Qualité des Milieux Naturels
Qualité des Milieux Naturels
(pp. 96 p., 29/04/2026)
IC2MP [Poitiers], UP, INC-CNRS, CNRS, LIENSs, INSU - CNRS, ULR, CNRS, IPREM, UPPA, INC-CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IC2MP [Poitiers], UP, INC-CNRS, CNRS, P3F, INRA, ECOSYS, INRA
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., 29/04/2026)
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
Towards the Development of a Storm Erosion EWS for the French Aquitaine Coast
Towards the development of a storm erosion EWS for the French Aquitanian coast. The 230-km long Aquitaine sandy coast, SW France, is vulnerable to erosion hazards owing to its full exposure to Atlantic storm waves. Since 2015, the Observatory of the Aquitaine Coast and several academic and local partners have developed a network to better survey and forecast storm-driven morphological changes at regional scale. This paper presents the implementation of an early warning system (EWS) with the primary objective to alert the network members 2-3 days ahead in order to perform pre-storm and post-storm surveys. Regional bulletins are edited to identify the most exposed coastal sections. At local scale, tests are realized on two morphological indicators used to forecast qualitatively and quantitatively the likelihood of beach and dune erosion. The two indicators (namely the Collision Regime Indicator, CRI, and the Eroded Volume Indicator, EVI, were calibrated and further validated at two nearby beaches where extensive morphological data are collected regularly: bimonthly surveys from 2009 to 2015 at Truc Vert beach and surveys every 2 to 7 days during the winters since 2015 at Biscarrosse beach. Results indicate promising performance, with the CRI predicting collision regime when front dune erosion was indeed observed, and the EVI predicting fairly accurate eroded sediment volume on cross shore beach profile. Nevertheless, more extensive validation of the CRI and EVI is needed to extend the indicators to the entire Aquitaine coast and for a wide range single storms and storm clusters.
(Journal of Coastal Research. vol. SI 85, n° 0749-0208, pp. 5 p., 29/04/2026)
BRGM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Interaction of freshwater diatom with gold nanoparticles: adsorption, assimilation, and stabilization by cell exometabolites
The rising concern about the potential toxicity of synthetic gold nanoparticles (AuNPs) in aquatic environments requires a rigorous estimation of physico-chemical parameters of reactions between AuNPs and major freshwater microorganisms. This study addresses the interaction of 10-nm size, positively charged AuNPs with periphytic freshwater diatoms (Eolimna minima). The adsorption experiments on viable cells were performed in 10 mM NaCl and 5 mM NaCl + 5 mM NaHCO3 solution at a variable pH (3–10), at an AuNPs concentration from 1 µg/L to 10,000 µg/L, and an exposure time from a few minutes to 55 days. Three types of experiments, adsorption as a function of time (kinetics), pH-dependent adsorption edge, and constant-pH “Langmuirian” type isotherms, were conducted. In addition, long-term interactions (days to weeks) of live diatoms (under light and in the darkness) were performed. The adsorption was maximal at a pH from 3 to 6 and sizably decreased at a pH of 6 to 10. Results of adsorption experiments were modeled using a second order kinetic model, a Linear Programming Model, Freundlich isotherm, and a ligand binding equation for one site competition. The adsorption of AuNPs(+) most likely occurred on negatively-charged surface sites of diatom cell walls such as carboxylates or phosphorylates, similar to previously studied metal cations. Under light exposure, the AuNPs were stabilized in aqueous solution in the presence of live cells, probably due to the production of exometabolites by diatoms. The adsorbed amount of AuNPs decreased after several days of reaction, suggesting some AuNPs desorption. In the darkness, the adsorption and assimilation were stronger than under light. Overall, the behavior of positively charged AuNPs at the diatom–aqueous solution interface is similar to that of metal cations, but the affinity of aqueous AuNPs to cell exometabolites is higher, which leads to the stabilization of nanoparticles in solution in the presence of diatoms and their exudates. During photosynthetic activity and the pH rising above 9 in the vicinity of diatom cells, the adsorption of AuNPs strongly decreases, which indicates a decreasing potential toxicity of AuNPs for photosynthesizing cells. The present study demonstrates the efficiency of a thermodynamic and kinetic approach for understanding gold nanoparticles interaction with aquatic freshwater peryphytic microorganisms.
(Minerals. vol. 8, n° 2075-163X, pp. 99, 29/04/2026)
IOCAG, ULPGC, GET, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, TSU, FECIAR UrB RAS, RAS, IPGG SB RAS, SB RAS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ICMCB, UB, INC-CNRS, CNRS
Influence des conditions édaphiques sur la réponse des communautés alpines au changement global
Les effets du réchauffement climatique et de l'augmentation de la sécheresse estivale sur la composition et la diversité des communautés alpines ont été largement étudiés. Cependant le rôle modulateur des facteurs locaux tels que la roche mère, la mésotopographie et l'enneigement, est encore mal connu. Dans cette étude nous ré-échantillonnons la végétation d'un site de l'alpin inférieur des Alpes dauphinoises (France) étudié en 1997 et où se juxtaposent des variations importantes de roches mères (calcaire et siliceuse), de mésotopographie et d'enneigement susceptibles de moduler la réponse des communautés alpine au changement climatique. 112 relevés effectués en 1997 et 2017 et précisément géo-référencés, sont analysés par Analyse Factorielle des Correspondances. La végétation a très sensiblement évolué en 20 ans et montre une tendance vers la xérophilisation et l'oligotrophisation. La xérophilisation s'observe le long de l'axe 1 de l'AFC par déplacement de la position des relevés vers un pôle caractérisé par des sols superficiels calcaires à disponibilité en eau réduite, qui s'oppose à un autre pôle représenté par des sols acides développés sur roche siliceuse ou sur matériau mixte. Cet effet est particulièrement sensible au milieu du gradient de disponibilité en eau, en bordure de combes à neige. L'oligotrophisation, est probablement due à une baisse du pâturage et s'observe principalement le long de l'axe 2 de l'AFC, par déplacement de la position des relevés vers un pôle caractérisé par des sites exposés à déneigement précoce (mésotopographie convexe) sur sols siliceux. La richesse spécifique de l'ensemble des communautés décroit en moyenne de 15%, très probablement sous l'effet de l'augmentation de la compétition par les ligneux induite par la baisse du pâturage. Nos résultats montrent que les facteurs édaphiques locaux peuvent limiter la remontée altitudinale des espèces telle qu'elle est prédite par les principaux modèles de niche, la plupart des espèces pouvant trouver à la même altitude des refuges microclimatiques leur permettant d'éviter les effets du changement climatique.
(Botany / Botanique. vol. 4, n° 1916-2790, pp. 81-91, 29/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UB, UR LESSEM, IRSTEA, UGA [2016-2019], Fédération OSUG, UGA [2016-2019], LECA, USMB [Université de Savoie] [Université de Chambéry], CNRS, UGA [2016-2019]
The influence of natural dissolved organic matter on herbicide toxicity to marine microalgae is species-dependent
Microalgae, which are the foundation of aquatic food webs, may be the indirect target of herbicides used for agricultural and urban applications. Microalgae also interact with other compounds from their environment, such as natural dissolved organic matter (DOM), which can itself interact with herbicides. This study aimed to evaluate the influence of natural DOM on the toxicity of three herbicides (diuron, irgarol and S-metolachlor), singly and in ternary mixtures, to two marine microalgae, Chaetoceros calcitrans and Tetraselmis suecica, in monospecific, non-axenic cultures. Effects on growth, photosynthetic efficiency (Ф’M) and relative lipid content were evaluated. The chemical environment (herbicide and nutrient concentrations, dissolved organic carbon and DOM optical properties) was also monitored to assess any changes during the experiments. The results show that, without DOM, the highest irgarol concentration (I0.5: 0.5 mg.L−1) and the strongest mixture (M2: irgarol 0.5 μg.L−1 + diuron 0.5 μg.L−1 + S-metolachlor 5.0 μg.L−1) significantly decreased all parameters for both species. Similar impacts were induced by I0.5 and M2 in C. calcitrans (around −56% for growth, −50% for relative lipid content and −28% for Ф’M), but a significantly higher toxicity of M2 was observed in T. suecica (−56% and −62% with I0.5 and M2 for growth, respectively), suggesting a possible interaction between molecules. With DOM added to the culture media, a significant inhibition of these three parameters was also observed with I0.5 and M2 for both species. Furthermore, DOM modulated herbicide toxicity, which was decreased for C. calcitrans (−51% growth at I0.5 and M2) and increased for T. suecica (-64% and −75% growth at I0.5 and M2, respectively). In addition to the direct and/or indirect (via their associated bacteria) use of molecules present in natural DOM, the characterization of the chemical environment showed that the toxic effects observed on microalgae were accompanied by modifications of DOM composition and the quantity of dissolved organic carbon excreted and/or secreted by microorganisms. This toxicity modulation in presence of DOM could be explained by (i) the modification of herbicide bioavailability, (ii) a difference in cell wall composition between the two species, and/or (iii) a higher detoxification capacity of C. calcitrans by the use of molecules contained in DOM. This study therefore demonstrated, for the first time, the major modulating role of natural DOM on the toxicity of herbicides to marine microalgae.
(Aquatic Toxicology. vol. 198, n° 0166-445X, pp. 103-117, 29/04/2026)
UR EABX, IRSTEA, BE, IFREMER, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, EPM
Updated calibration of the clumped isotope thermometer in planktonic and benthic foraminifera
Accurate reconstruction of past ocean temperatures is of critical importance to paleoclimatology. Carbonate clumped isotope thermometry (“Δ47 ”) is a relatively recent technique based on the strong relationship between calcification temperature and the statistical excess of 13C–18O bonds in carbonates. Its application to foraminifera holds great scientific potential, particularly because Δ47 paleotemperature reconstructions do not require assumptions regarding the 18O composition of seawater. However there are still relatively few published observations investigating the potential influence of parameters such as salinity or foraminiferal size and species. We present a new calibration data set based on 234 replicate analyses of 9 planktonic and 2 benthic species of foraminifera collected from recent core-top sediments, with calcification temperatures ranging from −2 to 25 °C. We observe a strong relationship between Δ47 values and independent, oxygen-18 estimates of calcification temperatures:
Δ47 = 41.63 × 103/T2 + 0.2056
The formal precision of this regression (± 0.7–1.0 °C at 95 % confidence level) is much smaller than typical analytical errors. Our observations confirm the absence of significant species-specific biases or salinity effects. We also investigate potential foraminifer size effects between 200 and > 560 μm in 6 species, and conclude that all size fractions from a given core-top location and species display statistically undistinguishable Δ47 values. These findings provide a robust foundation for future inter-laboratories comparisons and paleoceanographic applications.
(Geochimica et Cosmochimica Acta. vol. 239, n° 0016-7037, pp. 1-16, 29/04/2026)
LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, PALEOCEAN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LPG-ANGERS, LPG, UA, UN UFR ST, UN, INSU - CNRS, CNRS, CLIMAG, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA
A comparison between water circulation and terrestrially-driven dissolved silica fluxes to the Mediterranean Sea traced using radium isotopes
The circulation of seawater through permeable coastal sediments is increasingly recognized as an important source of nutrients, including dissolved silica (DSi), to the coastal ocean. Here, we utilized a Ra isotope (223 Ra, 224 Ra ex , 228 Ra) mass balance to quantify DSi fluxes driven by water circulation to a small shallow coastal lagoon (La Palme; French Mediter-ranean) during June 2016, as compared to karstic groundwater spring inputs. The DSi flux driven by lagoon water circulation (derived from 224 Ra ex) was approximately one order of magnitude greater (1900 ± 1700 mol d À1) than the DSi load of the karstic groundwater spring (250 ± 50 mol d À1) and greater than molecular diffusion (970 ± 750 mol d À1). Lagoon water circulation was a negligible source of 228 Ra, indicating that circulation-driven DSi inputs occur over a timescale of days. Offshore transects were studied to quantify fluxes of marine-derived submarine groundwater discharge (SGD) from the permeable sandy coastline adjacent to the lagoon, into the Mediterranean Sea. Surface water transects revealed near-shore enrichments of Ra and DSi, attributed to wave-setup and water exchange through the permeable beach between the lagoon and the sea. Upscaling over the 9.5 km stretch of sandy beaches results in a marine SGD-driven DSi flux of 2.3 ± 1.3 Â 10 4 mol d À1 , similar in magnitude to the Têt river during November 2016 (3.3 ± 2.4 Â 10 4 mol d À1), the largest river in the region. A positive relationship between DSi and 224 Ra ex in lagoon water and seawater, but not 228 Ra, suggests that 224 Ra ex and DSi enrichments are derived from a similar source, the sediment (i.e. lithogenic particle dissolution), operating on short timescales. A marine SGD-driven DSi flux to the Gulf of Lions (3.8 ± 2.2 Â 10 5 mol d À1) is likely continuous over time. The relatively constant DSi inputs from water circulation for the shallow lagoons and beaches along the French Mediterranean Sea
(Geochimica et Cosmochimica Acta. vol. 238, n° 0016-7037, pp. 496-515, 29/04/2026)
LEGOS, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, UAB, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LOMIC, INSU - CNRS, SU, CNRS, OOB, SU, CNRS, GET, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, CEREGE, IRD, INRA, AMU, CdF (institution), INSU - CNRS, CNRS, JCU, VUB
Whole-transcriptome response to wastewater treatment plant and stormwater effluents in the Asian clam, Corbicula fluminea
The increase in human population and urbanization are resulting in an increase in the volume of wastewater and urban runoff effluents entering natural ecosystems. These effluents may contain multiple pollutants to which the biological response of aquatic organisms is still poorly understood mainly due to mixture toxicity and interactions with other environmental factors. In this context, RNA sequencing was used to assess the impact of a chronic exposure to wastewater treatment plant and stormwater effluents at the whole-transcriptome level and evaluate the potential physiological outcomes in the Asian clam Corbicula fluminea. We de-novo assembled a transcriptome from C. fluminea digestive gland and identified a set of 3,181 transcripts with altered abundance in response to water quality. The largest differences in transcriptomic profiles were observed between C. fluminea from the reference site and those exposed to wastewater treatment plant effluents. On both anthropogenically impacted sites, most differentially expressed transcripts were involved in signaling pathways in relation to energy metabolism such as mTOR and FoxO, suggesting an energy/nutrient deficit and hypoxic conditions. These conditions were likely responsible for damages to proteins and transcripts in response to wastewater treatment effluents whereas exposure to urban runoff might result in immune and endocrine disruptions. In absence of comprehensive chemical characterization, the RNAseq approach could provide information regarding the mode of action of pollutants and then be useful for the identification of which parameters must be studied at higher integration level in order to diagnose sites where the presence of complex and variable mixtures of chemicals is suspected.
(Ecotoxicology and Environmental Safety. vol. 165, n° 0147-6513, pp. 96-106, 29/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GENOTOUL, UT3, Comue de Toulouse, ENVT, Toulouse INP, INSERM, CNRS, Toulouse INP, Comue de Toulouse, INRAE, MIAT INRAE, INRAE, INRAE
Migrations néandertaliennes et variations climatiques pendant le Saalien supérieur. Apport des modélisations analogiques en enceintes thermo-regulées
(pp. 23-24, 29/04/2026)
CReAAH, UM, UR, UR2, CNRS, UFR HHAA, UN, MC, NSU, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS