The Late Pleistocene - Holocene meandering lower Garonne River, southwest France: Architecture of the valley fill and chronology, comparison with other European rivers
The architecture and chronology of Late Pleistocene to Holocene alluvial deposits in the lower Garonne have been studied in details based on data (boreholes, trenches, ground-penetrating radar profiles, numerical dating) collected in quarries and during archaeological surveys. The preserved alluvial bodies, dated between ca. 38 ka and present, show that the river retained a meandering or anabranching pattern throughout this period, associated with the formation of lateral accretion packages and scroll bars in the convexity of meanders. Valley incision in connection to the LGM low sea level reached up to 19 m in the study area, and occurred between ca. 26 and 18 ka. Since ca. 18 ka, the lateral migration of meanders widened the plain without any significant incision of the Oligocene marl bedrock. The Early-Middle Holocene was characterized by the development of highly sinuous meanders, while sinuosity decreased in a late phase including the Little Ice Age. Comparison with other lowland European rivers shows that the persistence of a meandering or anabranching pattern during MIS 2 is not an isolated case. The documented examples are associated with rivers typified by low valley slope, or situated in southern regions unaffected by permafrost and characterized by dense vegetation. The latter conditions would not have led to a drastic change in river discharge and bedload transport during the Last Glacial, as was the case for more northerly rivers where braiding seems to have been common.
(Geomorphology. vol. 468, n° 0169-555X, pp. 109469, 01/01/2025)
Inrap, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UNIROUEN, NU, IDEES, UNICAEN, NU, ULH, NU, UNIROUEN, NU, CNRS, IRIHS, UNIROUEN, NU, BRGM, LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France], M2C, UNICAEN, NU, INSU - CNRS, UNIROUEN, NU, CNRS
Active biomonitoring of river pollution using an ex-situ exposure system with two model species
In the context of increasing pollution pressure on aquatic ecosystems, it is essential to improve our knowledge of habitat quality and its suitability for organisms. It is particularly relevant to better integrate early life stages of fish into pollution biomonitoring programs, as they are reliable indicators of ecosystem integrity and because of their high sensitivity to pollutants. To avoid the influence of environmental parameters on their development, a lab-on-field approach, called the ex-situ exposure method, was developed. Aquatic organisms were exposed to a continuous flux of water under semi-controlled temperature, oxygen, and photoperiod conditions to avoid the influence of these confounding factors when interpreting the results. To investigate the potential role of water contamination, this active biomonitoring method was applied to the Garonne River (Southwest France), where migratory fish populations have declined. Two model species from different taxa were used: embryos of the Japanese medaka (Oryzias latipes) and adults of the crustacean Gammarus fossarum. The results showed a significant impact of water quality on embryo mortality and early hatching in two separate experiments on Japanese medaka. In addition, an induction of feeding rate was observed in exposed gammarids, but no impact on their embryo survival, suggesting differences in sensitivity between the two species selected. Chemical and biological analyses did not identify trace metals, pesticides, or microorganisms as potential sources of toxicity in medaka embryos or G. fossarum. These results raise concerns about the quality of the water in the Garonne River and its toxicity to aquatic organisms.
(Science of the Total Environment. vol. 959, n° 0048-9697, pp. 178159, 01/01/2025)
UR EABX, INRAE, RiverLy, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, MFP, UB, CNRS
Toxicity assessment of DMSO extracts of environmental aged beached plastics using human cell lines
Plastic products contain complex mixtures of chemical compounds that are incorporated into polymers to improve material properties. Besides the intentional chemical additives, other compounds including residual monomers and non-intentionnaly added substances (NIAS) as well as sorbed pollutants are usually also present in aged plastic. Since most of these substances are only loosely bound to the polymer via non-covalently interactions, i.e., van der Waals forces, they may leach to the surrounding environment. Although there is increasing knowledge about toxicity of weathered plastic to aquatic organisms, only little is known about how plastic associated chemicals affect human health. Seafood consumption is one of the routes of human exposure to microplastics. The aim of this study was to evaluate the ability of naturally aged plastic associated chemicals to induce harmful effects to human health via the consumption of MP-contaminated seafood. Human colorectal adenocarcinoma Caco-2 and human hepatocyte carcinoma HepG2 cells were selected as model of the colon and liver cells respectively. They are known for their high capacity to metabolize organic contaminants. Both cell lines were exposed to DMSO extracts of different plastics to investigate the effects of chemicals on cell viability, oxidative stress induction and genotoxicity. In addition, the estrogenic effects of DMSO-extracts were evaluated using an estrogen-dependent reporter gene assay in T47D-Kbluc human breast cancer cells. Chemical profiles of the DMSO extracts were polymer-dependent, with polyvinyl chloride (PVC) highly contaminated with metals while polypropylene (PP) contained the lowest concentration of metals. Organic pollutants, including polycyclic aromatic hydrocarbons, were mainly found in PVC, high density polyethylene (HDPE) and PP extracts, whereas other extracted plastics had less (PP) to no organic contamination (polyethylene terephthalate PET). PVC was the most toxic plastic inducing cytotoxicity for both cell lines. DNA damage was observed for Caco-2 cells exposure to HDPE, PVC and nylon. Reactive oxygen species were induced only with nylon extracts in intestinal cells. No toxicity was observed for PP and PET and none of the tested plastics had any estrogenic effect. Our results demonstrate that some environmental aged plastic material released a variety of known and unknown chemical compounds some of which are toxic in vitro and contribute to the knowledge on adverse human health effects of plastics.
(Ecotoxicology and Environmental Safety. vol. 289, n° 0147-6513, pp. 117604, 01/01/2025)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CBMN, UB, ENITAB, INC-CNRS, CNRS, Cedre
The Northern Central Andes and Andean tectonic evolution revisited: An integrated stratigraphic and structural model of three superimposed orogens
The mechanism for crustal thickening and superposition of several orogens is critical for understanding the growth of mountain ranges. Our study focuses on a trans-orogen crustal cross-section to revisit the Andean tectonic evolution in the Northern Central Andes (5°-8°S). It is based on a review of the geological setting, the definition of long-term tectono-sedimentary successions, and for the first time, a crustal balanced cross-section 895 km long through the entire orogen. We show that the Northern Central Andes were born in the Jurassic, and correspond to the superposition of several orogens representing a minimum total shortening of ∼207 km. They were built over 180 Ma during three orogenic periods (180–140 Ma; 100–50 Ma; 30–0 Ma), separated by two post-orogenic periods during which most Andean relieves were erased (140–100 Ma; 50–30 Ma). Each post-orogenic period was recorded by 1) a major regional erosional unconformity sealed by a widespread marine transgression, and 2) extensional tectonics in the forearc. Crustal shortening was driven by westward South America Plate displacement and continental crustal underthrusting, and not by oceanic subduction. The propagation of the Andean wedge has been controlled by successive inversions of two pre-existing rifts. The sequential restoration of the trans-orogen balanced cross-section, constrained by the sedimentary record, provides a realistic picture of each orogenic and post-orogenic stage. For the first time, the pre-Neogene basins are reconstructed respecting the Andean shortening. The first-order factors that have controlled the complex growth evolution of Northern Central Andes are South America Plate dynamics changes associated with shifts in the geometry of the subducting oceanic slab. Some correlations can be established with Phanerozoic climate changes.
(Earth-Science Reviews. vol. 260, n° 0012-8252, pp. 104998, 01/01/2025)
GET, IRD, INSU - CNRS, CNES, CNRS, EPE UT, Comue de Toulouse, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UNMSM, UMR ISEM, Cirad, IRD, EPHE, PSL, CNRS, UM, MHN, UNMSM, CIDIS, UPCH
Phases of Magmatism and Tectonics Along the Madagascar‐Comoros Volcanic Chain, and Synchronous Changes in the Kinematics of the Lwandle and Somalia Plates
This paper aims to solve the longstanding debate on the origin of the Comoros volcanic archipelago (Mozambique Channel, Indian Ocean) concerning whether it represents a hotspot trail or a boundary between the Lwandle and Somalia plates in possible connection with the East African Rift System (EARS). To achieve this goal, we analyzed rock samples from recently discovered and previously uninvestigated volcanoes and edifices by means of geochemistry and geochronology. Major-trace element analyses and radiometric dating ( 40 Ar/ 39 Ar, K-Ar, and (U-Th)/He) allow us to identify a widespread phase of Comorian volcanism initiated at 9-8 Ma, involving the Zélée, Geyser, and Leven banks, three atolls east of the Comoros. Another tectono-magmatic phase initiated at 2.5 Ma led to a N-S widening of seamount volcanism, and to the progressive development of en-échelon NW-SE structures. With this new addition of atolls and seamounts, the Comoros Archipelago becomes a ∼700 km-long, ∼200 km-wide E-W chain extending from the Cenozoic volcanoes of Madagascar to the EARS. The reactivation of this chain at 9-8 and 2.5 Ma coincides with abrupt changes in the motion of the Somalia plate relative to the Lwandle plate, and with plate boundary modifications. The en-échelon reorganization of structures also matches the kinematic evolution of Somalia relative to Lwandle, from transtension (>3 Ma) to pure dextral slip (≤3 Ma) in the northern Mozambique Channel. We conclude that the Madagascar-Comoros volcanic chain is a branch of the EARS and a plate boundary, further strengthening the link between magmatism and the Rovuma-Lwandle-Somalia plate kinematics
(Journal of Geophysical Research : Solid Earth. vol. 130, n° 2169-9313, pp. e2024JB029488, 01/01/2025)
IPG Paris, UR, LGSR, UR, IPG Paris, IPGP - UMR_7154, INSU - CNRS, IGN, UR, IPG Paris, CNRS, UPCité, GEOPS, INSU - CNRS, CNRS, LMV, IRD, INSU - CNRS, CNRS, UCA, GR, UR, INSU - CNRS, CNRS, OVSG, IPG Paris, GEO-OCEAN, UBS, IFREMER, INSU - CNRS, UBO EPE, CNRS, BRGM, SU, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UNIGE, GFZ, UHM
Investigation of critical copper release rates for dose optimization of antifouling coatings
Antifouling coatings are applied to ship and boat hulls to prevent the unwanted attachment of marine organisms known as biofouling. Most antifouling coatings do so through toxic means by continuously releasing copper from the paint film to the surrounding water and are thus of environmental concern. Few studies have investigated the minimum dose of copper from an antifouling coating required to inhibit biofouling, commonly referred to as the critical release rate. This study presents a comprehensive investigation into the critical release rates of copper from commercial antifouling coatings in European coastal waters, with study sites in the Atlantic (Arcachon, France), Kattegat (Hundested, Denmark) and Skagerrak (Tjärnö, Sweden). Employing a combination of X-ray Fluorescence (XRF) analysis and visual inspection, this six-month field study has evaluated the efficacy of various antifouling coatings with differing copper contents. The findings of this study indicate that a release rate of 7 μg cm -2 d -1 was sufficient to inhibit macrofoulers at all three sites during static conditions. Results also indicate that the critical release rate is a parameter that coating manufacturers can optimize, as the performance of the coatings was not solely dependent on the copper release rates. The general critical release rate of 7 μg cm -2 d -1 could serve as a benchmark for dose optimization of coatings for both the yacht and ship sectors in the studied waters to reduce their environmental impact. It can also be used as support for decision-makers to phase out coatings with unnecessarily high copper release rates from the market.
(Progress in Organic Coatings. vol. 198, n° 0300-9440, 01/01/2025)
DTU, GU, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UB, OFB - DR NAQ, OFB
Biological features for a minimum conservation reference size revision – case of Ruditapes philippinarum in Arcachon Bay (French Atlantic coast)
The Minimum Conservation Reference Size (MCRS) for marine resources ensure that individuals can mature and reproduce at least once before being caught. For management purposes, MCRS should be revised for specific populations in given areas. In Arcachon Bay (southwest France), fishers have repeatedly requested a review of the MCRS for R. philippinarum. In 2020, a joint recommendation, supported by France, was addressed to the European Commission suggesting a possible reduction in the MCRS of R. philippinarum from 35 mm to 32 mm for Arcachon Bay. This paper provides an overview of the biological features that need to be considered to support such a review, primarily focusing on sexual maturity, individual growth and natural mortality. The reproductive cycle and size at first maturity, estimated at 26.7 mm for the Bay, were found to be similar to other locations in France and in Portugal. The greatest length at which growth slowdown occurred ranges between 24.0 and 31.5 mm with few differences among sites and no significant differences within each site (at hypsometric levels). The natural mortality coefficients were high with 0.67 yr−1 and 0.51 yr−1 for juveniles and adults, respectively. Regarding productivity (resulting from growth and mortality processes) and all methods combined, the optimal balance between individual growth and natural mortality above 30 mm was found at a mean length of 32.2 mm for the intra-lagoon sites and at a mean length of 36.8 mm for the oceanic sites. Based on available information, reducing the MCRS to 32 mm would not threaten population viability. However, the European Commission has raised warning points, which are discussed in light of current regulations in Arcachon Bay.
(Estuarine, Coastal and Shelf Science. vol. 320, n° 0272-7714, pp. 109288, 11/10/2026)
LMAP, UPPA, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Machine Learning Beach Attendance Forecast Modelling from Automatic Video-Derived Counting
Accurate predictions of beach user numbers are important for coastal management, resource allocation, and minimising safety risks, especially when considering surf-zone hazards. The present work applies an XGBoost model to predict beach attendance from automatically video-derived data, incorporating input variables such as weather, waves, tide, and time (e.g., day hour, weekday). This approach is applied to data collected from Biscarrosse Beach during the summer of 2023, where beach attendance varied significantly (from 0 to 2031 individuals). Results indicate that the optimal XGBoost model achieved high predictive accuracy, with a coefficient of determination (R2) of 0.97 and an RMSE of 70.4 users, using daily mean weather data, tide and time as input variables, i.e., disregarding wave data. The model skilfully captures both day-to-day and hourly variability in attendance, with time of day (hour) and daily mean air temperature being the most influential variables. An XGBoost model using only daily mean temperature and hour of the day even shows good predictive accuracy (R2 = 0.90). The study emphasises the importance of daily mean weather data over instantaneous measurements, as beach users tend to plan visits based on forecasts. This model offers reliable, computationally inexpensive, and high-frequency (e.g., every 10 min) beach user predictions which, combined with existing surf-zone hazard forecast models, can be used to anticipate life risk at the beach.
(Journal of Marine Science and Engineering. vol. 13, n° 2077-1312, pp. 1181, 11/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR ETTIS, INRAE, UR EABX, INRAE, EPOC, SMGBL
Projet IMPEC : IMpact de la PEChe sur les écosystèmes benthiques du large - Evaluation des habitats benthiques du circalittoral du large dans le golfe du Lion au regard des pressions issues des activités de la pêche démersale aux arts traînants : approche multi-indicateurs - Note de synthèse
Ce projet s'inscrit dans le cadre de l'acquisition de connaissance nécessaire au développement et à la consolidation d'indicateurs DCSMM permettant de qualifier l’intégrité des fonds face aux pressions anthropiques sur le plateau continental. Parmi les indicateurs appliqués actuellement pour quantifier le pourcentage de surface impactée et plus précisément l’intensité de l’impact, aucun n’a été spécifiquement développé et/ou testé sur une perturbation physique telle que celle résultant des pêcheries démersales. Or, la pêche aux arts traînants (chaluts et dragues) est la source de perturbation majeure des fonds sur le plateau continental (e.g. Amoroso et al., 2018 ; Brivois et al., 2018 ; Jac et al., 2020). Cette tâche est rendue d’autant plus difficile qu’il est complexe de qualifier des états de référence, au sens « non-impacté » par les pressions d’origine anthropique. Le projet IMPEC propose d’étudier l’impact de la pêche aux arts traînants sur les fonds marins du plateau continental du golfe du Lion en Méditerranée. Le but du projet est de tester plusieurs indicateurs applicables à différentes composantes benthiques (méga-épifaune, macrofaune, méiofaune, foraminifères) pour évaluer l’état des habitats benthiques meubles au regard de l’impact de la pêche de type dragage et chalutage le long d’un gradient de pression d’abrasion.
(pp. 25, 11/10/2026)
LPG-ANGERS, LPG, UM, UA, INSU - CNRS, CNRS, Nantes univ - UFR ST, LECOB, SU, CNRS, OOB, SU, CNRS, LPG, UM, UA, INSU - CNRS, CNRS, Nantes univ - UFR ST, Nantes Univ, BIAF, UA, NOC, LPTC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UMR MARBEC, IRD, IFREMER, CNRS, UM
Highway runoff and wastewater effluents as drivers of platinum dynamics in an urban river: Insights from a comprehensive monitoring study
The contribution of a single rain event to daily and annual platinum (Pt) transport in an urban river (Jalle River, South-West of France), assessed from high resolution and annual monitoring, is discussed in terms of dissolved (Pt-d) and particulate (Pt-p) partitioning, sources and fluxes. In normal discharge conditions, the Jalle River Pt-d and Pt-p concentrations are respectively 1.90 +/- 1.62 ng L-1 and 19.8 +/- 6.9 mu g kg(-1) and Pt is mostly transported in the dissolved form (similar to 96 %, 110 +/- 123 mgPt(d) d(-1)), due to low sediment yield and urban discharges from a wastewater treatment plant (WWTP). The Pt-d flux in sewage (36-340 mgPt(d) d(-1)) was mainly attributed to excretions from patient undergoing chemotherapy with Pt-drugs (up to 480,000 mgPt(d) yr(-1) at the watershed scale). After a 2-months dry period, an intense rainstorm discharged >= 112 mg of Pt-p in 4 h from the urban highway, resulting in additional 295 mgPt(p) d(-1) exceptionally transported by the Jalle River. In contrast to normal conditions, during the rainstorm up to similar to 95 % of Pt was transported in particulate form during the first flush, and 80 % of the highway Pt-p flux during the first 40 min contributing to similar to one third of the annual Pt-p flux. Short, intense discharge events must be monitored at a high resolution to accurately estimate annual Pt fluxes in urban rivers.
(Applied Geochemistry. vol. 193, n° 0883-2927, 11/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, M2C, UNICAEN, NU, INSU - CNRS, UNIROUEN, NU, CNRS, I2M-BX, UB, CNRS, INRAE