Benthic fluxes and mineralization processes at the scale of a coastal lagoon: Permeable versus fine-grained sediment contribution
Benthic fluxes of biogenic compounds play a major role in the biogeochemistry of shallow aquatic environments. Quantifying these fluxes at the scale of a lagoon is a challenge, especially when sediments are heterogeneous and fluxes at the sediment-water interface combine diffusive and advective transport processes. Diagenetic processes and associated benthic fluxes were quantified across different seasons in a lagoon of the French Mediterranean coast (La Palme lagoon) from vertical profiles of pore water and sedimentary solid fraction carried out at many representative stations of the lagoon. The northwestern part of the lagoon is covered with fine-grained sediment with low permeability and the rest of the lagoon contains permeable sandy sediment. We obtained vertical profiles with centimetre-scale resolution of water content, salinity, and major particulate and dissolved biogenic compounds of C, N, P, Si, S, Fe and Mn. This study allowed us to refine the sedimentary mapping of the lagoon, to specify the spatio-temporal evolution of biogeochemical processes, and to determine more precisely the part of the diffusive fluxes of nutrient compared to advective fluxes. Comparison of the vertical profiles with a molecular diffusion transport model shows that molecular diffusion is the dominant process in fine-grained sediments, while sandy sediments are dominated by advection due to circulation of lagoon water in shallow sediments. Benthic respiration renders fine-grained and sandy sediments anoxic from the first few mm below the sediment-water interface, particularly due to the availability of labile organic matter. Benthic dissolved inorganic nitrogen fluxes are of the same order of magnitude in both sediment types, despite the different flux mechanisms. This suggests that the intensity of organic matter mineralization processes is the same in fine and sandy sediments. Benthic phosphate fluxes are greater in sandy than in fine sediments because phosphorus is more efficiently retained in the solid fraction of fine sediments. Thus, sandy sediments play a dominant role in the pelagic-benthic coupling of the lagoon.
(Marine Chemistry. vol. 254, n° 0304-4203, 24/02/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEGOS, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, OMP, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS
Toxicity assessment of environmental MPs and NPs and polystyrene NPs on the bivalve Corbicula fluminea using a multi-marker approach
Small plastic particles, microplastics (MPs) and nanoplastics (NPs) represent a major threat in aquatic environments. Freshwater organisms are exposed to MPs and NPs, particularly in industrial and urban areas. The present study aimed to compare the toxicity between polystyrene NPs (PS NPs) and environmental microplastics (ENV MPs) and nanoplastics (ENV NPs) generated from macro-sized debris collected in the Garonne River on the freshwater bivalve C. fluminea. The organisms were exposed to the different plastic particles at three environmentally relevant concentrations: 0.008, 10, and 100 μg L−1 for 21 days. The biological responses of organisms were assessed using a multi-biomarker approach from the sub-individual to the individual level. The results demonstrated that: i) ENV NPs triggered more effects on detoxification processes and immune response, confirming that using manufactured NPs for laboratory exposure can lead to misleading conclusions on the risks posed by plastic particles; ii) effects of ENV MPs were less marked than ENV NPs, emphasizing the importance of testing a size continuum of plastic particles from NPs to MPs; iii) some effects were only observed for the low and/or intermediate concentrations tested, underlining the importance of using environmentally relevant concentrations. In light of these results, laboratory studies should be continued by exposing aquatic species to environmental MPs and NPs. The properties of these particles have to be characterized for a better risk assessment of environmental plastic particles.
(Comparative Biochemistry and Physiology - Part C: Toxicology and Pharmacology. vol. 273, n° 1532-0456, pp. 109714, 24/02/2026)
BIOSSE, UCO, BiOSSE, UM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GR, UR, INSU - CNRS, CNRS, ULaval, IPGP - UMR_7154, INSU - CNRS, IGN, UR, IPG Paris, CNRS, UPCité
Le GIS Sol dans les départements et régions d’Outre-mer français
Cet article présente les axes des travaux pédologiques effectués dans les régions ultramarines françaises dans le cadre du Groupement d’Intérêt Scientifique Sol. Ces travaux concernent les programmes « Réseau de mesures de la qualité des sols » (RMQS) et « Inventaire, Gestion et Conservation des Sols » (IGCS), conduits aux Petites Antilles, Martinique et Guadeloupe, à La Réunion et Mayotte, et en Guyane. Ces travaux revêtent un caractère particulier du fait que les territoires concernés sont soumis à des climats variés dans la bande intertropicale et des conditions de développement des sols contrastées sur des lithologies continentales du socle et insulaires volcaniques. Dans le cadre du programme IGCS, les travaux se sont axés dans un premier temps sur l’inventaire et la sauvegarde numérique des connaissances de la distribution des sols acquises dans ces territoires depuis les années 1950. Dans un second temps, des synthèses morpho-pédologiques ont été réalisées grâce à ces données pédologiques numérisées et intégrées à une base de données, complétées par des données géologiques et géomorphologiques. Ces travaux sont illustrés dans cet article à travers le cas de la Guadeloupe. La première campagne du programme RMQS, qui s’est déroulée entre 2006 et 2015, a porté sur 67 sites dans les mêmes territoires. La mise en place de ce programme en Outre-mer s’est faite avec quelques adaptations par rapport au dispositif mis en place dans l’Hexagone, et qui concernent l’implantation des sites, les analyses de sols réalisées et la gestion des échantillons de sols. Quelques résultats de ce programme sont discutés, concernant les stocks de carbone du sol en Guyane, et les teneurs en éléments traces métalliques et hydrocarbures aromatiques polycycliques dans les territoires insulaires. Enfin, les pistes d’évolution du programme sont discutées, afin d’améliorer le suivi des propriétés des sols dans ces territoires.
(Étude et Gestion des Sols. vol. 30, n° 1252-6851, pp. 145-168, 24/02/2026)
UMR Eco&Sols, Cirad, IRD, INRAE, Institut Agro, Info&Sols, INRAE, PNRL, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IRD, iEES Paris, IRD, SU, UPEC UP12, CNRS, INRAE
Unraveling the climate control on debris-free glacier evolution in the Everest region (Nepal, central Himalaya) during the Holocene
Current mass balance and meteorological surveys of Mera glacier located about 30 km south of Mount Everest in Nepal show the dominant role of Asian monsoon precipitation on interannual mass balance variability while temperature controls the altitude of snow-rain threshold. As these observations on mass balance variability only explore the recent decades, studies on paleo glacial extents are useful to investigate the long-term climate forcing on glacier evolution. To do so, we investigated the long-term evolution of the debris-free Mera glacier and a neighbouring small debris-free South Khare glacier. Fifty-one 10Be CRE ages were obtained from samples collected on moraine boulders and roches moutonnées. 10Be CRE ages of the boulders span from the end of the Lateglacial (19.0–11.7 ka) to the Little Ice Age (∼0.6–0.1 ka). The oldest dated moraine in this study was observed at the base of South Khare glacier with an age of 13.6 ± 0.5 ka. The two glaciers subsequently experienced their largest Holocene extent in the Early Holocene with moraines dated to 11.0 ± 0.3 ka at the base of Mera glacier and 10.8 ± 0.5 ka at the base of South Khare glacier. We did not observe any moraine from the Mid-Holocene. During the Late Holocene several glacier advances were recorded around 2.3 ± 0.2 ka, 1.5 ka and then during the last centuries at Mera glacier and around 2.8 ± 0.6 ka, and during the Little Ice Age at South Khare glacier. To explore the links between long-term Nepalese glacier changes and climate, we used oceanic and terrestrial Indian Summer monsoon reconstructions and temperature and precipitation output from two transient global climate models TraCE and LOVECLIM. These climate data outputs were corrected by a reconstruction of the Atlantic Meridional Overturning Circulation (AMOC) over the Holocene and its associated climatic impacts. We also used sensitivity experiments from the IPSL (Institut Pierre Simon Laplace) model to discuss the possible influence of horizontal resolution, land hydrology, vegetation and runoff on changes in Asian summer monsoon. Importantly, we show this long-term Nepalese glacier pattern does not perfectly conform neither to the Indian monsoon precipitation that is documented from terrestrial and marine records nor to temperature and precipitation changes simulated by the models. While the maximum glacier extent in the Early Holocene corresponds to enhanced precipitation documented by proxies and models, the Late Holocene glacier advance remains puzzling. We claim that new paleo glacier records and improved climate simulations are necessary to get a better understanding of past glacier changes and the associated climate dynamics, which might be crucial to gain confidence in both glacier and climate future evolutions.
(Quaternary Science Reviews. vol. 310, n° 0277-3791, pp. 108109, 24/02/2026)
CEREGE, IRD, AMU, CdF (institution), INSU - CNRS, CNRS, INRAE, IRD, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IGE, IRD, INSU - CNRS, CNRS, INRAE, Fédération OSUG, UGA, Grenoble INP, UGA, GEOPS, INSU - CNRS, CNRS
Global coastal groundwater and subterranean estuary nutrients
These data were compiled from original and published datasets of coastal groundwater / subterranean estuary research efforts along global coastline (sites within 1km of shoreline). The dataset includes sampling site names, locations, original sample information, sample depth, temperature, salinity, dissolved nitrogen concentrations, and dissolved phosphorus concentrations. The data source or curator is also included in the dataset.
(PANGAEA, 24/02/2026)
USM, GU, UiB, OSU, SC State, OUC, AU, UC, ZMT, SYSU, OFFIS, SNU, WHOI, WHOI, IIMyC, CONICET, UNMdP, UQAR, HU, UAB, UA, ECNU, UFZ, AIMS, CSIRO, CENPAT, SCU, ODU, SBU, SUNY, CEREGE, IRD, AMU, CdF (institution), INSU - CNRS, CNRS, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, NCESS, IO-PAN, PAN, UNSW, UNSW, UFRN, SJSU, UCONN, VIMS, GU
Sea-level fluctuations control the distribution of highly liquefaction-prone layers on volcanic-carbonate slopes
Understanding and quantifying the hazards related to earthquake-induced submarine liquefaction and landslides are particularly significant offshore of tropical volcanic-carbonate islands, where carbonate production competes with volcanism to create highly contrasted lithological successions. To improve the detection of liquefaction-prone layers, we analyzed physical properties and mineralogy and performed 70 dynamic triaxial tests on 25 sediment cores offshore of the eastern side of Mayotte (Comoros archipelago in the western Indian Ocean) in an area that has experienced significant seismicity since 2018. We found that the main parameter controlling the liquefaction potential offshore of Mayotte is the presence of low-density layers with high calcite content accumulating along the slope during lowstands. This phasing with sea-level fluctuations implies a significant recurrent geohazard for tropical volcanic-carbonate islands worldwide. Furthermore, the relationship we found between the cyclic resistance of sediment and its density and magnetic susceptibility represents a time-effective approach for identifying the hazards related to earthquake-induced liquefaction.
(Geology. vol. 51, n° 0091-7613, pp. 402-407, 24/02/2026)
GEO-OCEAN, UBS, IFREMER, INSU - CNRS, UBO EPE, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Tour d’horizon du bassin stéphano-permien de Graissessac-Lodève
Fin mai 2023, l’Association des Géologues du Permien et du Trias (AGPT) a consacré en grande partie son excursion annuelle au bassin stéphano-permien de Graissessac-Lodève. Cet article, extrait principalement du livret-guide, récapitule l’histoire tectono-sédimentaire du bassin à partir d’une sélection de sites et de panoramas remarquables
(Géochronique. vol. 168, n° 0292-8477, pp. 56-67, 24/02/2026)
INSU - CNRS, CNRS, UA, UM, UMR AMAP, Cirad, CNRS, IRD [Occitanie], INRAE, UM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GR, UR, INSU - CNRS, CNRS
LA SÉCHERESSE FLUVIALE ET SES IMPACTS SOCIO-ENVIRONNEMENTAUX : CAS DE LA VALLÉE DE MANOMBO, SUD-OUEST DE MADAGASCAR
Le fleuve Manombo, avec la baisse de son débit ces dernières années, est révélateur du dérèglement climatique qui affecte le Sud-ouest de Madagascar. Or, la présence de ce cours d'eau demeure un des piliers majeurs sur lesquelles reposent les activités socio-économiques des populations riveraines. Notre recherche a pour objectif d'évaluer les impacts socio-environnementaux de cette diminution de la ressource en eau, à partir d'observations directes et d'enquêtes auprès des utilisateurs de la basse vallée du Manombo. Les premiers résultats montrent l'asséchement et l'ensablement de nombreuses terres agricoles situées en contexte fluvial (Baiboho) ou en parcelle irriguée (Tanety) ; les formations de mangroves sont également affectées. Ces changements se traduisent par : (i)une déstabilisation des sociétés en place en raison de pratiques agricoles devenues inadaptées mais également (ii) une dégradation des écosystèmes forestiers qui résulte de ponctions accrues de la part de populations devenues vulnérables en quête de nouvelles ressources.
(24/02/2026)
LAM, IEP Bordeaux, IRD, UBM, CNRS, UBM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Temperature variations in caves induced by atmospheric pressure variations-Part 1: Transfer functions and their interpretation
According to thermodynamics, atmospheric pressure variations (APV) cause temperature variations in air. However, such variations are difficult to observe, except in thermally stable environments such as underground cavities. We have studied the properties of these temperature variations in four natural caves in France, where continuous time-series have been collected since 1998: Esparros, Aven d'Orgnac, Pech Merle and Chauvet-Pont d'Arc Caves, the last two containing unique prehistoric wall paintings. The pressure to air temperature transfer function (TF), evaluated from 8 × 10-7 to 8 × 10-4 Hz, strongly depends on frequency; its modulus, at the barometric tide S2 (12 h), varies from 2 to 14 × 10-3 °C/hPa. While the TFs show pluriannual stability, seasonal variations are observed when sufficiently long data sets are available. Rock surface temperature is also affected by APV and we extract the air to rock surface temperature TF at Esparros, Chauvet and Pech Merle Caves. The observed TFs are accounted for by an improved analytical model including gas adiabatic compressibility, heat exchange with the rock, heat diffusion in the rock, phase changes of water at the rock surface and an advective term due to barometric pumping motion in the air volume. This model has three free parameters: the effective rock surface to air volume ratio, the time constant of heat exchanges and the effective adiabatic coefficient of cavity air. It is sufficient to account for the various situations observed in natural caves. Using this model, the observed TFs can be interpreted; they reflect the type of thermodynamics active at a given location, in particular the presence of barometric winds, but the actual values of parameters remain difficult to predict. Thus, temperature variations induced by APV emerge as a fundamental tool to characterize underground environments, relevant in some cases for cave heritage preservation, illustrating the coupled processes active in the Critical Zone.
(Geosystems and Geoenvironment. vol. 2, 24/02/2026)
IPGP - UMR_7154, INSU - CNRS, IGN, UR, IPG Paris, CNRS, UPCité, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GET, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS
A protocol for lixiviation of micronized plastics for aquatic toxicity testing.
Plastics contain various types and amounts of additives that can leach into the water column when entering aquatic ecosystems. Some leached plastic additives are hazardous to marine biota at environmentally relevant concentrations. Disparate methodological approaches have been adopted for toxicity testing of plastic leachates, making comparison difficult. Here we propose a protocol to standardize the methodology to obtain leachates from microplastics (MPs) for aquatic toxicity testing. Literature reviewing and toxicity tests using marine model organisms and different types of MPs were conducted to define the main methodological aspects of the protocol. Acute exposure to leachates from the studied plastics caused negative effects on the early life stages of sea urchins and marine bacteria. We provide recommendations of key factors influencing lixiviation of MPs , such as particle size (<250 μm), solid-to-liquid ratio (1-10 g/L), mixing conditions (1-60 rpm), and lixiviation time (72 h). The proposed methodology was successful to determine the toxicity of leachates from different micronized plastics on marine biota. Our recommendations balance sensitivity, feasibility and environmental relevance, and their use would help ensure comparability amongst studies for a better assessment of the toxicity of plastic leachates on aquatic biota.
(Chemosphere. vol. 333, n° 0045-6535, pp. 138894, 24/02/2026)
ULPGC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, DTU