Calibration of the microcharcoal proxy preserved in marine sediments and reconstruction of paleo-fires in the Western Mediterranean region during the Holocene
(Quaternaire. vol. vol. 35/3, n° 1142-2904, pp. 147-150, 01/11/2024)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Radon-222 signatures of atmospheric dynamics in the Pech Merle Painted Cave, France: Consequences for management and conservation
(Science of the Total Environment. vol. 949, n° 0048-9697, pp. 174648, 01/11/2024)
IPGP - UMR_7154, INSU - CNRS, IGN, UR, IPG Paris, CNRS, UPCité, GET, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, GEOTRAC, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, USC
Two-dimensional determination of dissolved manganese in sediment porewaters
We present a new method for imaging dissolved manganese at millimeter scale by coupling DET (diffusive equilibrium in thin film) and colorimetric techniques. The method is an adaptation of the porphyrin approach for the measurement of dissolved Mn by substitution of Mn(II) and Mn(III) to Cd in the Cd(II)-POR complex. Optimization of the Cd-POR concentrations was required for transposition to 2D-DET. A commercial flatbed scanner and a hyperspectral camera were used for imaging. Using the hyperspectral camera, detection limit is about 5 μM and measuring range is up to 520 μM. The method was applied on the field in a tidal mudflat of the French Atlantic coast and in sediments inhabited by polychaetes. These first images allowed to precisely describe two-dimensional millimeter features such as burrows and highlighted the role of bioirrigation in benthic Mn fluxes. This new technique offers the possibility to investigate the reactivity of microenvironments towards dissolved Mn in two dimensions in a wide range of laboratory and in situ studies using a non-destructive tool.
(Marine Chemistry. vol. 267, n° 0304-4203, pp. 104454, 01/11/2024)
LPG, UM, UA, INSU - CNRS, CNRS, Nantes univ - UFR ST, Nantes Univ, MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS, IPREM, UPPA, INC-CNRS, CNRS, LUSAC, UNICAEN, NU, Cnam, ENTROPIE [Nouvelle-Calédonie], IRD [Nouvelle-Calédonie], IFREMER, UNC, CNRS, IPGP - UMR_7154, INSU - CNRS, IGN, UR, IPG Paris, CNRS, UPCité, CARRTEL, USMB [Université de Savoie] [Université de Chambéry], INRAE, Fédération OSUG, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Investigating sediment dynamics on a continental shelf mud patch under the influence of a macrotidal estuary: a numerical modeling analysis
Shelf mud patches represent major sinks for fine-grained particles on continental shelves, as well as for carbon and contaminants of continental origin. The West Gironde Mud Patch (WGMP) is an interesting example of such offshore marine systems as it is an active mud deposition area located offshore the Gironde estuarine mouth (France) at depths between 30 and 70 m. It is known to be the trap of fine particles coming from the estuary, but the contribution of this material to the total mass of the depocenter is poorly quantified. In addition, despite the economic and ecological issues at stake, the response of such subtidal sedimentary structure to the combination of tidal currents, waves, and river supply remain poorly understood. Thus, using a realistic 3-D hydrodynamic and mixed (mud/sand) sediment transport model, this study aims at investigating the sediment dynamics of the WGMP under different hydrometeorological conditions. The analysis of the residual fluxes at the estuarine mouth exhibited large discrepancies between the different sediment classes as well as for contrasted hydro-and meteorological conditions induced by different dominant transport mechanisms. During winter, the reinforced density gradients drive strong up-estuary baroclinic circulation at the bottom that dominates the sediment dynamics over the barotropic export of mud particles. The model also reproduced the signature of a subtidal mud accumulation area over the continental shelf around 30-40 m water depth, on the proximal side of the observed WGMP. On average over two years, 26% of the mud mass accumulating on the simulated subtidal mudflat comes from the estuary. The trapping efficiency of this mud patch is negatively correlated with the significant wave height. Moreover, due to the estuarine turbid plume being more concentrated and developed at the surface during high river discharge, the trapping efficiency of the mud body is enhanced compared to lower discharge. This study highlights the sensitivity of mud and sand fluxes to vertical and horizontal residual circulation, and points out the uncertainties associated with the simulation of short-term (i.e., years) fine particle deposits compared to long-term (i.e., centuries) sediment accumulation trends. In addition, these results show the primordial effects of both wave action and riverine sediment supply on the dynamics of such subtidal muddy structures, which raises concern about their fate facing climate change and human activities in the future.
(Continental Shelf Research. vol. 282, n° 0278-4343, pp. 105334 (17p.), 01/11/2024)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, DYNECO, IFREMER
Wave Climate Projections off Coastal French Guiana based on High-Resolution Modelling over the Atlantic Ocean
Global warming is altering the atmosphere and ocean dynamics worldwide, including patterns in the generation and propagation of ocean waves, which are important drivers of coastal evolution, flood risk, and renewable energy. In French Guiana (northern South America), where most of the population is concentrated in coastal areas, understanding future wave climate change is critical for regional development, planning and adaptation purposes. The most energetic waves typically occur in boreal winter, in the form of long-distance swell originating from the mid-latitude North Atlantic Ocean. However, existing high-resolution wave climate projections that cover the French Guiana region focus on the hurricane season only (summer-fall). In this study, we used a state-of-the-art basin-scale spectral wave model and wind fields from a high-resolution atmospheric global climate model to simulate present and future winter (November to April) wave climate offshore of French Guiana. The model performance was evaluated against wave data from ERA5 reanalysis, satellite altimetry and coastal buoys between 1984 and 2013. For the future greenhouse gas emission scenario (Representative Concentration Pathway) RCP-8.5, we found a statistically significant overall projected decrease (~5%) in wintertime average significant wave height and mean wave period, with a ~1° clockwise rotation of mean wave direction. The results suggest that these decreasing trends are primarily driven by changes in large-scale patterns across the Atlantic that counteract an expected increase in local wind speed. We discuss the implications of such projections for mud-bank dynamics along coastal French Guiana, although further local studies are required to address future coastal evolution and hazards. Finally, we identify a need for more in situ wave data near French Guiana to improve quantitative assessments of model performance and allow a correction of possible model biases.
(Ocean Modelling, n° 1463-5003, 01/11/2024)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BRGM, PSL, CNRM, INSU - CNRS, CNRS, Comue de Toulouse, DIRAG
Late Middle Pleistocene (MIS 11‐6) in Europe – introduction
The following collection of contributions presents both unique and synthesized regional evidence that provides considerable clarification regarding this part of the European Quaternary stratigraphical sequence. It is a reliable step forward to overcome an over‐simplistic view, because progress over recent years in many different fields has led to significant advances in our understanding regarding the interactions between environmental processes and climate.
(Boreas. vol. 53, n° 0300-9483, pp. 453-454, 28/10/2024)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Unlocking the potential of hydrogen isotopes (δ2H) in tracing riverine particulate organic matter sources and dynamics
This study explores the efficacy of hydrogen isotopes in tracing the origins and dynamics of particulate organic matter (POM) in the Loire River, employing a novel dual vapor equilibration method to measure its nonexchangeable hydrogen (δ2Hn). By integrating δ2Hn with traditional carbon (δ13C) and nitrogen (δ15N) isotopes and C/N ratios of POM, we compared the ecological information using multivariate analyses. Fortnightly river sampling over three years showed seasonal patterns in the δ2Hn values of POM, highlighting two primary POM end-members: phytoplankton and terrestrial matter. Bayesian mixing models confirmed that using δ2Hn as a tracer effectively discriminated these riverine POM end-members, with phytoplankton predominating in spring-summer and terrestrial matter in winter. Redundancy analyses revealed the main environmental drivers of POM composition, identifying significant correlations between the POM sources, chlorophyll a, suspended particulate matter, and river discharge. Our findings demonstrate that δ2Hn, alone or combined with δ13C, δ15N or N/C ratio, provided a new robust tracer for POM source dynamics, thereby offering valuable insights into riverine biogeochemical cycles and ecosystem functioning. Our study underscores the novel potential of δ2Hn as a tool in environmental and ecological research, advocating for its broader application across various aquatic ecosystems to enhance our understanding of organic matter dynamics.
(Aquatic Sciences - Research Across Boundaries. vol. 87, n° 1015-1621, pp. 5, 24/10/2024)
UB, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, WasserCluster Lunz, BOKU
Perceived risks and its relation to bathing rate at a high energy surf beach in France
Background: despite the many benefits gained from contact with water, bathing in the ocean is a risky activity. To properly analyse these risks, beachgoers exposure is still a poorly understood component of the risk. In this study, we investigate the decision of beachgoers to enter the water at a high-energy supervised beach in southwest France, where strong rip currents and heavy shore-break waves can discourage beachgoers to enter the water. Methods: We estimated regression models based on a dataset which combine data on personal factors collected by means of an on-site survey (N=722) with marine and weather data collected at nearby stations. Results: The beachgoers global bathing risk perception is influenced by both environmental (i.e. wave height and wave period) and personal factors (i.e. beachgoer’s age, confidence in escaping from a rip current and drowning risk concerns in general). By comparison, insolation and outdoor temperature are the primary environmental factors influencing respondent decision. Tide level and wave height only affect bathing rate when the beachgoer's personal variables are not taken into account in the model. Self-assessment of swimming ability in the ocean and individual risk perception are the two statistically significant human predictors of bathing rate. When perceptions specific to rip currents and shore break risks are simultaneously introduced into the regression models, only rip current perceived risk has a significant influence on the bathing probability. Conclusion: Our results provide new avenues for communication by highlighting a number of beach safety issues still poorly understood by the general public. As regards risk forecasting, this research fills a gap by refining our ability to assess exposure by pinpointing the proportion of beachgoers who enter the water.
(18/10/2024)
UR ETTIS, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Attitudes, perceived bathing risks and behaviours among recreational users at a high-energy beach in South-West France. A dataset containing human and environmental data, beachgoers and lifeguards assessments
The dataset provides data on beachgoers’ behaviours, attitudes and perceptions of coastal bathing risks at a high energy beach in South-West France. Data were collected from a face-to-face quantitative survey conducted at La Lette Blanche beach, during the lifeguard-patrolled summer period (July-August) 2022 from a sample of 722 visitors. Beachgoers were interviewed across various times of the day (i.e. morning or afternoon), on various days of the week (i.e. weekdays or weekends) and various marine and weather conditions. All respondents provided informed consent after reading a participant information form at the beginning of the survey. The survey was conducted in French or English and consisted of forty questions convering four main topics: (1) attitudes toward risk in general and concerns about risks in everyday life, including leisure and water based recreation context; (2) risk experience (participation in beach activities in general, visits at southwest France beaches, recreational activities, previous accidents); (3) visits to La Lette-Blanche beach at the time of the survey (attractiveness, bathing behaviour and perception of risks); (4) sources of information and preventive behaviours related to bathing risks. Respondents socio-demographic characteristics were collected at the beginning of the survey. At the same time, environmental data were collected by a nearby directional wave buoy, tide gauge and weather station, and an hourly estimate of rip current hazard, shore break wave hazard and of the total beach crowd during the patrolling hours has been provided by the chief lifeguard of the study beach. The dataset can be used to conduct quantitative analyses or to compare with others studies in the domain of beach safety research.
(Data in Brief. vol. 57, n° 2352-3409, pp. 111001, 17/10/2024)
UR ETTIS, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, SMGBL
La Cyber-carothèque nationale : la collection dédiée aux prélévements stratigraphiques, sédimentaires : des métadonnées standardisées pour aller vers des écosytèmes de données ouvertes
La gestion des données constitue l’un des défis de la Science Ouverte de la prochaine décennie. Ceci est particulièrement important dans le domaine des Sciences de la Terre et de l’Environnement dans lequel la multiplication des échantillons de terrain et de mesures qui sont réalisées sur chacun d’entre eux, (DR1) conduit à une croissance exponentielle du nombre de données. Or, l’absence de systèmes d’information dédiés empêche de capitaliser sur cette grande richesse en reliant les données entre elles, notamment par des métadonnées riches et fiables. Dans cette contribution, nous présentons un système mis en production depuis 2017 afin de bancariser les informations de terrain collectées lors du prélèvements de carottes sédimentaires. Ce système tend à répondre au plus près des principes d’ouverture de la données F.A.I.R. et est constitué de deux modules opérationnels : i) le CoreBook, qui est une application mobile de collecte d’information sur le terrain sous Android, et ii) la Cyber-carothèque nationale (Base de données MySQL), qui est un portail d’import multi-institutionnels de consultation et de diffusion des données collectées. A ce duo sera rattaché un troisième module opérationnel en 2023, Collec-Science. Ce système de gestion de base de données (SGBD) est développé par l’INRAe de Bordeaux. Il permettra, par interopérabilité, de faciliter la gestion des stocks d’échantillons dans les entrepôts d’échantillons gérés par des laboratoires français. CoreBook est une application embarquée sur tablette Android qui apporte une plus-value en qualité lors des opérations de carottage sur le terrain, notamment les opérations complexes de carottages multi-sections et/ou multi-trous. Il est adapté à tout type de méthode de carottage (carottier russe, gravitaire, piston stationnaire, etc.). Que ce soit par une opération de synchronisation du Corebook, ou par l’import via un fichier d’inventaire respectant un format spécifique, ou par le flux de données entrant CSW (Ie IFREMER), les métadonnées de carottage sont ainsi capitalisées et tracées au niveau du portail national de la Cybercarothèque. Ainsi, chaque échantillon peut se voir attribuer un identifiant unique au format international IGSN, permettant de les identifier sans ambiguïté lors de citations dans des publications ou d’intégration dans des systèmes d’information tiers. Il s’agit là d’étapes préalables indispensables vers la bancarisation, la qualité, le partage et l’utilisabilité des données de qualité. ∗IntervenantEn prenant le problème de la gestion des données à la base, au niveau des opérations de terrain, le système CoreBook- Cyber-carothèque- Gestion d’échantillons fournit à la communauté scientifique nationale un socle solide pour aller vers des des bases de données tournées vers les données instrumentales. La Cyber-carothèque est accessible à l’adresse : www.cybercarotheque.fr, page sur laquelle figure le lien et les instructions pour créer le compte de son laboratoire et de ses utilisateurs, ses référentiels d’outils et télécharger l’application CoreBook.
(14/10/2024)
EDYTEM, USMB [Université de Savoie] [Université de Chambéry], CNRS, Fédération OSUG, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, DTI, INSU - CNRS, CNRS, OASU, UB, INSU - CNRS, ULR, CNRS, INRAE, INSU - CNRS, CNRS, UA, UM