Fire variability in the southeastern France over the past 8500 years
(23/05/2022)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CEFREM, UPVD, INSU - CNRS, CNRS, LOCEAN-VOG, LOCEAN, MNHN, IRD, INSU - CNRS, SU, CNRS, IPSL (FR_636), ENS-PSL, UVSQ, CEA, INSU - CNRS, X, CNES, SU, CNRS, UPCité, HNHP, MNHN, UPVD, CNRS
Effects of Biofilms and Particle Physical Properties on the Rising and Settling Velocities of Microplastic Fibers and Sheets
Vertical dynamics of microplastics (MPs) in the water column are complex and not fully understood due to the diversity of environmental MPs and the impact of weathering and biofouling on their dynamical properties. In this study, we investigate the effects of the particle properties and biofilm on the vertical (settling or rising) velocity of microplastic sheets and fibers under laboratory conditions. The experiments focus on 3 types of MPs (polyester PES fibers, polyethylene terephthalate PET sheets, and polypropylene PP sheets) of 9 sizes and 2 degrees of biological colonization. Even though pristine PES fibers and PET sheets had a similar density, the sinking velocity of fibers was much smaller and independent of their length. The settling or rising velocity of sheets increased with the particle size up to a threshold and then decreased due to the wake of horizontal oscillations in large particles. Biofilm had unexpected effects on vertical velocities. Irregular biofilm distributions can trigger motion instabilities that decrease settling velocities of sheets despite the increase of density. Biofilm can also modify the orientation of fibers, which may increase their settling velocity. Finally, we selected the most performant theoretical formulation for each type of particle and proposed modifications to consider the effect of biofilm distribution.
(Environmental Science and Technology, n° 0013-936X, 20/05/2022)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS, SIAME, UPPA
Approche multi-analytique optique et moléculaire pour construire des empreintes de matière organique dissoute (MOD) typiques de sources naturelles et anthropiques
Dans un contexte d’amélioration de la connaissance des apports anthropiques dans les cours d’eau, la question de l’utilisation de la matière organique dissoute (MOD) pour différencier les types d’apports (e.g. agricoles, industriels et urbains) reste un réel défi. L’objectif de cette étude est de déterminer des marqueurs physico-chimiques caractéristiques de sources naturelles (e.g. apports terrigènes, production autochtone) et anthropiques (e.g. rejets de stations de traitement des eaux usées STEU, ruissellement urbain) de MOD à l’échelle de bassins versants. Pour cela, les principaux types de sources de MOD ont été identifiés et échantillonnés à partir de ressources géographiques. Ensuite, la MOD de chaque type de source a été caractérisée en utilisant un large panel de techniques analytiques : dosage du carbone organique dissous, analyse par spectroscopie UV-Visible et fluorescence 3D, analyse par chromatographie d’exclusion stérique couplée à la détection UV et fluorescence (HPSEC-UV/Fluo), et analyse moléculaire par chromatographie liquide couplée à la spectrométrie de masse haute résolution (LC-HRMS). Enfin, une série de tests statistiques (analyses classiques et multivariées) appliquée à un jeu de données qui regroupe plus de 200 échantillons, a permis d’identifier des marqueurs et de construire des empreintes spécifiques des sources de MOD sélectionnées apriori.
(18/05/2022)
RiverLy, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Characterization of the metabolomic response of freshwater biofilms to urban wastewater
Urban wastewater treatment plants (WWTPs) release large amounts of pollutants (e.g. chemicals, microbes) into aquatic environments that may impact exposed organisms. Among these organisms, aquatic biofilms as a complex assemblage of microorganisms with a short life cycle (e.g. microalgae, bacteria, etc.) and by their key role in aquatic ecosystems (e.g. primary production) are relevant and increasingly used to investigate the impact of chemical contamination at the community level. Despite increasing knowledge on the impact of chemical stress on these communities, the underlying (molecular/biochemical) mechanisms remain poorly described while usual descriptors provide a partial picture of phenotype. To tackle this issue, untargeted metabolomics approach is relevant through the simultaneous characterization of chemical exposure and the global response of the whole biofilm. In this context, this study focuses on the characterization of the potential impact of urban (WWTPs) on aquatic periphytic microbial communities by implementing an untargeted metabolomic approach. To do so, colonization/exposure was carried out during 4 weeks at upstream and downstream sites from three WWTPs along a tributary of the Arcachon Basin (Belin Beliet: upstream, Salles: intermediate; Mios: downstream). First, multivariate analyses (PCA and HCA) showed discrepancies in the metabolomics profile between the three WWTPs and between upstream and downtream site of each WWTP. This difference is more marked at the downstream site (Mios), likely because of increasing disturbances along the tributary (e.g detection of pesticides only on the downstream site). Moreover, the strong discrimination between upstream and dowstream sites at Mios suggested that this WWTP is a source of pollutants. At this site, further univariate analysis combined to pathways analysis allowed preliminary annotation (i.e. based only on MS1) that highlighted a potential impact on the respiration and photosynthesis pathways. Further investigations are ongoing to improve the annotation through the analysis of MS² spectra and by using an internal database. Overall, this study confirms the relevance of untargeted metabolomics to highlight potential impact of urban discharges on aquatic microbial communities.
(15/05/2022)
UR EABX, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UB, CNRS, INRAE
Estimation of Local Equilibrium Foam Model Parameters as Functions of the Foam Quality and the Total Superficial Velocity
In this paper, the behavior of foam in a porous medium is studied in order to understand the effect of the fluid velocity on foam properties. This aspect is crucial during foam injection, as due to radial effects the foam velocity largely decreases around the injection well. The foam properties are detailed through the use of a new local equilibrium foam model parameter estimation approach using an improved new shear function and based on the most widely used STARS model developed by the Computer Modeling Group (CMG). A new mode of calculation of the STARS model parameters is then presented in order to allow both a semiautomated fitting of several quality scan pressure curves and a consideration of the role of the total velocity. The approach is tested through column experiments done at various velocities and gas fractions. Furthermore, the proposed model is also tested on literature results in order to validate it for very different experimental conditions. This study and the fitted results are then used to understand, on both our column experiments and the literature data, the existence of two shear effects and their origins.
(ACS Omega. vol. 7, n° 2470-1343, pp. 16866-16876, 12/05/2022)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, Bordeaux INP, UBM, I2M-BX, UB, CNRS, INRAE
Performance and Uncertainty of Satellite-Derived Bathymetry Empirical Approaches in an Energetic Coastal Environment
Objectives of this study are to evaluate the performance of different satellite-derived bathymetry (SDB) empirical models developed for multispectral satellite mission applications and to propose an uncertainty model based on inferential statistics. The study site is the Arcachon Bay inlet (France). A dataset composed of 450,837 echosounder data points and 89 Sentinel-2 A/B and Landsat-8 images acquired from 2013 to 2020, is generated to test and validate SDB and uncertainty models for various contrasting optical conditions. Results show that water column optical properties are characterized by a high spatio-temporal variability controlled by hydrodynamics and seasonal conditions. The best performance and highest robustness are found for the cluster-based approach using a green band log-linear regression model. A total of 80 satellite images can be exploited to calibrate SDB models, providing average values of root mean square error and maximum bathymetry of 0.53 m and 7.3 m, respectively. The uncertainty model, developed to extrapolate information beyond the calibration dataset, is based on a multi-scene approach. The sensitivity of the model to the optical variability not explained by the calibration dataset is demonstrated but represents a risk of error of less than 5%. Finally, the uncertainty model applied to a diachronic analysis definitively demonstrates the interest in SDB maps for a better understanding of morphodynamic evolutions of large-scale and complex coastal systems
(Remote Sensing. vol. 14, n° 2072-4292, pp. 2350, 12/05/2022)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BRGM
Sensibilité des stades précoces de l'esturgeon sterlet à des concentrations environnementales de deux fongicides : le boscalid et l'imazalil
(11/05/2022)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR EABX, INRAE
Peer Community In… A free recommendation process of preprints based on peer reviews
Les Peer Community In… (PCI, https://peercommunityin.org/) sont des communautés scientifiques qui organisent des processus éditoriaux de science ouverte. Il s'agit de communautés spécialisées effectuant une évaluation scientifique par les pairs et à la demande des auteurs, de preprints déposés sur des serveurs de preprints ou des archives ouvertes institutionnelles. Dans chaque PCI, les recommandeurs, qui sont les équivalents des éditeurs scientifiques de revues, constituent une équipe de reviewers qui réalisent une évaluation détaillée de l’article. S’ensuit une décision éditoriale qui mène soit au rejet, soit à la demande de corrections, soit à la validation de l’article scientifique, éventuellement après plusieurs rounds d'évaluation. Dans ce dernier cas, le recommandeur écrit un texte de recommandation dans lequel il explique pourquoi il a validé l’article. L’ensemble de la communauté scientifique a ainsi accès gratuitement au contenu validé de l'article et aux évaluations/recommandations. La publication dans les PCI est de plus en plus reconnue par les instances d’évaluation.
(Webinaires de la Fédération FIRE, pp. https://www.canal-u.tv/chaines/fire/christian-mougin-l-initiative-peer-community-in, 11/05/2022)
ECOSYS, INRAE, FIRE, MNHN, IRD, SU, CNRS, UPCité, INRAE, IFREMER, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UMR CBGP, Cirad, IRD [Occitanie], IRD, INRAE, Institut Agro, UM, ISA, UNS, CNRS, INRAE, UniCA, DipSO, INRAE
Sensitivity of newly transformed juveniles of the freshwater pearl mussel: Margaritifera margaritifera to acute toxicity of a wide range of contaminants
The freshwater pearl mussel (FWPM) Margaritifera margaritifera is a bivalve mollusk critically endangered in Europe. There is a special concern about the conservation of this species, but little is known about its sensitivity to environmental pollution. Here, acute toxicity tests were conducted at 16°C according to a standard guide for conducting toxicity tests on freshwater mussels (ASTM international E2455), in order to assess toxicity thresholds for arsenic (As), aluminum (Al), cadmium (Cd), copper (Cu), nickel (Ni), nitrates (NO3−), and orthophosphates (PO43−) on newly transformed juveniles of M. margaritifera. The comparison with toxicity data for other newly transformed freshwater mussel juveniles from the same family and superfamily, Margaritiferidae and Unionidae, showed that FWPM juveniles were the most sensitive species to NO3−, among the most sensitive species to Ni, the least sensitive species to Cd, and showed an intermediate sensitivity to Cu compared to other freshwater mussels. This study is the first to provide toxicity thresholds for several pollutants on newly transformed juveniles of the FWPM. This brings new knowledge on its sensitivity to environmental pollution that could be helpful data for conservation strategies and these findings represent the first window for further complex studies.
(Hydrobiologia. vol. 849, n° 0018-8158, pp. 2029-2041, 01/05/2022)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Metals and metalloids concentrations in three genotypes of pelagic Sargassum from the Atlantic Ocean Basin-scale
Since 2011, in Caribbean Islands, unprecedented massive stranding of a pelagic brown algae Sargassum spp. has damaged coastal ecosystems and disrupted the economy. Brown algae have a high capacity to concentrate heavy metals contaminants. Through accumulation of heavy metals during their journey, floating Sargassum can play a role of contaminant transfer from off shore to the coast. In July and August 2019, three morphotypes of sargasso (S. fluitans III, S. natans I and S. natans VIII) were sampled in seven stations, regularly spaced, along a 3,400 km transect from the middle of Atlantic Ocean to Guadeloupe Islands (French West Indies). For each of the 72 samples of sargasso algae, concentrations of 15 heavy metal(loid)s elements were analyzed by Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES). Mean metal concentrations in all morphotypes and stations were ranked in the following descending order: As > Fe > Al > Mn > Cd > Zn > Ni > V > Cu > Cr > Hg. The metalloid As is the most largely present in all our samples with a mean concentration of 92.72 μg.g −1 and an maximum value of 115 μg. g −1 which is in accordance with concentrations previously observed in the Caribbean area (80-150 ppm). Those value are above different maximum safety level, therefore, strategies proposed for valorization of Sargassum should consider this As content to avoid potential environmental and health issues. At the scale of the Atlantic Ocean, metallic element concentration do not present spatial longitudinal gradient. Morphotype of Sargassum present different metal(loids) contamination patterns with distinction between S. fluitans III and the two others morphotypes (S. natans I and VIII).
(Marine Pollution Bulletin. vol. 178, n° 0025-326X, pp. 113564, 01/05/2022)
ISYEB, MNHN, EPHE, PSL, SU, CNRS, UA, ULaval, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IBED, UvA