Comparison of periphytic biofilm and filter-feeding bivalve metal bioaccumulation (Cd and Zn) to monitor hydrosystem restoration after industrial remediation: a year of biomonitoring
Despite a significant decrease in the metallic waste emissions from an industrial site and a remediation process initiated in 2007, the Riou-Mort watershed (southwest France) still exhibits high Cd and Zn concentrations. Metal wastes have long been proven to significantly disturb aquatic communities. In this study, bioaccumulation capacities and responses to the chemical improvement of the hydrosystem were assessed for a year along the contamination gradient through the comparison of two biological models: Corbicula fluminea and periphytic biofilms, both considered as good bioindicators. Bioaccumulation results confirmed the persistence of water contamination in Corbicula fluminea and biofilms with, respectively, maximum Cd concentrations reaching 80.6 and 861.2 mg gDW1, and Zn concentrations 2.0 and 21.3 mg gDW1. Biofilms exhibited bioaccumulation in close correlation with water contamination, while Corbicula fluminea presented Cd bioaccumulation clearly regulated by water temperature and metal concentrations, affecting the ventilatory activity, as revealed by condition indices measurements. Also, a linear regression using Cd bioaccumulation and temperature (Fig. 7) showed that below approximately 6 C Corbicula fluminea did not appear to accumulate metals. Bioconcentration factors (BCFs) were higher in biofilms in comparison with Corbicula fluminea and showed the great accumulation capacity of suspended particulate matter in biofilms. However, bioaccumulation capacities are known to be influenced by many factors other than metal concentrations, such as temperature, water oxygenation or plankton and nutrient concentrations. Thus, this study demonstrates the power of a combined assessment using both Corbicula fluminea and biofilms as bioindicators to give a more integrated view of water quality assessment. Finally, when comparing our results with previous studies, the start of hydrosystem restoration could be shown by decreasing bioaccumulation in organisms.
(International Journal of Environmental Monitoring and Analysis. vol. 13, n° 2328-7659, pp. 3386-3398, 27/06/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR REBX, CEMAGREF
Bilan des gaz à effet de serre d’origine agricole: oxyde nitreux et méthane
Les bilans agricoles d’émissions de méthane (CH4) et de l’oxyde nitreux (N2O) ont été réalisés à l’échelle du bassin de la Seine, sur la base de mesures acquises sur les sols et dans le réseau hydrographique. Le réseau hydrographique émet environ 140 103 kg N-N2O et 170 103 kg C-CH4 auxquelles s’ajoutent les émissions par les zones humides estimées à 500 – 800 103 kg NN2O et 400 - 4000 103 kg C-CH4. Ces émissions indirectes représentent environ 10% et 1% des émissions directes par les sols agricoles pour le N2O et le CH4 respectivement. Les émissions directes sont en majorité celles des sols arables 10400 103 kg N-N2O pour le N2O, alors que les émissions directes du CH4 sont essentiellement liées à la digestion entéro-gastrique du cheptel, et en particulier des bovins, soit 194660 103 kg C-CH4. Les sols sont un puits pour le CH4 : - 10000 103 kg C-CH4.. Les émissions de N- N2O et de CCH4représentent 12.3 106 tonnes CO2 équivalent an-1. A ces émissions, il faut ajouter celles émises par le fuel pour les activités agricoles et celles liées à la fabrication des engrais synthétiques qui représentent respectivement 0.1% et 10%.
(pp. 18 p., 27/06/2026)
SISYPHE, UPMC, EPHE, PSL, PSL, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, EGC, INRA
Glacial-interglacial vegetation dynamics in South Eastern Africa coupled to sea surface temperature variations in the Western Indian Ocean
Glacial-interglacial fluctuations in the vegetation of South Africa might elucidate the climate system at the edge of the tropics between the Indian and Atlantic Oceans. However, vegetation records covering a full glacial cycle have only been published from the eastern South Atlantic. We present a pollen record of the marine core MD96-2048 retrieved by the Marion Dufresne from the Indian Ocean ∼120 km south of the Limpopo River mouth. The sedimentation at the site is slow and continuous. The upper 6 m (spanning the past 342 Ka) have been analysed for pollen and spores at millennial resolution. The terrestrial pollen assemblages indicate that during interglacials, the vegetation of eastern South Africa and southern Mozambique largely consisted of evergreen and deciduous forests. During glacials open mountainous scrubland dominated. Montane forest with Podocarpus extended during humid periods was favoured by strong local insolation. Correlation with the sea surface temperature record of the same core indicates that the extension of mountainous scrubland primarily depends on sea surface temperatures of the Agulhas Current. Our record corroborates terrestrial evidence of the extension of open mountainous scrubland (including fynbos-like species of the high-altitude Grassland biome) for the last glacial as well as for other glacial periods of the past 300 Ka.
(Climate of the Past. vol. 7, n° 1814-9324, pp. 1209 - 1224, 27/06/2026)
MARUM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, NIOZ
Copper addition by organic matter degradation in the freshwater reaches of a turbid estuary
This study reports on the relationship between copper (Cu) behavior and organic matter (OM) transformation along the turbidity gradient in the freshwater reaches of the Gironde Estuary. During a one-year survey, surface water and suspended particulate matter (SPM) were sampled at least monthly at three sites along the Garonne Branch, representing the main fluvial branch of the Gironde Estuary. Additionally, a longitudinal high resolution profile was sampled along the Garonne Branch, covering the turbidity gradient from the river water endmember to the maximum turbidity zone (MTZ). Seasonal variability and spatial distribution of Cu in both the dissolved phases (<0.2μm, Cu0.2 and <0.02μm, Cu0.02) and particulate Cu (CuP) clearly suggested Cu0.2 addition during summer, that increased the Cu0.2 concentrations by a factor ~2, mainly manifested by an increase in the Cu0.02 fraction. At the annual timescale (2004), this internal Cu reactivity increased Cu0.02 fluxes in the Garonne Branch by ~20% (3.6tyear-1), with the equivalent of ~2.9tyear-1 derived from the CuP fraction and ~0.7tyear-1 from the colloidal (0.02-0.2μm) fraction, without involving and/or affecting the CuC18 (hydrophobic metal-organic complexes) fraction.Combining data on Cu speciation with the results obtained by several independent techniques (DOC and POC measurements, 3D-fluorescence, and TEM) suggested close relationships between Cu behavior and OM transformation/restructuration along the turbidity gradient in the Garonne Branch. The observed Cu0.02 addition was related to increasing humification (humification index HIX increased from 9 to 12, network formation) and labile OM degradation (Iγ/Iα ratio decreased from 0.70 to 0.44), going along with decreasing DOC and POC concentrations. Mass-balances suggest that in the studied system, degradation of OM may account for the release of ~25μmol potentially bioaccessible Cu0.02 per mole of particulate organic carbon mineralized. \textcopyright 2011 Elsevier B.V.
(Science of the Total Environment. vol. 409, n° 0048-9697, pp. 1539--1549, 27/06/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UB
X-ray fluorescence microchemical analysis and autoradiography applied to cave deposits: speleothems, detrital rhythmites, ice and prehistoric paintings
This article presents recent research on the sedimentary endokarstic infillings in connection with the new contributions of geochemical analysis by autoradiography and X-ray fluorescence (portable analyser, core scanner, micro-XRF, microprobe) in the context of the ‘Climanthrope’ ANR programme. Coupled with sedimentological analysis (stratigraphy, laser grain size analysis, micromineralogy, and micromorphology), geochemical analysis and imaging refine the study of underground deposits such as carbonated sediments (speleothems), rhythmites, subterranean ice, and prehistoric cave paintings. Formed following a seasonal cycle, stalagmites and rhythmites are likely to provide important data not only on the two main parameters of regional climate, i.e. hydrology and temperature, but also on human impacts (speleothems in urban tunnels) and the rural environment. The microdebris and dusts sampled in subterranean ice record the palaeoenvironment by snow trapping. Parietal paintings can be studied directly with a portable XRF analyser without sampling. In every case, the notion of the ‘site effect’ is discussed for four French examples (Pyrenees, Aquitaine, Charente, Rhône) and three foreign examples (Italy, Chile, China).
(Géomorphologie : relief, processus, environnement. vol. 17, n° 1266-5304, pp. 407-426, 27/06/2026)
ADES, UBM, CNRS, CENBG, UB, IN2P3, CNRS, AMPERE, ECL, UCBL, INSA Lyon, INSA, CNRS, INRAE, EDYTEM, USMB [Université de Savoie] [Université de Chambéry], CNRS, Fédération OSUG, TRACES, EHESS, UT2J, Comue de Toulouse, MCC, Inrap, CNRS, Inrap, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GEOTOP, EPM, UdeM, UQAT, UQAR, UQAM, ArScAn, UP1, UP8, UPN, MCC, CNRS
Contamination des mollusques bivalves par des phycotoxines : interactions entre niveaux de toxicité et réponses physiologiques
Résumé non disponible
(pp. 1-8, 27/06/2026)
PHYC, DYNECO, IFREMER, LEMAR, IRD, IFREMER, UBO EPE, CNRS, UEB, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BRM, IFREMER
Anaerobic ammonium oxidation mediated by Mn-oxides: from sediment to strain level
Nitrite and N-29(2) productions in slurry incubations of anaerobically sediment after (NO3)-N-15 or (NH4)-N-15 labelling in the presence of Mn-oxides suggested that anaerobic Mn-oxides mediated nitrification coupled with denitrification in muddy intertidal sediments of Arcachon Bay (SW Atlantic French coast). From this sediment, bacterial strains were isolated and physiologically characterized in terms of Mn-oxides and nitrate reduction as well as potential anaerobic nitrification. One of the isolated strain, identified as Marinobacter daepoensis strain M4AY 14, was a denitrifier. Nitrous oxide production by this strain was demonstrated in the absence of nitrate and with Mn-oxides and NH4 amendment, giving indirect proof of anaerobic nitrate or nitrite production. Anaerobic Mn-oxide-mediated nitrification was confirmed by N-29(2) production in the presence of (NO3)-N-15 and (NH4)-N-14 under denitrifying conditions. Anaerobic nitrification by M4AY14 seemed to occur only in the absence of nitrate, or at nitrate levels lower than that of Mn-oxides. Most of the other isolates were affiliated with the Shewanella genus and were able to use both nitrate and Mn-oxides as electron acceptors. When both electron acceptors were present, whatever their concentrations, nitrate and Mn-oxide reduction co-occurred. These data indicate that bacterial Mn-oxide reduction could be an important process in marine sediments with low oxygen concentrations, and demonstrate for the first time the role of bacteria in anaerobic Mn-mediated nitrification. (C) 2011 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.
(Research in Microbiology. vol. 162, n° 0923-2508, pp. 848-857, 27/06/2026)
MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS, LMGEM, CNRS, MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS, LMGEM, CNRS, MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS, LMGEM, CNRS
Potentiel of TerraSAR-X imagery for mapping intertidal coastal wetlands
This work presents preliminary results about the use of TerraSAR-X imagery for mapping intertidal habitats (oyster parks, seagrass meadows of Zostera noltii, sediments) along coastal lagoons (Arcachon lagoon, France). The combination of SAR and optical data appears to be useful to improve the discrimination of the various sediment and vegetation covers into classification schemes. Unlike optical imagery which may lead to misinterpret sediment type, the potential of the multi-polarization SAR data is assessed notably regarding its efficiency for separating intertidal (Z. noltii) from supratidal salt-marsh vegetation species (spartina, salicornia, and so on). TerraSAR-X imagery is also an excellent highlighter of areas colonized by oysters (both cultivated and invasive ones) due to their relevant roughness signature among neighbored facies. In contrast, mapping methods based on optical data alone often do not perform well because of the presence of algae on oyster shelves. Moreover, potential exists for discrimating unvegetated soils but biofilm-covered from low-vegetated ones. As a conclusion, TerraSAR-X imagery offers many tracks to increase the performance of thematic mapping products along intertidal environments, in complement of optical data.
(pp. 9, 27/06/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UMR TETIS, Cirad, CEMAGREF, IRSTEA
Evolution taxonomique de biofilms diatomiques en condition de décontamination métallique expérimentale après colonisation sur site contaminé
Le système fluvio-estuarien de la Gironde (France) est soumis depuis plus d'un siècle à une contamination polymétallique (Cd et Zn) s'étendant du Lot jusqu'à l'estuaire de la Gironde. Des études géochimiques ont montré que les apports en Cd et Zn proviennent essentiellement d'un site industriel spécialisé dans le traitement du minerai de zinc, localisé environ 400 km en amont de l'estuaire. Depuis 2007, un important plan de remédiation du site industriel a été mis en place. Ces travaux devraient durer jusqu'en 2012. Dans ce contexte de gestion corrective, et en référence à l'état initial de contamination déterminé par des études antérieures (programme national Ecodyn), cette étude s'intègre dans le cadre d'un projet ANR pluridisciplinaire (RESYST) et a pour objectif d'étudier l'impact de la mise en place de la remédiation sur les biofilms diatomiques. Afin de caractériser les cinétiques de récupération des diatomées, une étude expérimentale de décontamination du biofilm a été menée en laboratoire. La colonisation des biofilms s'est déroulée durant 24 jours sur un site subissant les rejets métalliques industriels et parallèlement sur un site en amont sans métaux, considéré comme témoin. Les biofilms ont ensuite été ramenés et maintenus en laboratoire durant 56 jours en condition de décontamination, ou de contamination artificielle à partir de solutions de Cd et de Zn. Différentes analyses ont été réalisées du niveau communautaire - mesures de la bioaccumulation métallique, des densités cellulaires et investigations taxonomiques - jusqu'au niveau individuel : déformation des frustules. Après 56 jours de décontamination, les concentrations en Cd dans les biofilms montrent une forte décroissance mais restent significativement supérieures aux concentrations mesurées dans les biofilms témoins. Par ailleurs, les inventaires taxonomiques ne permettent pas de mettre en évidence une restauration des communautés diatomiques dans les biofilms en décontamination comparativement à la condition témoin. En effet, après 56 jours de décontamination, malgré l'apparition d'espèces opportunistes sensibles aux métaux, pouvant être liées aux conditions expérimentales, les espèces résistantes aux métaux présentes initialement après colonisation sur site contaminé, persistent en abondances élevées dans les biofilms en décontamination. A la lumière de ces premiers résultats sur le comportement des biofilms diatomiques en conditions expérimentales de décontamination, l'amélioration de l'état chimique de l'hydrosystème naturel apparaît rapidement mais un éventuel retour au bon état écologique préconisé dans la DCE semble différé avec la persistance d'espèces tolérantes aux métaux. Ces résultats seront confrontés aux investigations menées en parallèle in situ afin de révéler ou non les prémices d'un retour au bon état écologique.
(pp. 1, 27/06/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR REBX, CEMAGREF
Suivi de la contamination des tributaires du Bassin d'Arcachon par les pesticides et tests écotoxicologiques sur diatomées
L'échantillonnage passif des substances organiques de synthèse suscite un intérêt croissant depuis son apparition par son gain de représentativité temporelle, sa facilité de mise en ½uvre et son coût acceptable. Depuis le début des années 1990, plusieurs dispositifs ont été développés pour échantillonner différents types de contaminants. Le Polar Organic Chemical Integrative Sampler (POCIS) est l'outil le plus adapté à l'échantillonnage des pesticides pour différentes applications (e.g. monitoring ; appui à l'écotoxicologie), en particulier grâce à l'utilisation d'un composé de performance et de référence (PRC). L'objectif de cette étude est de caractériser la pollution à pesticides dans neuf des principaux tributaires du Bassin d'Arcachon. Des POCIS ont été déployés pour l'échantillonnage des pesticides neutres (i.e. 1
(pp. 1, 27/06/2026)
UR REBX, CEMAGREF, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS