Sur les inocérames de Tercis (Landes,France) : le meilleur outil corrélatif entre Europe et Amérique du Nord autour de la limite Campanien–Maastrichtien     

Gilles Serge Odin  Ireneusz Walaszczyk 《Comptes Rendus Geoscience》2003,335(2):239-246

Four hundred inoceramids have been collected in the geological site at Tercis, where the Campanian–Maastrichtian boundary has been recently defined. At Tercis, a distinct drop of the adult size of inoceramids is observed between levels 111 and 117 and two turnovers of faunal composition were documented between levels 94 and 96 and between levels 111 and 117; the latter interval encompasses the stage boundary. The recognised inoceramid assemblages are very close to those known from North America, allowing better correlation than before between the two domains in the interval 77–70 Ma. The presence of these faunas perfectly located in the section leads to consider the Tercis section as the best known reference for this fossil group, the surprisingly good correlative potential of which has still to be considered in many areas.  相似文献   

Contexte lithostructural, âges 40K40Ar et géochimie du volcanisme calco-alcalin tertiaire de Cap-d'Ail dans le tunnel ferroviaire de Monaco     

Jean-Pierre Ivaldi  Hervé Bellon  Pierre Guardia  Christian Mangan  Carla Müller  Jean-Louis Perez  Serge Terramorsi 《Comptes Rendus Geoscience》2003,335(4):411-421

Lithostratigraphic and structural framework, chronology and geochemistry of the Tertiary calc-alkaline volcanism of Cap-d'Ail (French Maritime Alps) are specified according to the new data collected during the earthworks of the recent railway tunnel built between Cap-d'Ail and Monaco. Two different magmatic events were dated: the first one, to Palaeogene, the other one, to Neogene. To cite this article: J.-P. Ivaldi et al., C. R. Geoscience 335 (2003).  相似文献   

Étude des colorations apparaissant dans un nuage produit par détente rapide de l'air     

Serge Godard 《Pure and Applied Geophysics》1961,50(1):198-202

Résumé Les colorations et les couronnes apparaissant dans un nuage produit par détende rapide de l'air dans une chambre sont étudiées à l'aide d'un dispositif photographique simple; simultanément on mesure les dimensions des gouttelettes constituant le nuage au moyen de lames de verre recouvertes d'un film de collargol. La relation théorique entre le diamètre des couronnes de diffraction et de diamètre des gouttelettes n'est pas retrouvée expérimentalement. On constate l'existence de couronnes de grand diamètre (30 degrés). L'évanouissement rapide des couronnes permet d'autre part de penser que le spectre dimensionnel des gouttelettes du nuage, étroit au début, a tendance à s'étaler ensuite au cours du temps.

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Summary The colorations and the coronas which appear in a cloud producted by an air rapid expansion in a chamber, are studied by a simple photographic apparatus; the size of the droplets which constitute the cloud are simultaneously measured, by mean of slides covered with collargol. The theoretical relation between the diffraction coronas diameter and the droplets diameter is not experimentally verificated. We ascertain the large diameter coronas existence (30°). The rapid evanescence of the coronas allows, on the other side, to think that the dimensional spectrum of the cloud droplets, which is first very narrow, has a disposition to spread then in the course of time.

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Fishery systems and linkages: from clockworks to soft watches   总被引：2，自引：0，他引：2  

Garcia  Serge M.; Charles  Anthony T. 《ICES Journal of Marine Science》2007,64(4):580-587

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Nutrient Enrichments of Waters of "Golfo de San Jose" (Argentina, 42 ^oS), Growth and Species Selection of Phytoplankton     

Claude J.  Charpy-Roubaud†  Loic J.  Charpy† Serge Y.  Maestrini 《Marine Ecology》1983,4(1):1-18

Abstract. Coastal Patagonian sea waters had been differentially nutrient-enriched to determine (i) the magnitude of the algal biomass supported and (ii) which species were able to best compete for the available nutrients. Nitrogen was found to be the nutrient limiting growth of the natural phytoplankton population. The addition of NO₃ at 25 μg at 1^-1 led to a 10 to 30 μg 1^-1 increase in chlorophyll a in all but those treatments containing trace metal additions. The best yield coefficients were obtained when a chelator (EDTA) was added with NO₃. A pool of nine diatom species were common in the N0₃ supplemented waters and the addition of vitamins along with NO₃ allowed two of the nine species to dominate.  相似文献   

Lower Kungurian shallow-water lagoon biota of Middle Cis-Urals,Russia:towards paleoecological reconstruction     

Serge V.Naugolnykh 《世界地质(英文版)》2017,(1)

The paper deals with the Lower Kungurian( Philippovian Horizon; Lower Permian) biota of the Middle Cis-Urals,Russia.The biota is characterized on the basis of four representative localities( Philippovskoe Bus-stop,Philippovskian Quarry,Kamai and Kiselevo-Suksun Highway),which are situated in the stratotype area of the Kungurian stage.All the localities can be regarded as Lagersttten,but of authentically low biodiversity,since they represent oligotrophic lagoons of abnormal fluctuating salinity.General reconstruction of the Philippovian near-shore shallow-water ecosystem is given.Two new species of algae Algites philippoviensis sp.nov.,A.shurtanensis sp.nov.,and a new species of the limulids Paleolimulus kunguricus sp.nov.are described for the first time.  相似文献   

The science of European marine reserves: Status,efficacy, and future needs     

Phillip B. Fenberg  Jennifer E. Caselle  Joachim Claudet  Michaela Clemence  Steven D. Gaines  Jose Antonio García-Charton  Emanuel J. Gonçalves  Kirsten Grorud-Colvert  Paolo Guidetti  Stuart R. Jenkins  Peter J.S. Jones  Sarah E. Lester  Rob McAllen  Even Moland  Serge Planes  Thomas K. Sørensen 《Marine Policy》2012

The ecologically and socio-economically important marine ecosystems of Europe are facing severe threats from a variety of human impacts. To mitigate and potentially reverse some of these impacts, the European Union (EU) has mandated the implementation of the Marine Strategy Framework Directive (MSFD) in order to achieve Good Environmental Status (GES) in EU waters by 2020. The primary initiative for achieving GES is the implementation of coherent networks of marine protected areas (MPAs). Marine reserves are an important type of MPA in which no extraction is allowed, but their usefulness depends upon a number of ecological, management, and political factors. This paper provides a synthesis of the ecological effects of existing European marine reserves and the factors (social and ecological) underlying their effectiveness. Results show that existing European marine reserves foster significant positive increases in key biological variables (density, biomass, body size, and species richness) compared with areas receiving less protection, a pattern mirrored by marine reserves around the globe. For marine reserves to achieve their ecological and social goals, however, they must be designed, managed, and enforced properly. In addition, identifying whether protected areas are ecologically connected as a network, as well as where new MPAs should be established according to the MSFD, requires information on the connectivity of populations across large areas. The adoption of the MSFD demonstrates willingness to achieve the long-term protection of Europe's marine ecosystems, but whether the political will (local, regional, and continent wide) is strong enough to see its mandates through remains to be seen. Although the MSFD does not explicitly require marine reserves, an important step towards the protection of Europe's marine ecosystems is the establishment of marine reserves within wider-use MPAs as connected networks across large spatial scales.  相似文献   

Biogeochemistry and dynamics of settling particle fluxes at the Antikythira Strait (Eastern Mediterranean)     

Philippe Kerherv  Serge Heussner  Bruno Charrire  Spyros Stavrakakis  Jean-Luc Ferrand  Andr Monaco  Nicole Delsaut 《Progress in Oceanography》1999,44(4):295

For the first time, a 12-month trap experiment was conducted on both sides of the strait between Crete and Antikythira Island (Eastern Mediterranean Sea) from June 1994 to June 1995 as part of the PELAGOS experiment. Analyses of major chemical constituents, including carbohydrates and stable lead isotopes and Scanning Electron Microscope studies were performed on the trap samples. Total mass fluxes varied between 1 and 1273 mg m⁻² d⁻¹. The lowest fluxes observed were in summer and autumn 1994, when stratification of the water column was at its deepest. In general, mass fluxes exhibited very low values throughout this experiment confirming the strong oligotrophy of this area. The mean contents of the major constituents (carbonates, opal, lithogenic fraction) were quite similar during the survey and between traps, with the exception of organic carbon contents, which were highest (7–10%) in summer 1994, i.e. during the period of lowest mass fluxes. During the first 6-month deployment (summer–autumn 1994) there was an important mass flux peak, which was depleted in organic carbon, at the Ionian near-bottom trap. This event coincided with a violent wind episode, which may have caused the resuspension of particles, which were then transported down the steep continental slope on the Ionian side of the strait. A smaller peak in mass flux occurred at the Aegean near-bottom trap, coincident with rainfall. Both these events indicate that environmental factors can control flux variations in an oligotrophic environment. During the second 6-month deployment (winter–spring 1995) there was another important increase in mass fluxes, which occurred at all three traps, although in the Ionian traps mass flux peaks were delayed by one to two sampling intervals. The distance between the two mooring sites gives a rough estimate of a minimum horizontal advection speed of 2 cm s⁻¹ for this particulate transfer from the Aegean to the Ionian area. This estimate is in good agreement with the measured current velocities.  相似文献   

Contribution of the ground corona ions to the convective charging mechanism     

Serge Chauzy  Serge Soula 《Atmospheric Research》1999,51(3-4)

The convective charging mechanism of thunderclouds is based on the vertical transport of space charge generated by corona from ground irregularities under the influence of the surface electric field. The present work estimates the amount of charge which is expected to reach cloud base by conduction and convection processes during the lifetime of a thunderstorm. This estimate is made using the numerical model PICASSO, previously designed to characterize the evolution of this corona space charge between ground level and cloud base. Experimentally determined values of surface electric field are introduced into the model in order to initiate the computation. These values are based on six events documented during four different field experiments carried out in Florida and in France. As an upper limit, the convective transport is uniformly applied as a linearly increasing vertical air speed profile and competes with the conductive transport. The fraction of the positive charge generated at the surface by corona which finally reaches the upper limit of the layer varies between 26 and 86%, essentially depending on the electric field evolution at altitude. Assuming that the vertical transport conditions remain the same over an area of 10 km×10 km, the overall charge amount can be roughly estimated. It ranges between about 63 and over 300 C. Because the present assumptions probably lead to an overestimate of these amounts, such a range suggests that the convective charging mechanism is unlikely to be able to account for the major electrification process of the thundercloud. However, it could be considered as a relevant mechanism contributing to the lower positive charge center of the thundercloud, often observed close to cloud base.  相似文献   

Coupled ocean-atmosphere surface variability and its climate impacts in the tropical Atlantic region     

B. Fontaine  Serge Janicot  P. Roucou 《Climate Dynamics》1999,15(6):451-473

 This study examines time evolution and statistical relationships involving the two leading ocean-atmosphere coupled modes of variability in the tropical Atlantic and some climate anomalies over the tropical 120 °W–60 °W region using selected historical files (75-y near global SSTs and precipitation over land), more recent observed data (30-y SST and pseudo wind stress in the tropical Atlantic) and reanalyses from the US National Centers for Environmental Prediction (NCEP/NCAR) reanalysis System on the period 1968–1997: surface air temperature, sea level pressure, moist static energy content at 850 hPa, precipitable water and precipitation. The first coupled mode detected through singular value decomposition of the SST and pseudo wind-stress data over the tropical Atlantic (30 °N–20 °S) expresses a modulation in the thermal transequatorial gradient of SST anomalies conducted by one month leading wind-stress anomalies mainly in the tropical north Atlantic during northern winter and fall. It features a slight dipole structure in the meridional plane. Its time variability is dominated by a quasi-decadal signal well observed in the last 20–30 ys and, when projected over longer-term SST data, in the 1920s and 1930s but with shorter periods. The second coupled mode is more confined to the south-equatorial tropical Atlantic in the northern summer and explains considerably less wind-stress/SST cross-covariance. Its time series features an interannual variability dominated by shorter frequencies with increased variance in the 1960s and 1970s before 1977. Correlations between these modes and the ENSO-like Nino3 index lead to decreasing amplitude of thermal anomalies in the tropical Atlantic during warm episodes in the Pacific. This could explain the nonstationarity of meridional anomaly gradients on seasonal and interannual time scales. Overall the relationships between the oceanic component of the coupled modes and the climate anomaly patterns denote thermodynamical processes at the ocean/atmosphere interface that create anomaly gradients in the meridional plane in a way which tends to alter the north–south movement of the seasonal cycle. This appears to be consistent with the intrinsic non-dipole character of the tropical Atlantic surface variability at the interannual time step and over the recent period, but produces abnormal amplitude and/or delayed excursions of the intertropical convergence zone (ITCZ). Connections with continental rainfall are approached through three (NCEP/NCAR and observed) rainfall indexes over the Nordeste region in Brazil, and the Guinea and Sahel zones in West Africa. These indices appear to be significantly linked to the SST component of the coupled modes only when the two Atlantic modes+the ENSO-like Nino3 index are taken into account in the regressions. This suggests that thermal forcing of continental rainfall is particularly sensitive to the linear combinations of some basic SST patterns, in particular to those that create meridional thermal gradients. The first mode in the Atlantic is associated with transequatorial pressure, moist static energy and precipitable water anomaly patterns which can explain abnormal location of the ITCZ particularly in northern winter, and hence rainfall variations in Nordeste. The second mode is more associated with in-phase variations of the same variables near the southern edge of the ITCZ, particularly in the Gulf of Guinea during the northern spring and winter. It is primarily linked to the amplitude and annual phase of the ITCZ excursions and thus to rainfall variations in Guinea. Connections with Sahel rainfall are less clear due to the difficulty for the model to correctly capture interannual variability over that region but the second Atlantic mode and the ENSO-like Pacific variability are clearly involved in the Sahel climate interannual fluctuations: anomalous dry (wet) situations tend to occur when warmer (cooler) waters are present in the eastern Pacific and the gulf of Guinea in northern summer which contribute to create a northward (southward) transequatorial anomaly gradient in sea level pressure over West Africa. Received: 14 April 1998 / Accepted: 24 December 1998  相似文献