Budget of methane emissions from soils, livestock and the river network at the regional scale of the Seine basin (France)
We used various approaches to establish a comprehensive budget of methane (CH4) emissions from the Seine basin, including direct emissions from livestock and soils as well as emissions from the drainage network. For the direct emissions from livestock, we used official livestock census numbers and emission factors (CH4 emitted by each animal species per head per year) available in the literature. For the emissions from soils, we based our estimates on experimental measurements in closed chambers installed on different agricultural plots, forest, and grasslands in 2008 and 2009. The results were extrapolated to the whole Seine basin, including grassland, cropland, and forest soil distributions in the Seine basin. The CH4 emissions from the Seine drainage network were also based on measurements of sampled waters in various rivers and streams (from headwaters to estuary) during different seasons in 2007, 2008, and 2010. After chemical analysis of CH4 concentrations in the water samples using a gas chromatographic technique and calculation of the CH4 supersaturation by stream order in rivers of the Seine basin (from 1 to 8) and by season we could estimate the CH4 emissions for the whole water surface area of the Seine drainage network. The livestock of the Seine basin produce CH4 emissions amounting to 166 × 106 kg C year−1, among which cattle are responsible for 85 %. The total CH4 emission from the Seine drainage network was estimated at 0.3 × 106 kg C year−1, large rivers being responsible for the largest proportion. Ebullition could account for an additional 0.2 × 106 kg C year−1. Soils of the Seine basin are a net sink for CH4 (9.4 × 106 kg C year−1). The water and soils fluxes are low with regard to emissions by livestock, but domestic waste, through landfills, could contribute an additional 40 × 106 kg C year−1.
(Biogeochemistry. vol. 116, n° 0168-2563, pp. 199-214, 19/04/2026)
SISYPHE, UPMC, EPHE, PSL, PSL, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, EGC, INRA
Vulnerability of sandy coasts to climate variability
The main objective of the VULSACO (VULnerability of SAndy COasts to climate change and anthropic pressure) project was to investigate present day and potential future vulnerability of sandy coasts at the 2030 horizon, i.e. on a time scale related to climate variability. The method, based on a multidisciplinary approach bringing together geologists, geographers, physicists, social psychologists, engineers and stakeholders, was structured around 4 axes: field data analysis; numerical modelling; analysis of governance and stakeholder perceptions; and development of vulnerability indexes. This approach was designed to investigate vulnerability at a local scale and was applied to 4 contrasting beaches located in France: Sète Lido (Mediterranean Sea), Truc Vert and La Tresson beaches (Atlantic Ocean), and Dewulf (English Channel). The results focus on decadal and multi-annual beach trends at the Truc Vert beach site. There is almost no trend in beach volume at Truc Vert beach, although there is a variation in this parameter on a cycle of 2 to 3 yr, with variations related to wave energy and probably to indexes of climate variability. Numerical modelling identified the sensitivity of beach responses to changes in wave height and direction, especially in terms of subtidal morphology and the potential development of shoreline instability. Together with the observed offshore wave angle at the Biscay Buoy, these model results suggest that a potential change in wave angle due to climate variability could significantly modify the bars’ morphology. The combination of data analysis and numerical modelling contributed to the development of vulnerability indexes designed for sandy coasts, which take into account climate-dependant variables such as waves. This allowed the differentiation of the sites in terms of vulnerability to erosion: Sète Lido and Truc Vert beach were the most and least vulnerable sites, respectively. These indexes help in identifying the dominant components of beach vulnerability, and provide potential for the study of how anthropogenic factors affect vulnerability. The study of stakeholder perceptions and decision-making with regard to climate-related risk also highlighted potential anthropogenic effects on beach vulnerability, and identified possible site-specific outcomes.
(Climate Research. vol. 57, n° 0936-577X, pp. 19-44, 19/04/2026)
BRGM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UAG, INSU - CNRS, UM, CNRS, UPC, CEFREM, UPVD, INSU - CNRS, CNRS, LETG, UNICAEN, NU, UA, EPHE, PSL, UBO EPE, UR2, CNRS, IGARUN, UN, UC / UniCan, LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France], ULCO, LEGI, UJF, Grenoble INP, CNRS
Genotoxic effects of exposure to waterborne uranium, dietary methylmercury and hyperoxia in zebrafish assessed by the quantitative RAPD-PCR method
Release of chemicals and fluctuation in oxygen content in the aquatic environment represent hazards for fish health. The present study aims at assessing the genotoxic impact of low concentration exposures to waterborne uranium (U), dietary methyl mercury (MeHg) and hyperoxia in zebrafish by using the RAPD-PCR quantitative method. A significant increase of the number hybridization sites was observed in fish exposed to 30 μg U/L and 100 μg U/L and hyperoxia. In fish exposed to MeHg (13.5 μg Hg/g, dry weight) no change in the number of hybridization sites were found, however, the frequency of PCR products showed significant variation. The mechanisms of toxicity leading to DNA damage in fish exposed to waterborne uranium, mercury and hyperoxia are discussed and the results from the literature given by the comet assay, micronucleus test and RAPD-PCR method compared. The study provides new data regarding the genotoxic effects of MeHg, hyperoxia and low U concentrations (30 μg U/L) in fish. The present work highlights the use of the RAPD-PCR as a sensitive method in the assessment of chemically-induced DNA damage in animals.
(Mutation Research - Genetic Toxicology and Environmental Mutagenesis. vol. 755, n° 1383-5718, pp. 55-60, 19/04/2026)
LIENSs, INSU - CNRS, ULR, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IRSN/PRP-ENV/SERIS/LECO, IRSN/PRP-ENV/SERIS, IRSN
Deglacial and Holocene vegetation and climatic changes in the southern Central Mediterranean from a direct land–sea correlation
Despite a large number of studies, the long-term and millennial to centennial-scale climatic variability in the Mediterranean region during the last deglaciation and the Holocene is still debated, including in the southern Central Mediterranean. In this paper, we present a new marine pollen sequence (core MD04-2797CQ) from the Siculo-Tunisian Strait documenting the regional vegetation and climatic changes in the southern Central Mediterranean during the last deglaciation and the Holocene. The MD04-2797CQ marine pollen sequence shows that semi-desert plants dominated the vegetal cover in the southern Central Mediterranean between 18.2 and 12.3 ka cal BP, indicating prevailing dry conditions during the deglaciation, even during the Greenland Interstadial (GI)-1. Across the transition Greenland Stadial (GS)-1 -Holocene, Asteraceae-Poaceae steppe became dominant till 10.1 ka cal BP. This record underlines with no chronological ambiguity that even though temperatures increased, deficiency in moisture availability persisted into the early Holocene. Temperate trees and shrubs with heath underbrush or maquis expanded between 10.1 and 6.6 ka, corresponding to Sapropel 1 (S1) interval, while Mediterranean plants only developed from 6.6 ka onwards. These changes in vegetal cover show that the regional climate in southern Central Mediterranean was wetter during S1 and became drier during the mid-to late Holocene. Wetter conditions during S1 were likely due to increased winter precipitation while summers remained dry. We suggest, in agreement with published modeling experiments, that the early Holocene increased melting of the Laurentide Ice Sheet in conjunction with weak winter insolation played a major role in the development of winter precipitation maxima in the Mediterranean region in controlling the strength and position of the North Atlantic storm track. Finally, our data provide evidence for centennial-scale vegetation and climatic changes in the southern Central Mediterranean. During the wet early Holocene, alkenone-derived cooling episodes are synchronous with herbaceous composition changes that indicate muted changes in precipitation. In contrast, enhanced aridity episodes, as detected by strong reduction in trees and shrubs, are recorded during the mid-to late Holocene. We show that the impact of the Holocene cooling events on the Mediterranean hydroclimate depend on baseline climate states, i.e. insolation and ice sheet extent, shaping the response of the mid-latitude atmospheric circulation.
(Climate of the Past. vol. 9, n° 1814-9324, pp. 767-787, 19/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, PALEOCEAN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, FSS, BTP, LOCEAN, IPSL, ENS-PSL, UVSQ, UPMC, CEA, INSU - CNRS, X, CNES, CNRS, MNHN, IRD, UPMC, INSU - CNRS, CNRS, LCE, CNRS, UFC, UBFC, GEOPS, UP11, 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, 19/04/2026)
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, 19/04/2026)
IFREMER, LEMAR, IRD, IFREMER, UBO EPE, CNRS, INRA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR REBX, IRSTEA, 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, 19/04/2026)
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, 19/04/2026)
CEREGE, IRD, INRA, AMU, CdF (institution), INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IFREMER, PROTEE, UTLN
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, 19/04/2026)
GEOLAB, UBP, IR SHS UNILIM, UNILIM, UCA [2017-2020], CNRS, UCA, LMV, UBP, INSU - CNRS, UJM, CNRS, IMTV, UdA, INSERM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Effect-directed analysis of endocrine-disrupting compounds in multi-contaminated sediment: identification of novel ligands of estrogen and pregnane X receptors
Effect-directed analysis (EDA)-based strategies have been increasingly used in order to identify the causative link between adverse (eco-)toxic effects and chemical contaminants. In this study, we report the development and use of an EDA approach to identify endocrine-disrupting chemicals (EDCs) in a multi-contaminated river sediment. The battery of in vitro reporter cell-based bioassays, measuring estrogenic, (anti)androgenic, dioxin-like, and pregnane X receptor (PXR)-like activities, revealed multi-contamination profiles. To isolate active compounds of a wide polarity range, we established a multi-step fractionation procedure combining: (1) a primary fractionation step using normal phase-based solid-phase extraction (SPE), validated with a mixture of 12 non-polar to polar standard EDCs; (2) a secondary fractionation using reversed-phase-based high-performance liquid chromatography (RP-HPLC) calibrated with 33 standard EDCs; and (3) a purification step using a recombinant estrogen receptor (ER) affinity column. In vitro SPE and HPLC profiles revealed that ER and PXR activities were mainly due to polar to mid-polar compounds, while dioxin-like and anti-androgenic activities were in the less polar fractions. The overall procedure allowed final isolation and identification of new environmental PXR (e.g., di-iso-octylphthalate) and ER (e.g., 2,4-di-tert-butylphenol and 2,6-di-tert-butyl-alpha-methoxy-p-cresol) ligands by using gas chromatography coupled with mass spectrometry with full-scan mode acquisition in mid-polar fractions. In vitro biological activity of these chemicals was further confirmed using commercial standards, with di-iso-octylphthalate identified for the first time as a potent hPXR environmental agonist.
(Analytical and Bioanalytical Chemistry. vol. 405, n° 1618-2642, pp. 2553-2566, 19/04/2026)
INERIS, LPTC, UB, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IRCM - U896 Inserm - UM1, UM1, INSERM, UM