Predicting individual’s decision to enter the water at a high-energy recreational surf beach in France
Objectives To predict beachgoer decision to enter the water at a high-energy surf beach, in southwest France. Methods We built a unique multidisciplinary database combining data collected by an on-site beachgoers survey, weather stations, marine buoys and tidal reconstruction. Human, weather and meteocean factors were considered as potentially predictive of beachgoer behaviour. We employed a logistic regression analysis to predict beachgoers’ decision to enter the water on any given day at a high-energy recreational beach. Results We demonstrated that both environmental and human factors influence a beachgoer’s decision to enter the water. Daily mean wave height and daily mean insolation duration were significant predictors at the p<0.001 level, while age, place of residence and self-confidence in swimming out of a rip current were significant at the p<0.05 level or higher. Beachgoers were more likely to enter the water on sunny days with lower waves. Younger individuals, those living outside the Landes département, and those who declared themselves to be ‘confident’ or ‘uncertain’ about their ability to swim out of a rip current expressed a higher propensity to enter the water. Our model has an accuracy, F-Score, precision and recall of 71%, 73%, 86%, 79%, respectively. Conclusions Beachgoer exposure on any given day can ultimately be predicted by coupling our model with beach attendance models. This would allow for the design of rescue and preventive operations on days with high expected exposure. While models based solely on environmental factors can be used to forecast beach risks, incorporating human factors into the model provides valuable insight for crafting prevention messages. In this regard, lifeguards could engage more actively with beach users to deliver appropriate safety messages.
(Injury Prevention, n° 1353-8047, pp. ip-2024-045574, 08/05/2025)
UR ETTIS, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Estimating Contaminated Soil Volumes Using a Generative Neural Network: A Hydrocarbon Case in France
The estimation of the volumes of contaminated soil to be treated is a crucial step in soil remediation. Numerous techniques exist for estimating the distribution of pollutants in soils, such as inverse distance weighting, kriging, Gaussian sequential simulation, and sequential indicator simulation. Unfortunately, these methods require significant computational resources to achieve precise estimations. Moreover, both kriging and Gaussian simulation require the transformation of non-normal distributions, often seen in hydrocarbon contamination, to produce accurate results. In this paper, we propose a generative neural network to generate 3D maps of contaminant distributions without prior training, and to estimate the contaminated volumes. This differentiates this work from other Deep Learning approaches that necessitate training data. The proposed method relies on a convolutional neural network for image reconstruction and inpainting. Rather than solely depending on the concentration of chemicals determined in the laboratory, we utilize hyperspectral imaging data from soil cores to achieve a more precise depiction of soil contaminants. We assess the proposed method using a synthetic 3D dataset and a real case of hydrocarbon pollution on a polluted site in France. The method demonstrates competitive performance with efficiently managed computation time, achieved through the use of GPU accelerator. This study offers a new, practical way to improve soil pollution management using fast, and data-driven techniques.
(Mathematical Geosciences, n° 1874-8961, 05/05/2025)
LITIS - App, LITIS, ULH, NU, UNIROUEN, NU, INSA Rouen Normandie, INSA, NU, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Beach-dune dynamics and coastal management along the North-Médoc coastline, southwest France: a decade of morphological change and erosion mitigation
The North-Médoc coastline, exposed to energetic waves and meso-macro tides and exhibiting major erosion hotspots, has experienced notable changes in beach and dune volumes over the last decades due to a combination of natural forcings and human interventions, including coastal defenses and beach nourishment. Annual LiDAR data (2011-2023) combined with interspersed annual GNSS surveys were used to quantify spatial and temporal variations in beach-dune topography along approximately 14.5 km of coastline. Beach-dune changes along the North-Médoc coast over the past decade were influenced by multiple factors at varying scales. (1) Long-term changes, such as chronic erosion or accretion of up to 7 m/yr, are mainly inherited from large-scale shoal welding originating from the estuary mouth (internal forcing). (2) Coastal structures have localized impacts on shoreline dynamics, sometimes altering trajectories. While alongshore structures stabilize the shoreline, they may cause issues at their ends. Cross-shore structures, like groynes, have variable effects; for instance, extending one of the groyne after winter 2013-14 led to rapid accretion, widening beach, and raising elevations updrift. This accreting area is now used as a sediment extraction area to nourish the eroding southern beaches. (3) Interannual shoreline variability, linked to winter wave height fluctuations driven by climate modes of atmospheric variability, overlaps with trends from (1) and (2). However, this external forcing is more pronounced farther from the estuary, indicating a continuum from external forcing on open coasts to internal processes near the estuary.
(Geomorphology. vol. 482, n° 0169-555X, pp. 109758, 01/05/2025)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BRGM
Experimental and computational analysis of the DNA damage induced in zebrafish, Danio rerio, early life stages after exposure to tritiated thymidine
Tritium is an ubiquitous radioactive hydrogen isotope. It is found in all environmental compartments, in three different forms: tritiated water (HTO), gaseous tritium (HT) and organically bound tritium (OBT). Once internalized in the organism, it can either be found free in the tissues (TFWT) or bound to organic matter (OBT). This study aims to assess if tritiated thymidine, an organic form of tritium, induces DNA breaks once internalized in a model organism and its DNA. To do so, both experimental procedures and nanodosimetry simulations have been used. Zebrafish embryos (3.5 hpf, hours post fertilization) were exposed to three tritiated thymidine activity concentrations (7.5, 40, 110 kBq/mL, leading to internal dose rates of 22, 170 and 270 μGy/h) for four days. Individuals were sampled after 1 and 4 days of exposure and DNA break levels were assessed by the comet assay. Results showed that, even at the lowest activity concentration, tritiated thymidine induced DNA breaks in both embryos (1 dpf) and larvae (4 dpf). It was also highlighted that there was no increase nor decrease in DNA break level between 1 and 4 dpf, except in the case of the exposure to 170 μGy/h, where a slight decrease was observed. Geant4-DNA Monte Carlo simulations, performed on two spherical zebrafish nuclei of two different radii (2.5 and 5 μm), highlighted that organic tritium mainly induced single strand breaks (SSB). The results also showed that most of the damage was indirectly induced. Those results, combined with various experimentations, expose tritiated thymidine genotoxic pathways that could lead to both short- and long-term health effects.
(Journal of Environmental Radioactivity. vol. 285, n° 0265-931X, pp. 107682, 01/05/2025)
IRSN/PSE-ENV/SERPEN/LECO, IRSN/PSE-ENV/SERPEN, IRSN, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IRSN/PSE-SANTE/SDOS/LDRI, IRSN/PSE-SANTE/SDOS, IRSN
Juveniles at risk: behaviour and colour changes in sole juveniles (Solea solea) after exposure to estuarine ragworms (Hediste diversicolor) contaminated with microplastics
Due to strong anthropogenic pressures and their location at the interface between continental and oceanic environments, estuarine areas are affected by significant diverse pollution and species that live in these areas are particularly exposed. Microplastic (MPs) pollution is a worldwide issue and causes substantiated trouble in estuaries where sometimes the number of MPs equal or exceed the number of fish larvae which suggest a high risk of contamination of biota especially in benthic organisms and demersal fish. There are growing evidence that, beyond intrinsic toxicity, MPs can transfer chemicals (additives or pollutants). In order to get closer to environmental situations, in this study we tackled an issue that is rarely dealt with, namely the trophic transfer of MPs and chemicals through the food chain between a sediment- and a benthic-feeder. To take into account these specificities, we used an emblematic and common species of the European coastlines, the common sole (Solea solea) and its annelid prey. Sole juveniles were fed with estuarine ragworms (Hediste diversicolor) previously exposed to MPs via enriched MPs sediment. The MPs used were either a mixture of micronized plastics collected from the Seine Estuary (eMPs, two environmental concentrations at 1 or 100 mg/kg of sediment, median size range 52-77 μm) or model MPs of PVC particles (at 1 g/kg of sediment, size range 125-250 μm), either uncontaminated or contaminated with Benzo(a)Pyrene (BaP, 11.5 μg/g MPs) or benzophenone-3 (BP3, 66 ng/g MPs). Several indicators of health status such as survival, growth, behaviour, energy metabolism, and histopathology were studied. Sole individuals fed ragworms exposed to eMPs or PVC MPs displayed a change in behaviour (place preference between black/white background). Seine Estuary eMPs lead to an increase in body colour chroma for the highest concentration and behaviour was modified with an increase in time spent on white bottom and transition number for the highest concentration when distance moved increased only at the lowest concentration. Sole exposed to BaP-PVC-MPs displayed the lowest time spent on white background compared to control and BP3-PVC-MPs group. Soles exposed to BP3-PVC MPs displayed a significant skin colour increase in chroma and a wider combination of value/chroma reflecting more diverse skin colours. Finally, lipid content in muscle and DNA damage were significantly higher in BP3-MPs. Although the exact mechanisms underpinning such changes are largely unknown, these observations are indicative of physiological stress which may have a significant impact on survival by increasing predation risks for fish juveniles, hence the ecosystem health and calls for further trophic transfer experimental research.
(Marine Environmental Research. vol. 209, n° 0141-1136, pp. 107197, 01/05/2025)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UMR MARBEC, IRD, IFREMER, CNRS, UM, BTSB, INUC, Comue de Toulouse, OFB - DR NAQ, OFB, UB, BIOSSE, UCO, PAnTher, ONIRIS, INRAE, APEX, PAnTher, ONIRIS, INRAE, IPREM, UPPA, INC-CNRS, CNRS, GERS-LEE, UMR MARBEC PALAVAS, UMR MARBEC, IRD, IFREMER, CNRS, UM
Characterization of the daily and circadian valve behavior of the European flat oyster Ostrea edulis
Marine organisms exhibit a multitude of biological rhythms synchronized with the interactions of the sun-, earth-, and moon cycles. However, the biological rhythms in bivalves remain poorly studied. This study focuses on the native European flat oyster (Ostrea edulis), an endangered species of coastal ecosystems and a key organism in restoring of biogenic reef habitats. We aim to determine whether a molecular endogenous circadian rhythm exists in O. edulis and to characterize its daily expression. To address these questions, the oysters' valve behavior, as an output of the circadian clock expression, was recorded under different light conditions and free-running regimes using non-invasive valvometry. This work demonstrates the existence of a circadian clock mechanism that generates a labile behavioral circadian oscillation under free-running conditions. In light: dark conditions, a diel rhythm appears nocturnal, synchronizable to a shift of light phase, and remains unmodified whether the oysters are fed or not. This rhythm anticipates light: dark changes, indicating its endogenous origin. Finally, when exposed to artificial light at night the daily behavior is disrupted. This study characterizes the circadian behavioral rhythm of O. edulis's as plastic and labile. This plasticity would be advantageous in terms of ecological adaptability but increases sensitivity to anthropogenic pressures such as light pollution.
(Scientific Reports. vol. 15, n° 2045-2322, pp. 14952, 29/04/2025)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, HIFMB, OFFIS, GEODE, UT2J, Comue de Toulouse, CNRS, AWI, AWI
Temporal, Morphological, and Taxonomic Frameworks for Calibrating Benthic Foraminiferal Pore Patterns as a Paleoxygenation Proxy
Abstract Calcareous benthic foraminifera commonly develop pores in their test wall for gas exchange (e.g., O 2 , CO 2 ) with seawater. Pore patterns, that is, porosity, pore density, and pore size, are influenced by environmental factors like bottom water dissolved oxygen concentration (BWDO). Certain benthic foraminifera species show increased test porosity under low BWDO, making them a useful proxy for reconstructing past BWDO. The pore patterns as a proxy for BWDO are validated in the Southeast Pacific (SEP) by examining six benthic foraminifera species in relation to estimated BWDO on the sediment sites. Specimens were collected from surface sediments between 24 and 3,252 m water depth across the SEP (12°–44°S). Specimens were selected based on their Rose Bengal staining, oxygen isotopes, and calibrated sediment radiocarbon age to reflect modern conditions. Porosity, pore density and size were measured on the umbilical and spiral sides of the foraminifera, including all visible chambers, and the penultimate and antepenultimate chambers (PAC). Pores on the umbilical side, facing the water column, and the spiral side, commonly used for attachment, are measured to test their response to changes in oxygen uptake. In the SEP, the strongest correlations between BWDO and porosity is found for measurements from the umbilical side of the benthic foraminiferal test, indicating that this area is the most sensitive to BWDO changes. Combined benthic foraminifera species, and C. wuellerstorfi , increase umbilical porosity under lower BWDO. These findings align with global calibrations, supporting the quantitative use of benthic foraminifera pore patterns to reconstruct past BWDO, with an error range of around ±60 μmol kg −1 for BWDO above 100 μmol kg −1 , and around ±20 μmol kg −1 for lower than 100 μmol kg −1 .
(Paleoceanography and Paleoclimatology. vol. 40, n° 2572-4525, 28/04/2025)
BGS, JAMSTEC, LPG, UM, UA, INSU - CNRS, CNRS, Nantes univ - UFR ST, Nantes Univ, D-ERDW, ETH Zürich, LID, UPCH, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UCHILE, UdeC
Past trajectory of a socio-ecosystem at the land-sea interface: the case of the northern watersheds of the Bay of Brest over the last 150 years
(pp. EGU25-17787, 27/04/2025)
GEO-OCEAN, UBS, IFREMER, INSU - CNRS, UBO EPE, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BEEP, IFREMER, UBO EPE, CNRS, GEOARCHI, UBS, UBO EPE, IBSHS, UBO EPE, GR, UR, INSU - CNRS, CNRS, LEMAR, IRD, IFREMER, UBO EPE, CNRS, GEO-OCEAN, UBS, IFREMER, INSU - CNRS, UBO EPE, CNRS, LMBA, UBS, UBO EPE, CNRS, DYNECO, IFREMER
Confined aquifers: a need for an adaptation of sustainability concepts
Confined aquifers, distinguished by their large storage and long-term flow dynamics, are often overlooked in groundwater sustainability assessments and rely on frameworks developed for unconfined systems. Unlike unconfined aquifers, confined systems release water through the compressibility of the porous medium, without pore drainage. These properties lead to lower storativity and higher hydraulic diffusivity, resulting in different responses to hydraulic perturbations, such as pumping or recharge temporal variations. Addressing these differences is essential to develop tailored approaches for the sustainable management of confined aquifers, particularly in the context of balancing water supply for different competing demands with the environmental and socioeconomic impacts of abstraction. We develop a framework for the sustainable management of confined aquifers based on numerical models over synthetic cross sections of multi-layer flow systems. We explore the fundamental differences between confined and unconfined aquifers, particularly in terms of their hydraulic behaviour, response time to hydraulic perturbations, and the interactions with surrounding hydrogeological units. This modelling study also illustrates how confined aquifers indirectly interact with unconfined systems and surface water systems, through their connection via confining layers. A critical aspect of this work involves understanding the transient response of aquifers, which is governed by their hydraulic diffusivity and described by the concept of response time. Diffusivity governs the rate at which hydraulic disturbances propagate, and the response time describes the time required for the aquifer to reach a new equilibrium. Existing analytical formulations highlight the distinct behaviour of confined aquifers, particularly their faster response times compared to unconfined systems. However, for large-scale confined or mixed systems, response time scales may approach or even exceed those of unconfined aquifers with similar hydraulic properties and, generally, smaller extension. This underscores the importance of a proper delimitation of aquifer boundaries in the assessment of their response times. In practice, water sustainability policies are inherently scoped within site-specific areas and timeframes. Today, these policies must address increasing pressures from population growth, climate change, surface water quality issues, and other contributing factors. Groundwater models, which support management decisions, should include these factors through accurate conceptualizations of hydrogeological systems, evaluations of their response times, and scenario analyses. Through the adaptation of sustainability concepts for confined and mixed aquifer systems, this study contributes to the development of a framework that will support groundwater management strategies for confined aquifers and highlights their role as a valuable resource for long-term adaptation, emphasizing the need to protect and optimize their use in response to environmental and societal challenges.
(27/04/2025)
Bordeaux INP, UB, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CEREGE, IRD, AMU, CdF (institution), INSU - CNRS, CNRS, INRAE
Enigmatic deep-water seafloor depressions east of Tortue Island, Northern Haiti margin
A widespread area of seafloor depressions—ranging from circular and arcuate to elongated in shape—has been identified along the northern coast of Haiti, at water depths of 600–2000 m. These features are characterized by wavelengths spanning several hundred meters and heights of tens of meters and are associated with a series of narrow ridges exhibiting varied morphologies. Our integrated analysis, utilizing multichannel seismic reflection, high-resolution bathymetry, and sedimentological and geochemical evaluations of surface sediment cores, indicates that along-slope bottom currents significantly influence sedimentary processes in the region. Sediment cores reveal deposits comprising hemipelagites, silty and sandy contourites, fine-grained turbidites, and reworked sand layers, indicative of sedimentation within a contourite drift system. This interpretation is further supported by seismic reflection data, which display wavy reflectors and aggradational stacking patterns typical of contourite drifts.The seafloor depressions are likely erosional features that formed on the surface of a contourite drift, shaped by the interaction of bottom currents with irregular seafloor topography. Initial disturbance of the equilibrium seafloor appears to have been triggered by mass-wasting events. Subsequently, the quasi-steady flow of along-slope bottom currents influenced sediment distribution and played a critical role in the development and reshaping of the seafloor depressions through erosion along their flanks. The resulting rugged seafloor morphology likely facilitated the destabilization of bottom currents, leading to the formation of erosive eddies that further shaped the current configuration of the depressions. This study emphasizes the dynamic interplay between sedimentary processes and hydrodynamic activity, demonstrating how their combined effects govern slope sedimentation and seafloor geomorphology, producing distinctive erosional features.
(. vol. 26, pp. e2024GC012089, 27/04/2025)
iSTeP, INSU - CNRS, SU, CNRS, CY, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CEFREM, UPVD, INSU - CNRS, CNRS, IFPEN, UCM, UEH