Portail HAL de l'Université du Littoral Côte d'Opale
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Theoretical estimation of iron isotope fractionation during cloud processing of aerosols
No full textInternational audienc
The immeasurable value of plankton to humanity
No full textInternational audiencePlankton, a diverse group of aquatic organisms, make Earth livable, regulate aquatic life, and provide benefits to human societies such as access to clean water, food security, and well-being. They also support economies and inspire biotechnological innovations. This article aims to raise awareness of the value of plankton to humanity and serves as an informative guide for aquatic professionals, policymakers, and anyone interested in plankton. We present the value of plankton across six themes of human interest: biogeochemistry; ecology; climate; the evolution of science; economy; and culture, recreation, and well-being. Guided by the 2022 Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services values assessment, we introduce the six themes under the Life Framework of Values to offer a comprehensive summary of the significance of plankton to humanity. In addition, we provide examples of plankton variables used in policy frameworks and recommendations for enhancing understanding of their value through long-term sustainable research and monitoring
Blue Carbon in the Authie estuary : Carbon sequestration and exchanges in surface sediments in a context of dyke removal
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A quantitative assessment of the behavior of metallic elements in urban soils exposed to industrial dusts near Dunkerque (northern France)
No full textInternational audienceIn urban and industrialized areas, soil contamination and degradation caused by industrial dust deposition may pose significant health and environmental risks. Generally, the mobility and thus bioavailability of potentially toxic elements (PTEs) are key factors in these issues. In the Dunkerque agglomeration, one of the most industrialized regions in France, the soils are periodically exposed to metallurgical dust fallout, rich in PTEs. However, no study has reported on the behavior of these PTEs once integrated into the soils. The aim of this study is therefore to assess the fate of PTEs in the urban soils of Dunkerque in terms of vertical migration and potential bioavailability.Four soil short cores were collected in the city of Gravelines (Dunkerque agglomeration) along a gradient from industrial emitters to deposition sites. Each soil core was cut into discrete 1 cm sections for PTE concentration analyses (ICP-AES/MS). Single HCl extractions were performed to evaluate PTE mobility in soils and their behavior according to the current soil parameters. For this purpose, key soil properties were identified, including grain-size distribution, mineralogy, pH, cation exchange capacity (CEC), TOC (total organic carbon), calcium carbonates and water contents in addition to the soil chemical composition (XRF, ICP-AES/MS).The studied soils revealed globally low absorbent capacities for pollutants (CEC averaging ), partially counterbalanced by the buffering effect of calcium carbonates (contents ranging from 8 %–30 %). Near the industrial emitters, minor (1 < EF <3) to moderately severe (5 < EF < 10) enrichment factors (EFs) were highlighted for industrial PTE (Cr, Ni, Mo, Mn, Cd and Zn) in the top 3 cm of soils near the industrial emitters. The contamination profiles of these soils are assigned to atmospheric inputs of metallurgical dust. Using a relatively strong leaching reagent (1 M HCl), we estimated a low vertical mobility for Cr, Ni and Mo (average leached ratios < 25 %) in soils, suggesting their association with refractory phases (natural or anthropogenic). In contrast, Mn, Cd and Zn, which are related to industrial and/or urban sources, present a higher mobility (average leached ratios>60 % for Mn and Cd and about 44 % for Zn).Our study points out the stability of industrial PTEs in soils under the current physicochemical conditions (calcareous soils with a slightly basic pH of 7.8). In this context, the monitoring of industrial PTEs in these urban soils is highly recommended, considering (1) the presence of allotment gardens in the vicinity of emitters and (2) the potential evolution of soil conditions due to increasing flood events
De la rareté au tsunami de données : une histoire de la séparation aveugle de sources
No full textNational audienceNous revisitons l'histoire de la séparation de sources au regard des volumes de données disponibles : nous montrons comment ces derniers ont permis le développement de techniques d'apprentissage (profond). Nous présentons en conclusion quelques perspectives prenant en compte les contraintes environnementales, énergétiques et matérielles qui surviendront dans un futur plus ou moins proche
Comment le sport participe au changement socio-culturel à Mayotte ?
No full textInternational audienceCette question problématique sert de fil rouge à la présente communication. Elle relate une partie de monenquête exploratoire qui s’est déroulée entre septembre 2018 et juillet 2022, avec 8 périodes continues de plusde 4 mois sur le terrain. La démarche de recherche se veut inductive et compréhensive (avec un matériauconstitué d’un travail archivistique qui retrace la chronologie de l’histoire sportive de l’archipel, desobservations consignées dans un carnet de terrain et des verbatims d’entretiens formalisés et informels avec lesacteurs enquêtés). Elle s’appuie, au départ, sur cette question, assez large, et relative aux effets socio-culturelsde l’implantation du système sportif à Mayotte avec, en toile de fond, le changement socio-culturel, les normesen transition qui l’accompagne et la gestion « déterritorialisée » des politiques sportives comme cadre d’analyse.L’enquête ethnographique concerne les dynamiques d'urbanisation qui entraînent l'implantation de nouveauxéquipements dédiés aux sports. Elles suggèrent une modification des usages sociaux et des rapports au territoireen tant qu’ils deviennent rapidement des hauts-lieux de la vie des villages et posent indissolublement desproblèmes de médiation [appropriation spontanée et conflits de représentation]. D’autre part, le déploiementrécent des politiques publiques [domino-centrées] sera questionné au regard des spécificités insulaires etculturelles ainsi que des modalités de diffusion du modèle sportif français (exemple : sportivisation de la coursede pneus, folklorisation du Murengue. Enfin, il s’agit de mettre en exergue les modalités bureaucratiques et les exigences fixées par les modes de gouvernances du monde sportif : de ses cadres institutionnels à ses évolutions réglementaires
Vol d’objets sacrés à Roquetoire en 1791 ?
No full textInternational audienceEn plein cœur de l’été 1791, un vol d’objets sacrés à l’église de Roquetoire semble bien révéler l’état d’esprit d’une partie de la population du village, un an après la mise en place de la Constitution civile du clergé. Il illustre sur le terrain les divisions entre le clergé jureur et le clergé réfractaire
Coupled VAE and interpolator approach for fast hyperspectral image emulation
No full textInternational audienceGenerating high-fidelity hyperspectral data is an essential component of observation missions but traditionally involves expensive numerical simulations. This challenge can be addressed by constructing a statistical model approximating the distribution of simulated data. This process is referred to as emulation. This paper introduces a novel hyperspectral emulation approach pairing a Variational Autoencoder and a Neural Interpolator for fast hyperspectral image (HSI) emulation. The VAE is trained to reproduce data, and an interpolator is then used to link biophysical parameters to the latent space learned by the VAE. This method enables the sampling of HSI from biophysical parameters efficiently and accurately. This approach is evaluated on Sentinel-3 Ocean Colour Images and shows significant improvements in accuracy, efficiency, and scene-level information synthesis compared to existing methods
Microplastic contaminations in a set of beverages sold in France
No full textInternational audienceMicroplastics are present in all environments and have even been detected in humans. As a result, more and more worldwide studies are focusing on the contamination of food and beverages by microplastics. To date, none of these studies has examined the contamination levels in beverages sold in France. The current study was set up to address this gap and investigate the level of microplastic contamination in water, soft drinks, beer and wine. This study does not aim to provide an exhaustive overview of all the drinks sold in France. However, efforts were made to study the impact of different containers: plastic, glass, brick, can, cubitainer, on this contamination. Heterogeneous results were obtained with mean contamination levels of 2.9 ± 0.7 MPs/L in waters, 31.4 ± 16 MPs/L in colas, 28.5 ± 13.1 MPs/L in teas, 45.2 ± 21.4 MPs/L in lemonades, 82.9 ± 13.9 MPs/L in beers and 8.2 ± 3.3 MPs/L in wines. It was observed that the most contaminated containers were glass bottles. Caps were suspected to be the main source of contamination, as the majority of particles isolated in beverages were identical to the color of caps and shared the composition of the outer paint
Exposure to the main Organic Plastic Additives through food contamination
No full textInternational audienceThe use of organic plastic additives (OPAs) in food packaging has led to their widespread presence in various foodstuffs. These additives, including mainly flame-retardants, bisphenols, UV-stabilizers and plasticizers, are known for their potential hazards and environmental impact. This review aims to comprehensively assess the contamination of food products by OPAs and evaluate their role as vectors of exposure to hazardous chemicals. A review of recent literature was conducted, focusing on studies that report on the presence and concentrations of OPAs in different food categories, including aquatic products, beverages, cereals, dairy products, eggs, oils, fats, meat, poultry, vegetables, fruits and other food categories. The review also examines regional variations in contamination levels and identifies the pollutants. Significant contamination of foodstuffs by OPAs are highlighted, with varying concentrations reported across different regions and food types. Potential sources of contamination include food-packaging materials and environmental pollution. This review also identifies research gaps and proposes future directions to improve the study of OPAs in food, aiming to enhance the reliability and comparability of findings while supporting efforts to mitigate contamination risks