Hydroclimate change in subtropical South Africa during the mid-Piacenzian Warm Period
The mid-Piacenzian Warm Period (mPWP, 3.264–3.025 Ma) of the Pliocene epoch has been proposed as an analog for future climate scenarios. Disagreement between the paleoenvironmental reconstruction and model simulations of the climate in subtropical regions for this period suggests that more investigation of the subtropical climate variability of the mPWP is needed. This study presents pollen, microcharcoal and benthic foraminifera oxygen isotope records generated from marine sediment cores of International Ocean Discovery Program (IODP) Exp. 361 Site U1479 from the Cape Basin offshore of South Africa for the period between 3.337 and 2.875 Ma. With an average sample resolution of 3 ka, this record represents the highest-resolution record of mPWP vegetation change from the region. Our results indicate that the vegetation during the mPWP was dominated by fynbos (species-rich heathy vegetation in the Cape Floristic Region) with variable proportions of Ericaceae. Moreover, the development of the Afrotemperate forest (tall, multilayered indigenous forests in South Africa) reflects shifts in the amounts of precipitation between winter and summer in the year-round rainfall zone. The vegetation variation is probably influenced by the latitudinal insolation gradient in response to precession forcing. Several glacials depicted by the benthic foraminifera oxygen isotope record were characterized by lower percentage values of Restionaceae, higher percentage values of ericoid fynbos and Afrotemperate forest. These events correspond well with cooler SE Atlantic sea surface temperatures driven by interactions of both atmospheric and oceanographic processes. The cooler sea surface temperatures attributed to Antarctic ice sheet expansion, reduced Agulhas leakage (heat and salt transfer from the Indian Ocean to the Atlantic Ocean) and/or intensified southern Benguela upwelling, resulted in less precipitation in the winter rainfall zone of South Africa.
(Quaternary Science Reviews. vol. 249, n° 0277-3791, pp. 106643, 17/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Acute Toxicity of Sodium Chloride, Nitrates, Ortho-Phosphates, Cadmium, Arsenic and Aluminum for Juveniles of the Freshwater Pearl Mussel: Margaritifera Margaritifera (L.1758)
The freshwater pearl mussel (FWPM) Margaritifera margaritifera (L.1758) is critically endangered in Europe and ecotoxicological studies on the species are scares. Here, 96 h acute toxicity tests were conducted at 16 °C with sodium chloride (NaCl), nitrates (NO3−), ortho-phosphates (PO43−), cadmium (Cd), aluminum (Al) and arsenic (As) on 13- to 28-month-old post-parasitic juveniles. The experimental protocol was developed according to conditions described in a standard guide and was modified in order to assess toxicity thresholds for the Dronne River. Results showed that juveniles were tolerant to concentrations of Al, Cd, As, PO43−, NO3− and NaCl, largely higher than those found in the Dronne river, since 96 h EC50s (effective concentrations) were >954 µg/L for Al; >110 µg/L for Cd; >127 µg/L for As; >5.01 mg/L for PO43−; between 1000 and 1500 mg/L for NO3− and were 1.19 and 1.33 g/L for NaCl. Moreover, the use of a substrate in experiments was found not to affect juvenile responses and younger juveniles seemed more sensitive than older individuals. This study thus provides new data about the tolerance of FWPM to environmental pollution and suggests that pollutant concentrations in the river are significantly lower than levels affecting them.
(Environments. vol. 7, n° 2076-3298, pp. 48, 17/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
AquaVIT Quand les plantes aquatiques invasives transcendent les frontières : approche pluridisciplinaire des relations entre espèces, milieux et gestionnaires
Le projet de recherche AquaVIT vise à accompagner l’évolution des modalités de gestion des grands lacs aquitains, confrontés à des enjeux environnementaux liés à la colonisation par les plantes aquatiques invasives. Ces plantes exotiques à caractère envahissant peuvent occuper une place importante au sein des écosystèmes lacustres et, par la même occasion, entraver de nombreux usages des lacs, notamment la pratique d’activités de loisirs. En Nouvelle-Aquitaine, ces macrophytes invasifs font l’objet d’une attention de la part des gestionnaires, élus et scientifiques depuis maintenant plus de trente ans. Néanmoins, un certain nombre d’interrogations demeurent. Les plantes présentent encore des dynamiques de colonisation importantes dans de nombreux plans d’eau et les opérations de gestion visant à les réguler sont menées localement. Le projet de recherche AquaVIT s’intéresse particulièrement aux questions suivantes : - Les plantes invasives constituent-elles un élément perturbateur du bon fonctionnement écologique lacustre ? - Comment "faire avec" les plantes au quotidien ? - Comment "faire ensemble" ? Le projet AquaVIT affiche une ambition pluridisciplinaire forte, qui associe, dès sa conception, les sciences humaines et sociales d’une part, et les sciences biogéochimiques et écologiques d’autre part. Ce projet propose une alternative à la vision quantitative et mesurable, strictement centrée sur la plante (i.e distribution et biomasse des plantes), vers une approche plus qualitative, orientée sur les relations entre la plante et son environnement, celui-ci étant considéré d’un point de vue écosystémique et social. Appropriée par chacune des disciplines, cette posture a donné lieu à des approches empiriques diverses et spécifiques. Dans le projet AquaVIT ont été déployées, entre autres, des enquêtes (qualitatives et quantitatives) auprès des acteurs, des études sociohistoriques basées sur des analyses de documents, mais aussi des prélèvements et mesures biologiques et physico-chimiques in situ, ainsi que des expérimentations en laboratoire. Le croisement de ces regards et de ces méthodes constitue une des richesses du projet. Les résultats obtenus invitent à s’éloigner d’une représentation univoque des conséquences potentielles de la présence d’herbiers denses de plantes aquatiques invasives, tout comme à contextualiser la problématique socio-environnementale de leur gestion. Ceci peut être illustré par le fait que les processus écologiques et biogéochimiques à l’œuvre dans les herbiers sont étroitement liés aux conditions hydrodynamiques locales, ou encore que les représentations et les attitudes à leur sujet dépendent pour partie des usages et des pratiques de terrain. Dans certaines conditions, une telle « contextualisation » de la problématique a favorisé l’émergence d’innovations organisationnelles, se traduisant, par exemple, par des dispositifs à caractère participatif. En dépit des motivations et des intentions à s’engager, dont témoignent les usagers des plans d’eau, les soutiens (humains, techniques et financiers) des pouvoirs publics, restent essentiels. Sur un plan spatial, ces innovations peinent toutefois à dépasser l’échelle des sites, de sorte que la mise en relation entre plusieurs secteurs, que l’on est parfois en mesure d’attendre compte tenu de la dynamique des plantes et des processus, repose encore très largement sur les réseaux sociotechniques des gestionnaires traditionnels des milieux, et peu sur les utilisateurs finaux.
(pp. 125 p., 17/10/2026)
UR EABX, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR ETBX, INRAE
Field Observations of Wave-induced Headland Rips
Most of rip-current field experiments have focused on persistent rips along rip-channeled sandy beaches or transient rips along reasonably alongshore-uniform surf-zone morphology, while experiments on rip flowing against structures are scarce. In October 2018, a 3-week field experiment was performed at Anglet beach, SW France, aiming at examining the dynamics of high-energy rip currents in complex settings. The beach is barred with prominent inherited geology, characterized by the presence of a 500-m headland and a natural submerged reef. A large array of in-situ instruments was deployed to capture the temporal and spatial variability of rip flow circulations, including ADCPs, surf-zone drifters and video monitoring. The latter allowed to identify a wide range of rip-flow patterns. Among these patterns, a high-intensity rip current flowing against the headland was a dominant feature for obliquely incident waves. Such a boundary rip current was driven by the deflection of the longshore current against the headland, peaking at 0.7 m/s (5-min time-and depth-averaged) 800-m offshore in 12-m depth for a moderate storm event with 4-m obliquely incident waves. Very-lowfrequency (O(1h) and O(30min)) fluctuations of this rip current were observed around low tide. Measurements of the vertical structure of the rip reveal that the deflection rip was more vertically-sheared as the water depth increases, with higher velocities near the surface, which is typical of a theoretical rip head structure.
(Journal of Coastal Research. vol. 95, n° 0749-0208, pp. 578, 17/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, SIAME, UPPA, MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS
Reconstruction of Holocene oceanographic conditions in eastern Baffin Bay
Baffin Bay is a semi-enclosed basin connecting the Arctic Ocean and the western North Atlantic, thus making out a significant pathway for heat exchange. Here we reconstruct the alternating advection of relatively warmer and saline Atlantic waters versus the incursion of colder Arctic water masses entering Baffin Bay through the multiple gateways in the Canadian Arctic Archipelago and the Nares Strait during the Holocene. We carried out benthic foraminiferal assemblage analyses, X-ray fluorescence scanning, and radiocarbon dating of a 738 cm long marine sediment core retrieved from eastern Baffin Bay near Upernavik, Greenland (Core AMD14-204C; 987 m water depth). Results reveal that eastern Baffin Bay was subjected to several oceanographic changes during the last 9.2 kyr. Waning deglacial conditions with enhanced meltwater influxes and an extensive sea-ice cover prevailed in eastern Baffin Bay from 9.2 to 7.9 ka. A transition towards bottom water amelioration is recorded at 7.9 ka by increased advection of Atlantic water masses, encompassing the Holocene Thermal Maximum. A cold period with growing sea-ice cover at 6.7 ka interrupts the overall warm subsurface water conditions, promoted by a weaker northward flow of Atlantic waters. The onset of the neoglaciation at ca. 2.9 ka is marked by an abrupt transition towards a benthic fauna dominated by agglutinated species, likely in part explained by a reduction of the influx of Atlantic Water, allowing an increased influx of the cold, corrosive Baffin Bay Deep Water originating from the Arctic Ocean to enter Baffin Bay through the Nares Strait. These cold subsurface water conditions persisted throughout the Late Holocene, only interrupted by short-lived warmings superimposed on this cooling trend.
(Climate of the Past. vol. 16, n° 1814-9324, pp. 1075-1095, 17/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Reconstructing climatic modes of variability from proxy records using ClimIndRec version 1.0
Modes of climate variability strongly impact our climate and thus human society. Nevertheless, the statistical properties of these modes remain poorly known due to the short time frame of instrumental measurements. Reconstructing these modes further back in time using statistical learning methods applied to proxy records is useful for improving our understanding of their behaviour. For doing so, several statistical methods exist, among which principal component regression is one of the most widely used in paleoclimatology. Here, we provide the software ClimIndRec to the climate community; it is based on four regression methods (principal component regression, PCR; partial least squares, PLS; elastic net, Enet; random forest, RF) and cross-validation (CV) algorithms, and enables the systematic reconstruction of a given climate index. A prerequisite is that there are proxy records in the database that overlap in time with its observed variations. The relative efficiency of the methods can vary, according to the statistical properties of the mode and the proxy records used. Here, we assess the sensitivity to the reconstruction technique. ClimIndRec is modular as it allows different inputs like the proxy database or the regression method. As an example, it is here applied to the reconstruction of the North Atlantic Oscillation by using the PAGES 2k database. In order to identify the most reliable reconstruction among those given by the different methods, we use the modularity of ClimIndRec to investigate the sensitivity of the methodological setup to other properties such as the number and the nature of the proxy records used as predictors or the targeted reconstruction period. We obtain the best reconstruction of the North Atlantic Oscillation (NAO) using the random forest approach. It shows significant correlation with former reconstructions, but exhibits higher validation scores.
(Geoscientific Model Development. vol. 13, n° 1991-9603, pp. 841 - 858, 17/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CQFD, IMB, UB, Bordeaux INP, CNRS, Inria, UOR, LOCEAN-VARCLIM, LOCEAN, MNHN, IRD, INSU - CNRS, SU, CNRS, IPSL (FR_636), ENS-PSL, UVSQ, CEA, INSU - CNRS, X, CNES, SU, CNRS, UPCité
Environmental samples of microplastics induce significant toxic effects in fish larvae.
Microplastics (MPs) are present throughout aquatic ecosystems, and can be ingested by a wide variety of organisms. At present, the physical and chemical effects of environmental MPs on aquatic organisms are poorly documented. This study aims to examine the physiological and behavioral effects caused by fish consuming environmental microplastics at different life stages. MP samples were collected from beaches on three islands (Easter Island, Guam and Hawaii) located near the North and South gyres of the Pacific Ocean. Larvae and juveniles of Japanese Medaka were fed for 30days with three doses of MPs (0.01, 0.1 and 1% w/w in fish food) approximate to the concentrations measured in moderately and heavily contaminated ocean areas. Ingestion of MPs by medaka larvae caused (variously) death, decreased head/body ratios, increased EROD activity and DNA breaks and, alterations to swimming behavior. A diet of 0.1% MPs was the most toxic. Two-month-old juveniles fed with 0.01% MPs did not exhibit any symptoms except an increase in DNA breaks. Our results demonstrate ingestion and mainly sublethal effects of environmental MPs in early life stages of fish at realistic MP concentrations. The toxicity of microplastics varies from one sample to another, depending on polymer composition, weathering and pollutant content. This study examines the ecological consequences microplastic build-up in aquatic ecosystems, more particularly in coastal marine areas, which serve as breeding and growing grounds for a number of aquatic species.
(Environment International. vol. 134, n° 0160-4120, pp. 105047, 17/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CNRS, PAnTher, Oniris VetAgroBio, INRAE, APEX, PAnTher, Oniris VetAgroBio, INRAE, ANSES
The Zebra Mussel (Dreissena polymorpha) as a Model Organism for Ecotoxicological Studies: A Prior 1H NMR Spectrum Interpretation of a Whole Body Extract for Metabolism Monitoring
The zebra mussel (Dreissena polymorpha) represents a useful reference organism for the ecotoxicological study of inland waters, especially for the characterization of the disturbances induced by human activities. A nuclear magnetic resonance (NMR)-based metabolomic approach was developed on this species. The investigation of its informative potential required the prior interpretation of a reference 1 H NMR spectrum of a lipid-free zebra mussel extract. After the extraction of polar metabolites from a pool of whole-body D. polymorpha powder, the resulting highly complex 1D 1 H NMR spectrum was interpreted and annotated through the analysis of the corresponding 2D homonuclear and heteronuclear NMR spectra. The spectrum interpretation was completed and validated by means of sample spiking with 24 commercial compounds. Among the 238 detected 1 H signals, 53% were assigned, resulting in the identification of 37 metabolites with certainty or high confidence, while 5 metabolites were only putatively identified. The description of such a reference spectrum and its annotation are expected to speed up future analyses and interpretations of NMR-based metabolomic studies on D. polymorpha and to facilitate further explorations of the impact of environmental changes on its physiological state, more particularly in the context of large-scale ecological and ecotoxicological studies.
(Metabolites. vol. 10, n° 2218-1989, pp. 256, 17/10/2026)
SEBIO, INERIS, URCA, ULH, NU, URCA, CNRS, LIEC, INSU - CNRS, UL, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, TBI, INSA Toulouse, INSA, Comue de Toulouse, CNRS, INRAE, ICMR, URCA, INC-CNRS, URCA, CNRS, URCA, CNRS
Bounding Global Aerosol Radiative Forcing of Climate Change
Aerosols interact with radiation and clouds. Substantial progress made over the past 40 years in observing, understanding, and modeling these processes helped quantify the imbalance in the Earth's radiation budget caused by anthropogenic aerosols, called aerosol radiative forcing, but uncertainties remain large. This review provides a new range of aerosol radiative forcing over the industrial era based on multiple, traceable, and arguable lines of evidence, including modeling approaches, theoretical considerations, and observations. Improved understanding of aerosol absorption and the causes of trends in surface radiative fluxes constrain the forcing from aerosol-radiation interactions. A robust theoretical foundation and convincing evidence constrain the forcing caused by aerosol-driven increases in liquid cloud droplet number concentration. However, the influence of anthropogenic aerosols on cloud liquid water content and cloud fraction is less clear, and the influence on mixed-phase and ice clouds remains poorly constrained. Observed changes in surface temperature and radiative fluxes provide additional constraints. These multiple lines of evidence lead to a 68% confidence interval for the total aerosol effective radiative forcing of -1.6 to -0.6 W m-2, or -2.0 to -0.4 W m-2 with a 90% likelihood. Those intervals are of similar width to the last Intergovernmental Panel on Climate Change assessment but shifted toward more negative values. The uncertainty will narrow in the future by continuing to critically combine multiple lines of evidence, especially those addressing industrial-era changes in aerosol sources and aerosol effects on liquid cloud amount and on ice clouds.
(Reviews of Geophysics. vol. 58, n° 8755-1209, 17/10/2026)
IPSL (FR_636), ENS-PSL, PSL, UVSQ, CEA, INSU - CNRS, X, IP Paris, CNES, SU, CNRS, UPCité, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LMD, INSU - CNRS, X, IP Paris, ENPC, SU, CNRS, ENS-PSL, PSL
Hygroscopic behavior of aerosols generated from solutions of 3-methyl-1,2,3-butanetricarboxylic acid, its sodium salts, and its mixtures with NaCl
Secondary organic aerosols (SOAs), which are formed and transformed through complex physicochemical processes in the atmosphere, have attracted considerable attention over the past decades because of their impacts on both climate change and human health. Recently, 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA), a low volatile, highly oxidized, secondary generation product of monoterpenes, is one of the most relevant tracer compounds for biogenic SOAs. Therefore, MBTCA was selected to understand its hygroscopic properties better. In addition, interactions between the organic acid and inorganic components have been reported, which may alter their hygroscopic properties mutually. In this study, laboratory-generated, micrometer-sized, pure MBTCA, mono-/di-/tri-sodium MBTCA salts, and MBTCA-NaCl mixture aerosol particles of four mixing ratios (molar ratios = 1 : 1, 1 : 2, 1 : 3, and 2 : 1) were examined systematically to observe their hygroscopic behavior by varying the relative humidity (RH) from RH = ~95 % to ~1 % through a dehydration process, followed by a humidification process from RH = ~1 % to ~95 %, using in-situ Raman microspectrometry (RMS) assembled with a see-through impactor where the particles were deposited on a Si wafer. The hygroscopic behavior of pure MBTCA and MBTCA-NaCl mixture aerosol particles of three mixing ratios (molar ratios = 1 : 1, 1 : 2, and 1 : 3) were also examined using a levitation system mounted on in-situ RMS through a humidification process from RH = ~10 % to ~80 % after a quenching process from droplets, followed by dehydration from RH = ~80 % to ~10 %. The pure MBTCA droplets effloresced at RH = ~30–57.8 % and did not dissolve until RH > 95 %. The mono- and di-sodium MBTCA salt aerosols did not show clear efflorescence RH (ERH) and deliquescence RH (DRH). In contrast, the tri-sodium MBTCA salt exhibited ERH = ~44.4–46.8 % and DRH = ~53.1 %, during the hygroscopic experiment cycle. The mixture aerosols generated from solutions of MBTCA : NaCl = 1 : 1 and 2 : 1 showed no visible ERH and DRH in the see-through impactor because of the partial and total consumption of NaCl, respectively, through chemical reactions during the dehydration process. The mixture particles with a 1 : 1 molar ratio in the levitation system exhibited a clear DRH at ~71 % and ERH at ~50 %. This suggests less reaction between the mixtures and a larger portion of NaCl remaining in the levitation system. The other mixtures of MBTCA : NaCl = 1 : 2 and 1 : 3 displayed single-stage efflorescence and deliquescence at ERH = ~45–50 % and DRH = ~74 %, respectively, because of the considerable amount of NaCl present in the mixture aerosols in both systems. Observations and Raman analyses indicated that only monosodium MBTCA salt aerosols could be formed through a reaction between MBTCA and NaCl. The reaction occurred more rapidly with a more elevated concentration of either MBTCA or NaCl, and the controlling factor for the reactivity of the mixtures depended mostly on the availability of H+ dissociated from the MBTCA tricarboxylic acid. The lower degree of reaction of the mixture particles in the levitation system might be caused by the relatively airtight circumstance inside, i.e., the less release of HCl. In addition, the quenching process, i.e., the starting point of the hygroscopicity experiments, induced the solidification of MBTCA, and further, a slow reaction between MBTCA and NaCl. The study revealed that the interactions between the MBTCA and NaCl could modify the properties of the organic acid in the atmosphere, leading to enhanced capability of the probable heterogeneous chemistry in the aqueous aerosols.
(Atmospheric Chemistry and Physics. vol. 20, n° 1680-7316, pp. 14103–14122, 17/10/2026)
ISM, UB, INC-CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS