Field measurements of wave and flow dynamics along a high-energy meso-macrotidal coast adjacent to a large estuary mouth
The North-Médoc coast, located to the south of the Gironde estuary, exhibits complex hydrodynamic conditions driven by high-energy incident waves and large tides, which are influenced by large-scale rocky outcrops, shoals, and tidal channels on the inner shelf. These wave- and tide-driven hydrodynamics result in rapid morphological changes, with shoreline erosion peaking locally at 5 m/year. In autumn 2022, an intensive two-week field campaign was conducted along three cross-shore transects distributed across the North-Médoc coast to, for the first time, document and analyze the hydrodynamics in this area. The campaign involved collecting measurements of waves and currents across both the inner shelf and nearshore regions, using six current profilers and 13 pressure sensors. Tides were found to predominantly modulate wave transformation and flow in both the nearshore and inner shelf regions of the North-Médoc coast. Strong alongshore currents were measured across the entire study site, increasing southward, which is linked to the overall morphology of a tidal channel. Tidal currents are flood-dominated in the northern part and ebb-dominated in the southern and central parts of the study area. Total currents and wave heights are modulated by tidal elevation, with, for example, increased wave height at the coast during higher tide levels. Nearshore waves, which undergo complex transformation across the inner shelf, such as wave refraction over shoals and rocky outcrops, also drive longshore currents in the surf zone, superimposed on the tidal current. These conditions result in a strong, net, northeastward longshore current, even during low-energy wave conditions. These observations provide new insights into the hydrodynamics of this rapidly evolving coastline and establish a comprehensive dataset that will be crucial for the development and validation of process-based and reduced-complexity models in this region
(Estuarine, Coastal and Shelf Science. vol. 317, n° 0272-7714, pp. 109205, 01/06/2025)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BRGM, LIENSs, INSU - CNRS, ULR, CNRS
Distinct toxicity profiles of conventional and biodegradable fishing nets’ leachates after artificial aging
Fishing nets (FNs) represent a significant source of plastic waste, but their contribution to pollution by micro- and nanoplastics (MNPs) and associated additives is poorly understood. We studied the degradation of a highperformance- polyethylene-polypropylene (HPPE-PP) trawl net and two trammel nets made of polyamide 6 (PA6) or biodegradable polybutylene-succinate-polybutyrate-adipate-terephthalate (PBS-PBAT). Accelerated artificial ageing (AA) was performed using UV irradiation under environmental or extreme conditions followed by abrasion in water with glass microbeads. FN degradation and organic compound release were studied as well as the toxicity of leachates on the marine bacteria Allivibrio fischeri and larvae of the fish Oryzias latipes. AA of FNs under environmental conditions caused slight polymer degradation and did not produce significant MNPs. However, under extreme conditions, PA6 and PBS-PBAT FNs produced 9.1 × 104 MP/mL and 2.0 × 104 MP/mL, respectively. FNs released a total of 27 organic compounds in the leachates from which 7 were quantified at concentrations between 0.35 μg/L (Phthalimide) to 200 μg/L (Succinic-acid 2-methylallyl-undecyl-ester). Only the PBS-PBAT FN leachates induced significant toxicity on bacteria, bioluminescence inhibition ranging from26 % to 56 %. Exposure of fish larvae to leachates of AA FNs disrupted their behavior. PBS-PBAT FN leachates caused the highest behavior stress indicator at day 12 (8.5), followed by PA6 at day 25 (8) and HPPE-PP at day 12 (7). We concluded that the toxicity of FN leachates was related more to the release of organic compounds than to the release of MPs. The toxicity of bio-based and biodegradable FNs should be further evaluated before their wider implementation in the fishing sector.
(Journal of Hazardous Materials. vol. 489, n° 0304-3894, pp. 137609, 01/06/2025)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CBMN, UB, ENITAB, INC-CNRS, CNRS
Record of trace organic contaminants in a river sediment core: From historical wastewater management to historical use
(01/06/2025)
METIS, EPHE, PSL, INSU - CNRS, SU, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, LEHNA, UCBL, ENTPE, CNRS, GéHCO, UT
Study of aerobic and anaerobic cultivable sedimentary microbiota - Capability of isolates to produce and degrade extracellular polymeric substances and possible use in biotechnology
The thesis is part of a larger project aiming to analyze the Extracellular Polymeric Substances (EPS) contents of sediments from modern and ancient estuaries (ANR “EXODIA”). EXODIA aims to better define the composition and function of EPS in modern and ancient estuaries, and their interaction with clay and metals through diagenesis. The aim of the thesis is to isolate, characterize and identify the culturable microorganisms potentially involved in the estuarine sediment EPS cycle (anaerobic and aerobic bacteria), in particular strains able to produce high quantities of EPS and/or able to degrade EPS. A maximum of microorganisms from the most representative sediment horizons on 6-m deep cores will be isolated by a culturomics strategy relying on the use of 16 media and 2 temperatures of incubation as well as enrichment strategies to focus on EPS degrading and biofilm-forming strains. After isolation and constitution of a strain’s library, each strain will be grown as planktonic and sessile pure culture and their ability to produce EPS (mucoid character), to form biofilms and to produce EPS-modifying enzymes (DNAses, proteases, hydrolases, lyases) will be assayed. Antibiosis and antibiofilm activities of isolates against bacterial reference strains in biofilm research (Escherichia coli and Pseudomonas aeruginosa) will be carried out. All the information relative to the isolates will be listed in a publicly available database. The identification of isolates will be performed in first intention by mass spectrometry. In parallel, genomic identification of the microbiome in sediment samples will be performed. This will allow us to estimate if our isolates are representative of the global community.
(27/05/2025)
CBMN, UB, ENITAB, INC-CNRS, CNRS, ICMCB, UB, INC-CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
A karst rather than periglacial origin for small enclosed depressions of the Landes Triangle, southwest France
Small topographic depressions offer insight into past and present groundwater recharge processes. The Landes Triangle (SW France) is dotted with over 2,400 such depressions, whose origins and hydrogeological implications remain unclear. This paper aims to disentangle their origin, with emphasis on the Villagrains-Landiras anticline sector: a key recharge zone, which also features the highest density of depressions. We first evaluate three historical hypotheses with open GIS data at the regional scale, then detail the near-surface structure of a depression near the anticline with electrical resistivity tomographies and ground-penetrating radar. We identify two groups of depressions based on their morphology, distribution and geological context. One aligns with an aeolian origin. The other (encompassing 97% of the depressions near the anticline) suggests a karst origin, with more circular shapes and proximity to karst, streams, faults and neighbouring depressions. However, 18% of these lie outside the crypto-karst area derived from GIS references and may rather be of periglacial origin. Yet, our geophysical survey revealed subsidence but no evidence of cryogenic sediment or solifluction. We conclude that a karst origin remains the best hypothesis in the anticline area, and highlight that sole reliance on GIS references may underestimate crypto-karst extent. Further geological investigation is therefore needed to map its full extent and related water pathways near the anticline.
(Earth Surface Processes and Landforms. vol. 50, n° 0197-9337, 25/05/2025)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ULaval
LEON-BLOOM project - Origin, spatial and temporal dynamics of cyanobacteria blooms in lake Léon, France
Lake Léon (Landes) has recently experienced important cyanobacteria blooms, leading to severe restrictions on recreational activities of this popular tourist waterbody of the Atlantic coast in France. To investigate the origins of these algal blooms, the dynamics of biological patterns, and to provide management strategies for mitigation, the "Léon-Bloom" research project established a collaboration between environmental watershed managers and research scientists. The project aims to identify the potential sources of algal growth and gain a better understanding of their spatial and temporal dynamics. The project is structured in several workpackages, each investigating a potential mechanism. (1) Firstly, nutrient fluxes from the watershed are analyzed, including the use of passive phosphorus samplers. We also set up an experimental design to investigate the role temperature, light and phosphorus on the development of phytoplankton biomass. (2) Secondly, a chemical analysis of the lake’s sediments is carried out resorting to sediment coring and experimentation to measure the potential of phosphorus release under anoxic conditions. (3) Thirdly, the role of temperature and oxygen on phytoplankton composition will be assessed using a statistical modeling approach. We measured temperature and oxygen in several stations of the lake to calibrate these models using autonomous high-frequency sensors. (4) The phytoplankton community is studied both spatially and temporally, at the taxonomic and algal group level. Cyanotoxins are also regularly monitored. Finally, two modeling-based workpackages will focus on (5) analyzing the role of wind in the spatial distribution of the plankton community and physical parameters and (6) developing remote sensing methods for monitoring algal concentrations in this lake. Ultimately, we aim to decipher the relative contribution of wind, nutrients (fluxes and internal release), and environmental variables, to understand the conditions of cyanobacterial blooms emergence.
(21/05/2025)
UR EABX, INRAE, ECLA, USMB [Université de Savoie] [Université de Chambéry], INRAE, OFB, OFB - DRAS, OFB, UMR ISPA, Bordeaux Sciences Agro, INRAE, RECOVER, AMU, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, OFB Service EcoAqua, OFB - DRAS, OFB
Rescuelog : Collecte numérique et reporting des interventions de sauveteurs à l’océan avec (ru)ODK, Shiny et SK8
Les plages du Sud-Ouest de la France présentent des risques élevés de noyades, nécessitant des dispositifs de surveillance efficaces. Le projet Rescuelog modernise la collecte et l’analyse des données sur les interventions de sauveteurs grâce à un workflow entièrement intégré dans l’écosystème R. Les interventions sont enregistrées via des tablettes Android utilisant ODK Collect, les données étant ensuite extraites avec ruODK (Mayer 2020) et structurées dans une base PostgreSQL après validation. Des données environnementales, incluant les prévisions météo et marines, sont enrichies via l’API de Météo-France grâce au package httr2 (Wickham 2023). Ces données alimentent un modèle prédictif, construit avec tidymodels (Kuhn and Wickham 2020), permettant d’anticiper les jours à haut risque de noyade. Ce modèle est versionné et stocké grâce au package vetiver (Silge 2023), puis exploité par une application Shiny déployée via le service sécurisé SK8 (SK8 Team 2024) d’INRAE. Cette solution démontre la capacité des outils R à proposer des workflows robustes, sécurisés et scalables pour des problématiques opérationnelles critiques comme la prévention des noyades.
(18/05/2025)
UR EABX, INRAE, UR ETTIS, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Biomonitoring of azole fungicides in free-living blackbird plasma using on-line solid-phase extraction coupled to liquid chromatography-tandem mass spectrometry (SPE HPLC-MS/MS)
In this study, a rapid and sensitive method using on-line solid-phase extraction (SPE) coupled to liquid chromatography - tandem mass spectrometry (SPE HPLC-MS/MS) was developed to analyse 15 azole fungicides currently used in vineyards in blackbird plasma samples. The monitored fungicides included 13 triazoles (cyproconazole, difenoconazole, epoxiconazole, fenbuconazole, flusilazole, flutriafol, metconazole, penconazole, propiconazole, tebuconazole, tetraconazole, triadimefon, triadimenol) and 2 imidazoles (imazalil and prochloraz). After a rapid preparation step by protein precipitation with acetonitrile on 25 µL of plasma samples, final extracts diluted with Milli-Q water were analyzed by on-line SPE-LC-MS/MS in positive electrospray mode (ESI+) using the dynamic multi-reaction monitoring mode (dMRM). Following optimization, method validation was achieved through studies of linearity, sensitivity, accuracy, precision, and sample extract conservation. The limits of quantification (LOQs) obtained for a low volume of plasma (25 µL) ranged from 0.01 to 0.43 ng g−1 plasma, except for triadimenol (1.37 ng g−1). Finally, the validated method was successfully applied to 34 Eurasian blackbird plasma samples, with blackbirds from different habitats (city, forest, vineyards) submitted to contrasted azole pressures. Five of them were detected, tebuconazole and tetraconazole being the predominant ones. As expected, azoles concentrations were more elevated in blackbirds sampled in vineyards where most of these fungicides are used.
(Journal of Chromatography A. vol. 1748, n° 0021-9673, pp. 465725, 10/05/2025)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CEBC, ULR, CNRS, INRAE
Molecular characterization of organic aerosols in urban and forested areas of Paris using high-resolution mass spectrometry
In order to study aerosols in environments influenced by anthropogenic and biogenic emissions to variable extents, PM1 samples were collected during summer 2022 in the greater Paris area (ACROSS campaign, Atmospheric Chemistry Of the Suburban Forest, 14 June to 25 July) at two locations that represent the urban Paris and the suburban forested areas. They were analyzed using high-resolution mass spectrometry (HRMS) together with total carbon (TC) with a thermo-optical method. Both sites are compared here to explore differences in aerosol composition from urban and forested environments. The TC analysis shows similar organic carbon (OC) concentrations at both sites (3.2 ± 1.8 µg m−3 for Paris and 2.9 ± 1.5 µg m−3 for Rambouillet) and higher elemental carbon (EC) values in the urban area. Both OC and EC concentrations did not show significant variations for daytime and nighttime conditions. This work highlights the influence of anthropogenic inputs on the chemical composition of urban and forested areas, derived from the presence of CHO and CHON compounds but also the detection of two sulfur-containing compounds (C5H12SO7 and C10H17NSO7), which could be tentatively assigned as organosulfates. A smaller number of aromatic compounds were observed for clean periods that better represent the local biogenic and anthropogenic contributions in Rambouillet and Paris, respectively.
(Atmospheric Chemistry and Physics. vol. 25, n° 1680-7316, pp. 4885-4905, 09/05/2025)
LISA (UMR_7583), INSU - CNRS, UPEC UP12, CNRS, UPCité, CAM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, INERIS
Atmospheric stability of six particulate biogenic secondary organic aerosol markers towards photolysis, hydroxyl radicals and ozone
This study aimed to investigate the kinetics of the heterogeneous reactions of six biogenic secondary organic aerosol (BSOA) markers of atmospheric interest, i.e. the terebic, terpenylic, cis-pinonic, pinic, 3-methyl-1,2,3-butanetricarboxylic (MBTCA) and β-caryophyllinic acids. For this purpose, these compounds were individually adsorbed onto silica model particles and exposed either to solar irradiation, hydroxyl radicals, or ozone. Marker concentrations extracted from particles were subsequently analyzed by liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (LC-QTOF/MS). Pseudo-first-order rate constants were derived from simulations (using either exponential functions or the tangent slope at t0) of particulate marker concentration decays as a function of exposure time to different oxidants or light. Second-order rate constants were calculated considering the oxidant concentrations under different experimental conditions. The overall atmospheric lifetime of each marker was calculated, revealing that β-caryophyllinic acid is the most reactive compound studied, with a lifetime of <14.3 min, followed by cis-pinonic acid (8.6 h), MBTCA (19 h), pinic acid (>2.8 days), terpenylic acid (>4.8 days), and terebic acid (>5.8 years).This work confirms that the atmospheric stability of some BSOA markers is insufficient, to justify their relevance as tracers of particle formation or aging processes.
(Chemosphere. vol. 380, n° 0045-6535, pp. 144453, 09/05/2025)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS