Histopathology alterations and histochemistry measurements in mussel, Mytilus edulis collected offshore from an aluminium smelter industry (Norway)     

N. Aarab  D.M. Pampanin  A. Nvdal  K.B. ysd  L. Gastaldi  R.K. Bechmann 《Marine pollution bulletin》2008,57(6-12):569

Histopathological characteristics of specific organs express condition, and represent time-integrated impacts on the organism stemming from alterations at lower levels of biological organisation. As integrative parameters, histochemical investigations have proved to be sensitive tools to detect effects of chemical compounds.The objective of this study was to determine changes in the tissues of mussels collected at a PAH contaminated site compared to a reference site using histopathological and histochemical parameters: lipofuscin (LF) accumulation in mussel digestive gland, and lysosomal membrane stability (LMS), and using additional information provided by body burden analysis to compare the sensitivity of these parameters.The histochemical measurements for both LF and LMS gave a clear indication of a high level of stress in animals from the PAH contaminated site. This LF accumulation in lysosomes is the result of peroxidation of autophagocytosed proteins associated with protein aggregates and oxidatively damaged organelles. These measurements were able to detect the effects of PAHs, and showed a strong relationship with the body burden results.  相似文献   

Electrical structure of the upper mantle beneath Central Europe: Results of the CEMES project     

Vladimir Yu. Semenov  Josef Pek  Antal Ádám  Waldemar Jóźwiak  Boris Ladanyvskyy  Igor M. Logvinov  Pavel Pushkarev  Jan Vozar 《Acta Geophysica》2008,56(4):957-981

In the years 2001–2003, we accomplished the experimental phase of the project CEMES by collecting long-period magnetotelluric data at positions of eleven permanent geomagnetic observatories situated within few hundreds kilometers along the south-west margin of the East European Craton. Five teams were engaged in estimating independently the magnetotelluric responses by using different data processing procedures. The conductance distributions at the depths of the upper mantle have been derived individually beneath each observatory. By averaging the individual cross-sections, we have designed the final model of the geoelectrical structure of the upper mantle beneath the CEMES region. The results indicate systematic trends in the deep electrical structure of the two European tectonic plates and give evidence that the electrical structure of the upper mantle differs between the East European Craton and the Phanerozoic plate of west Europe, with a separating transition zone that generally coincides with the Trans-European Suture Zone.  相似文献   

The snowball Earth aftermath: Exploring the limits of continental weathering processes     

Guillaume Le Hir  Yannick Donnadieu  Yves Goddéris  Raymond T. Pierrehumbert  Galen P. Halverson  Mélina Macouin  Anne Nédélec  Gilles Ramstein 《Earth and Planetary Science Letters》2009,277(3-4):453-463

Carbonates capping Neoproterozoic glacial deposits contain peculiar sedimentological features and geochemical anomalies ascribed to extraordinary environmental conditions in the snowball Earth aftermath. It is commonly assumed that post-snowball climate dominated by CO₂ partial pressures several hundred times greater than modern levels, would be characterized by extreme temperatures, a vigorous hydrological cycle, and associated high continental weathering rates. However, the climate in the aftermath of a global glaciation has never been rigorously modelled. Here, we use a hierarchy of numerical models, from an atmospheric general circulation model to a mechanistic model describing continental weathering processes, to explore characteristics of the Earth system during the supergreenhouse climate following a snowball glaciation. These models suggest that the hydrological cycle intensifies only moderately in response to the elevated greenhouse. Indeed, constraints imposed by the surface energy budget sharply limit global mean evaporation once the temperature has warmed sufficiently that the evaporation approaches the total absorbed solar radiation. Even at 400 times the present day pressure of atmospheric CO₂, continental runoff is only 1.2 times the modern runoff. Under these conditions and accounting for the grinding of the continental surface by the ice sheet during the snowball event, the simulated maximum discharge of dissolved elements from continental weathering into the ocean is approximately 10 times greater than the modern flux. Consequently, it takes millions of years for the silicate weathering cycle to reduce post-snowball CO₂ levels to background Neoproterozoic levels. Regarding the origin of the cap dolostones, we show that continental weathering alone does not supply enough cations during the snowball melting phase to account for their observed volume.  相似文献   

Numerical Study Of The Impact Of Coherent Structures On Vertical Transfers In The Atmospheric Boundary Layer     

F. Lohou  A. Druilhet  B. Campistron  J.-L. Redelspergers  F. Saïd 《Boundary-Layer Meteorology》2000,97(3):361-383

In two preceding papers, coherent structures of theatmospheric boundary layer (ABL), such as rollvortices or cells, were investigated through radar andaircraft observations collected during the TRAC-93(Turbulence Radar Aircraft Cells) experiment held inFrance in June 1993. The analysis of this experimentaldata set provided information on the spatialcharacteristics of these organisations (length scale,orientation, type ... ), their temporal and verticalevolution, and their relation with the dynamic andthermodynamic conditions of the ABL. For the thirdpaper in this series, a large eddy simulation model is used to examine the impact of thecoherent structures on the ABL vertical fluxes. Theanalysis of the simulated horizontal fields is madewith two-dimensional auto and cross-correlationsapplied on different pertinent ABL variables. Theresults emphasise a directional anisotropy of theseorganised fields throughout the ABL, much morepronounced in the heat flux fields, not only at thelength scale of organisations but also at theturbulence scales. This finding has an importantconsequence for traditional ABL flux measurementsbased on the hypothesis of isotropic and homogeneousturbulence. It can explain part of the underestimationof the surface fluxes often mentioned in theliterature. This approach makes it possible tomodify the concept of diffusion time (in chemicalmodelling) and could also lead to revised ABLparameterisations in Range Scale models.  相似文献   

Genetic and morphological variation in the endangered crayfish species, Austropotamobius pallipes (Lereboullet) (Crustacea, Astacidae) from the Poitou-Charentes region (France)     

Frédéric Grandjean  Catherine Souty-Grosset 《Aquatic Sciences - Research Across Boundaries》2000,62(1):1-19

  相似文献   

Photometry and analysis of the star HD 199497     

C. Sezer  Ö. Gülmen  N. Güdür 《Astrophysics and Space Science》1985,115(2):309-316

Two-colour photoelectric observations of the new eclipsing binary HD 199497 are presented. Our observations confirm that the system is a W UMa type eclipsing binary. The light curves were analysed with the Wilson-Devinney approach. The system is found to be in contact configuration. The inclination is amazingly small. Although there are no spectroscopic data, the photometric mass ratio of the system is well determined.  相似文献   

Ionospheric delay gradient model for GBAS in the Asia-Pacific region     

Saito  Susumu  Sunda  Surendra  Lee  Jiyun  Pullen  Sam  Supriadi  Slamet  Yoshihara  Takayuki  Terkildsen  Michael  Lecat  Frédéric 《GPS Solutions》2017,21(4):1937-1947

GPS Solutions - We investigated characteristics of anomalous spatial gradients in ionospheric delay on GNSS signals in the Asia-Pacific (APAC) low-magnetic latitude region in the context of the...  相似文献   

The late Quaternary sedimentary infill of Lake Annecy (northwestern Alps): an overview from two seismic-reflection surveys     

Christian Beck  Pieter Van Rensbergen  Marc De Batist  Fernand Berthier  Serge Lallier  Frédéric Manalt 《Journal of Paleolimnology》2001,25(2):149-161

The sedimentary fill of Lake Annecy (northwestern Alps) - related to the last glacial/post-glacial episode - was investigated through high resolution (sparker) and very high resolution (2.5 kHz) seismic-reflection surveys. A seismostratigraphic approach led to subdivision of a 150 m-thick pile (maximum thickness in axial part) into five units. Basal units (1 and 2) represent an imbrication of subglacial and glacio-lacustrine deposits, close to the grounding line of the glaciers' fronts (respectively at the northern and southern terminations of the lake). The first acoustically well-stratified unit (3) developed during a fast retreat of the glaciers fronts far from the lake basin, and a progradational alluvial regime, with abundant underflows, in a lake larger than the present one. Unit 4 represents the progressive decrease of this clastic input mixed with the progressive development of in situ bio-induced production. As in many other alpine lakes, a topmost unit (5), relatively thin (about 8-10 m) and with a conspicuous drape configuration, is the signature of the Holocene interglacial climatic conditions with a sedimentation rate of about 1 mm/yr. On the lacustrine basin slopes, slumps and debris flow occurred mainly within Unit 3; they may be due to, either climate-induced high rate terrigenous sedimentation, or/and to a period of increased seismo-tectonic activity.  相似文献   

The environmental significance of magnetic measurements of Late Pleistocene and Holocene sediments from the Grand Lac d'Annecy, eastern France     

Yuguan Hu  Frank Oldfield  Frédéric Manalt  Christian Beck 《Journal of Paleolimnology》2001,25(2):193-203

The results of a series of magnetic measurements on sediment samples are illustrated by means of examples selected from a more specialized parallel publication (Hu & Oldfield, submitted). They are interpreted in terms of magnetic components, notably, 'magnetite' of varying grain size/domain state, haematite, goethite and greigite. Wherever possible, some indication is given of changes in the relative importance of the various magnetic grain size and mineral phases through time. The main components of the magnetic assemblage are described for each of the main lithological units identified in the long core which is considered elsewhere in this volume. These assemblages are related to source areas and to depositional processes, especially in the pre-Holocene parts of the core. In the Holocene sediments, the magnetic properties cannot be interpreted solely in terms of shifts in detrital mineral sources. Evidence is presented for the presence of both biogenic magnetite and authigenic greigite. The most recent sediments point to renewed catchment erosion, probably as a result of human activity during historical times.  相似文献   

Experimental study of the atmospheric marine boundary layer from in-situ aircraft measurements (TOSCANE-T Campaign): Variability of boundary conditions and eddy flux parameterization     

Frédérique Saïd  Aimé Druilhet 《Boundary-Layer Meteorology》1991,57(3):219-249

The need for a thorough knowledge of boundary conditions over the vast oceanic surfaces makes remote sensing appear as the most suitable tool for future development. Remote sensing techniques require calibration data and consequently in-situ experiments to yield those data. Over the sea, aircraft seem to be the most convenient means of conducting validation experiments because they allow exploration of a large range of scales (from local measurements to measurements of pixel scale). This paper reports on some in-situ atmospheric aircraft measurements that were conducted as part of the TOSCANE-T experiment organized by the European Space Agency to calibrate the scatterometer for launch on ERS-1 in the early 1990's for global ocean wind measurement.The data analysed are the thermodynamic and turbulent variables measured by an instrumented aircraft, the Hurel Dubois, flying at a constant level of 50 m over the sea surface. Special attention was drawn to the variability of the boundary conditions within areas of 25 × 30 km. In fact, the two-dimensional fields of fluxes and thermodynamic parameters were inhomogeneous with some rather strong wind distortion.The eddy fluxes were parameterized with the aid of bulk aerodynamic formulations at a basic scale of 30 km samples, which corresponds to the aircraft flux computation legs. The bulk aerodynamic coefficients for momentum and heat were found to remain independent of windspeed (for wind velocities less than 12 m/s). Fluxes and thermodynamic parameters were also investigated at two other scales: the integration scale was either reduced to small areas of which size always remains larger than several characteristic lengths of turbulent transfer, or extended to a large area of 25 × 30km. The results of the bulk aerodynamic relationships appeared to be scale invariant, which would therefore justify the application of average values, within the range of scales under study.  相似文献