding of the interactions between all these processes based on field observations or numerical modelling is crucial to define management strategies that aim to develop the resilience of coastal dune against sea level rise. The analysis of multi-annual topographic data collected along the Gironde coast in SW France show a strong landward migration of the coastal dunes caused by strong wind events and a decrease in vegetation cover. The same data were also used to calibrate and validate a numerical model, AeoLiS, that simulated Aeolian sediment transport. This model showed good performance to reproduce the landward migration of non-vegetated dune.
(. vol. 41, pp. 141-146, 05/03/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BRGM