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The PRIMA promise of deciphering interstellar dust evolution with observations of the nearby Universe
No full textInternational audienceThis paper develops a few science cases, using the PRIMA far-IR probe, aimed at achieving several breakthroughs in our understanding of the dust properties and their evolution. We argue that the specific observational capabilities of PRIMA, namely its unprecedented sensitivity over the whole far-IR range and the possibility to obtain continuous spectra between wavelengths 24 and 235 microns, are essential to progress in our understanding of the physics of the interstellar medium and galaxy evolution. Our science cases revolve around observations of nearby galaxies. We discuss the importance of detecting the IR emission of the diffuse interstellar medium of these galaxies, including very low-metallicity systems. We also discuss the opportunity of detecting various solid-state features to understand the mineralogy of interstellar grains. Finally, we stress the unique opportunity brought by the possible simultaneous measures of both the dust continuum and the far-IR fine-structure gas lines. These science cases could be distributed in a few large programs
Prévision des étiages à l’échelle nationale par la plateforme opérationnelle PREMHYCE
No full textNational audienceMieux prévoir les sécheresses, qu’elles soient météorologiques, agricoles ou hydrologiques, est un enjeu majeur pour la protection des milieux naturels et pour de nombreux secteurs d’activité, comme l’agriculture, la production d’énergie, la production d’eau potable, la navigation, le tourisme, etc.Conscients de la nécessité de doter les gestionnaires de l’eau d’outils performants de prévision des étiages dans un contexte de changement climatique, l’Office français de la biodiversité (OFB) et la Direction de l’eau et de la biodiversité (DEB) ont soutenu depuis 2011 une initiative visant à construire une plateforme opérationnelle de prévision des étiages. Cette plateforme, appelée PREMHYCE, est le fruit d’une collaboration scientifique et technique de long terme entre INRAE, Météo-France, l’Université de Lorraine, le BRGM et EDF (Tilmant et al., 2023).Elle exploite cinq modèles hydrologiques et divers ensembles de scénarios météorologiques, pour produire des prévisions de débit probabilistes, permettant d’estimer les risques de passer sous les seuils d’étiage (typiquement vigilance, alerte, alerte renforcée ou crise). Les échéances de prévision vont de quelques jours à plusieurs semaines, en fonction des objectifs et des bassins concernés. Ces dernières années, cette plateforme a évolué et a été mise à jour dans le cadre d’un projet de recherche (ANR CIPRHES, 2021-2025), avec notamment des travaux sur les prévisions météorologiques, la modélisation hydrologique, la quantification des incertitudes et l’amélioration de l’interface en concertation avec les utilisateurs. La plateforme fournit tous les jours des prévisions de débit sur plus de 1200 points répartis sur le réseau hydrographique français, pour des échéances allant jusqu’à 90 jours. Ces prévisions sont actuellement utilisées par plus d’une quarantaine d’utilisateurs (DREAL, DDT, EPTB, etc.). Le poster vise à présenter le service hydrologique PREMHYCE, ses principales fonctionnalités, son spectre d’application, et ses évolutions récentes
Endocrine effects of Imazalil on aromatase expression, vitellogenesis and ovarian histology using cyp19a1a-eGFP-casper transgenic zebrafish
No full textInternational audienceConsidering the hazards and risks posed by endocrine disrupting chemicals (EDC) to organisms, there is a need to study their effects. To that end, transgenic fish are powerful models that can provide mechanistic information regarding the endocrine activity of test chemicals. In this study, we used a newly developed transgenic zebrafish line (cyp19a1a-eGFP-casper) in the OECD 21-day fish assay (OECD TG 230) to provide additional mechanistic insight on Imazalil (IMZ; 1.9; 9.9 and 140.7 μg/L). After 21 days of exposure to IMZ, the circulating concentrations of 17-β-estradiol (E2) and vitellogenin decreased in females, reflecting the aromatase activities inhibition. Exposure to 140.7 μg/L of IMZ for 21 days also resulted in a change in the proportion of the different oocyte stages in the ovaries, with an accumulation of large oocytes in exposed females. In addition to the classical endpoints, in vivo GFP fluorescence was quantified in the ovaries during the time course of the exposure to follow gonadal aromatase expression. After seven days of exposure, ovarian aromatase expression increased in females exposed to medium and high concentrations of IMZ, persisting over the 21-day of exposure in fish from the highest concentration group and reflecting a compensatory response to the aromatase enzymatic activities inhibition. Results from the present study provided valuable information on the mode of action and the effects of IMZ in zebrafish. Transgenic zebrafish exposure to IMZ caused a cascade of responses consistent with effects reported for wild-type fish exposed to azole fungicides, both qualitatively and quantitatively. The cyp19a1a-eGFP (-casper) transgenic zebrafish lines, allowed in vivo monitoring of gonadal aromatase expression in a time- and concentration-dependent manner thereby demonstrating their relevance to provide complementary mechanistic information on aromatase in regulatory assays such as OECD TG 230
Suivis in situ et expérimental des dépôts industriels de l'Orne (Lorraine) en contexte de renaturation : devenir des composés aromatiques polycycliques
No full textIron and steelmaking plants in Lorraine were located near iron ore deposits, transport routes and water supplies. In this context, the Orne River, a tributary of the Moselle in France, has undergone major physical changes, such as canalisation, dam construction, and dredging, as well as chemical changes due to the discharge of industrial sludges. In order to comply with the Water Framework Directive (2000/60/EC), two dams were completely opened in 2019, exposing the riverbanks composed of steel industry sludge. This thesis focuses on monitoring and analyzing the evolution of these iron and steel deposits since the opening of the dams and is based on (1) in situ monitoring and (2) experimentally simulating of the deposits. Monitoring was carried out by annual coring from 2017 to 2022, focusing on the mineralogy, chemical composition and particle size distribution of the deposits. The iron and steel deposits are characterised by fine granulometry (decile 50, D50 ≈ 20 µm) and high contents of iron and trace metals (Fe = 20 - 30%, Zn and Pb > 10,000 mg/kg). The content of polycyclic aromatic compounds (PACs) fluctuates with depth, from 20 to 194 µg/g. The presence of certain polar PAHs, which are oxygenated, nitrogenated or sulphurated, has allowed the identification of different levels. Some of the levels are characterised by the contribution of coal tar, a by-product of the coking process. The availability of polycyclic aromatic hydrocarbons (PAHs), estimated by thermal analysis, varies with depth (0 - 60% of PAHs) and is independent of the total concentration of PAHs. After the dam opening, bank erosion was estimated by superimposing elemental and D50 profiles. The presence of gypsum throughout the core indicates the oxidation of the entire deposit. The PAH profile along the length of the sample remains similar before and after opening, with concentrations of the same order of magnitude. However, a change in the PAH profile was observed, while molecular ratios (isomeric PAHs and between PAHs and polar PACs containing a ketone function, known as Keto-CAPs) highlighted the leaching of certain compounds in the first 20 to 30 cm. This also resulted in a reduction in the availability of PAHs, suggesting the mobilisation of the most available molecules. Multi-year monitoring confirmed the observed trends and indicated oxidation of some PAHs. The aging of the deposits was simulated through laboratory oxidation experiments at low temperature of 45°C, while contaminant (re)mobilisation was assessed using batch leaching experiments. Attenuation of PAHs and certain polar CAPs was observed and Keto-CAPs were found to be formed from PAHs. The release of certain elements and the acidification of the leachate strongly suggest a slight oxidation of certain mineral phases, especially sulphides. Mobilisation of the more soluble polar PAHs was also observed. The equilibrium partitioning of PAHs and oxygenated PACs in the batch experiments was dominated by the phenomenon of dissolution, as described by Raoult's law. Overall, the deposits showed minimal release of elements and organic contaminants to the aqueous phase.Les sites sidérurgiques en Lorraine ont été installés à proximité des gisements de fer, des voies de transport et des zones d'approvisionnement en eau. Dans ce contexte, l'Orne, affluent de la Moselle (France), a subi de fortes modifications physiques (chenalisation, barrages, curages) et chimiques (rejets des boues industrielles). Pour répondre à la directive cadre sur l'eau (2000/60/CE), deux barrages ont été entièrement ouverts en 2019, mettant à nu des berges constituées de boues sidérurgiques. Ces travaux de thèse s'intéressent au suivi et à l'évolution de ces dépôts sidérurgiques depuis l'ouverture des barrages et s'articulent autour de (1) le suivi in situ et (2) une simulation expérimentale des dépôts. Le suivi a été réalisé par carottage annuel de 2017 à 2022 par la mesure de leur minéralogie, leur composition chimique et leur granulométrie. Les dépôts sidérurgiques sont caractérisés par une granulométrie fine (décile 50, D50 ≈ 20 µm) et des teneurs en fer et métaux traces élevées (Fe = 20 - 30 %, Zn et Pb > 10 000 mg/kg). Les teneurs en composés aromatiques polycycliques (CAP) fluctuent en fonction de la profondeur (20 - 194 µg/g). La présence de certains CAP polaires (oxygénés, azotés ou sulfurés) a permis de distinguer différents niveaux dont certains sont marqués par la contribution de goudron de houille (sous-produit obtenu lors de la cokéfaction). La disponibilité des hydrocarbures aromatiques polycycliques (HAP), estimée par analyse thermique, est variable selon la profondeur (0 - 60 % des HAP) et indépendante de la concentration totale en HAP. Après ouverture, une érosion des berges a été estimée par superposition des profils élémentaires et granulométriques. L'apparition de gypse sur l'ensemble de la carotte, démontre l'oxydation de l'ensemble du dépôt. Le profil des CAP le long du prélèvement est semblable avant et après ouverture, avec des concentrations de même ordre de grandeur. Un changement dans le profil des HAP a néanmoins été observé tandis que les rapports moléculaires (HAP isomériques et entre HAP et CAP polaires comportant une fonction cétone, notés Keto-CAP) ont permis de mettre en évidence la lixiviation de certains composés dans les 20 à 30 premiers cm. Cela s'est également traduit par une diminution de la disponibilité des HAP, suggérant une mobilisation des molécules les plus disponibles. Le suivi pluriannuel a permis de confirmer les tendances observées et suggère une oxydation de certains HAP. Le vieillissement des dépôts a été simulé à l'aide d'expériences en laboratoire (oxydation à basse température, 45 °C) tandis que la (re)mobilisation des contaminants a été évaluée par des expériences de lixiviation en batch. Tandis qu'une atténuation des HAP et de certains CAP polaires a été observée, les Keto-CAP ont été formés à partir des HAP. Le relargage de certains éléments ainsi qu'une acidification des eaux de lixiviation suggèrent fortement une légère oxydation de certaines phases minérales, notamment des sulfures. Une mobilisation des CAP polaires, plus solubles, a été observée. Le partitionnement à l'équilibre des HAP et des CAP oxygénés lors des expériences en batch est dominé par le phénomène de dissolution (loi de Raoult). Globalement, les dépôts présentent un faible relargage d'éléments et de contaminants organiques en phase aqueuse
Spatio-Temporal Distribution of Intertidal Shrimps, P. serratus and P. elegans from Two Western and Eastern Cotentin Sites (Normandy, France)
No full textInternational audienceLa distribution spatio-temporelle de deux espèces de crevettes Palaemon a été étudiée sur deux sites, Grandcamp Maisy (GRE) et Blainville sur Mer (BLE), sur la côte de la Manche (Normandie, France). Un suivi saisonnier (printemps, été, automne 2022 et hiver 2023) sur 15 stations d’échantillonnage (trois transects et cinq niveaux hypsométriques) à GRE et neuf stations d’échantillonnage (trois transects et trois niveaux hypsométriques) à BLE a révélé la présence de deux espèces, Palaemon serratus et Palaemon elegans. L’abondance des deux espèces présentait des variations saisonnières liées à la reproduction et au recrutement, ainsi qu’aux migrations entre l’estran et le large dans le cas de P. serratus. Sur le plan spatial, dans la zone intertidale, P. elegans était plus répandu aux niveaux hypsométriques supérieurs, tandis que P. serratus était plus abondant aux niveaux inférieurs, sauf en automne, lorsque les jeunes crevettes étaient recrutées aux niveaux hypsométriques les plus élevés. La largeur de la « niche écologique » s’est révélée plus importante pour P. serratus que pour P. elegans à GRE, et particulièrement variable pour P. serratus sur ce site. Enfin, le plus grand chevauchement de niche a été enregistré en été (GRE) – automne (BLE), mais il est resté assez limité tout au long des saisons (valeur maximale de 0,246 à BLE). Bien que les deux espèces étudiées partagent des similitudes biologiques (elles appartiennent toutes deux à la famille des Palaemonidae) et des caractéristiques écologiques communes (par exemple, leur présence dans la zone intertidale rocheuse), les résultats obtenus suggèrent une compétition interspécifique relativement limitée entre les deux espèces
Euclid Quick Data Release (Q1). Extending the quest for little red dots to z<4
No full textInternational audienceRecent James Webb Space Telescope (JWST) observations have revealed a population of sources with a compact morphology and a `v-shaped' continuum, namely blue at rest-frame A and red at longer wavelengths. The nature of these sources, called `little red dots' (LRDs), is still debated, since it is unclear if they host active galactic nuclei (AGN) and their number seems to drastically drop at z<4. We utilise the 63 covered by the quick Euclid Quick Data Release (Q1) to extend the search for LRDs to brighter magnitudes and to lower z than what has been possible with JWST to have a broader view of the evolution of this peculiar galaxy population. The selection is done by fitting the available photometric data (Euclid, Spitzer/IRAC, and ground-based griz data) with two power laws, to retrieve the rest-frame optical and UV slopes consistently over a large redshift range (i.e, z<7.6). We exclude extended objects and possible line emitters, and perform a visual inspection to remove imaging artefacts. The final selection includes 3341 LRD candidates from z=0.33 to z=3.6, with 29 detected in IRAC. Their rest-frame UV luminosity function, in contrast with previous JWST studies, shows that the number density of LRD candidates increases from high-z down to z=1.5-2.5 and decreases at even lower z. Less evolution is apparent focusing on the subsample of more robust LRD candidates having IRAC detections, which is affected by low statistics and limited by the IRAC resolution. The comparison with previous quasar UV luminosity functions shows that LRDs are not the dominant AGN population at z<4. Follow-up studies of these LRD candidates are key to confirm their nature, probe their physical properties and check for their compatibility with JWST sources, since the different spatial resolution and wavelength coverage of Euclid and JWST could select different samples of compact sources
Euclid Quick Data Release (Q1): From spectrograms to spectra: the SIR spectroscopic Processing Function
No full textInternational audienceThe Euclid space mission aims to investigate the nature of dark energy and dark matter by mapping the large-scale structure of the Universe. A key component of Euclid's observational strategy is slitless spectroscopy, conducted using the Near Infrared Spectrometer and Photometer (NISP). This technique enables the acquisition of large-scale spectroscopic data without the need for targeted apertures, allowing precise redshift measurements for millions of galaxies. These data are essential for Euclid's core science objectives, including the study of cosmic acceleration and the evolution of galaxy clustering, as well as enabling many non-cosmological investigations. This study presents the SIR processing function (PF), which is responsible for processing slitless spectroscopic data. The objective is to generate science-grade fully-calibrated one-dimensional spectra, ensuring high-quality spectroscopic data. The processing function relies on a source catalogue generated from photometric data, effectively corrects detector effects, subtracts cross-contaminations, minimizes self-contamination, calibrates wavelength and flux, and produces reliable spectra for later scientific use. The first Quick Data Release (Q1) of Euclid's spectroscopic data provides approximately three million validated spectra for sources observed in the red-grism mode from a selected portion of the Euclid Wide Survey. We find that wavelength accuracy and measured resolving power are within requirements, thanks to the excellent optical quality of the instrument. The SIR PF represents a significant step in processing slitless spectroscopic data for the Euclid mission. As the survey progresses, continued refinements and additional features will enhance its capabilities, supporting high-precision cosmological and astrophysical measurements
Environmental Evaluation of the Mining Industry, Proposal of a New Method: Mining Environmental Impact Assessment Methodology (MEIAM)
No full textInternational audienceThe Mining Environmental Impact Assessment Methodology (MEIAM) is developed to allow predicting environmental and human health impacts on mining projects. It combines both the chronic and the accidental sources of impacts, and that at all phases of the life cycle of the project, including the prospection and the after closure of the mine. The method is designed to address all environmental problems: groundwater, surface water, soil, air, fauna and flora. A case study to test the feasibility of MEIAM and to compare its outputs to the usual approach has been carried out for the Afema gold mine located in Côte d’Ivoire. The case study was restricted to the groundwater. The results of this implementation were compared with those obtained by using the matrices method in the EIA study of this mining project. The two methods led to different conclusions. Unlike the EIA study, MEIAM identifies and evaluates many pollution scenarios. In the EIA study the potential groundwater pollution scenario involving soils leaching and, working face (open pit borders) were not considered. In addition, the exploration phase was not considered in the EIA study. The present work concluded that the impact of groundwater pollution is high at the operation and the closure phases, while previous study indicated an average impact (for the few considered scenarios). For these high impacts, some measures have been proposed to protect groundwater resources. MEIAM better assesses the impact of pollution by considering the intrinsic parameters (geology, climate, initial state of the environmental component) of the mine site, the nature of the potential pollutants and feedbacks. It may therefore be of considerable value in mining projects
The Expression of Shmt Genes in Amphioxus Suggests a Role in Tissue Proliferation Rather than in Neurotransmission
No full textInternational audienceSerine hydroxymethyltransferases (SHMTs) are key enzymes in one-carbon metabolism, with vertebrates possessing two paralogs, cytosolic SHMT1 and mitochondrial SHMT2, implicated in nucleotide biosynthesis and glycine metabolism. In this study, we investigate the evolutionary history of animal Shmt genes and analyze the expression patterns of Shmt genes in developing amphioxus (Branchiostoma lanceolatum). Phylogenetic analyses indicate the presence of Shmt1 and Shmt2 orthologs in deuterostomes, spiralians and placozoans, which is consistent with an ancient Shmt gene duplication event predating bilaterian diversification. Gene expression analyses in developing amphioxus show that Shmt2 expression is confined to the somites and absent from neural tissues. In contrast, Shmt1 is broadly expressed across germ layers, but its transcription is restricted to tissues characterized by strong cell proliferation. Notably, Shmt1 expression in the nervous system does not match the distribution of glycinergic neuron populations, implying a negligible role in glycine neurotransmitter synthesis. Instead, the spatial correlation of Shmt1 expression with mitotically active domains suggests a primary function in nucleotide biosynthesis via one-carbon metabolism. These findings indicate that SHMTs predominantly support cell proliferation rather than neurotransmission in amphioxus
Constraints and Adaptations to Global Change at the Land-Sea Interface: For a Shared Ecological and Energy Transition
No full textInternational audienceCoastal or semi-enclosed seas, coastal or interface zones between land and sea are areas widely coveted by numerous human activities. These activities do not assess the effects and impacts of their cumulative pressures on the natural environment: coastal development, tourism, terrestrial pollution, maritime transport, dredging and piling, extraction of marine aggregates and development or planned development of marine wind farms or tidal turbines. In this context and despite the high productivity of these ecosystems, fishing and shellfish farming, which also exert their own environmental pressures, have some difficulties in ensuring their sustainability in an increasingly man-made environment and generating increasingly exacerbated conflicts of use.The symposium will address some aspects of resilience (via their capacity to adapt to global change) of these coastal ecosystems and adaptation of human communities to climate change in a context of full use of natural resources.A more holistic approach to the impact of all uses on the environment to ensure a more optimal management of the Commons, needs to be implemented. In Japan, the concept of Sato-umi (harmony between the coastal sea and local communities) is being implemented and incorporates participatory science and active restoration projects in an integrated coastal zone management framework