Les effets de la crue de juin 2016 sur la qualité de l'eau du bassin de la Seine
Page de couverture Le PIREN-Seine est un programme de recherche interdisciplinaire en environnement dont l'objectif est de développer une vision d'ensemble du fonctionnement du bassin versant de la Seine et de la société humaine qui l'investit, pour permettre une meilleure gestion qualitative et quantitative de la ressource en eau. Il est l’un des programmes composant la Zone Atelier Seine du CNRS. La cellule transfert des connaissances a pour but de valoriser les productions de savoirs scientifiques issues des recherches du PIREN-Seine, et de favoriser la mise à disposition de ces informations à un large public, des professionnels de la gestion de l’eau aux élus en passant par les usagers. Soutenue par l'Agence de l'eau Seine-Normandie et l'EPTB Seine Grands Lacs, et animée depuis octobre 2016 par l'association ARCEAU-IdF, cette cellule répond à une forte volonté de la part des chercheurs de participer au transfert des savoirs scientifiques et techniques vers la société civile. Elle est ainsi chargée de la rédaction et de l’édition de documents thématiques, de la mise en ligne de contenus scientifiques adaptés à la fois aux professionnels et au grand public, et de la mise en place d’ateliers de co-réflexion du programme. La collection des fascicules du PIREN-Seine analyse différents aspects du fonctionnement du bassin de la Seine, correspondant aux multiples domaines de recherche du programme. Ils s’adressent à tous les publics concernés par l’analyse et la gestion du bassin versant de la Seine et des problématiques environnementales et humaines qui y sont liées. Tous ces fascicules sont disponibles en téléchargement gratuit au format PDF sur le site du programme. Une première série de neuf fascicules a été publiée en 2009. En 2011, six nouveaux titres sont venus enrichir la collection. En 2017, la production des fascicules reprend avec une nouvelle collection, pour permettre aux acteurs du domaine de l’eau et de l’environnement de rester informés des dernières recherches scientifiques menées par le PIREN-Seine.
(pp. 70 p., 01/09/2026)
GEOSCIENCES, PSL, METIS, EPHE, PSL, INSU - CNRS, SU, CNRS, GIP-Seine-Aval, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEESU, ENPC, UPEC UP12, GEDI, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, LISIS, CNRS, INRAE
Mission Baelo Claudia. Rapport d'activités
(01/09/2026)
LIENSs, INSU - CNRS, ULR, CNRS, HALMA, CNRS, MC, IRAA, UL2, AMU, CNRS, HeRMA [Poitiers], UP, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
First record of the invasive species Ianiropsis serricaudis Gurjanova, 1936 (Crustacea: Isopoda) in Arcachon Bay, Bay of Biscay (NE Atlantic)
The invasive isopod Ianiropsis serricaudis Gurjanova, 1936, originally described from the North-West Pacific Ocean, is herein reported for the first time on the French Atlantic coast. Its presence is probably due to oyster import activity, and the sampling of many brooding females in Arcachon Bay since 2013 suggests a well-established species. Its current European distribution is summarised and some morphological characters are discussed.
(BioInvasions Records. vol. 7, n° 2242-1300, pp. 171-176, 01/09/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Late Holocene record from a Loire River incised paleovalley (French inner continental shelf): insights into regional and global forcing factors
(01/09/2026)
LPG-ANGERS, LPG, UA, UN UFR ST, UN, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, SHOM
Retrospective analysis of the ecological changes in the Laurentian ecosystem using sclerochronology
(01/09/2026)
MSSMat, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEMAR, IRD, IFREMER, UBO EPE, CNRS, UFR Santé [Poitiers], UP
Dispersive and dispersive-like bores in channels with sloping banks
In this paper, a detailed analysis of undular bore dynamics in channels of variable cross-section is presented. Two undular bore regimes, Low Froude Number (LFN) and High Froude Number (HFN), are simulated with a Serre-Green-Naghdi model, and the results are compared with the experiments by Treske. We show that contrary to Favre waves and HFN bores, which are controlled by dispersive non-hydrostatic mechanisms, LFN bores correspond to a hydrostatic phenomenon. The dispersive-like properties of the LFN bores is related to wave refraction on the banks in a way similar to that of edge waves in the nearshore. A fully hydrostatic theoretical model allowing to describe these dispersive-like bores is derived and compared to the observations, confirming our claim.
(01/09/2026)
IRSTEA, UGA [2016-2019], EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CARDAMOM, IMB, UB, Bordeaux INP, CNRS, Inria
Equilibrium modeling of the beach profile on a macrotidal embayed low tide terrace beach
Eleven-year long time series of monthly beach profile surveys and hourly incident wave conditions are analyzed for a macrotidal Low Tide Terrace beach. The lower intertidal zone of the beach has a pluriannual cycle, whereas the upper beach profile has a predominantly seasonal cycle. An equilibrium model is applied to study the variation of the contour elevation positions in the intertidal zone as a function of the wave energy, wave power, and water level. When forcing the model with wave energy, the predictive ability of the equilibrium model is around 60% in the upper intertidal zone but decreases to 40% in the lower intertidal zone. Using wave power increases the predictive ability up to 70% in both the upper and lower intertidal zones. However, changes around the inflection point are not well predicted. The equilibrium model is then extended to take into account the effects of the tide level. The initial results do not show an increase in the predictive capacity of the model, but do allow the model free parameters to represent more accurately the values expected in a macrotidal environment. This allows comparing the empirical model calibration in different tidal environment. The interpretation of the model free parameter variation across the intertidal zone highlights the behavior of the different zones along the intertidal beach profile. This contributes to a global interpretation of the four model parameters for beaches with different tidal ranges, and therefore to a global model applicable at a wide variety sites.
(Ocean Dynamics. vol. 68, n° 1616-7341, pp. 1207-1220, 01/09/2026)
LGO, UBS, IFREMER, UBO EPE, CNRS, LHSV, ENPC, EDF R&D, EDF [E.D.F.], Cerema Equipe-projet HA, Cerema, Cerema Equipe-projet HA, Cerema, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UBO EPE, LETG - Brest, LETG, UNICAEN, NU, UA, EPHE, PSL, UBO EPE, UR2, CNRS, IGARUN, UN
Deltaic and Coastal Sediments as Recorders of Mediterranean Regional Climate and Human Impact Over the Past Three Millennia
Deltaic and shallow marine sediments represent unique natural archives to study the evolution of surface coastal ocean water properties as compared to environmental changes in adjacent continents. Sea surface temperatures (SSTs) and higher plant biomarker records were generated from the Rhone and Var River deltaic sediments (NW Mediterranean Sea), and three sites in the South Adriatic Sea (Central/Eastern Mediterranean Sea), spanning all or part of the past three millennia. Because of the high sediment accumulation rates at all core sites, we were able to produce time series at decadal time scale. SSTs in the Gulf of Lion and the convection area of the South Adriatic Sea indicate similar cold mean values (around 17 °C) and pronounced cold spells, reflecting strong wind‐driven surface water heat loss. However, they differ in the rate of postindustrial warming, which is steeper in the Gulf of Lion. The three Adriatic Sea SST records are notably different reflecting different hydrological influence from nearshore to open sea sites. The compositional features of higher plant n‐alkanes in the Rhone and Var delta sediments and inferred vegetation types show differences consistent with the latitudinal extension of the drainage basins of both river streams. In the Adriatic Sea, both coastal and open sea sediments indicate enhanced land‐derived material over the past 500 years, which is not seen in the NW Mediterranean record. We suggest that increased erosion as the result of changes in land use practices is the most likely cause for this trend.
(Paleoceanography and Paleoclimatology. vol. 33, n° 2572-4525, pp. 579-593, 01/09/2026)
LOCEAN-VOG, LOCEAN, MNHN, IRD, INSU - CNRS, SU, CNRS, IPSL (FR_636), ENS-PSL, UVSQ, CEA, INSU - CNRS, X, CNES, SU, CNRS, UPCité, BTP, LOCEAN, IPSL, ENS-PSL, UVSQ, UPMC, CEA, INSU - CNRS, X, CNES, CNRS, MNHN, IRD, UPMC, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CNR, CEFREM, UPVD, INSU - CNRS, CNRS, GM, IFREMER, DiSTAR, UNINA, LOCEAN-CYBIOM, LOCEAN, MNHN, IRD, INSU - CNRS, SU, CNRS, IPSL (FR_636), ENS-PSL, UVSQ, CEA, INSU - CNRS, X, CNES, SU, CNRS, UPCité
Hydro-ecological controls on dissolved carbon dynamics in groundwater and export to streams in a temperate pine forest
We studied the export of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) from forested shallow groundwater to first-order streams, based on groundwater and surface water sampling and hydrological data. The selected watershed was particularly convenient for such study, with a very low slope, with pine forest growing on sandy permeable podzol and with hydrology occurring exclusively through drainage of shallow groundwater (no surface runoff). A forest plot was instrumented for continuous eddy covariance measurements of precipitation, evapotranspiration, and net ecosystem exchanges of sensible and latent heat fluxes as well as CO2 fluxes. Shallow groundwater was sampled with three piezometers located in different plots, and surface waters were sampled in six first-order streams; river discharge and drainage were modeled based on four gauging stations. On a monthly basis and on the plot scale, we found a good consistency between precipitation on the one hand and the sum of evapotranspiration, shallow groundwater storage and drainage on the other hand. DOC and DIC stocks in groundwater and exports to first-order streams varied drastically during the hydrological cycle, in relation with water table depth and amplitude. In the groundwater, DOC concentrations were maximal in winter when the water table reached the superficial organic-rich layer of the soil. In contrast, DIC (in majority excess CO2) in groundwater showed maximum concentrations at low water table during late summer, concomitant with heterotrophic conditions of the forest plot. Our data also suggest that a large part of the DOC mobilized at high water table was mineralized to DIC during the following months within the groundwater itself. In first-order streams, DOC and DIC followed an opposed seasonal trend similar to groundwater but with lower concentrations. On an annual basis, leaching of carbon to streams occurred as DIC and DOC in similar proportion, but DOC export occurred in majority during short periods of the highest water table, whereas DIC export was more constant throughout the year. Leaching of forest carbon to first-order streams represented a small portion (approximately 2 %) of the net land CO2 sink at the plot. In addition, approximately 75% of the DIC exported from groundwater was not found in streams, as it returned very fast to the atmosphere through CO2 degassing.
(Biogeosciences. vol. 15, n° 1726-4170, pp. 669 - 691, 01/09/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UMR ISPA, INRA, Bordeaux Sciences Agro, UFF, LOCEAN, MNHN, IRD, INSU - CNRS, SU, CNRS, IPSL (FR_636), ENS-PSL, PSL, UVSQ, CEA, INSU - CNRS, X, IP Paris, CNES, SU, CNRS, UPCité
Ingestion and contact with polyethylene microplastics does not cause acute toxicity on marine zooplankton
Toxicity of polyethylene microplastics (PE-MP) of size ranges similar to their natural food to zooplanktonic organisms representative of the main taxa present in marine plankton, including rotifers, copepods, bivalves, echinoderms and fish, was evaluated. Early life stages (ELS) were prioritized as testing models in order to maximize sensitivity. Treatments included particles spiked with benzophenone-3 (BP-3), a hydrophobic organic chemical used in cosmetics with direct input in coastal areas. Despite documented ingestion of both virgin and BP-3 spiked microplastics no acute toxicity was found at loads orders of magnitude above environmentally relevant concentrations on any of the invertebrate models. In fish tests some effects, including premature or reduced hatching, were observed after 12 d exposure at 10 mg L-1 of BP-3 spiked PE-MP. The results obtained do not support environmentally relevant risk of microplastics on marine zooplankton. Similar approaches testing more hydrophobic chemicals with higher acute toxicity are needed before these conclusions could be extended to other organic pollutants common in marine ecosystems. Therefore, the replacement of these polymers in consumer products must be carefully considered.
(Journal of Hazardous Materials. vol. 360, n° 0304-3894, pp. 452-460, 01/09/2026)
IEO | CSIC, CSIC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, NEOLAiA, GABI, INRA, IFREMER, UMR MARBEC, IRD, IFREMER, UM, CNRS, CNR