Abnormal features of Macoma balthica (Bivalvia) in the Baltic Sea: alerting symptoms of environmental adversity?     

Sokołowski A  Wołowicz M  Hummel H  Smolarz-Górska K  Fichet D  Radenac G  Thiriot-Quiévreux C  Namieśnik J 《Marine pollution bulletin》2004,49(1-2):17-22

Recent studies of the Baltic clam Macoma balthica (L.) from the southern Baltic (the Gulf of Gdansk) have revealed striking morphological, histological and cytogenetic features. Strong deformation of the shell, including elongation of the posterior end and the appearance of an easily visible flexure in this part, has been recorded. The population contribution of the deformed blunt shelled ("irregular") clams ranged from 0% to 65% and tended to increase with depth. The morphologically "irregular" clams had higher accumulated tissue concentrations of trace metals (As, Ag, Cd, Pb, Cu and Zn), indicating a different metal handling ability. Adverse conditions in deeper water regions of the Gulf (e.g. hypoxia, hydrogen sulphide, elevated bioavailability of contaminants) have been suggested as inducers of the phenotypical changes (morphological deformation) in part of the population and, in parallel, of the specific physiological adaptations that result in higher metal accumulation in the "irregular" clams. Cytogenetic and histological analyses showed the presence of tumours in gill cells and digestive system of the affected clams, the prevalence of disseminated neoplasia ranging from 0% to 94% depending on the site. The disease was manifested by a modified karyotype (i.e. an abnormal number and morphology of chromosomes), a higher activity of nucleolar organizer regions (AgNORs), and tissue lesions (enlarged cells, actively proliferative with pleomorphic nuclei). Bottom sediments showed acute toxicity and have been proposed as a source of an initialising carcinogenic factor. However, none of the ecotoxicological studies provided was successful in the clear demonstration of a single (or multifactorial) agent that can account for the disseminated neoplasia.  相似文献   

Applications of C and N stable isotopes to ecological and environmental studies in seagrass ecosystems   总被引：2，自引：0，他引：2  

Lepoint G  Dauby P  Gobert S 《Marine pollution bulletin》2004,49(11-12):887-891

Stable isotopes of carbon and nitrogen are increasingly used in marine ecosystems, for ecological and environmental studies. Here, we examine some applications of stable isotopes as ecological integrators or tracers in seagrass ecosystem studies. We focus on both the use of natural isotope abundance as food web integrators or environmental tracers and on the use of stable isotopes as experimental tools. As ecosystem integrators, stable isotopes have helped to elucidate the general structure of trophic webs in temperate, Mediterranean and tropical seagrass ecosystems. As environmental tracers, stable isotopes have proven their utility in sewage impact measuring and mapping. However, to make such environmental studies more comprehensible, future works on understanding of basic reasons for variations of N and C stable isotopes in seagrasses should be encouraged. At least, as experimental tracers, stable isotopes allow the study of many aspects of N and C cycles at the scale of a plant or at the scale of the seagrass ecosystem.  相似文献   

The 1‐million‐year‐old quartz assemblage from Pont‐de‐Lavaud (Centre,France) in the European context          下载免费PDF全文

Jackie Despriée  Marie‐Hélène Moncel  Marta Arzarello  Gilles Courcimault  Pierre Voinchet  Jean‐Jacques Bahain  Christophe Falguères 《第四纪科学杂志》2018,33(6):639-661

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Influence of the Surf Zone on the Marine Aerosol Concentration in a Coastal Area     

Gilles Tedeschi  Alexander M. J. van Eijk  Jacques Piazzola  Jolanta T. Kusmierczyk-Michulec 《Boundary-Layer Meteorology》2017,163(2):327-350

Sea-salt aerosol concentrations in the coastal zone are assessed with the numerical aerosol-transport model MACMod that applies separate aerosol source functions for open ocean and the surf zone near the sea–land transition. Numerical simulations of the aerosol concentration as a function of offshore distance from the surf zone compare favourably with experimental data obtained during a surf-zone aerosol experiment in Duck, North Carolina in autumn 2007. Based on numerical simulations, the effect of variations in aerosol production (source strength) and transport conditions (wind speed, air–sea temperature difference), we show that the surf-zone aerosols are replaced by aerosols generated over the open ocean as the airmass advects out to sea. The contribution from the surf-generated aerosol is significant during high wind speeds and high wave events, and is significant up to 30 km away from the production zone. At low wind speeds, the oceanic component dominates, except within 1–5 km of the surf zone. Similar results are obtained for onshore flow, where no further sea-salt aerosol production occurs as the airmass advects out over land. The oceanic aerosols that are well-mixed throughout the boundary layer are then more efficiently transported inland than are the surf-generated aerosols, which are confined to the first few tens of metres above the surface, and are therefore also more susceptible to the type of surface (trees or grass) that determines the deposition velocity.  相似文献   

Non-parametric seismic data recovery with curvelet frames   总被引：12，自引：0，他引：12  

Felix J. Herrmann  Gilles Hennenfent 《Geophysical Journal International》2008,173(1):233-248

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Impact of cross-reef water fluxes on lagoon dynamics: a simple parameterization for coral lagoon circulation model,with application to the Ouano Lagoon,New Caledonia     

Cristele Chevalier  Damien Sous  Jean-Luc Devenon  Marc Pagano  Gilles Rougier  Jean Blanchot 《Ocean Dynamics》2015,65(11):1509-1534

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Jahresbericht 2008 und Bericht über die 124. Ordentliche Generalversammlung der Schweizerischen Geologischen Gesellschaft in Lugano     

Gilles Borel 《Swiss Journal of Geoscience》2009,102(2):365-369

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Modelling the impact of tectonics,surface conditions and sea surface temperatures on Saharan and sub-Saharan climate evolution     

Pierre Sepulchre  Gilles Ramstein  Mathieu Schuster 《Comptes Rendus Geoscience》2009,341(8-9):612-620

Using an Atmospheric Global Circulation Model, we assess the relevance of selected atmospheric mechanisms for climate evolution of Saharan and sub-Saharan regions since the Miocene. First, we test the influence of the East-African Rift System uplift on atmospheric dynamics. Although the uplift played an important role in triggering East-African rainfall, no significant impact over central and western Africa has been detected. We also analyse the feedbacks of a giant lake on the climate of Chad basin. First results infer a negative feedback of the giant lake on the water balance, as convection is weakened by the cold water surface and as water evaporated from the lake does not feed the basin hydrological cycle. Lastly, we suggest that colder than present sea surface temperatures over the Gulf of Guinea reinforce the West-African monsoon, by enhancing the moisture advection engine via stronger thermal contrast between the ocean and the continent.  相似文献   

Triassic <Superscript>40</Superscript>Ar/<Superscript>39</Superscript>Ar ages from the Sakaigawa unit,Kii Peninsula,Japan: implications for possible merger of the Central Asian Orogenic Belt with large-scale tectonic systems of the East Asian margin     

Koen de Jong  Chikao Kurimoto  Gilles Ruffet 《International Journal of Earth Sciences》2009,98(6):1529-1556

The 218.4 ± 0.4, 228.8 ± 0.9 and 231.9 ± 0.7 Ma ⁴⁰Ar/³⁹Ar laser probe pseudo-plateau ages (2σ; 49–63% ³⁹Ar-release) of very low-grade meta-pelitic whole-rocks from the Sakaigawa unit date high-P/T metamorphism. We argue that this event occurred in a subduction–accretion complex, not along the East Asian continental margin, but on the Pacific side of the proto-Japan superterrane. Proto-Japan was a Permian magmatic arc, presently dispersed in the Japanese islands, which also contained older subduction–accretion complexes. The arc system was fringing but not yet part of the Eurasian continent. The Middle to Late Triassic high-P/T tectono-metamorphic event was partly coeval with proto-Japan’s collision with proto-Eurasia along the southward extension of the Central Asian Orogenic Belt, causing the main metamorphism in the Hida-Oki terrane. It is possible that this system continued via the Cathaysia block (China) to Indochina. The Late Permian to Middle Triassic Indosinian event might stem from docking of Pacific-derived terranes with Southeast Asia’s continental margin. The concept of the proto-Japan superterrane implies that the Qinling-Dabie-Sulu suture zone joined the Central Asian Orogenic Belt to the east of the North China craton and did not continue to Japan, as commonly assumed.  相似文献   

Structure and nuclear density distribution in the cheralite—CaTh(PO4)2: studies of its behaviour under high pressure (36?GPa)     

Philippe E. Raison  Stephen Heathman  Gilles Wallez  Carmen E. Zvoriste  Denis Bykov  Ga?l Ménard  Emmanuelle Suard  Karin Popa  Nicolas Dacheux  Rudy J. M. Konings  Roberto Caciuffo 《Physics and Chemistry of Minerals》2012,39(8):685-692

The crystal structure of the cheralite—CaTh(PO₄)₂—has been revisited by neutron diffraction and its behaviour under high pressure investigated by X-ray diffraction up to 36?GPa. The neutron diffraction data at ambient pressure gave a more accurate determination of the Ca/Th cation position than previous XRD data, taking advantage that the neutron scattering lengths of calcium and thorium are of same order of magnitude. The nuclear density distribution was also determined using the maximum entropy method (MEM) confirming that the two cations are not located at the same position in the unit cell but are slightly displaced from one another along a specific direction in order to minimize the electrostatic repulsion with the surrounding phosphorus atoms. At high pressure, the compound did not show any phase transition or amorphization. From the evolution of the unit-cell volume as a function of the pressure, the zero-pressure bulk modulus B₀ and its pressure derivative B₀ ^′ have been determined by fitting the experimental compressibility curve to the Birch–Murnaghan equation of state. The results are B₀?=?140(2) GPa and B ₀ ^′ ?=?4.4(4) GPa.  相似文献