Fouiller sur l'estran : des contraintes et des opportunités
Sur estran, les vestiges apparaissent très bien conservés et parfois même immédiatement apparents lors de périodes d’érosion. Mais les contraintes s’accumulent à tous les niveaux : temps d’intervention limité, présence de l’eau, alternance des marées, rapidité de l’érosion dans certains secteurs, conditions d’accès ou de fouille, difficulté de mise en place d’infrastructures lourdes. Pour ces raisons, les interventions sur cet espace sont longtemps restées limitées à de simples observations accompagnées de prélèvements. La montée en puissance des problématiques littorales et l’accélération des processus d’érosion a alors motivé la mise au point de véritables projets de prospection et de fouille. Réalisés ni dans des conditions terrestres classiques ni dans des conditions subaquatiques, ces opérations ont souvent nécessité une méthodologie originale et l’appel à de nouveaux outils ou des modalités de prélèvements particulières. Quelques exemples choisis dans des contextes variés illustrent la réactivité et les adaptations nécessaires à des sites généralement bien conservés, souvent dotés de vestiges organiques, voire de restes de poissons ou de crustacés.
(Les Nouvelles de l'archéologie, n° 0242-7702, pp. 48-52, 27/04/2026)
CReAAH, UM, UR, UR2, CNRS, UFR HHAA, UN, MC, DRAC Normandie, MCC, MC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UP1, CNRS, Inrap, LASCARBX, UB, UBM, LETG - Brest, LETG, UNICAEN, NU, UA, EPHE, PSL, UBO EPE, UR2, CNRS, IGARUN, UN, UBM, CNRS
Spatial variability and sources of platinum in a contaminated harbor – tracing coastal urban inputs
Biogeochemical cycles that include processes to control platinum (Pt) distribution remain widely unknown in aquatic environments, especially in coastal systems. Dissolved Pt concentrations in coastal seawater (PtD) and in suspended particulate matter (SPM, PtP) were measured, together with master variables comprising dissolved oxygen, dissolved and particulate organic carbon, chlorophyll-a, turbidity, and ammonium levels, along two longitudinal profiles in the industrial Genoa Harbor (north-west Italy). Concentrations and spatial distribution of PtD and PtP levels reflect distinct concentration gradients that were attributed to different Pt sources such as hospital, domestic and industrial wastewater, atmospheric deposition, and/or road runoff. Concentrations reaching up to 0.18 ng L−1 PtD and 14 ng g−1 PtP reflect the impact of Pt urban inputs to coastal sites. These first data highlight considerable anthropogenic contamination in a confined harbor compared with the proposed reference value for the western Mediterranean surface seawater measured at external sites. Identified correlations between Pt levels and human pollution signals suggest the potential use of Pt as a new tracer of anthropogenic inputs that can be applied to other urbanised coastal systems. Biogeochemical processes that induce changes in the partitioning and fate of Pt in coastal seawater reflect a spatial variability and highlight the need for comprehensive environmental monitoring at an appropriate spatial scale.
(Environmental Chemistry. vol. 17, n° 1448-2517, pp. 105-117, 27/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UNIGE, UniGe
Coral carbon isotope sensitivity to growth rate and water depth with paleo-sea level implications.
Although reef coral skeletal carbon isotopes (δC) are routinely measured, interpretation remains controversial. Here we show results of a consistent inverse relationship between coral δC and skeletal extension rate over the last several centuries in Porites corals at Fiji, Tonga, Rarotonga and American Samoa in the southwest Pacific. Beginning in the 1950s, this relationship breaks down as the atmospheric C Suess effect shifts skeletal δC > 1.0‰ lower. We also compiled coral δC from a global array of sites and find that mean coral δC decreases by -1.4‰ for every 5 m increase in water depth (R = 0.68, p < 0.01). This highlights the fundamental sensitivity of coral δC to endosymbiotic photosynthesis. Collectively, these results suggest that photosynthetic rate largely determines mean coral δC while changes in extension rate and metabolic effects over time modulate skeletal δC around this mean value. The newly quantified coral δC-water depth relationship may be an effective tool for improving the precision of paleo-sea level reconstruction using corals.
(Nature Communications. vol. 10, n° 2041-1723, pp. 2056, 27/04/2026)
LDEO, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ZMT
Declining maerl vitality and habitat complexity across a dredging gradient: Insights from in situ sediment profile imagery (SPI)
Maerl beds form complex biogenic benthic habitats, characterized by high productivity as well as diverse biological communities. Disturbances associated with extraction and/or fishing activities using mobile bottom-contacting gears such as clam-dredges induce the most severe and long-term effects on these fragile habitats. We here investigated the effects of dredge-fishing on maerl in the bay of Brest (France). We quantified maerl beds structure and vitality across a fine scale quantified dredging intensity gradient through the acquisition of in-situ images of beds cross-section using Sediment Profile Imaging system (SPI). Declines in the proxies of maerl vitality and habitat complexity were measured across the gradient, and were associated with significant changes in the vertical distribution of live and dead maerl as well as of interstitial space. Fishing with dredges caused maerl mortality, substratum compaction, and decreasing habitat complexity. SPI imaging techniques also allowed for an assessment of changes in spatial heterogeneity that dredging created on several aspects of the structure and vitality of maerl beds. It suggests that direct and indirect disturbances induced by dredging are not acting at the same spatial scale, and can thereby differentially affect the ecosystem functions linked to vitality and habitat complexity.
(Scientific Reports. vol. 9, n° 2045-2322, pp. 16463, 27/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Application of the European Water Framework Directive: Identification of reference sites and bioindicator fish species for mercury in tropical freshwater ecosystems (French Guiana)
Mercury (Hg) is a toxic metal subject to several international regulations. The European Water Framework Directive (WFD) established in 2008 an Environmental Quality Standard for biota (EQSbiota) at 0.02 µg.g.
(Ecological Indicators. vol. 106, n° 1470-160X, pp. 14, 27/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IRSTEA
Identifying 2010 Xynthia Storm Signature in GNSS-R-Based Tide Records
In this study, three months of records (January-March 2010) that were acquired by a geodetic Global Navigation Satellite Systems (GNSS) station from the permanent network of RGP (Réseau GNSS Permanent), which was deployed by the French Geographic Institute (IGNF), located in Socoa, in the south of the Bay of Biscay, were used to determine the tide components and identify the signature of storms on the signal to noise ratio (SNR) during winter 2010. The Xynthia storm hit the French Atlantic coast on the 28th of February 2010, causing large floods and damages from the Gironde to the Loire estuaries. Blind separation of the tide components and of the storm signature was achieved while using both a singular spectrum analysis (SSA) and a continuous wavelet transform (CWT). A correlation of 0.98/0.97 and root mean square error (RMSE) of 0.21/0.28 m between the tide gauge records of Socoa and our estimates of the sea surface height (SSH) using the SSA and the CWT, respectively, were found. Correlations of 0.76 and 0.7 were also obtained between one of the modes from the SSA and atmospheric pressure from a meteorological station and a mode of the SSA. Particularly, a correlation reaches to 0.76 when using both the tide residual that is associated to surges and atmospheric pressure variation.
(Remote Sensing. vol. 11, n° 2072-4292, pp. 782, 27/04/2026)
LEGOS, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, GET, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, DTP, UT3, Comue de Toulouse, INSU - CNRS, CNRS, BRGM, SIAME, UPPA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Monsoon-driven Saharan dust variability over the past 240,000 years
Reconstructions of past Saharan dust deposition in marine sediments provide foundational records of North African climate over time scales of 10(3) to 10(6) years. Previous dust records show primarily glacial-interglacial variability in the Pleistocene, in contrast to other monsoon records showing strong precessional variability. Here, we present the first Saharan dust record spanning multiple glacial cycles obtained using Th-230 normalization, an improved method of calculating fluxes. Contrary to previous data, our record from the West African margin demonstrates high correlation with summer insolation and limited glacial-interglacial changes, indicating coherent variability in the African monsoon belt throughout the late Pleistocene. Our results demonstrate that low-latitude Saharan dust emissions do not vary synchronously with high-and mid-latitude dust emissions, and they call into question the use of existing Plio-Pleistocene dust records to investigate links between climate and hominid evolution.
(Science Advances. vol. 5, n° 2375-2548, pp. eaav1887, 27/04/2026)
GEOPS, UP11, CNRS, EAPS, MIT, MIT, LDEO, UdeC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Introduction to the Special Issue on Breaking Waves
(European Journal of Mechanics - B/Fluids. vol. 73, n° 0997-7546, pp. 1-5, 27/04/2026)
UiB, CARDAMOM, IMB, UB, Bordeaux INP, CNRS, Inria, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, I2M-BX, UB, CNRS, INRAE
Ozone production in a maritime pine forest in water-stressed conditions
During two growing seasons of a maritime pine stand, in 2014 and 2015, ozone (O-3) fluxes have been determined using the eddy covariance (EC) method and compared to the outputs of a big-leaf O-3 deposition model including stomatal, cuticular and soil pathways. The model developed in this study generally allowed to properly reproduce the measured ozone deposition. Ozone fluxes showed a strong reduction during two water stressed periods in September 2014 and July 2015. The model partly explain this fall due to the reduction of stomatal deposition. Despite this stomatal closure, measured O-3 fluxes presented systematically lower negative values than the model outputs, and sometimes even positive values around midday during periods marked by strong water stress. In other words, the difference between observed and modelled O-3 fluxes (hereinafter referred to as the residual O-3 flux) is systematically positive on daytime during these water-stressed periods. This positive residual flux traduced the existence of an O-3 source below the flux measurement level, responsible for positive fluxes that counterbalance deposition fluxes. We developed an O-3 production module based on a terpene emission algorithm and an OH concentration proxy, to try to explain the observed ozone production. As this parametrisation allowed us to reproduce well the daily and inter-daily dynamics of the residual O-3 flux, it confirms that the latter actually resulted from O-3 production processes. This ozone production is here highlighted for the first time using O-3 fluxes measurements by the EC method. The chemical reactions possibly involved in O-3 production processes in this maritime pine forest have been discussed and different mechanisms are proposed, based on peroxy radicals chemistry or stress-induced BVOCs.
(Atmospheric Environment. vol. 197, n° 1352-2310, pp. 131-140, 27/04/2026)
UMR ISPA, INRA, Bordeaux Sciences Agro, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Nouveau modèle analytique pour une meilleure estimation des flux nets annuels en métaux dissous. Cas du cadmium dans l’estuaire de la Gironde
Nouveau modèle analytique pour une meilleure estimation des flux nets annuels en métaux dissous. Cas du cadmium dans l'estuaire de la Gironde New computation for a better estimation of the annual dissolved metal net fluxes. The case of the cadmium in the Gironde estuary
(Hydroécologie Appliquée, n° 1147-9213, 27/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IGE, IRD, Grenoble INP, INSU - CNRS, CNRS, UGA [2016-2019], Fédération OSUG