Carbonate slopes and gravity deposits
In this special volume a series of papers are presented that concentrate on sedimentation patterns observed on the slopes and within the basins surrounding shallow-water carbonate depositional systems. Four papers discuss depositional patterns on the slope to basin transect of the Cainozoic sedimentary system of the Bahamas; four other papers examine gravity deposits of Jurassic and Cretaceous carbonate depositional systems.
(Sedimentary Geology, n° 0037-0738, 01/11/2014)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
SOPHIE velocimetry of Kepler transit candidates XII. KOI-1257 b: a highly eccentric three-month period transiting exoplanet
In this paper we report a new transiting warm giant planet: KOI-1257 b. It was first detected in photometry as a planet-candidate by the Kepler space telescope and then validated thanks to a radial velocity :follow-up with the SOPHIE spectrograph. It orbits its host star with a period of 86,647661 d +/- 3 s and a high eccentricity of 0.772 +/- 0.045. The planet transits the main star of a metal-rich, relatively old binary system With stars of mass of 0.99 +/- 0.05 M-circle dot and 0.70 +/- 0.07 M-circle dot for the primary and secondary, respectively. This binary system is constrained thanks to a self-consistent modelling of the Kepler transit light curve; the SOPHIE radial velocities; line bisector and full-width half maximum (FWHM) variations, and the spectral energy distribution. However, future observations are needed to confirm it. The PASTIS fully-Bayesian software was used to validate the nature of the planet and to determine which star of the binary system is the transit host. By accounting for the dilution from the binary both in photometry and in radial velocity, we find that the planet has a mass of 1.45 +/- 0.35 M-4, and a radius of 0.94(4) +/- 0.12 R-4 and thus a bulk density of 2.1 +/- 1.2 g cm(-3). The planet has an equilibrium temperature of 511 +/- 50K, making it one of the few known members of the warm-Jupiter population. The HARPS-N spectrograph was also used to observe a transit of KOI-1257 b, simultaneously with a joint amateur and professional photometric follow up, with the aim of constraining the orbital obliquity of the planet. However, the Rossiter-McLaughlin effect was not clearly detected, resulting in poor constraints on the orbital obliquity of the planet.
(Astronomy & Astrophysics - A&A. vol. 571, n° 0004-6361, 01/11/2014)
CAUP, IAP, UPMC, INSU - CNRS, CNRS, LAM, AMU, INSU - CNRS, CNES, CNRS, IMCCE, UPMC, INSU - CNRS, CNRS, PSL, CNRS, CBMSO, CSIC, UAM, UNIGE, OHP, OSU PYTHEAS, IRD, AMU, IRSTEA, CNRS, LMNO, UNICAEN, NU, CNRS, LAGRANGE, UNS, INSU - CNRS, UniCA, CNRS, UniCA, ESO, AUDE, DFA/FCUP, FCUP, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CALA, EDF R&D STEP, EDF R&D, EDF [E.D.F.], UniCA
Utilisation du comportement natatoire de Daphnia magna comme indicateur sensible et précoce de toxicité pour l'évaluation de la qualité de l'eau
Les paramètres comportementaux sont de plus en plus considérés comme étant des indicateurs sensibles et précoces de toxicité chez les organismes aquatiques. Cependant, l’utilisation du comportement natatoire comme critère de toxicité pour l’analyse de risque environnemental ou pour le contrôle de la qualité de l’eau reste pour l’heure encore limitée. En effet, il est actuellement difficile de quantifier la sensibilité des paramètres comportementaux et d’établir un lien entre les seuils d’effets comportementaux et les effets aigus et subaigus classiquement mesurés dans les tests en écotoxicologie. Dans le but d’améliorer notre compréhension des effets comportementaux des polluants sur Daphnia magna, nous avons développé un nouveau système de mesure du comportement multi-cuves baptisé «Multi-DaphTrack ». Douze substances toxiques, couvrant une large gamme de modes d’action différents ont été testées dans ce système. Un test standard d’immobilisation ainsi que des analyses de comportement dans le toximètre DaphToxI®, ont également été effectués pour chaque substance afin de comparer les seuilsd’effets comportementaux avec les paramètres classiques d’immobilisation. Les résultats des expositions aux différentes substances ont démontré que notre nouveau système d’exposition multi-cuves permet de détecter des effets comportementaux (i.e.,augmentation de la vitesse de nage) significatifs et précoces pour l’ensemble des substances testées et ce, à des concentrations proches de la CE10(48 h) du test aigu d’immobilisation dès la première heure d’exposition. Des profils comportementaux différents ont été observés selon les substances testées (i.e., intensité, temps de latence et durée de l’effet) mais ceux-ci ne sont pas spécifiques d’un mode d’action particulier. Les résultats obtenus avec le toximètre DaphToxI®ont révélé des profils d’effet similaires (i.e.,augmentation de la vitesse de nage) bien que ce système soit globalement moins sensible par rapport au système «Multi-DaphTrack». Pour conclure, notre nouveau système d’exposition multi-cuves «Multi-DaphTrack» est un outil plus sensible et précoce que letest standard d’immobilisation pour l’évaluation de la toxicité de substances chimiques. L’utilisation du système «Multi-DaphTrack» pourrait donc être envisagée, après quelques améliorations et validation supplémentaires, pour l’évaluation de la qualité des masses d’eauet des effluents.
(30/10/2014)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, EDF R&D LNHE, EDF R&D, EDF [E.D.F.]
Large-Scale Carbonate Submarine Mass-Wasting along the Northwestern Slope of the Great Bahama Bank (Bahamas): Morphology, Architecture, and Mechanisms
Along the northwestern margin of the Great Bahama Bank (Bahamas), high-resolution multibeam bathymetry maps have revealed large escarpments, 80-100 m in height, and gigantic carbonate Mass Transport Complexes (MTCs), characterized by megablocks, several hundred to several thousand meters in size.The present-day configuration of this mass-wasting deposit is the result of the specific basinal sedimentation of the GBB during the Neogene. Marginal sedimentation was produced by: (i) massive gravity-flow slope apron carbonates, feeding from the eastern prograding platform, including oversized MTCs; and (ii) thick, elongated, and muddier drift contourite flowing from south to north along the toe of slope. Four distinct MTCs (MTC-1 to -4) resulted from repeated slope failures in the Late Pliocene and the Pleistocene. These MTCs all glided along a common privileged décollement surface, dated Late Messinian – Early Pliocene, which coincided with a regional diagenetic key stratigraphic surface. The MTCs collapsed down from the steep mid- to upper-slope apron, partially draped the drift deposits, and flowed basinward over 10-20 km, extending over an area of approximately 400 km2.With the support of good-quality seismic reflection data, a detailed analysis was produced of the stratigraphic architecture of these MTCs, highlighting the high variability of the seismic facies from tabular bounded strata to chaotic patterns. The analysis of the facies demonstrated the internal stratigraphic complexity of the MTCs as well as that of the subsequent filling of the associated headwall scar-related depressions.A depositional reconstitution of the MTCs is proposed from collapse initiation to final deposition, resulting in the present-day irregular seafloor morphology. The model accounts for the influence of the Early Pliocene drift-induced topography on the distribution and internal architecture of the successive MTCs. Most likely due to sedimentation rate increase, the contourite displayed lateral morphological variations, forming flat to mound-shaped features when upslope collapses occurred. Depending on lee-side steepness, it then acted either as secondary décollement ramp or as natural obstacle for mass-wasting deposits.Strips of sharply-bounded chaotic facies preserved within the Pliocene contourite are interpreted as far-reaching fluid escape-related facies (thixotropy), resulting from frontal impact with the contourite at the toe of the MTCs.The MTCs are not unique mass-wasting carbonate deposits, as similar features with comparable dimensions have been reported in the geological record in the Bahamas and in other carbonate basins. However, they clearly illustrate a significant volume of sediment remobilization over short distances in carbonate slope environments.
(Sedimentary Geology. vol. 317, n° 0037-0738, pp. 27-42, 28/10/2014)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Evolution morphologique et processus sédimentaires actuels du plateau continental interne sud-aquitain : étude comparée des zones de la Salie-Biscarosse (Sud des passes d'Arcachon) et la zone de la tête du canyon de Capbreton.
Ce travail présente une analyse de l'évolution morphologique et des processus sédimentaires actuels du plateau continental interne sud-aquitain, (sud-est du Golfe de Gascogne, France),secteur riche en données, mais sur lequel de nombreuses questions restent néanmoins en suspens. Il s'articule autour de deux zones ateliers complémentaires : la zone de « La Salie-Biscarrosse » sur le plateau continental interne sud-aquitain au sud des passes du Bassin d'Arcachon (entre 5 et 50 m de profondeur d’eau), et la tête du canyon de Capbreton et ses abords (entre 5 et 120 m de profondeur d’eau). Deux approches sont utilisées : (1) une approche descriptive et comparative (dans le temps), utilisant des données géo-acoustiques(sondeur multi faisceaux, sonar latéral et sondeur de sédiments), des prélèvements et (2) une approche mettant en oeuvre des modélisations numériques des interactions houles / courants /sédiments. Les résultats obtenus sur le plateau interne aquitain ont permis d'améliorer la connaissance de la morphologie, de la nature et de la géométrie interne des corps sédimentaires, d'étudier leur évolution au cours des 29 dernières années (entre 1984 et 2013)et de proposer des facteurs à l’origine de cette évolution. Le résultat majeur est la mise en évidence de « sorted bebforms » entretenus par la houle; dont la surprenante migration vers le nord-est est à associer à la récente découverte d'intenses épisodes de « poleward current » sur le plateau. Le suivi entre 1998 et 2013 de l’évolution morphologique de la tête du Canyon de Capbreton, située à seulement 250 m du littoral montre une évolution rapide qui fluctue cependant autour d'une position d'équilibre. Par ailleurs l’influence de la dérive littorale sur les transferts de sédiments du plateau vers le canyon a pu être démontrée. En-effet, les arguments morphologiques et sédimentaires, associés à la modélisation numérique, prouvent que la dérive littorale aquitaine alimente épisodiquement (conditions de houle forte) la tête de canyon en sables littoraux.
(23/10/2014)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Effects of standard humic materials on relative bioavailibility of NDL-PCBs in juvenile swine
(05/10/2014)
URAFPA, INRA, UL, LPTC, UB, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Origin and architecture of a Mass Transport Complex on the northwest slope of Little Bahama Bank (Bahamas): Relations between off-bank transport, bottom current sedimentation and submarine landslides
The analysis of the sedimentary dynamics of the carbonate slope of the northwest part of Little Bahama Bank (LBB, Bahamas) reveals a complex interaction between slope destabilisations, off-bank sediment export and longitudinal transport, the latter being driven by the Antilles and the Florida currents, at the northern end of the Florida Strait. Their combined action since the middle Miocene resulted in an extensional growth slope, previously called ‘LBB Drift’ (Mullins et al., 1980). Deposition within this extensional growth slope is dominated by either platform-derived downslope sedimentation or bottom current sedimentation. The latter induces the formation of a plastered drift, showing both upslope and downslope migrations, which do not correspond to the ‘LBB Drift’ as described by Mullins et al. (1980). Interestingly, a large submarine landslide affects the upper part of this plastered drift, and displays a complex and striking geomorphology on the seafloor. A new high-quality multibeam echosounder and seismic dataset allowed a detailed characterisation of the architecture of this Mass Transport Complex (MTC). A 44 km-long circular incision at 275 m and 460 m water depths, with a steep external edge (from 40 to 70 m high), forms the only present day evidence of this ancient MTC. It comprises confined Mass Transport Deposits (MTDs), which are delimited by frontal and lateral edges that developed inside the plastered drift. The top of this plastered drift is marked by a major erosional surface, most likely induced by an increase in oceanic current circulation. Channelised geometries, laterally associated with overspill deposits, developed within the depression induced by the MTC, and are an additional evidence of bottom current activity in this area. In addition, recent pockmarks are visible on the seafloor in front of the circular scarp of the MTC and probably relate to fluid escape, originating from the underlying MTDs' compressional area.
(Sedimentary Geology. vol. 317, n° 0037-0738, pp. 9-26, 01/10/2014)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
21,000 Years of Ethiopian African monsoon variability recorded in sediments of the western Nile deep-sea fan
(Regional Environmental Change. vol. 14, n° 1436-3798, pp. 1685-1696, 01/10/2014)
GEOAZUR 6526, IRD, UPMC, UNS, INSU - CNRS, UniCA, CNRS, GEOPS, UP11, CNRS, ETH Zürich, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, PALEOCEAN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GEOAZUR 7329, INSU - CNRS, UniCA, CNRS, IRD [Occitanie], IRD, UniCA, UAG, INSU - CNRS, UM, CNRS, CTAD, ENS-PSL, PSL, EHESS, UPN, CNRS, DREAM, Inria, IRISA-D7, IRISA, UR, INSA Rennes, UBS, ENS Rennes, Inria, CNRS, OOVM, UPMC, INSU - CNRS, CNRS
Analysis of airborne pesticides from different chemical classes adsorbed on Radiello® Tenax® passive tubes by thermal-desorption-GC/MS
An analytical methodology using automatic thermal desorption (ATD) and GC/MS was developed for the determination of 28 pesticides of different chemical classes (dichlobenil, carbofuran, trifluralin, clopyralid, carbaryl, flazasulfuron, mecoprop-P, dicamba, 2,4-MCPA, dichlorprop, 2,4-D, triclopyr, cyprodinil, bromoxynil, fluroxypyr, oxadiazon, myclobutanil, buprofezin, picloram, trinexapac-p-ethyl, ioxynil, diflufenican, tebuconazole, bifenthrin, isoxaben, alphacypermethrin, fenoxaprop and tau-fluvalinate) commonly used in nonagricultural areas in atmospheric samples. This methodology was developed to evaluate the indoor and outdoor atmospheric contamination by nonagricultural pesticides. Pesticides were sampled passive sampling tubes containing Tenax® adsorbent. Since most of these pesticides are polar (clopyralid, mecoprop-P, dicamba, 2,4-MCPA, dichlorprop, 2,4-D, triclopyr, bromoxynil, fluroxypyr, picloram, trinexapac-p-ethyl and ioxynil), a derivatisation step is required. For this purpose, a silylation step using N-(t-butyldimethylsilyl)-N-methyltrifluoroacetamide (MtBSTFA) was added before thermal desorption. This agent was chosen since it delivers very specific ions on electronic impact (m/z = M-57). This method was established with special consideration for optimal thermal desorption conditions (desorption temperature, desorb flow and duration; trap heating duration and flow; outlet split), linear ranges, limits of quantification and detection which varied from 0.005 to 10 ng and from 0.001 to 2.5 ng, respectively, for an uncertainty varied from 8 to 30 %. The method was applied in situ to the analysis of passive tubes exposed during herbicide application to an industrial site in east of France.
(Environmental Science and Pollution Research. vol. 22, n° 0944-1344, pp. 2726-2734, 11/09/2014)
ICPEES, UNISTRA, INC-CNRS, CNRS, MNGE, UNISTRA, Université de Haute-Alsace (UHA), INSERM, INC-CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Communities: Are they groups of hidden interactions?
Questions Ecologists are increasingly interested in community-level consequences of biotic interactions. However, community-level studies have not considered that biotic interactions might have contrasting directions within communities, and indirect interactions are rarely quantified although they may influence community-level outcomes. We tested the hypotheses that in species-rich plant communities from intermediate severe environmental conditions: (1) direct facilitation by dominant functional groups is balanced by negative indirect interactions among beneficiary species with no net effect at the community level on diversity and biomass, and (2) both direct and indirect interactions contribute to community composition. Location A species-rich subalpine community of the eastern Tibet Plateau (China). Methods We removed dominant shrubs and graminoids and quantified, at the community and species levels, their direct and indirect effects on 43 forb species. We used multivariate analyses to assess the contribution of direct and indirect effects on community composition. Results There were no community-level effects of either dominant life form on forb diversity and biomass. There were multiple species-level interactions that we grouped into six types based on the direction and intensity of indirect effects. We found significant relationships between species-level interactions and community composition. Conclusions Our study highlights that communities are sets of hidden interactions that contribute to community composition, although no interaction might be detected at the community level because hidden interactions balance each other. Future studies should assess the ecological and functional drivers of these hidden interactions.
(Journal of Vegetation Science. vol. 26, n° 1100-9233, pp. 207-218, 01/09/2014)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS