Calibration of benthic foraminifera elemental ratios from the Northeastern Atlantic
(27/04/2026)
GEOPS, UP11, CNRS, LPG-ANGERS, LPG, UA, UN UFR ST, UN, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Étude de la contamination atmosphérique par les pesticides à l'aide d'échantillonneurs passifs de type PUF (Polyurethane Foam) : application à l'étude de vergers de pommiers
La France, dont plus de la moitié du territoire est dédiée à l'agriculture, se situe au premier rang européen et au cinquième rang mondial des utilisateurs de pesticides agricoles. L'importance de ce secteur et de l'usage de substances chimiques pour accroître la productivité au cours des dernières décennies suscitent des interrogations tant du point de vue environnemental que de celui de la santé publique. Un rapport récent de l'ANSES montre la nécessité de mettre en oeuvre de nouveaux outils et une surveillance nationale des pesticides dans l'air ambiant. En effet, la connaissance des niveaux de contamination en pesticides dans l'atmosphère demeure toujours partielle et hétérogène. De plus, une stratégie spatio-temporelle d'échantillonnage est nécessaire pour l'étude des impacts des pesticides sur l'Environnement et sur la Santé Humaine. Le projet CANEPA (Cancers et Expositions aux pesticides Agricoles ; IdEx U Bordeaux) vise à caractériser la contamination externe des agriculteurs et la contamination environnementale par les pesticides en arboriculture. La technique de l'échantillonnage passif s'est largement développée ces 20 dernières années. Elle permet le suivi de polluants dans l'environnement et peut-être appliquée à l'eau, l'air ou encore le sol. Les échantillonneurs passifs présentent l'avantage d'intégrer la contamination du milieu pendant une période d'exposition donnée et d'abaisser les limites de détection grâce à l'accumulation des substances. Ces outils de surveillance ne nécessitent pas d'énergie et permettent un déploiement spatio-temporel plus pertinent. Au cours de ce projet, un suivi annuel par échantillonnage passif à l'aide de mousses en polyuréthane (PUF) a été mis en place début 2017 au sein d'une exploitation de pommiers pour un suivi des concentrations en pesticides dans l'air intérieur et extérieur afin de mieux comprendre l'exposition des travailleurs agricoles. L'analyse des différents échantillons du projet permettra de déterminer les débits de prélèvements des pesticides détectés dans l'air ambiant. De plus, les basses limites de quantification obtenues au cours des développements analytiques permettent un suivi très large de ces composés.
(pp. 2, 27/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, INSERM U1219 - UB - ISPED, BPH, UB, INSERM, UR ETBX, IRSTEA
Natural dissolved organic matter decreases toxic effects of herbicide mixtures towards freshwater microalgae
As primary producers, microalgae are the basis of aquatic food webs. Thus, they can be directly impacted by herbicides which are, in turn, affected by complex and changing conditions of freshwater environments. For instance, dissolved organic matter (DOM) may interact with pesticides and affect their fate and ecotoxicity. Therefore, the present study aimed to investigate whether the natural DOM influences the toxicity of herbicide mixtures towards two freshwater microalgae. To that aim, a diatom (Gomphonema gracile) and a chlorophyte (Sphaerellopsis sp.) isolated from a pristine river were exposed to a mixture of three herbicides, with or without natural DOM. Herbicide concentrations were selected to represent environmentally realistic conditions (0.05µg/L for irgarol and diuron, 0.5µg/L for metolachlor) and a 10-times higher exposure. The responses of the microalgae were assessed over a growth cycle, by monitoring daily their growth and photosynthetic efficiency. On the last day, the intracellular relative lipid content was quantified, as well as the proportion of bacteria in the microcosms to ensure no bloom had occurred. In the absence of DOM, photosynthetic activity decreased in Sphaerellopsis at both concentrations of herbicides, whereas Gomphonema was only impacted at the highest one. DOM alone had no influence on the parameters measured for Gomphonema, but significantly stimulated the growth of Sphaerellopsis. Surprisingly, combined exposure to DOM and herbicides removed the toxic impacts observed without DOM for both species. Our results demonstrate species-specific responses to DOM and herbicides, and highlight a mitigation of pesticides impacts towards microalgae in the presence of natural DOM.
(pp. 21, 27/04/2026)
UR EABX, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IFREMER
The role of natural hazards and human activities on change of sedimentation patterns: The case of Lake Yamanaka (Fuji Five Lakes, Japan)
The last eruption of Mt Fuji (Japan) occurred in A.D. 1707. The eruption lasted 16 days from 16 December 1707 to 1 January 1708 (Tsuya, 1955) and 1.8 km3 of volcanic materials were ejected in total (Miyaji et al., 2011). Lake Yamanaka, a very shallow lake (max. 14. 3 m depth) located at the foot of the east-north-eastern flank of Mt Fuji, was heavily impacted by the eruption. A thick scoria layer entirely covered the catchment of Lake Yamanaka. The thickness of the deposit varies from 5 to 37 cm around Lake Yamanaka and reaches up to 149 cm at the south-west extremity of the catchment (Miyaji et al., 2011). In order to study the influence of Hoei eruption on Lake Yamanaka, 5 gravity cores were taken during the 2014 QuakeRecNankai campaign. The Hoei scoria was present at the bottom of the one core and in the core catcher of the four other cores. High resolution magnetic susceptibility, XRD, XRF, LOI, C/N and 210Pb/137Cs analyses were performed on the gravity cores. The results shows three distinct periods of sedimentation: (1) From Hoei eruption to A.D. 1900; (2) From A.D. 1900 to A.D. 1990; (3) From A.D. 1990 to A.D. 2014. The first period is characterized by a very low sedimentation rate (~0.07 cm/yr). During this period, the sediments of the catchment were trapped below the thick Hoei scoria layer. However, peaks of terrigenous input are recorded. We link such detrical signals with violent typhoons that hit the Fuji Five Lakes region. The water from the heavy rains percolated through the porous thick scoria layer and saturated it. As a result, surface runoffs carried the sediments from the catchment into Lake Yamanaka. The second period (from A.D. 1900 to A.D. 1990) is defined by an increase of the sedimentation rate (~0.16 cm/yr). The development of soil and the agriculture (e.g. pastureland, rice field, mulberry plantations) reduced the impact of Hoei scoria. The terrigenous inputs are higher than previously but remained more or less constant during this period of time. As the thickness of the scoria layer is partially reduced or covered by new soil, rains triggered by smaller typhoons could drain the sediments from watershed and transport them into the lake. The most recent period representing the last 27 years is characterized by a very high sedimentation rate (~1.036 cm/yr). The transition between period 2 and period 3 corresponds to the development of mass tourism and the urbanization around Lake Yamanaka. It is marked by an increasing of atmospheric pollution (Pb, Zn). In the upper part of the cores, a peak of 137Cs is observed. Such peak is related to cesium fall-out after Fukushima incident in 2011. In addition to the fingerprint of human impact, the lake also record a terrigenous signal related to the 2007 Fitow typhoon which provoked damage in the area. This study highlights the influence of eruptions and typhoons on the sedimentation of Lake Yamanaka. In the present day, the sedimentation recovery after a major eruption is accelerated by human activity.
(27/04/2026)
ULiège, ULiège, AGEs, ULiège, UEC, EDYTEM, USMB [Université de Savoie] [Université de Chambéry], CNRS, Fédération OSUG, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ULiège, AORI, UTokyo, UGent, UGent
Repeated fluid expulsions during events of rapid sea-level rise in the Gulf of Lion, western Mediterranean Sea
Based on a High-Resolution 3D seismic block acquired in the Gulf of Lion in 2004-2005 we investigated fluid pipes and pockmarks on the top of the interfluve between the Hérault canyon and the Bourcart canyon both created by turbidity currents and gravity flows from the shelf to the deep basin in the northwestern Mediterranean Sea. Combining the geometry of the potential fluid pipes with the induced deformation of surrounding sediments leads then to the ability to differentiate between potential fluid sources (root vs source) and to better estimate the triggering mechanisms (allochtonous vs. autochtonous cause). We linked together a set of derived attributes, such as Chaos and RMS amplitude, to a 3D description of pipes along which fluids may migrate. As previously shown in other basins, the induced deformation, creating cone in cone or V-shaped structures, may develop in response to the fluid pipe propagation in unconsolidated sediments in the near surface. The level at the top of a cone structure is diachronous. It means that stratigraphic levels over this surface are deformed at the end of the migration. They collapse forming a depression called a pockmark. These pipes are the result of repeated cycles of fluid expulsion that might be correlated with rapid sea-level rise instead of sediment loading. The most recent event (MIS 2.2 stage) has led to the formation of a pockmark on the modern seafloor. It has been used as a reference for calculating the effect of a rapid sea-level rise on fluid expulsion. As all physical and geometrical parameters are constrained, we were able to define that a þ 34 m of sea level rise may account for triggering fluid expulsion from a very shallow silty-sandy layer at 9 m below seafloor since the last glacial stage. This value is consistent with a sea level rise of about 102 m during this period. This study shows that the episodic nature of fluid release resulted from hydromechanical processes during sea-level rise due to the interactivity between high pressure regimes and principal in situ stresses.
(Bulletin de la Société Géologique de France. vol. 188, n° 0037-9409, pp. 24, 27/04/2026)
INSU - CNRS, UM, CNRS, UA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IFREMER
From Antarctica to the subtropics: contrasted geographical concentrations of selenium, mercury, and persistent organic pollutants in skua chicks (Catharacta spp.)
Seabirds integrate bioaccumulative contaminants via food intake and have revealed geographical trends of contamination in a variety of ecosystems. Pre-fledging seabird chicks are particularly interesting as bioindicators of chemical contamination, because concentrations in their tissues reflect primarily dietary sources from the local environment. Here we measured 14 trace elements and 18 persistent organic pollutants (POPs) in blood of chicks of skuas that breed in four sites encompassing a large latitudinal range within the southern Indian Ocean, from Antarctica (Adélie Land, south polar skua Catharacta maccormicki), through subantarctic areas (Crozet and Kerguelen Islands, brown skua C. lonnbergi), to the subtropics (Amsterdam Island, C. lonnbergi). Stables isotopes of carbon (δ13C, feeding habitat) and nitrogen (δ15N, trophic position) were also measured to control for the influence of feeding habits on contaminant burdens. Concentrations of mercury (Hg) and selenium (Se) were very high at all the four sites, with Amsterdam birds having the highest concentrations ever reported in chicks worldwide (4.0 ± 0.8 and 646 ± 123 µg g-1 dry weight, respectively). Blood Hg concentrations showed a clear latitudinal pattern, increasing from chicks in Antarctica to chicks in the subantarctic and subtropical islands. Interestingly, blood Se concentrations showed similar between-population differences to Hg, suggesting its involvement in protective mechanisms against Hg toxicity. Chicks’ POPs pattern was largely dominated by organochlorine pesticides, in particular DDT metabolites and hexachlorobenzene (HCB). Skua chicks from subantarctic islands presented high concentrations and diversity of POPs. By contrast, chicks from the Antarctic site overall had the lowest concentrations and diversity of both metallic and organic contaminants, with the exception of HCB and arsenic. Skua populations from these sites, being naturally exposed to different quantities of contaminants, are potentially good models for testing toxic effects in developing chicks in the wild.
(Environmental Pollution. vol. 228, n° 0269-7491, pp. 464-473, 27/04/2026)
CEBC, INRA, ULR, CNRS, LIENSs, INSU - CNRS, ULR, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Enjeux environnementaux et sanitaires associés aux pesticides : de leur usage à leur dispersion dans l’environnement en lien avec leur impact
(27/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IC2MP [Poitiers], UP, INC-CNRS, CNRS, URVVC, URCA, URCA, CNRS
Synchronous precipitation reduction in the American Tropics associated with Heinrich 2
During the last ice age temperature in the North Atlantic oscillated in cycles known as Dansgaard-Oeschger (D-O) events. The magnitude of Caribbean hydroclimate change associated with D-O variability and particularly with stadial intervals, remains poorly constrained by paleoclimate records. We present a 3.3 thousand-year long stalagmite δ18O record from the Yucatan Peninsula (YP) that spans the interval between 26.5 and 23.2 thousand years before present. We estimate quantitative precipitation variability and the high resolution and dating accuracy of this record allow us to investigate how rainfall in the region responds to D-O events. Quantitative precipitation estimates are based on observed regional amount effect variability, last glacial paleotemperature records, and estimates of the last glacial oxygen isotopic composition of precipitation based on global circulation models (GCMs). The new precipitation record suggests significant low latitude hydrological responses to internal modes of climate variability and supports a role of Caribbean hydroclimate in helping Atlantic Meridional Overturning Circulation recovery during D-O events. Significant in-phase precipitation reduction across the equator in the tropical Americas associated with Heinrich event 2 is suggested by available speleothem oxygen isotope records.
(Scientific Reports. vol. 7, n° 2045-2322, 27/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, EPHE, PSL
Atmospheric Corrections and Multi-Conditional Algorithm for Multi-Sensor Remote Sensing of Suspended Particulate Matter in Low-to-High Turbidity Levels Coastal Waters
The accurate measurement of suspended particulate matter (SPM) concentrations in coastal waters is of crucial importance for ecosystem studies, sediment transport monitoring, and assessment of anthropogenic impacts in the coastal ocean. Ocean color remote sensing is an efficient tool to monitor SPM spatio-temporal variability in coastal waters. However, near-shore satellite images are complex to correct for atmospheric effects due to the proximity of land and to the high level of reflectance caused by high SPM concentrations in the visible and near-infrared spectral regions. The water reflectance signal ((w)) tends to saturate at short visible wavelengths when the SPM concentration increases. Using a comprehensive dataset of high-resolution satellite imagery and in situ SPM and water reflectance data, this study presents (i) an assessment of existing atmospheric correction (AC) algorithms developed for turbid coastal waters; and (ii) a switching method that automatically selects the most sensitive SPM vs. (w) relationship, to avoid saturation effects when computing the SPM concentration. The approach is applied to satellite data acquired by three medium-high spatial resolution sensors (Landsat-8/Operational Land Imager, National Polar-Orbiting Partnership/Visible Infrared Imaging Radiometer Suite and Aqua/Moderate Resolution Imaging Spectrometer) to map the SPM concentration in some of the most turbid areas of the European coastal ocean, namely the Gironde and Loire estuaries as well as Bourgneuf Bay on the French Atlantic coast. For all three sensors, AC methods based on the use of short-wave infrared (SWIR) spectral bands were tested, and the consistency of the retrieved water reflectance was examined along transects from low- to high-turbidity waters. For OLI data, we also compared a SWIR-based AC (ACOLITE) with a method based on multi-temporal analyses of atmospheric constituents (MACCS). For the selected scenes, the ACOLITE-MACCS difference was lower than 7%. Despite some inaccuracies in (w) retrieval, we demonstrate that the SPM concentration can be reliably estimated using OLI, MODIS and VIIRS, regardless of their differences in spatial and spectral resolutions. Match-ups between the OLI-derived SPM concentration and autonomous field measurements from the Loire and Gironde estuaries' monitoring networks provided satisfactory results. The multi-sensor approach together with the multi-conditional algorithm presented here can be applied to the latest generation of ocean color sensors (namely Sentinel2/MSI and Sentinel3/OLCI) to study SPM dynamics in the coastal ocean at higher spatial and temporal resolutions.
(Remote Sensing. vol. 9, n° 2072-4292, 27/04/2026)
LOV, OOVM, UPMC, INSU - CNRS, CNRS, UPMC, INSU - CNRS, CNRS, MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS, IRSNB / RBINS, UB, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, MMS, UM, UN UFR ST, UN, UFR SPB, UN
Proposition de concentrations de références en mercure dans l'ichtyofaune de Guyane
La pollution des écosystèmes aquatiques par le mercure est un problème majeur de la Guyane française, soumis à l'orpaillage illégal intensif depuis de nombreuses années. Au niveau européen, une norme de qualité environnementale pour le biote (NQEbiote : 0,02 mg Hg.kg-1 poids frais) a été définie dans le cadre de la directive cadre sur l'eau (DCE). Ce rapport a pour but d'aider à la mise en place de la NQEbiote en Guyane française par : 1/ si possible, l'identification de sites non pollués par le mercure d'origine anthropique ; 2/ la détermination de concentrations de références en mercure pour l'ichtyofaune associées à ces sites ; 3/ l'identification d'espèces de poissons sentinelles potentielles de cette pollution. Une base de données d'environ 9000 poissons (3000 pour les criques et 6000 pour les fleuves) a été constituée à partir des résultats des programmes de recherche et de surveillance depuis 1993. Les concentrations en mercure mesurées dans le muscle de ces poissons se révèlent presque toujours supérieures à la NQEbiote (100% pour les criques et 89 % pour les fleuves). Peu de zones de références potentielles ont été identifiées sur plus de 200 stations échantillonnées. Ainsi pour les criques, 7 stations réparties sur 6 bassins versants différents présentent des concentrations significativement plus faibles que les autres stations. Sur les fleuves, seulement 2 zones (groupe de stations) ont été identifiées comme références potentielles sur le bassin versant de l'Oyapock. L'analyse de ces données a permis de proposer plusieurs espèces sentinelles, c'est à dire intégratives d'une contamination mercurielle. Pour les criques, il s'agit de Copella carsevennensis, Pyrrhulina filamentosa, Jupiaba (abramoides et keithi), Moenkhausia oligolepis, Pimelodella (cristata, geryi et macturki), Gymnotus carapo et Sternopygus macrurus. Pour les fleuves, 3 genres et espèces ont été retenus : Ageneiosus inermis, Acestrorhynchus (falcatus et microlepis) et Hoplias aïmara. Des recommandations opérationnelles sont proposées pour le suivi de la DCE telles que : i/ échantillonner moins de stations (en privilégiant celles suivies par l'OMS), ii/ espacer la fréquence des suivis (tous les 2 ans), iii/ mais, en contrepartie, augmenter l'effort de pêche sur les espèces sentinelles proposées.
(pp. 78, 27/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR MALY, IRSTEA