NMR relaxation of neritic carbonates: An integrated petrophysical and petrographical approach     

Benoit Vincent  Marc Fleury  Yannick Santerre  Benjamin Brigaud 《Journal of Applied Geophysics》2011,74(1):38-58

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Trophic importance of diatoms in an intertidal Zostera noltii seagrass bed: Evidence from stable isotope and fatty acid analyses     

Benoit Lebreton  Pierre Richard  Robert Galois  Gilles Radenac  Camille Pfléger  Gaël Guillou  Françoise Mornet  Gérard F. Blanchard 《Estuarine, Coastal and Shelf Science》2011

A current predominant paradigm emphasizes the role of epiphytic algae for invertebrates in most seagrass food webs. However, in some intertidal Zostera noltii beds, epiphyte biomass is very low compared to microphytobenthos and seagrass biomasses. We assessed the role of microphytobenthos in a temperate intertidal Z. noltii bed by combining stable isotope and fatty acid (FA) analyses on primary producers, composite sources — suspended particulate organic matter (SPOM) and sediment surface organic matter (SSOM) — and the main macrofaunal consumers. Z. noltii showed high δ¹³C (−9.9‰) and high 18:2(n-6) and 18:3(n-3) contents. Microphytobenthos was slightly more ¹³C-depleted (−15.4‰) and had high levels of diatom markers: 14:0, 16:1(n-7)c, 20:5(n-3). Low mean δ¹³C (−22.0‰) and large amounts of diatom and bacteria (18:1(n-7)c) markers indicated that SPOM was mainly composed of a mixture of fresh and decayed pelagic diatoms. Higher mean δ¹³C (−17.9‰) and high amounts of diatom FAs were found in SSOM, showing that microphytobenthic diatoms dominate. Very low percentages of 18:2(n-6) and 18:3(n-3) in consumers indicated a low contribution of Z. noltii material to their diets. Grazers, deposit and suspension-deposit feeders had δ¹³C close to microphytobenthos and high levels of diatom FAs, confirming that microphytobenthos represented the main part of their diet. Lower δ¹³C and higher amounts of flagellate FAs – 22:6(n-3) and 16:4(n-3) – in suspension feeders indicated that their diet resulted from a mixture of SPOM and microphytobenthos. These results demonstrate that invertebrates do not consume high amounts of seagrass and highlight the main role of benthic diatoms in this intertidal seagrass bed.  相似文献   

Including the Drag Effects of Canopies: Real Case Large-Eddy Simulation Studies     

Pierre Aumond  Valery Masson  Christine Lac  Benoit Gauvreau  Sylvain Dupont  Michel Berengier 《Boundary-Layer Meteorology》2013,146(1):65-80

We use the mesoscale meteorological model Meso-NH, taking the drag force of trees into account under stable, unstable and neutral conditions in a real case study. Large-eddy simulations (LES) are carried out for real orography, using a regional forcing model and including the energy and water fluxes between the surface (mostly grass with some hedges of trees) and the atmosphere calculated using a state-of-the-art soil-vegetation-atmosphere-transfer model. The formulation of the drag approach consists of adding drag terms to the momentum equation and subgrid turbulent kinetic energy dissipation, as a function of the foliage density. Its implementation in Meso-NH is validated using Advanced Regional Prediction System simulation results and measurements from Shaw and Schumann (Boundary-Layer Meteorol, 61(1):47?C64, 1992). The simulation shows that the Meso-NH model successfully reproduces the flow within and above homogeneous covers. Then, real case studies are used in order to investigate the three different boundary layers in a LES configuration (resolution down to 2 m) over the ??Lannemezan 2005?? experimental campaign. Thus, we show that the model is able to reproduce realistic flows in these particular cases and confirm that the drag force approach is more efficient than the classical roughness approach in describing the flow in the presence of vegetation at these resolutions.  相似文献   

Correction to: Spatial and temporal variability of rainfall: case of Bizerte-Ichkeul Basin (Northern Tunisia)     

Hiba Jemai  Manel Ellouze  Habib Abida  Benoit Laignel 《Arabian Journal of Geosciences》2018,11(10):230

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Caractérisation de l'effluent de vidange d'un étang de pisciculture extensive     

Dominique Vallod  Benoit Sarrazin 《水文科学杂志》2013,58(3):394-402

Résumé Afin d'évaluer l'impact potentiel de la vidange, les flux de nutriments et de matières sont quantifiés lors du remplissage et de la vidange d'un étang construit en dérivation, à l'aval d'une chaîne d'étangs. La cinétique de vidange a été établie à l'aide d'un modèle numérique de terrain restituant la surface topographique de l'étang. Les matières en suspension et les principaux nutriments ont été régulièrement quantifiés. La qualité hydrobiologique du cours d'eau récepteur a été contrôlée pendant et après la vidange. L'étang a exporté 8.5 tonnes de matières en suspension et des quantités de nutriments relativement élevées. Nos résultats confirment l'existence de deux phases critiques, ne concernant cependant qu'un très faible volume d'effluent. Compte tenu des capacités élevées de sédimentation des matières en suspension, la courte durée d'exposition associée à un linéaire de fossés suffisant pourrait limiter l'impact de ces matières rejetées.

Citation Vallod, D. & Sarrazin, B. (2010) Caractérisation de l'effluent de vidange d'un étang de pisciculture extensive. Hydrol. Sci. J. 55(3), 394–402.  相似文献   

Thermomechanical effects of a rapid depressurization in a gas cavern   总被引：1，自引：0，他引：1  

Pierre Bérest  Benoit Brouard  Hippolyte Djakeun-Djizanne  Grégoire Hévin 《Acta Geotechnica》2014,9(1):181-186

Rapid gas depressurization leads to gas cooling followed by slow gas warming when the cavern is kept idle. Gas temperature drop depends upon withdrawal rate and cavern size. Thermal tensile stresses, resulting from gas cooling, may generate fractures at the wall and roof of a salt cavern. However, in most cases, the depth of penetration of these fractures is small. These fractures are perpendicular to the cavern wall. The distance between two parallel fractures becomes larger when fractures penetrate deeper in the rock mass, as some fractures do not keep growing. These conclusions can be supported by numerical computations based on fracture mechanics. Salt slabs are created. However, these slabs remain strongly bounded to the rock mass and it is believed that in many cases their weight is not large enough to allow them to break off the cavern wall. Depth of penetration of the fractures must be computed to prove that they cannot be a concern from the point of view of cavern tightness.  相似文献   

Antenna-coupled arrays of NbSi micro-bolometers     

Aur��lien Bideaud  Benoit Belier  Alain Benoit  Laurent Berg��  Philippe Camus  Sophie Collin  Louis Dumoulin  Christian Hoffmann  Stefanos Marnieros  Alessandro Monfardini 《Experimental Astronomy》2011,32(2):179-191

Microbolometers are at present the most sensitive detectors for mm and sub-mm Astronomy. They are in use in most of the present instruments in that bandwidth. We have developed filled arrays of NbSi-based planar antenna coupled microbolometers. The fabrication details are given, together with characterization of the NbSi thermometers and optical results. The optical performances are potentially good for ground-based mm-wave astronomy applications, while the overall detectors performances are limited by low-frequency excess noise in the thermometric NbSi high-impedance sensors (Anderson insulator).  相似文献   

A watershed-scale study of climate change impacts on groundwater recharge (Annapolis Valley,Nova Scotia,Canada)     

Christine Rivard  Claudio Paniconi  Harold Vigneault  Diane Chaumont 《水文科学杂志》2013,58(8):1437-1456

Abstract

The potential impacts of future climate change on the evolution of groundwater recharge are examined at a local scale for a 546-km² watershed in eastern Canada. Recharge is estimated using the infiltration model Hydrologic Evaluation of Landfill Performance (HELP), with inputs derived from five climate runs generated by a regional climate model in combination with the A2 greenhouse gas emissions scenario. The model runs project an increase in annual recharge over the 2041–2070 period. On a seasonal basis, however, a marked decrease in recharge during the summer and a marked increase during the winter are observed. The results suggest that increased evapotranspiration resulting from higher temperatures does not offset the large increase in winter infiltration. In terms of individual water budget components, clear differences are obtained for the different climate change scenarios. Monthly recharge values are also found to be quite variable, even for a given climate scenario. These findings are compared with results from two regional-scale studies.