Were the 2.1-Gyr fossil colonial organisms discovered in the Francevillian basin (Palaeoproterozoic, Gabon) buried by turbidites?
The Francevillian series (Gabon) in which the Earth's oldest large colonial organisms were recently discovered (El Albani et al., 2010) were deposited 2 Gyr ago. These series are usually interpreted as a fining-upward basin-fill sequence composed by five superimposed lithological terms noted FA to FE. New studies initiated by AREVA, allowed new data to be collected on the southwestern edge of the Francevillian basin, particularly on newly excavated outcrops. Facies interpretations show that the Poubara sandstones and associated shales and black shales (upper part of FB,FB2a), correspond to turbidites deposited on an upper slope rather than one a shelf, submitted to tidal currents or storm wave action. These new interpretations based on facies association, sedimentary geometries, and basin evolution show that the depositional environment could be a turbidite lobe set at a palaeobathymetry deeper than 200 m.
(Comptes Rendus. Géoscience. vol. 345, n° 1631-0713, pp. 101-110, 27/10/2026)
AREVA-BU Mines, GR, UR, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Mise au point d’un indice diatomique pour les cours d’eau de la Réunion (IDR) : Rapport final sur la démarche d’élaboration de l’indice (Version finale, 05-02-2013)
La DCE a force d'application dans les DOM comme dans le contexte continental. Cependant l'environnement abiotique comme les espèces en place constituent un contexte biogéographique très spécifique rendant impossible l'utilisation d'indices biologiques préexistants mis au point pour l'Europe continentale. L’Office de l’Eau de la Réunion a donc décidé de porter un programme spécifique de recherche-développement, mis en ½uvre de 2008 à 2012 par le consortium Asconit Consultants – Irstea (ex-Cemagref). L'étude ayant conduit à la genèse de l'IDR (Indice Diatomique Réunion) s'est appuyée sur l’acquisition d’environ 370 relevés taxinomiques des espèces rencontrées sur place et de données associées de chimie des eaux, obtenues sur un réseau de 56 sites à l'occasion de 5 campagnes de prélèvements de terrain réalisées à 2 saisons différentes. L'analyse de ces données a permis une caractérisation plus ou moins consolidée des préférences écologiques de 343 espèces, le repérage de communautés diatomiques-types caractéristiques de conditions environnementales particulières (naturelles, altérées) et, au final, la mise au point de ce nouvel indice IDR qui mobilise les profils de qualité écologique de 172 espèces suffisamment occurrentes d'eau douce. Cet indice d’un principe de conception original mesure l’altération de la qualité de l’eau à partir du cumul de messages d’altération portés par 48 taxons d’alerte qualifiés de « Taxons –», dont la présence est synonyme indiscutable de dégradation anthropique de l’eau.
(pp. 130, 27/10/2026)
UR REBX, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
An integrated environmental approach to investigate biomarker fluctuations in the blue mussel Mytilus edulis L. in the Vilaine estuary, France
Estuarine areas represent complex and highly changing environments at the interface between freshwater and marine aquatic ecosystems. Therefore, the aquatic organisms living in estuaries have to face highly variable environmental conditions. The aimof this work was to study the influence of environmental changes from either natural or anthropogenic origins on the physiological responses of Mytilus edulis. Mussels were collected in theVilaine estuary during early summer because this season represents a critical period of active reproduction in mussels and of increased anthropogenic inputs from agricultural and boating activities into the estuary. The physiological status of the mussel M. edulis was evaluated through measurements of a suite of biomarkers related to: oxidative stress (catalase, malondialdehyde), detoxication (benzopyrene hydroxylase, carboxylesterase), neurotoxicity (acetylcholinesterase), reproductive cycle (vitelline, condition index, maturation stages), immunotoxicity (hemocyte concentration, granulocyte percentage, phagocytosis, reactive oxygen species production, oxidative burst), and general physiological stress (lysosomal stability). A selection of relevant organic contaminant (pesticides, (polycyclic aromatic hydrocarbons, polychlorobiphenyls) was measured as well as environmental parameters (water temperature, salinity, total suspended solids, turbidity, chlorophyll a, pheopigments) and mussel phycotoxin contamination. Two locations differently exposed to the plume of the Vilaine River were compared. Both temporal and inter-site variations of these biomarkers were studied. Our results show that reproduction cycle and environmental parameters such as temperature, organic ontaminants, and algal blooms could strongly influence the biomarker responses. These observations highlight the necessity to conduct integrated environmental approaches in order to better understand the causes of biomarker variations.
(Environmental Science and Pollution Research. vol. 20, n° 0944-1344, pp. 630-650, 27/10/2026)
IFREMER, LEMAR, IRD, IFREMER, UBO EPE, CNRS, INRA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR REBX, IRSTEA, CNRS
High-resolution analysis of a tsunami deposit: case-study from the 1755 Lisbon tsunami in southwestern Spain
(Marine Geology. vol. 337, n° 0025-3227, pp. 98-111, 27/10/2026)
GEOLAB, UBP, IR SHS UNILIM, UNILIM, UCA [2017-2020], CNRS, UCA, LMV, UBP, INSU - CNRS, UJM, UJM EPE, CNRS, IMTV, UdA, INSERM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Bi-hemispheric forcing for Indo-Asian monsoon during glacial terminations
The drivers of the Indo-Asian monsoon dynamics during terminations have recently emerged as a controversial issue. Cheng et al. (2009. Ice Age Terminations. Science 326, 248–252), using East-Asian speleothem records, proposed a strict northern hemisphere insolation control at the orbital timescale with weak monsoon intervals occurring at terminations. On the contrary, An et al. (2011. Glacial–Interglacial Indian Summer Monsoon Dynamics. Science 333, 719–723), using a record from the Hequing paleolake basin, highlight the importance of the southern hemisphere climate forcings on Indian summer monsoon dynamics at glacial–interglacial timescale. The purpose of this note is to propose an explanation of the weak monsoon intervals at terminations, using a deep sea sediment stack monsoon record. The mechanism involved is linked to interhemispheric interactions, as proposed by An et al. (2011), superimposed to the role of orbital forcing (precession and obliquity parameters). This explanation clarifies the combination of complex drivers acting on the Indo-Asian monsoon dynamic at terminations.
(Quaternary Science Reviews. vol. 59, n° 0277-3791, pp. 1-4, 27/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, CLIM, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, GLACCIOS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA
Mobility and fluxes of trace elements and nutrients at the sediment–water interface of a lagoon under contrasting water column oxygenation conditions
The early diagenesis of the major carrier phases (Fe and Mn minerals), trace elements (As, Co, Cr, Hg, MeHg, Ni) and nutrients (RNO 3 , NH þ 4 , RPO 4) and their exchange at the sediment water/interface were studied in the Berre Lagoon, a Mediterranean lagoon in France, at one site under two contrasting oxygen-ation conditions (strictly anoxic and slightly oxic) and at an adjacent site with perennially well-oxygen-ated water. From the concentration profiles of the primary biogeochemical constituents and trace elements of the pore and bottom waters, as well as the total and reactive particulate phases, it was possible to locate and identify the diagenetic reactions controlling the mobility of trace elements in the sediments and quantify their rates by coupling one-dimensional steady-state transport-reaction modelling and thermodynamic speciation calculations. Under oxic conditions and in the absence of benthic organisms, the main redox reactions were well identified vertically in the surface sediments and followed the theoretical sequence of oxidant consumption: O 2 > ΣNO 3/MnO 2 > Fe(OH) 3 > SO4 2-. However, under anoxic conditions, only MnO 2 , Fe(OH) 3 and SO 4 2- reduction were present, and they all occurred at the interface. The main biogeochemical controls on the mobility of As, Cr, Hg, MeHg and Ni in the surface sediments were identified as the adsorption/ desorption on and/or coprecipitation/codissolution with Fe oxy-hydroxides. In contrast, Co mobility was primarily controlled by its reactivity towards Mn oxy-hydroxides. In sulphidic sediments, As, Hg and MeHg were sequestered along with Fe sulphides, whereas Co and Ni precipitated directly as metallic sulphides and Cr mobility was enhanced by complexation with dissolved organic ligands. The fluxes of trace elements at the sediment–water interface are essentially dependent on the localisation of their remobilisation and immobilisation reactions under the interface, which in turn is governed by the ben-thic water oxygenation conditions and kinetic competition among those reaction and diffusion processes. Under oxic conditions, the precipitation of Fe or Mn oxy-hydroxides in the surface sediments constitutes the most efficient mechanism to sequester most of the trace elements studied, thus preventing their diffusion to the water column. Under anoxic conditions the export of trace elements to the water column is dependent on the kinetic competition during the reductive dissolution of Fe and/or Mn oxy-hydroxides, diffusion and immobilisation with sulphides. It is also shown that benthic organisms in the perennially oxygenated site have a clear impact on this general pattern. Based on the extensive dataset and geochem-ical modelling, it is predicted that the planned re-oxygenation of the entire lagoon basin, if complete, will most likely limit or reduce the export of the trace elements from the sediments to the water column and therefore, limit the impact of the contaminated sediment.
(Applied Geochemistry. vol. 31, n° 0883-2927, pp. 35-51, 27/10/2026)
CEREGE, IRD, INRA, AMU, CdF (institution), INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IFREMER, PROTEE, UTLN
Physical modeling of three-dimensional intermediate beach morphodynamics
Experiments have been performed in a large wave tank in order to study the morphodynamics of rip current systems. Both accretive and erosive shore-normal wave conditions were applied, the beach evolving through all the states within the intermediate beach classification, under the so-called down-state (accretive) and up-state (erosive) morphological transitions. Results show that any prescribed change in the wave conditions drastically increases the rate at which the morphology changes. The surf zone morphology tends toward a steady state when running a given wave climate for a long duration. We quantitatively describe a full down-state sequence characterized by the progressive evolution of an alongshore-uniform bar successively into a crescentic plan shape, a bar and rip channel morphology, and a terrace. From the analysis of a large data set of dense Eulerian measurements and bathymetric surveys, we depict several feedback mechanisms associated with wave-driven rip current circulation, wave nonlinearities and the seabed evolution. At first, a positive feedback mechanism drives a rapid increase in the rate of morphological change, beach three-dimensionality, and rip intensity. By the time the sandbar evolves into a bar and rip morphology, a negative feedback mechanism, characterized by a decaying beach change rate and an increasing beach alongshore uniformity, overwhelms the former mechanism. An erosive sequence characterized by both an overall offshore bar migration and an increase in beach three-dimensionality is also described.
(Journal of Geophysical Research: Earth Surface. vol. 118, n° 2169-9003, pp. 1045-1059, 27/10/2026)
LEGI, UJF, Grenoble INP, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR HHLY, IRSTEA
Role of short and long-wave interaction on wave celerity in the surf zone of a low-sloping beach
A good prediction of wave celerity is essential for wave propagation modeling in the nearshore. Previous studies have been focusing on the analysis of wave celerities averaged over several waves, neglecting the intra-wave variability due to long-wave transformation for instance. This paper is devoted to a study of individual wave transformation in the surf zone of a low-sloping beach, based on the analysis of a high-resolution laboratory dataset. The variability of the individual wave celerity in the surf zone is quantified and is seen to relate with the local elevation of the long waves normalized by the mean water depth. Lastly, individual wave celerities are compared to the predictions given by several linear and non-linear models.
(pp. 1677 - 1686, 27/10/2026)
LEGOS, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEGI, UJF, Grenoble INP, CNRS
Occurrence of selected micropollutants in treated wastewater and removal with optimised tertiary treatments
Two tertiary treatments were studied at pilot scale in three different plants. An advanced oxidation processes pilot was tested in two plants with two different upstream treatment processes: a membrane bioreactor and a low load activated sludge followed by a sand filter. An activated carbon pilot was tested in one plant, a low load activated sludge followed by a sand filter and an ozone reactor. 64 micropollutants were analysed in the samples of this study. The tertiary treatments studied, ozone, AOP and activated carbon, were efficient for the removal of most of the micropollutants analysed in this study, except metals.
(pp. 3 p., 27/10/2026)
CIRSEE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR MALY, IRSTEA
Direct exposure to PAH-spiked gravels induces developmental defects in Oncorhynchus mykiss early life stages
(27/10/2026)
UB, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LPGP, INRA, Biosit : Biologie - Santé - Innovation Technologique, BE, IFREMER