Rotating disk electrodes to assess river biofilm thickness and elasticity
The present study examined the relevance of an electrochemical method based on a rotating disk electrode (RDE) to assess river biofilm thickness and elasticity. An in situ colonisation experiment in the River Garonne (France) in August 2009 sought to obtain natural river biofilms exhibiting differentiated architecture. A constricted pipe providing two contrasted flow conditions (about 0.1 and 0.45 m s−1 in inflow and constricted sections respectively) and containing 24 RDE was immersed in the river for 21 days. Biofilm thickness and elasticity were quantified using an electrochemical assay on 7 and 21 days old RDE-grown biofilms (t7 and t21, respectively). Biofilm thickness was affected by colonisation length and flow conditions and ranged from 36 ± 15 μm (mean ± standard deviation, n = 6) in the fast flow section at t7 to 340 ± 140 μm (n = 3) in the slow flow section at t21. Comparing the electrochemical signal to stereomicroscopic estimates of biofilms thickness indicated that the method consistently allowed (i) to detect early biofilm colonisation in the river and (ii) to measure biofilm thickness of up to a few hundred μm. Biofilm elasticity, i.e. biofilm squeeze by hydrodynamic constraint, was significantly higher in the slow (1300 ± 480 μm rpm1/2, n = 8) than in the fast flow sections (790 ± 350 μm rpm1/2, n = 11). Diatom and bacterial density, and biofilm-covered RDE surface analyses (i) confirmed that microbial accrual resulted in biofilm formation on the RDE surface, and (ii) indicated that thickness and elasticity represent useful integrative parameters of biofilm architecture that could be measured on natural river assemblages using the proposed electrochemical method.
(Water Research. vol. 45, n° 0043-1354, pp. 1347-1357, 01/01/2011)
LEFE, INEE-CNRS, CNRS, UT3, Comue de Toulouse, CNRS, Toulouse INP, Comue de Toulouse, LISE, UPMC, INC-CNRS, CNRS, IMFT, UT3, Comue de Toulouse, CNRS, Toulouse INP, Comue de Toulouse, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
A gridded data set of sea surface salinity for the tropical Pacific with sample applications (1950-2008)
We present a gridded data set of Sea Surface Salinity (SSS) for the tropical Pacific (120°E-70°W; 30°N-30°S), with a grid resolution of 1° longitude, 1° latitude and 1 month, from 1950 to 2008. The product, together with its associated error field, is derived from an objective analysis of about 10 million validated SSS records, with most of the data originating from Voluntary Observing Ships, TAO/TRITON moorings and Argo profilers (during the most recent period). We expect this product to benefit studies in oceanography, meteorology and paleoceanography. As examples of applications, we analyse: (a) the seasonal and ENSO (El Niño Southern Oscillation) modes of observed SSS variability, (b) the ability of 23 coupled models used in the Intergovernmental Panel for Climate Change 4th Assessment Report (IPCC AR4) to simulate the mean SSS and these two time varying modes, and (c) the usefulness of the SSS product and of its associated error field in calibrating and validating the paleo-salinity time series. We anticipate improvements and regular updates to our product, as more SSS data become available from in situ networks and from the ongoing and near-future satellite-derived observations by SMOS (Soil Moisture and Ocean Salinity) and Aquarius.
(Deep Sea Research Part I: Oceanographic Research Papers. vol. 58, n° 0967-0637, pp. 38-48, 01/01/2011)
OLVAC, LEGOS, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, PMEL, NOAA
Nearshore bathymetric inversion from video using a fully non-linear Boussinesq wave model
This paper presents a new depth inversion methodology from video imagery. The strength of the method is the use of a fully non-linear Boussinesq wave model in combination with a very complete video-derived laboratory wave observation that includes period, celerity and wave height. Compared to the previous use of wave dispersion formulas, here the better description of wave dynamics substantially improves bathymetry estimation. For the considered laboratory case, error on bathymetry is as small as 8 % whereas other formulations, shallow water or non-linear derived solution can only attain 24 % and 14 %, respectively. More in-depth analysis on the error shows a fair sensitivity on video-derived breaker height and describes the large contribution of nonlinearities. The recent possibility of using Serre's dispersion relation in combination with video-derived wave height provides a reasonable performance and should be further envisaged for one-dimensional depth inversion. Future extensions of this work involve the use of a two-dimensional Boussinesq model to include more hydrodynamics processes such as wave-driven circulation over three-dimensional surfzone sandbars.
(Journal of Coastal Research. vol. SI 64, n° 0749-0208, pp. 20-24, 28/08/2026)
PUC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEGI, UJF, Grenoble INP, CNRS
Hydrological processes affecting the subtropical NE Atlantic (34-38° N) over the last 30 ka: Evidence from phyto- and zooplankton assemblages
New dinocyst analyses were conducted on core MD99-2339 retrieved from the central Gulf of Cadiz. Dinocyst and foraminiferal assemblages from this core are combined with existing data off SW Portugal and NW Morocco to investigate past hydrological and primary productivity regimes in the subtropical NE Atlantic Ocean over the last 30 ka. Our results have revealed highest upwelling intensity during Heinrich Stadial 1 (HS 1) and the Younger Dryas and weaker upwelling cells during the Last Glacial Maximum and HS 2, off the SW Iberian and NW Moroccan margins. Similar assemblages between Cadiz and Morocco and distinct species off Portugal were observed during the cold climatic extremes that punctuated the last 30 ka. This pattern has been linked to the occurrence of a hydrological structure between SW Iberia and Cadiz during the last glacial period, probably similar to the modern Azores Front. This front was probably responsible locally for heterotrophic dinocysts found in the Gulf of Cadiz during the last glacial period, even if this sector is not conductive to upwelling phenomena by Ekman transport. Regional reconstructions of paleo-sea-surface temperatures using dinocyst and foraminiferal transfer functions, as well as alkenones, are also discussed and depict coherent scenarios over the last 30 ka. However, some mismatches are observed between the different quantitative reconstructions such as during HS 1 in the Gulf of Cadiz and during the LGM at the three core locations. © 2011 Author(s).
(pp. 2281-2327, 28/08/2026)
LDO, INSU - CNRS, UBO EPE, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA
How early diagenesis reveals in situ biodegradation of herbicides in sediment
Globalisation of environment contamination is one of the actual major concerns. Concentrated in the developed countries during 1950s and 1960s, the use of pesticides, particularly the organic ones, has dramatically increased since 1970s (Alavanja, 2009). Agro chemistry expansion is parallel to diffusion of other technologies involving molecules proved to be environmental contaminants. Progressive prohibition of indiscriminate use of chemicals, considered as a threat for human and environmental health, highlights their persistence and their ubiquity. Although for partly natural contaminants like polycyclic aromatic hydrocarbons, the question is to dissociate the natural input (fires) from the anthropogenic one; the synthesised molecules like herbicides do not give rise to such a controversy. However, understanding their flux from contaminated parcels and their fate in the environment requires historical overview that can be achieved through coring. In order to be informative coring needs to be performed on quiescent, biotic and unconsolidated growing matrix and for these reasons sediments are the most often sampled.
(pp. p. 443 - p. 468, 28/08/2026)
UR AEMA, CEMAGREF, IRD, IMEP, AU, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Bio-évaluation de la qualité écologique des rivières de l'île de la Réunion à partir des diatomées : Guide taxonomique
L'Indice Diatomique Réunion (IDR) est un nouvel outil de bioindication mis en place pour l'évaluation de la qualité biologique des cours d'eau de l'île de la Réunion à partir de la composition spécifique des communautés locales de diatomées benthiques. Cet outil a été développé conjointement par Asconit et l'Irstea, dans le cadre d'un programme initial de Recherche-Développement mis en ½uvre de 2008 à 2011 par l'Office de l'Eau et la DEAL de la Réunion, avec une contribution financière de l'Union Européenne (FEDER) et de l'ONEMA. L'objectif poursuivi était de doter la Réunion d'un outil diatomique adapté aux conditions biogéographiques locales et pouvant servir à l'Evaluation d'Etat Ecologique telle que recommandée par la DCE, celle-ci étant entrée en vigueur depuis 2005 sur le territoire français métropolitain, mais ayant aussi vocation à s'appliquer dès que possible dans les DOM. A noter qu'un programme d'acquisition de données complémentaires va encore couvrir les 2 années à venir, qui permettra notamment de régler certains problèmes particuliers d'évaluation rencontrés avec la première version d'IDR et de consolider la signature écologique affectée à quelques taxons indiciels. L'IDR a été pensé et élaboré pour pouvoir faire l'objet d'une utilisation en routine dans les réseaux institutionnels de surveillance et tout particulièrement dans le cadre du RCS, qui servira de réseau de base pour les opérations de rapportage de l'Etat Ecologique vers l'Union Européenne. Il convient de mentionner que les espèces de diatomées rencontrées à la Réunion étaient encore fortement méconnues jusqu'au déroulement du présent programme, certaines étant complètement endémiques de la Réunion ou des Mascareignes et d'autres, éventuellement connues dans d'autres zones tropicales ou tempérées de la planète, devant faire l'objet d'une recherche bibliographique à l'échelle mondiale pour établir les correspondances taxonomiques et morphologiques avec les espèces trouvées localement. Aussi, le présent guide taxonomique permet de résumer en langue française la connaissance taxonomique et écologique acquise à ce stade sur les diatomées des cours d'eau de la Réunion, afin de la rendre plus facilement accessible aux gestionnaires des hydrosystèmes et aux intervenants amenés à effectuer les identifications et comptages diatomiques dans le cadre des réseaux de surveillance. La première partie de ce guide permet proposer une classification iconologique de l'intégralité des 463 taxons trouvés à la Réunion au cours de ce programme de Recherche-Développement, au moyen de 21 planches agencées en fonction de critères d'organisation générale de la classification taxonomique des diatomées. Elle est suivie d'un recueil des fiches-taxons qui ont pu être élaborées après application d'un double seuillage des données quantitatives recueillies sur le taxon (faisant intervenir le nombre d'occurrences et les données d'abondance relative). En effet, pour les espèces qui ont été insuffisamment rencontrées au hasard des prélèvements de ce programme (trop faible occurrence et/ou très faibles effectifs), les données de présence sont trop lacunaires et trop aléatoires pour qu'il puisse être affecté une écologie fiable à ce taxon. Au stade actuel, il a été possible de formaliser 90 fiches-taxons. Ce recueil est bien sûr amené à évoluer à la hausse dans les prochaines années, en fonction de l'augmentation des référentiels capitalisés sur chaque taxon des cours d'eau Réunionnais.
(pp. 349 p., 28/08/2026)
UR REBX, CEMAGREF, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEFE, INEE-CNRS, CNRS, UT3, Comue de Toulouse, CNRS, Toulouse INP, Comue de Toulouse
Transport of terrestrial organic matter in the Ogooué deep sea turbidite system (Gabon)
(Marine and Petroleum Geology. vol. 28, n° 0264-8172, pp. 1061-1072, 28/08/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, iSTeP, UPMC, CNRS, SHOM
Inclusions minérales et gazeuses dans les glaces
Les gaz à effet de serre* (GES) et les poussières atmosphériques affectent le bilan radiatif terrestre (cf. II-2) tandis que l’activité solaire module le flux des rayons cosmiques qui interagit avec les hautes couches de l’atmosphère. Déterminer le rôle joué par ces facteurs sur la variabilité climatique* naturelle ou son évolution récente requiert de les reconstituer au cours du temps grâce notamment à l’analyse des glaces polaires : les couches de neige conservent les poussières éoliennes et les aérosols. Entre 50 et 100 mètres de profondeur, ces couches se transforment en glace, emprisonnant des petites bulles d’atmosphère. Grâce aux forages conduits au travers de kilomètres de calottes polaires – suivis du transport réfrigéré des carottes, de leur stockage en chambre froide, de leur décontamination, de leur extraction et de leur analyse – on a pu reconstruire ces informations, qui couvrent à ce jour les derniers 800 000 ans
(pp. 201--203, 28/08/2026)
LGGE, OSUG, UJF, Grenoble INP, INSU - CNRS, IRSTEA, USMB [Université de Savoie] [Université de Chambéry], CNRS, INSU - CNRS, CNRS, LGGE, OSUG, UJF, Grenoble INP, INSU - CNRS, IRSTEA, USMB [Université de Savoie] [Université de Chambéry], CNRS, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CEREGE, IRD, AMU, CdF (institution), INSU - CNRS, CNRS, INRAE
Structure verticale des courants associés à la propagation de la marée dans la Garonne-impact du mascaret
Les ressauts en translation tidaux (parfois dénommés mascarets) représentent un phénomène naturel non linéaire et non hydrostatique, pouvant avoir une forte intensité et ayant un fort impact sur les écosystèmes fluvio-estuariens. Nous présenterons des résultats expérimentaux issus de la première campagne de mesure de grande ampleur au niveau international, réalisée sur la Garonne. Nous analyserons en particulier les forts cisaillements de vitesse liés au passage du ressaut et des ondes secondaires associées, qui génèrent une forte remise en suspension des sédiments.
(28/08/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Intense storm activity during the Little Ice Age on the French Mediterranean coast
Understanding long-term variability in the frequency of intense storm activity is important for assessing whether changes are controlled by climate evolution. Understanding this variability is also important for predicting present and future community vulnerability and economic loss. Our ability to make these assessments has been limited by the short (less than 50 years) instrument record of storm activity. Storm-induced deposits preserved in the sediments of coastal lagoons offer the opportunity to study the links between climatic conditions and storm activity on longer timescales. In this study, we present a record of these extreme climatic events that have occurred in the French Mediterrannean coast over the past 1500 years. The identification of these extreme events is based on the analysis of sediment cores from Gulf of Aigues-Mortes lagoons that contain a specific sedimentary and geochemical signature associated with intense storms.;Overwash deposits do not show any evidence of intense storm landfalls in the region for several hundred years prior to the late 17th century A.D. The apparent increase in intense storms around 250 years ago occurs during the latter half of the Little Ice Age, a time of lower continental surface temperatures. Comparison of the sediment record with palaeoclimate records indicates that this variability was probably modulated by atmospheric dynamics. The apparent increase of the superstorm activity during the latter half of the Little Ice Age was probably due to the thermal gradient increase leading to enhanced lower tropospheric baroclinicity over a large Central Atlantic/European domain and leading to a modification of the occurrence of extreme wind events along the French Mediterranean coast. A complete understanding of the relationship between climate fluctuations, storm activity, and the coastal response will be crucial to predicting the impacts of future climate change.
(Palaeogeography, Palaeoclimatology, Palaeoecology. vol. 299, n° 0031-0182, pp. 289-297, 28/08/2026)
Géosciences Montpellier, UAG, INSU - CNRS, UM, CNRS, UAG, INSU - CNRS, UM, CNRS, EDYTEM, USMB [Université de Savoie] [Université de Chambéry], CNRS, Fédération OSUG, ASM, UPVM, CNRS, MC, CERFACS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, GEOTRAC, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, GLACCIOS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA