Imaging hydrological dynamics in karst unsaturated zones by time-lapse electrical resistivity tomography
The hydrodynamics of karst terrain are highly complex due to the diverse fractures and reservoirs within limestone formations. The time delay between rainfall events and subsequent flow into reservoirs exhibits significant variability. However, these hydrological processes are not easily visualized in karst topography. Subsurface geophysics, specifically 2D time-lapse electrical resistivity tomography (ERT), provides an effective method for studying the relationships between hydrological and geophysical features. In our research, we adopted ERT in the Karst Critical Zone (KCZ) to visualize specific karstic zones, including cave galleries, water storage reservoirs, wetting fronts, soil layers, and potential preferential flow paths down to a depth of 20 m. To capture spatial and seasonal variations in resistivity, we presented a comprehensive approach by combining sixteen inversion models obtained between February 2020 and September 2022 above the Villars Cave in SW-France-a well-known prehistoric cave. We used a multi-dimensional statistical technique called Hierarchical Agglomerative Clustering (HAC) to create a composite model that divided the synthetic ERT image into eight clusters representing different karst critical zones. The ERT image clearly visualized the cave gallery with high resistivity values that remained consistent throughout the seasons. Our analysis revealed a close seasonal relationship between water excess and resistivity variations in most infiltration zones, with time delays increasing with depth. The karst reservoirs, located at significant depths compared to other clusters, displayed sensitivity to changes in water excess but were primarily affected by fluctuations in water conductivity, particularly during summer or dry periods. These findings have significant implications for predicting rainwater infiltration pathways into caves, thereby assisting in the conservation and preservation of prehistoric caves and their cultural heritage.
(Science of the Total Environment. vol. 907, n° 0048-9697, pp. 168037, 01/01/2024)
I2M-BX, UB, CNRS, INRAE, UB, UB, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Gamma irradiation-induced offspring masculinization is associated with epigenetic changes in female zebrafish
Sex ratio variation is a key topic in ecology, because of its direct effects on population dynamics and thus, on animal conservation strategies. Among factors affecting sex ratio, types of sex determination systems have a central role, since some species could have a sex determined by genetic factors, environmental factors or a mix of those two. Yet, most studies on the factors affecting sex determination have focused on temperature or endocrinedisrupting chemicals (EDCs), and much less is known regarding other factors. Exposure to gamma irradiation was found to trigger offspring masculinization in zebrafish. Here we aimed at deciphering the potential mechanisms involved, by focusing on stress (i.e. cortisol) and epigenetic regulation of key genes involved in sex differentiation in fish. Cortisol levels in exposed and control (F0) zebrafish females' gonads were similar. However, irradiation increased the DNA methylation level of foxl2a and cyp19a1a in females of the F0 and F1 generation, respectively, while no effects were detected in testis. Overall, our results suggest that parental exposure could alter offspring sex ratio, at least in part by inducing methylation changes in ovaries.
(Ecotoxicology and Environmental Safety. vol. 269, n° 0147-6513, pp. 115790, 01/01/2024)
IRSN/PSE-ENV/SERPEN/LECO, IRSN/PSE-ENV/SERPEN, IRSN, UMR MARBEC, IRD, IFREMER, CNRS, UM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Temperature and hydrological variations during the late-glacial in the Central Mediterranean: Application of the novel ostracod-clumped isotope thermometer
This study shows, for the first time, the absence of a vital effect in the clumped isotope carbonate (Δ47) fossil ostracod signal and confirms the ability of the novel ostracod-Δ47 thermometer to reconstruct past temperatures and hydrological conditions in complex lacustrine systems. Furthermore, the application of Δ47 analyses on the ostracod species Candona angulata and Cyprideis torosa from Lake Trasimeno record (central Italy), which today precipitate their shells during the cold and the warm season respectively provides evidence that by combining biological (i.e., ostracod shell precipitation timing), paleontological (i.e., identification of ostracod species) and geochemical (i.e., Δ47) approaches, the ostracod-Δ47 thermometer accurately reconstructs past seasonality. Despite the absence of a vital effect, not all species can be combined for Δ47 analyses in environments with seasonal temperature variations; only those that precipitate their shells during the same season should be considered. The application of the ostracod-Δ47 thermometer on the Trasimeno lacustrine record gives rise to the first continental warm season paleotemperature reconstruction of the last 43 ky in central Mediterranean area. The combination of Δ47 and oxygen isotope composition (δ18Oost) measured on ostracod shells provides the isotopic composition of the water from which the carbonate precipitated (δ18Ow) and thereby, changes in the evaporation/precipitation balance in this area. Before the Last Glacial Maximum (LGM), equivalent to the Marine Isotopic Stage 3 (MIS3, from 43 to 29ky), warm season temperatures ranged from 15 ± 1.6 °C to 22 ± 2.3 °C, equivalent to 2 to 6 °C colder than today. Hydrological conditions during this period are similar to the present-day ones, characterized by a permanent lake and a high evaporation/precipitation ratio (E/P). The drastic decrease of the warm season temperatures (ranging from 10 ± 2.9 °C to 17 ± 3.1 °C) and of the E/P ratio during LGM and Late-glacial (MIS2, from 29 to 11.6 ky) correspond to the global climate cooling and low summer insolation, suggesting an amplifying role, of the latter, in the effects of the millennial scale climatic variations. At the Pleistocene/Holocene transition, both warm season temperature (25 ± 2 °C) and the E/P ratio increased in conjunction with the summer insolation. During the early Holocene, warm season temperature (23 ± 2 °C) closely resembles present-day values. However, cold season temperature (12 ± 2 °C) is approximately 4 °CC warmer than today. Notably, no hydrological differences are identified between the warm and the cold season underlying a lower seasonality contrast compared to the present, along with enhanced warm season precipitation. The good agreement between the Δ47 temperatures reconstructed for the last 1 ky and the temperatures presently recorded at Lake Trasimeno (8 °C cold and 22 °C for warm season), confirms the accuracy of the analyses and the applicability of the ostracod-Δ47 thermometer to reconstruct seasonal temperature changes.
(Earth and Planetary Science Letters. vol. 625, n° 0012-821X, pp. 118470, 01/01/2024)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Expertise préalable à la création d’un tableau de maladie professionnelle ou à l’élaboration de recommandations aux comités régionaux de reconnaissance des maladies professionnelles - Expertise sur les tableaux de maladies professionnelles existants nécessitant une mise à jour
La commission chargée d'évaluer le coût de la sous-déclaration des accidents du travail et des maladies professionnelles pour la branche maladie instituée par l’article L. 176-2 du code de la Sécurité Sociale (CSS), a régulièrement souligné que la non-reconnaissance de certaines maladies professionnelles pouvait être due notamment « à l’obsolescence de certains tableaux de maladies professionnelles qui n’intègrent pas l’état des connaissances scientifiques et épidémiologiques, et, d’autre part, à la limitation des pathologies qu’ils peuvent prendre en compte pour ce qui est des durées d’exposition et des produits et substances prévus ». Le dernier rapport issu des travaux de la commission sur la sous-déclaration des AT-MP, remis au Parlement en juillet 2021 (Commission sur la sous-déclaration des accidents du travail et des maladies professionnelles 2021), mettait ainsi en avant le caractère inadapté ou incomplet de certains tableaux de maladies professionnelles (TMP), s’agissant notamment de la désignation de la maladie ou des travaux associés. Compte tenu des évolutions des connaissances relatives aux modalités diagnostiques des maladies indiquées dans les TMP mais aussi aux travaux en lien avec ces maladies, la Direction générale du travail, la Direction de la Sécurité sociale et le Secrétariat général du ministère de l’agriculture et de la souveraineté alimentaire ont saisi l’Anses le 16 mars 2023 pour réaliser un travail d’expertise visant à étudier d’une part l’opportunité scientifique et médicale d’actualiser les différents tableaux, et d’autre part de disposer, pour chaque tableau, des raisons justifiant ou non une évolution des conditions d’accès à ces tableaux.
(pp. 113 p., 01/01/2024)
Irset, UA, UR, EHESP, INSERM, Biosit : Biologie - Santé - Innovation Technologique, IRIS, EHESS, INSERM, CNRS, UJML, UMRESTTE UMR_T9405, UCBL, INED, UBO UFR MSS EUMB, UBO EPE, CHRU Brest, CESP, UVSQ, AP-HP, INSERM, UB, EPICENE, BPH, UB, INSERM, NU, IRISSO, PSL, CNRS, INRAE, CONSTANCES, UVSQ, INSERM, UPCité, INSERM, LABERS, UBS, UBO EPE, IBSHS, UBO EPE, AU, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, DER, ANSES, DiSSES, ANSES
New insights into the impact of leachates from in-field collected plastics on aquatic invertebrates and vertebrates.
The impact of leachates from micronized beached plastics of the Mediterranean Sea and Atlantic Ocean on coastal marine ecosystems was investigated by using a multidisciplinary approach. Chemical analysis and ecotoxicological tests on phylogenetically distant species were performed on leachates from the following plastic categories: bottles, pellets, hard plastic (HP) containers, fishing nets (FN) and rapido trawling rubber (RTR). The bacteria Alivibrio fischeri, the nauplii of the crustaceans Amphibalanus amphitrite and Acartia tonsa, the rotifer Brachionus plicatilis, the embryos of the sea urchin Paracentrotus lividus, the ephyrae of the jellyfish Aurelia sp. and the larvae of the medaka Oryzias latipes were exposed to different concentrations of leachates to evaluate lethal and sub-lethal effects. Thirty-one additives were identified in the plastic leachates; benzophenone, benzyl butyl phthalate and ethylparaben were present in all leachates. Ecotoxicity of leachates varied among plastic categories and areas, being RTR, HP and FN more toxic than plastic bottles and pellets to several marine invertebrates. The ecotoxicological results based on 13 endpoints were elaborated within a quantitative weight of evidence (WOE) model, providing a synthetic hazard index for each data typology, before their integrations in an environmental risk index. The WOE assigned a moderate and slight hazard to organisms exposed to leachates of FN and HP collected in the Mediterranean Sea respectively, and a moderate hazard to leachates of HP from the Atlantic Ocean. No hazard was found for pellet, bottles and RTR. These findings suggest that an integrated approach based on WOE on a large set of bioassays is recommended to get a more reliable assessment of the ecotoxicity of beached-plastic leachates. In addition, the additives leached from FN and HP should be further investigated to reduce high concentrations and additive types that could impact marine ecosystem health.
(Environmental Pollution. vol. 355, n° 0269-7491, pp. 124233, 09/04/2026)
IAS, CNR, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UNIVPM, ULPGC, LCPO, UB, ENSCBP, INC-CNRS, CNRS
Impact du barrage de l’usine marémotrice sur la sédimentation dans l’estuaire de la Rance
Rejoignant la Manche entre Dinard et Saint-Malo, les caractéristiques naturelles de l'estuaire de la Rance combinées à une amplitude de marée remarquable, jusqu'à 13,6 mètres en vive-eau, ont permis la mise en service en 1967 de la première usine marémotrice au monde. L'exploitation de l'usine induit des modifications du régime hydrologique à même de modifier la dynamique sédimentaire dans l'estuaire de la Rance. A l'initiative de l'EPTB Rance Frémur Baie de Beaussais, une étude a été menée pour y déterminer les taux d’accumulation sédimentaire à l’échelle de temps pluri-décennale au moyen du 210Pb (T1/2 = 22.3 ans) et du 137Cs (T1/2 = 30.08 ans). Une campagne de carottage, réalisée en mars 2022, a permis de prélever 19 carottes sédimentaires, réparties entre l’écluse du Chatelier au sud et le barrage au nord. Au laboratoire, toutes les carottes ont été ouvertes longitudinalement, photographiées, radiographiées puis échantillonnées en vue de la détermination de la teneur en eau, de la granulométrie et des radioéléments d’intérêt. Aux sites proches des rives ou dans des anses, les profils de 210Pbxs montrent souvent deux pentes dans l’évolution avec la profondeur de cet élément, dont la séparation se situe au niveau des couches où le maximum de 137Cs, attribué aux retombées des essais nucléaires (1963), est observé. Dans ce cas, les taux de sédimentation des couches les plus récentes sont supérieurs, d’un facteur 2 à 3, à ceux calculés pour les sédiments « pré-barrage ». Les résultats suggèrent qu’il y a eu une augmentation de la sédimentation dans les secteurs central et amont de l’estuaire de la Rance depuis la mise en service du barrage.
(Revue Paralia, n° 1760-8716, 09/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UB
Factors Controlling Mud Floc Settling Velocity in a Highly Turbid Macrotidal Fluvial‐Estuarine System
This study assesses the settling dynamics of suspended sediments along the hyper‐turbid Gironde Garonne fluvial‐estuarine system, with an innovative optical SCAF instrument (System of Characterization of Aggregates and Flocs). Two fields campaigns were carried out to determine the settling velocity and properties of suspended sediments during a semi‐diurnal tidal cycle, as well as hydrodynamic conditions and water properties. The two sampling stations were representative of two regions: a tidal river dominated by fresh water and an estuary affected by salty or brackish waters. A high spatial variability of the settling velocity was observed along the fluvial‐estuarine system and vertically along the water column. Settling velocities ranged from 0.02 to 0.4 mm/s. This study confirms that in hyper‐turbid systems, the suspended sediment concentration (SSC) is predominantly driving the settling dynamics of suspended sediment. Threshold concentrations have been defined for the flocculation and hindered regimes where the settling velocity may vary by one order of magnitude. Although in natural environments it is difficult to distinguish between the effects of SSC and turbulence (as they are correlated), in the Gironde‐Garonne system the turbulent shear G seems to affect the settling of suspended sediment to a lower extent. Settling velocity variations cannot be directly correlated to salinity or organic matter content. Despite differences in hydrodynamic and environmental conditions in fluvial and estuarine regions, a common prediction law has been found to estimate settling velocity of suspended sediment as a function of suspended sediment concentration.
(Journal of Geophysical Research. Oceans. vol. 129, n° 2169-9275, pp. e2024JC021558, 09/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, RHITME, Cerema, IGE, IRD, INSU - CNRS, CNRS, INRAE, Fédération OSUG, UGA, Grenoble INP, UGA, Fédération OSUG
Impacts of AMOC Collapse on Monsoon Rainfall: A Multi-Model Comparison
A collapse of the Atlantic Meridional Overturning Circulation (AMOC) would have substantial impacts on global precipitation patterns, especially in the vulnerable tropical monsoon regions. We assess these impacts in experiments that apply the same freshwater hosing to four state-of-the-art climate models with bistable AMOC. As opposed to previous results, we find that the spatial and seasonal patterns of precipitation change are remarkably consistent across models. We focus on the South American Monsoon (SAM), the West African Monsoon (WAM), the Indian Summer Monsoon (ISM) and the East Asian Summer Monsoon (EASM). Models consistently suggest substantial disruptions for WAM, ISM, and EASM with shorter wet and longer dry seasons (−29.07%, −18.76%, and −3.78% ensemble mean annual rainfall change, respectively). Models also agree on changes for the SAM, suggesting rainfall increases overall, in contrast to previous studies. These are more pronounced in the southern Amazon (+43.79%), accompanied by decreasing dry-season length. Consistently across models, our results suggest a robust and major rearranging of all tropical monsoon systems in response to an AMOC collapse.
(Earth's Future. vol. 12, n° 2328-4277, 09/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Trophic transfer effects of PS nanoplastics and field-derived nanoplastics in the freshwater clam Corbicula fluminea
Plastic pollution is of global concern. Many studies investigated the effect of micro and nanoplatics towards aquatic organisms. However, relatively few studies were assessed on freshwater organisms. Another aspect of this pollution is the impact of trophic transfer on plastic distribution and on food chain in order to evaluate its potential risk towards environmental and human health. In this context, the objective of this study was to assess the ecotoxicological impacts of different types of nanoplastics (NPs) on freshwater organisms exposed through trophic transfer. Freshwater microalgae Scenedesmus subspicatus were contaminated for 48 h with realistic concentrations of NPs (0.008, 10 and 100 mu g/L). Two types of NPs were tested: commercial PS NPs and NPs generated from macro-sized plastics collected in the field (ENV NPs). Freshwater Corbicula fluminea bivalves were then fed with the contaminated algae every 48 h for 21 days. Results showed that trophic exposure led to the induction of oxidative stress (CAT activity). Overall, NPs trophic exposure caused downregulations of genes implicated in many cellular processes (immunity, oxidative stress, neurotoxicity, endocytosis, apoptosis). This present study allowed to demonstrate the relevance of investigating the trophic transfer effects of NPs on a freshwater trophic chain. Further studies should focus more on larger levels of the food chain.
(Aquatic Toxicology. vol. 277, n° 0166-445X, pp. 107160, 09/04/2026)
BIOSSE, UCO, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UMS POREA, INSU - CNRS, CNRS, INRAE, GR, UR, INSU - CNRS, CNRS, ULaval, IPG Paris
Gestion quantitative de l’eau et usages agricoles sous contrainte climatique
Plus grande région agricole de France et d’Europe, la Nouvelle-Aquitaine subit comme l’ensemble du territoire national, les conséquences du changement climatique et notamment des sécheresses. L’eau et son accès sont des enjeux cruciaux pour une partie des agriculteurs mais une part de la population est inquiète des possibles conséquences environnementales. La question de la gestion de l’eau est donc au cœur de controverses publiques depuis quelques années. C’est dans ce contexte qu’ AcclimaTerra s’est proposé d’apporter une contribution au débat dans le but de réintroduire des données et des résultats scientifiques sur la ressource en eau.
(pp. 68, 09/04/2026)
BRGM, Bordeaux Sciences Agro, CED, IEP Bordeaux, UB, CNRS, AGIR, Toulouse INP, Comue de Toulouse, INP - PURPAN, Toulouse INP, Comue de Toulouse, INRAE, UMR G-EAU, Cirad, BRGM, IRD, INRAE, Institut Agro, UP, HydrASA, IC2MP [Poitiers], UP, INC-CNRS, CNRS, UMR EGFV, UB, Bordeaux Sciences Agro, INRAE, UFC, UBFC, UP, Solagro, ISVV, UB, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS