Tidal and geological controls on longshore sediment transport along the north of the Médoc coast, SW France
The north of the Médoc coast, SW France, is a sandy coast with complex environment settings including an irregular bathymetry, shallow bank, rocky outcrops, and an adjacent km-scale estuary. This coast is strongly affected by marine erosion and exhibits dramatic erosion trends, with shoreline retreats reaching locally several meters per year for decades. New coastal management scenarios for the next years, or even decades, need to be investigated. For this purpose, we may rely on the use of reduced-complexity shoreline change models. They are valuable tools to simulate past and future shoreline changes at time scales from seasons to centuries. These models usually rely on time and space integration of wave-driven longshore sediment transport, which is one of the main drivers of shoreline change along sandy coasts on the long-term. This longshore transport is computed from breaking wave conditions, which are controlled by several physical processes occurring within the nearshore area. However, the control of local environmental settings on breaking waves is usually over-simplified in reduced-complexity shoreline change models, if not neglected. This study investigates the sensitivity of the wave-driven longshore sediment transport along the north of the Médoc coast to different physical processes affecting the wave propagation. Results revealed that on a monthly scale the bathymetry and the bottom friction play a predominant role on longshore sediment transport patterns. In contrast, the contribution of tide-driven water levels is lower on this timescale, and even less for contribution of the tide-driven currents
(pp. 429-438, 25/06/2024)
BRGM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Contrasting platinum trajectories in three major French rivers using dated sediment cores (1910–2021): From geochemical baseline to emerging source signals
Platinum (Pt) is a Technology Critical Element (TCE) which, since the 1990s, has been mainly used in the industry in catalytic converters for automobile emission control. Previous studies have shown Pt contamination of road-side sediments and surface sediments in urban rivers and lakes but few of them have addressed temporal variations. The present work presents historical Pt concentration trends in 137Cs-dated sediment cores from floodplains or secondary channels at the outlets of three major French watersheds (Loire, Rhone, and Seine Rivers) covering the past ∼110 years, i.e., from the 1910s to 2021. Platinum baseline levels in the sediment were estimated for the Loire River (0.76 ± 0.22 μg kg−1 for the period ∼1910-∼1955) and the Rhone River (1.64 ± 0.41 μg kg−1), and historical Pt variations seem to reflect variations in hydrodynamics and grain size composition. Since the early 2000s, Pt concentrations in the Loire and the Rhone River sediments tend to increase (>2.5 μg kg−1) and were attributed to the use of car catalytic converters, an emerging technology since the 1990s using >50 % of European Pt demand. High and variable historical Pt concentrations (up to 14.6 μg kg−1) in the Seine River sediments may reflect legacy Pt sources due to former anthropogenic activities in this watershed, such as the use of Pt-based catalysts for petroleum refinery since the end of the 1940s, coal handling and precious metals refining, probably concealing the likely presence of an emerging traffic-related Pt signal. This first comparison of historical Pt concentration trends in sediments from contrasting watersheds allows to distinguish signals originating from different natural and anthropogenic sources (background level, historical sources, road traffic).
(Science of the Total Environment. vol. 931, n° 0048-9697, pp. 172937, 25/06/2024)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, M2C, UNICAEN, NU, INSU - CNRS, UNIROUEN, NU, CNRS, METIS, EPHE, PSL, INSU - CNRS, SU, CNRS, LEHNA IAPHY, LEHNA, UCBL, ENTPE, CNRS, GéHCO, UT, IRSN/PSE-ENV/STAAR/LRTA, IRSN/PSE-ENV/STAAR, IRSN
Conditions et temporalités de la remise en mobilité des dunes de la cote girondine
Les dunes sont des objets complexes des systèmes littoraux sableux, contrôlées par des mécanismes d’interactions multiples et non linéaires. Sur de nombreux secteurs dans le monde, et particulièrement en climat tempéré, les systèmes dunaires littoraux sont globalement stables et fixés. Néanmoins, sous certaines conditions (forçages marins et éoliens énergétiques, disponibilité sédimentaire modérée à forte, réduction du couvert végétal…) certaines dunes littorales peuvent se remobiliser. A partir d’un jeu de données constitués de Modèles Numérique de Terrain (MNT) issus de mesures LiDAR aéroportées, collectées en 2011 puis à fréquence annuelle sur près d’une décennie de 2014 à 2023, nous proposons une analyse des évolutions du cordon dunaire de la côte Girondine sur 85 km. Les résultats montrent que suite à une séquence d’érosion marine (hiver 2013-2014), le cordon dunaire a connu une mobilité importante à échelle décennale sous l’effet des flux éoliens, entrainant des réponses morphologiques variables spatialement. Ces réponses vont de la quasi-stabilité au passage de dunes fixes à transgressives le long de linéaires de plusieurs kilomètres. On observe que la remobilisation du cordon dunaire n’est pas conditionnée par la disponibilité sédimentaire, celle-ci pouvant aussi bien apparaitre en contexte de forte disponibilité que sur des sites en érosion chronique où les apports sont quasi nuls. Face aux problématiques posées par l’immobilité des cordons dunaires littoraux (i.e. réduction voire disparition des cordons bordiers), l’érosion marine potentiellement associée à des actions de gestion (écrêtage, adoucissement des pentes) peut être considérée comme une opportunité pour la remise en mobilité des dunes de front de mer.
(pp. 391-400, 24/06/2024)
BRGM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ONF, CEFREM, UPVD, INSU - CNRS, CNRS
Patterns in macrobenthic diversity in the lower shore of northeastern Atlantic macrotidal sandy beaches
Although knowledge of sandy beaches has increased recently, the benthic diversity of macrotidal sandy beaches in the northeastern Atlantic Ocean (more specifically, the western Channel and the northern Bay of Biscay) is poorly known. Here, we present a regional-scale account of the species diversity, both observed and estimated, of the macrobenthic fauna of Brittany based on an analysis of a species-level data set from 18 sandy beaches in Brittany that were sampled annually for 13 yr on the lower shore. In total, 526 species were identified, including 210 Annelida, 167 Arthropoda, 103 Mollusca, 19 Echinodermata and 27 species of other phyla. Four distinct habitats were distinguished based on their benthic communities and characterised using environmental variables. Sediment heterogeneity appeared to enhance diversity, as heterogeneous muddy sand harboured significantly more species than (muddy) fine sand. The role of environmental variables as structuring factors of benthic communities was investigated using redundancy analysis and variance partitioning. Beach morphodynamics and sediment structure explained most diversity variations (25.40 and 24.91%, respectively) followed by wave characteristics (13.46%). Finally, we offer some habitat-specific reference values regarding species richness and the Shannon index for M-AMBI computation during Water Framework Directive and Marine Strategy Directive evaluations for a more reliable characterisation of the ecological status of sandy beaches.
(Marine Ecology Progress Series. vol. 738, n° 0171-8630, pp. 21-40, 20/06/2024)
IUEM, IRD, INSU - CNRS, UBO EPE, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, FEM, LEMAR, IRD, IFREMER, UBO EPE, CNRS
Temporal trajectories of artificial radiocaesium 137Cs in French rivers over the nuclear era reconstructed from sediment cores
137Cs is a long-lived man-made radionuclide introduced in the environment worldwide at the earlybeginning of the nuclear Era during atmospheric nuclear testing’s followed by the civil use of nuclearenergy. Atmospheric fallout deposition of this major artificial radionuclide was reconstructed atthe scale of French large river basins since 1945, and trajectories in French nuclearized rivers wereestablished using sediment coring. Our results show that 137Cs contents in sediments of the studiedrivers display a large spatial and temporal variability in response to the various anthropogenicpressures exerted on their catchment. The Loire, Rhone, and Rhine rivers were the most affected byatmospheric fallout from the global deposition from nuclear tests. Rhine and Rhone also receivedsignificant fallout from the Chernobyl accident in 1986 and recorded significant 137Cs concentrations intheir sediments over the 1970–1985 period due to the regulatory releases from the nuclear industries.The Meuse River was notably impacted in the early 1970s by industrial releases. In contrast, theSeine River display the lowest 137Cs concentrations regardless of the period. All the rivers respondedsimilarly over time to atmospheric fallout on their catchment, underlying a rather homogeneousresilience capacity of these river systems to this source of contamination.
(Scientific Reports. vol. 14, n° 2045-2322, pp. 1-16, 20/06/2024)
IRSN/PSE-ENV/STAAR/LRTA, IRSN/PSE-ENV/STAAR, IRSN, IRSN/PSE-ENV/SAME/LMRE, IRSN/PSE-ENV/SAME, IRSN, LEHNA IAPHY, LEHNA, UCBL, ENTPE, CNRS, LIVE, UNISTRA, CNRS, ITES, ENGEES, UNISTRA, INSU - CNRS, CNRS, MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS, LCE, AMU, INC-CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, M2C, UNICAEN, NU, INSU - CNRS, UNIROUEN, NU, CNRS, LOTERR, UL, GéHCO, UT, SU, METIS, EPHE, PSL, INSU - CNRS, SU, CNRS, GEGENAA, URCA, Inrap, MSH-URCA, URCA, LIEC, INSU - CNRS, UL, CNRS, LTSER-ZAM, UL, CNRS, RZA, INEE-CNRS, CNRS, IRSN/PSE-ENV/SPDR/LT2S, IRSN/PSE-ENV/SPDR, IRSN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, GEDI, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA
Estimating Contaminated Soil Volumes Using a Generative Neural Network: A Hydrocarbon Case in France
(19/06/2024)
LITIS - App, LITIS, ULH, NU, UNIROUEN, NU, INSA Rouen Normandie, INSA, NU, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
What do we know about the ecology of aquatic Isoëtes species? Data gaps and opportunities to improve the global protection of truly iconic plants
The genus Isoëtes includes iconic plants, characteristic of a wide range of ecosystems including nutrient-poor aquatic waterbodies. They are wetland obligates which have suffered severe losses globally over time mainly due to alterations and loss in colonized habitats. This is due to their sensitivity to habitat alteration and eutrophication of water and sediment. Despite this, a global review of the ecological knowledge about aquatic species belonging to this genus is missing, and overall, we know very little at the global scale. An assessment of aquatic Isoëtes ecology is therefore important, particularly for a better understanding of what the main threats to their conservation are. Through a global, collaborative initiative a first global ecological assessment focusing on aquatic Isoëtes was carried out. It includes a literature review, an extensive new database on Isoëtes distribution and growth conditions, and ecological niche analyses. We first compiled a global aquatic Isoëtes database including all known environmental data collected between 1935 to 2023 (for a total of 1880 georeferenced records). We then used ordinations to quantify ecological niches and environmental drivers for a subset of species. Both well-established findings and unexpected results emerged, opening new perspectives for the conservation of aquatic Isoëtes.
(17/06/2024)
UNIROMA, UNIPR, ROMA TRE, CEAB, CSIC, UR EABX, INRAE, ECLA, USMB [Université de Savoie] [Université de Chambéry], INRAE, OFB, RAS, ITV, BIOLOGY CENTRE CAS, BIOLOGY CENTRE CAS, CAS, IBER, UW-La Crosse, UNITUS, NIVA, UCPH, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, USC, IUCN, RSHU
Modelling the fate of the transformation products generated by the degradation of carbamazepine in various water treatment processes
(16/06/2024)
LGC, UT3, Comue de Toulouse, CNRS, Toulouse INP, Comue de Toulouse, UR REVERSAAL, INRAE, LPTC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Les effets potentiels du fluorure de sodium sur la truite arc-en-ciel
(Les cahiers de la Recherche : Santé, Environnement, Travail, n° 2264-7597, pp. 34-36, 13/06/2024)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Global aquatic Isoëtes Database (acronym GaID) as of 2024
Isoëtes are iconic but understudied wetland plants, despite having suffered severe losses globally mainly because of alterations in their habitats. We therefore provide the first global, comprehensive data set of aquatic Isoëtes and their habitats. We compiled a global database that includes all known environmental data collected from 1935 to 2023 regarding aquatic Isoëtes. This resulted in 2,179 records. The environmental data taken at Isoëtes' sampling stations varied but may include measures of water quality, water depth, and substrate composition.
(. vol. 69, 11/06/2024)
UW-La Crosse, UNIROMA, UNIPR, ROMA TRE, CEAB, CSIC, UR EABX, INRAE, ECLA, USMB [Université de Savoie] [Université de Chambéry], INRAE, OFB, RAS, ITV, BIOLOGY CENTRE CAS, BIOLOGY CENTRE CAS, CAS, IBER, UNITUS, NIVA, UCPH, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, USC, IUCN, RSHU