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
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
Behavioral and Ecological Responses of an Invasive Freshwater Mussel to Noise Pollution
Biological invasions and anthropogenic noise represent two major threats to fresh water ecosystems but the response of invasive species to noise and how it can modulate their behavior and ecological impact have received scant attention. In this study, we conducted a two-phase laboratory experiment to investigate the effect of motorboat noise on the quagga mussel Dreissena bugensis, one of the world's most invasive species causing detrimental ecological and economic impacts. We first measured aggregation patterns during a 14 to 18day rearing phase where the mussels experienced laboratory background noise supplemented or not with motorboat sounds that mimic nautical activity during summmer. Afterwards, we monitored the valve activity and estimated the filtration rate of mussels from both rearing conditions in the presence or absence of motorboat noise for 12 hours. Our results showed that aggregation rate and mean aggregate size were higher with motorboat noise. Conversely, valve activity did not differ between the two noise conditions but was significantly increased by the previous repeated exposure to noise during the rearing phase. The relationship between valve activity and filtration rate was positive for the mussels not exposed to boat noise, positive but weaker for the mussels that experienced boat noise during one of the two experiment and not significant for those under boat noise during the whole investigation.
Further research is needed to understand the physiological origins of the response to noise and the consequences on life-history traits and mussel-based ecosystem processes such as phytoplanktonic primary production, benthification and biofouling.
(24/02/2026)
CRNL-ENES, CRNL, UCBL, UJM, INSERM, CNRS, BVPAM, UJM, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CARRTEL, USMB [Université de Savoie] [Université de Chambéry], INRAE, Fédération OSUG
Continuum from microplastics to nanoplastics: effects of size and source on the estuarine bivalve Scrobicularia plana
Plastic has been largely detected in estuarine environments and represents major concern towards aquatic living organisms. The present study evaluates the impact of microplastics (MPs) and nanoplastics (NPs) under realistic exposure conditions. Scrobicularia plana individuals were exposed to low concentrations (0.008, 10, and 100 µg L−1) of environmental MPs and NPs as well as to standard PS NPs, as a comparison condition. The aim of this study was to understand the ecotoxicological effects of environmental plastic particles on S. plana gills and digestive glands but also to compare the effects of plastic polymers size in order to highlight if the size could induce different toxicity profiles within this model organism, at different levels of biological organization. Results showed a differential induction of detoxification enzymes (CAT, GST), immunity (AcP), DNA damage processes as well as a differential effect on behavior and condition index of animals depending upon the type of plastic, the size, the concentration tested, and the type of organ. This study underlines the necessity of testing (i) plastics collected from the environment as compared to standard ones and (ii) the effect of size using plastics coming from the same batch of macrosized plastics. This study concludes on the future need directions that plastic-based studies must take in order to be able to generate a large quantity of relevant data that could be used for future regulatory needs on the use of plastic.
(Environmental Science and Pollution Research. vol. 30, n° 0944-1344, pp. 45725–45739, 24/02/2026)
BIOSSE, UCO, GR, UR, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Physical processes matters! Recommendations for sampling microplastics in estuarine waters based on hydrodynamics
Monitoring the abundance and characteristics of microplastics in estuarine waters is crucial for understanding the fate of microplastics at the land-sea continuum, and for developing policies and legislation to mitigate associated risks. However, if protocols to monitor microplastic pollution in ocean waters or beach sediments are well established, they may not be adequate for estuarine environments, due to the complex 3D hydrodynamics. In this note, we review and discuss sampling methods and strategies in relation to the main environmental forcing, estuarine hydrodynamics, and their spatio-temporal scales of variability. We propose recommendations about when, where and how to sample microplastics to capture the most representative picture of microplastic pollution. This note opens discussions on the urgent need for standardized methods and protocols to routinely monitor microplastics in estuaries which should, at the same time, be easily adaptable to the different systems to ensure consistency and comparability of data across different studies.
(Marine Pollution Bulletin. vol. 191, n° 0025-326X, pp. 114932, 24/02/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS