The role of biomolecules produced by invasive macrophytes in lake ecosystem processes
Egeria densa and Lagarosiphon major are the main invasive hydrophytes in French Atlantic Lakes. These exotic species can modify trophic levels by producing large quantities of biomass in lakes; previous investigations revealed the occurrence of endogenous metabolites in these plants known to be able to affect epiphytic communities, phytoplankton, or other plants, through allelopathic activity. Nevertheless, the actual excretion and environmental occurrence of these metabolites remain poorly documented. In order to gain knowledge of the concrete occurrence and potential ecological impact of E. densa and L. major exometabolome, untargeted metabolomics using high-resolution mass spectrometer and chemometrics approaches is relevant through its ability to depict, as a first step, the exometabolome chemical landscape.
(01/01/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR EABX, INRAE
Oceanic and climatic dynamics during the MIS 12–11 transition in the Gulf of Cádiz: Insights from coccolithophores
This study reconstructs environmental variability and surface-ocean dynamics across Termination V (MIS 12-11) in the Gulf of Cádiz using coccolithophore assemblages from International Ocean Discovery Program (IODP) Site U1386. Our data, combined with independent palaeoenvironmental proxies, including sea surface temperatures (SST), ice-rafted debris (IRD), benthic δ 18 O, and Mediterranean forest pollen assemblages, reveal a marked increase in coccolithophore productivity during MIS 11 compared to MIS 12. The end of the glacial period is characterised by higher abundances of Gephyrocapsa oceanica and reworked calcareous nannofossils, suggesting intensified Mediterranean Outflow Water (MOW). High abundances of the cold-water species Coccolithus pelagicus subsp. pelagicus, together with low SSTs and reduced Mediterranean forest pollen, reflect cold and dry conditions that were unfavourable for coccolithophore proliferation. These patterns suggest a weak westerly influence over southwestern Iberia, resulting in reduced precipitation and limited upwelling during the end of the MIS 12. In contrast, MIS 11 suggests stronger westerly influence, promoting wetter conditions and higher productivity. A sharp decline in productivity around 430 ka corresponds to a cooling event associated with increased IRD deposition, likely related to Heinrich-type event 4. These findings provide new insights into the coupling between atmospheric circulation, ocean dynamics, and primary productivity during the Mid-Brunhes Event.
(Palaeogeography, Palaeoclimatology, Palaeoecology. vol. 681, n° 0031-0182, 01/01/2026)
CIDIS, UPCH, UC Santa Cruz, UC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
In situ monitoring of LNAPL-contaminated aquifer remediation using ultraviolet light-induced fluorescence imaging
Groundwater contamination by light non-aqueous phase liquids (LNAPLs) represents a major environmental challenge, requiring efficient and adaptive remediation methods. This study proposes and validates an innovative implementation of an in situ monitoring technique for LNAPL remediation treatments, based on ultraviolet lightinduced fluorescence imaging (UVIF), combined with automated image post-treatment, to enable in situ and realtime monitoring of decontamination processes. Specifically, a mini-camera integrated into a set of transparent wells embedded in the subsurface of LNAPL-contaminated zones was used to monitor both a surfactant injection remediation process and a skimming operation involving groundwater drawdown. The technique was first calibrated and validated through laboratory and pilot-scale experiments, then tested on a real site, which was contaminated with diesel. The pilot test revealed differences of less than 5 % between recovery factors obtained via gas chromatography (GC) of soil samples and those measured with the proposed imaging technique. Sitespecific calibration correlated fluorescence intensity from endoscopic images in transparent tubes with GCanalyzed LNAPL content, showing a strong correlation (R² = 0.993) and relative errors below 10 %. This enabled accurate in situ estimation of LNAPL variations: content remained mostly unchanged without treatment (<5 % variation), decreased moderately during pumping and skimming (≈35 %), and dropped substantially during surfactant injection (≈60 %).This capability supports immediate treatment adjustments, thereby optimizing pollutant recovery rates. Beyond simple monitoring, the results demonstrate that UVIF can effectively guide remediation operations by providing rapid feedback (near real-time) on contaminant removal dynamics.
(Journal of Hazardous Materials. vol. 501, n° 0304-3894, 01/01/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, I2M-BX, UB, CNRS, INRAE
Northernmost record in the Bay of Biscay (northeastern Atlantic) of two leptothecate hydroids (Cnidaria: Hydrozoa) of southern affinity
Two leptothecate hydroids of southern affinity, Sertularella ornata Broch, 1933 and Sertularelloides cylindritheca (Allman, 1888) were collected in the southern sector of the Bay of Biscay off Saint Jean de Luz (France). The latter was also seen during several ROV surveys on rocky communities along the Cantabrian Sea and northwestern Spain. Each of the two species is herein described and illustrated and their worldwide distribution, bathymetric ranges and reproductive periods, revised; additionally, we allocate them in their biocoenological context, providing in situ images. The northern boundary limits are extended for both hydroids, which are new records for the Atlantic coast of France; the latter belongs to a genus previously unrecorded in the French mainland fauna. We also discuss the importance of having inventories of the sessile fauna of the exceptional sites at study, for the sake of their protection and detection of future modifications due to climate change.
(Journal of Marine Systems. vol. 253, n° 0924-7963, pp. 104158 (11p.), 01/01/2026)
INSUB, LERAR, COAST, IFREMER, IEO | CSIC, CSIC, LERPAC, COAST, IFREMER, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Organic carbon composition and preservation in macrotidal coastal wetland sediment: insights from biomarkers and isotopic signatures
Coastal wetlands store high amounts of organic carbon (OC) in their sediments, but long-term preservation of this carbon depends on habitat type, sediment depth, and the molecular characteristics of organic matter (OM). This study explores the dynamics of OC deposition and preservation across vertical profiles (0–30 cm) in two adjacent coastal habitats—mudflat, and salt-marsh—within the macrotidal system of the Aiguillon Bay (France). A multi-tracer approach was applied, combining stable isotopes δ13C, C/N ratios, lignin phenols, and fatty acids. Sediment OC content ranged from 13.4 to 23.2 mgC g−1, with the highest concentrations found in the salt-marsh. δ13C and C/N signatures revealed dominant marine source in the mudflat, with a secondary contribution from microphytobenthos, and mixed marine–C₃ plant inputs in the salt-marsh. Fatty acids and lignin compositions supported this partitioning, with surface mudflat layers enriched in labile microbial and algal-derived compounds, whereas deeper salt-marsh sediments retained more resistant, C3 plant-derived signatures resembling those of terrestrial OM source. OM degradation rates were closely linked to source composition and depth. Degradation was concentrated within the top 5 cm of salt-marsh and the top 10 cm of mudflat. Below these depths, biomarker profiles changed minimally, delineating a transition to longer-term preservation. First-order degradation constants were three times higher in mudflat (0.53 yr−1) than in salt-marsh (0.17 yr−1), despite similarly high sedimentation rates (1.8 and 2.2 cm yr−1, respectively). This reflects differences in OM lability, with even minor contributions from microphytobenthos enhancing reactivity in mudflats. Salt-marshes, with their intermediate OM reactivity and high sedimentation rates, emerged as hotspots of carbon accumulation (366 gC m−2 yr −1), while mudflats also contributed substantially to coastal carbon sequestration (239 gC m−2 yr −1). These results highlight the value of depth-resolved, biomarker-based approaches to identify habitat-specific degradation dynamics; ultimately better understanding carbon accumulation in coastal ecosystems.
(Science of the Total Environment. vol. 1020, n° 0048-9697, pp. 181542, 11/10/2026)
LIENSs, INSU - CNRS, ULR, CNRS, iEES Paris, IRD, SU, UPEC UP12, CNRS, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LPG-ANGERS, LPG, UM, UA, INSU - CNRS, CNRS, Nantes univ - UFR ST
The impact of suspended sediments on exchange flow in a macrotidal, hyperturbid estuary
This study investigates the sensitivity of the total exchange flow (TEF) with regard to suspended sediment concentrations (SSC) in water density calculations. We consider two scenarios of an idealized model based on a macrotidal, highly turbid estuary: one where density depends on both salinity and SSC and another where density depends only on salinity. These models are used to understand how TEF volume inflow ( Q in ) varies along the estuary over fortnightly and monthly time scales. The bulk values of TEF inflow between the two model scenarios show small differences (less than 4 %) over 5 months. However, differences in TEF bulk volume inflow reach 7 % downstream of the estuarine turbidity maximum (ETM), 22 % at the ETM, and nearly 70 % upstream of the ETM when quantified only over spring tides. The gradient Richardson number indicates that sediment-induced stratification suppresses shear production ∼ 30 km further upstream when suspended sediments are an active tracer. The most profound impact on TEF occurs during spring tides at, and upstream of, the ETM where sediment contributions to density exceed those from salinity. The sediment contribution leads to increased stratification in the upper reaches of the estuary, effectively reducing the longitudinal density gradient and therefore the exchange flow as much as 2000 m 3 s −1 , indicating a dominant role of suspended sediments in attenuating exchange in hyperturbid estuaries. The results from this work highlight the importance of SSC on density calculations in estuarine studies of the exchange flow.
(Ocean Science. vol. 22, n° 1812-0784, pp. 1311-1327, 11/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, RHITME, Cerema, M2C, UNICAEN, NU, INSU - CNRS, UNIROUEN, NU, CNRS
Faire face aux polluants éternels
(11/10/2026)
LEESU, UPEC UP12, ENPC, IP Paris, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Mineralogical Investigation of Riverine Suspended Particulate Matter: A Comprehensive Review of Sampling, Characterization and Analytical Techniques
Suspended particulate matter (SPM) governs the transport of sediments, nutrients, trace elements, radionuclides, and organic contaminants in water bodies, largely through its mineral fraction, which controls contaminant mobility and bioavailability. Characterizing this fraction remains challenging because of small particle size, complex organo-mineral associations, poor crystallinity, and the dynamic nature of aquatic particles. This review critically compares the principal sampling strategies and analytical techniques available for investigating the mineral fraction of riverine SPM, from bulk approaches (specific surface area, elemental and mineralogical analyses) to particle- and atomic-scale methods (manual and automated electron microscopy, X-ray absorption spectroscopy, isotopic analyses). For each technique, we synthesize the information it provides, its sample-preparation constraints and artefacts, and its complementarity with other methods, summarized in a comparative table. We show that no single technique is sufficient to characterize natural SPM. Only the integration of complementary methods across spatial scales provides a robust framework for understanding particle composition, reactivity, and contaminant dynamics. We further highlight emerging opportunities offered by in-situ and autonomous sampling technologies, cryogenic and in-situ electron microscopy, and machine-learning-based multimodal data fusion. Future progress will depend on harmonized sampling and analytical protocols, international SPM databases, and combined laboratory-field approaches.
(Minerals. vol. 16, n° 2075-163X, pp. 948, 11/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, HCMUT, VNU-HCM, VNU-HCM, VNU-HCM, UAlg
The Ediacaran volcanoclastic system of the Western Anti-Atlas (Morocco): Record of a rift – post-rift transition
The Upper Neoproterozoic volcano-sedimentary series are spectacularly exposed in the Anti-Atlas mountain ranges in Morocco. They offer a unique window into the tectonic-sedimentary and volcanic processes active during the transition between a rifting phase and a post-rift phase. In this context, our study aims to reconstruct the evolution of paleotopographies, and more specifically Ediacaran paleoreliefs, in order to understand the tectonic and volcanic processes responsible for their formation, as well as the mechanisms that have favored their preservation. Field observations within the inliers of the Western Anti-Atlas (Kerdous, Tagragra d'Akka, Aït Abdallah, Alma) have made it possible to recognize the nature and architecture of the last syn-rift series (Ouarzazate Group/PIII) and the post-rift ones (Adoudou Formation) of the Upper Neoproterozoic-Cambrian, as well as the syn-sedimentary tectonic structures that control them. In general, the rifting process begins with the activation of normal faults of variable directions, quickly followed by predominantly rhyolitic volcanism, whose deposits and lava flows are preserved in local tectonic depressions. Significant paleoreliefs become then apparent along the fault scarps. This pronounced paleotopography led to the formation of lacustrine fan-delta systems, recorded by large prisms of breccia deposits that quickly evolved to silty-carbonate facies in the axis of the newly formed depressions. These sedimentary or volcanosedimentary deposits gradually fossilize the paleoreliefs in a more homogeneous subsidence regime with reduced fault activity. A regional decrease in subsidence at the end of the rifting process is interpreted as the filling of the tectono-sedimentary systems, resulting in a flattened continental paleotopography. It was on this flattened paleosurface that the rise in relative sea level in the post-rift context led to the transgression of the peritidal platform deposits with microbial carbonate production of the Adoudou Formation at the Neoproterozoic-Cambrian transition. All of these series were then slightly deformed during the Hercynian orogeny to acquire their current arrangement in the Anti-Atlas inliers, without these appearing to be significantly influenced by the Neoproterozoic structures.
(. vol. 85, 11/10/2026)
ENSEGID, Bordeaux INP, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BRGM, ISTO, BRGM, INSU - CNRS, UO, CNRS, ISTO, BRGM, INSU - CNRS, UO, CNRS
Physical drivers of transport, dispersion and trapping of microplastics in a macrotidal, hyper-turbid fluvial–estuarine system: A modelling approach
Estuaries serve as both reservoirs and gateways for microplastics, yet the processes that control particle trapping, release, and redistribution are still insufficiently understood. This study assesses the relative importance of key physical processes in a macrotidal, hyperturbid Gironde estuary, influencing the transport and trapping of floating and settling microplastics -namely, interactions with shorelines, vertical mixing, effect of water density on particle buoyancy, interactions with bottom sediments, and microplastic-sediment flocculation and examines seasonal transport trends. Results show that floating microplastics are mainly exported seaward, although a fraction remains trapped as a longitudinal line in the middle estuary. The intensity of microplastic export and accumulation varies seasonally with river discharge. Shoreline interactions via beaching-refloating dynamics, along with flocculation with fine sediments, represent the dominant processes modulating the distribution and fate of floating microplastics. In contrast, settling microplastics exhibit limited export to the ocean and remain confined within the estuary. Although this retention is primarily governed by hydrodynamics, interactions with bottom sediments through (temporary or permanent) deposition and resuspension, as well as intra-tidal variability in vertical diffusivity, have a relatively stronger influence on the transport and distribution of settling microplastics. Two distinct accumulation zones, or Estuarine Microplastic Maxima (EMPM), are identified: a surface EMPM, formed by low-density floating particles associated with surface convergence, and a water-column EMPM of denser particles in suspension near the Estuarine turbidity maxima (ETM) linked to tidal pumping. Overall, macrotidal estuaries act as significant sinks for microplastics, where hydro-sedimentary dynamics govern particle retention and redistribution.
(Marine Pollution Bulletin. vol. 231, n° 0025-326X, pp. 119925, 11/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, SIAME, UPPA, MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS, RHITME, Cerema, M2C, UNICAEN, NU, INSU - CNRS, UNIROUEN, NU, CNRS