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排序方式: 共有189条查询结果,搜索用时 10 毫秒
31.
Catherine Heymans Ludovic Van Waerbeke David Bacon Joel Berge Gary Bernstein Emmanuel Bertin Sarah Bridle Michael L. Brown Douglas Clowe Håkon Dahle Thomas Erben Meghan Gray Marco Hetterscheidt Henk Hoekstra Patrick Hudelot Mike Jarvis Konrad Kuijken Vera Margoniner Richard Massey Yannick Mellier Reiko Nakajima Alexandre Refregier Jason Rhodes Tim Schrabback David Wittman 《Monthly notices of the Royal Astronomical Society》2006,368(3):1323-1339
32.
Ocean Dynamics - The existence of cross-sectionally averaged morphodynamic equilibria of tidal inlets is investigated, using a cross-sectionally averaged model, and their sensitivity to variations... 相似文献
33.
Wither A Bamber R Colclough S Dyer K Elliott M Holmes P Jenner H Taylor C Turnpenny A 《Marine pollution bulletin》2012,64(8):1564-1579
The construction of a new generation of coastal power stations in the UK and other western European countries has highlighted the absence of robust standards for thermal discharges to transitional and coastal waters. The proposed discharge volumes are greater than hitherto, yet there has been little independent critical examination of their potential impact, whilst much of the existing guidance has been adapted from freshwater practice. This review considers the available knowledge on the tolerance and behaviour of fish and other marine biota to heated effluents. Appropriate ways are suggested of grouping fish species to reflect their sensitivity to thermal effects. The plethora of existing standards are considered and their validity assessed in a framework of predicted seawater temperature rise. Those species or groups of organisms most likely to be affected are identified and finally specific recommendations for thermal standards consistent with long term sustainability are proposed. 相似文献
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Suzanne?E.?HollinsEmail author Jennifer?J.?Harrison Brian?G.?Jones Atun?Zawadzki Henk?Heijnis Stuart?Hankin 《Journal of Paleolimnology》2011,46(4):579-596
In this study, we combined grain size and geochemical analyses with radioisotope analysis of lead-210 (210Pb), caesium-137 (137Cs) and radiocarbon (14C) ages to reconstruct the sedimentation history of two urbanised coastal lagoons in south-east Australia. Towradgi and Fairy
Lagoons were both found to exhibit slow initial sedimentation of less than 1 mm year−1 prior to anthropogenic influences. Land clearing in the catchments increased runoff and erosion in the creeks feeding into
the estuaries, and has resulted in progradation of fluvial material into the estuarine systems with a marked increase in sedimentation
to between 2 and 7 mm year−1. The upper 20–50 cm of the sediment column in both lagoons contained elevated concentrations of heavy metals such as Pb,
Cu, Ni and Zn. This pollution trend was found to be consistent with the history of industrialisation and urbanisation in the
region, which expanded rapidly post World War 2. The total metal concentrations were consistent with other urbanised/industrialised
estuaries around the world. Despite the fairly disturbed nature of these coastal lagoons, the use of 210Pb, 137Cs and 14C dating in combination with bulk geochemical analyses allowed detailed reconstruction of sedimentation history. 相似文献
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Gerard J.M. Versteegh Henk Brinkhuis Henk Visscher Karin A.F. Zonneveld 《Global and Planetary Change》1996,11(4):155-165
High resolution palynological analysis of DSDP Cores 607/607A shows for the interval between 2.8 and 2.2 Ma B.P. (which includes the onset of major northern hemisphere glaciations) a 41 ka cyclicity characterised by much higher palynomorph concentrations for the cooler intervals than for the warmer ones. Variation in dilution and concentration of palynomorphs can neither be explained by differential input of terrigenous clastics or carbonate, nor by differences in sedimentation rate, sediment density or selective preservation of palynomorphs. Subdivision of the palynomorph record in terms of autochthonous and allochthonous components, provides a way to detect changes in open ocean productivity and transport through time. It seems that a negative correlation between productivity and temperature in the latest Pleistocene open Atlantic had already been established before the major onset of northern hemisphere glaciations. A conceptual model is proposed to explain the observed lead of the palynological record relative to the isotope and carbonate records is proposed. This early response can result from changes in North Atlantic surface ocean circulation induced by changing atmospheric circulation. 相似文献
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Quantitative subsidence analysis for a number of rifted basins in the northern Atlantic/Mediterranean region provides evidence for rapid phases of PlioQuaternary subsidence. The observed acceleration in tectonic subsidence occurs after a phase of general quiescence in subsidence in these basins and deviates from predictions of stretching models. The latter indicate a decay of subsidence with time after Mesozoic-Tertiary basin formatioh and a slow tectonic subsidence in Plio-Quaternary times. A possible explanation for the observed patterns of anomalous subsidence could be an increase in the level of intraplate compression in the northern Atlantic region. Intraplate stress changes in the Plio-Quaternary are related to the dynamics of African/ Eurasian collision processes and a reorganization of spreading directions in the AtlAntic, possibly reflecting a plate reorganization of global nature.
It seems that the Plio-Quaternary record reflects a period of increased levels of neotectonic activity, interplaying with periods of (de)glaciation. Stress-induced topography in the onshore parts of continental margins, coupled with the stress-induced subsidence in the offshore deeper parts of the basins, could have contributed to recent phases of uplift in Fennoscandia, augmenting the uplift induced by glacial unloading. Estimates of ice thicknesses are directly inferred from the observed uplift ignoring other driving mechanisms whereas topography plays a crucial role in the dynamics of glaciation. It is, therefore, important to quantdy the interplay of rapid tectonic uplift and subsidence phases with climatic effects during the Plio-Quaternary. 相似文献
It seems that the Plio-Quaternary record reflects a period of increased levels of neotectonic activity, interplaying with periods of (de)glaciation. Stress-induced topography in the onshore parts of continental margins, coupled with the stress-induced subsidence in the offshore deeper parts of the basins, could have contributed to recent phases of uplift in Fennoscandia, augmenting the uplift induced by glacial unloading. Estimates of ice thicknesses are directly inferred from the observed uplift ignoring other driving mechanisms whereas topography plays a crucial role in the dynamics of glaciation. It is, therefore, important to quantdy the interplay of rapid tectonic uplift and subsidence phases with climatic effects during the Plio-Quaternary. 相似文献
40.
Microbial mats were collected from a variety of sites near hydrocarbon vents along the slope in the northern Gulf of Mexico and, for comparison, from Warm Mineral Springs, Florida, USA. A predominant microorganism in each of the mats was the giant bacterium,Beggiatoa. Diameters of the bacterial filaments ranged from about 6 µm to approximately 200 µm. The latter organisms are the largest prokaryotic organisms yet found. All filaments over about 10 µm in diameter contained a large central vacuole, producing a cell with the cytoplasm as a cylindrical tube underlying the cytoplasmic membrane. Sulfur globules were confined to this peripheral layer. Push cores often contained pyrite tubules whose appearance is suggestive of aBeggiatoa origin. Determinations of
13C inBeggiatoa mats from vents along the Louisiana slope yielded values in the range of –26.6 to –27.9 (PDB), suggesting an unusually high degree of isotope fractionation (–24.9) relative to the carbon source in the ambient seawater, which is typical of sulfur-oxidizing chemoautotrophs. The presence of SO (elemental sulfur) within cells ofBeggiatoa resulting from oxidation of H2S supports the importance of bacterial sulfate reduction processes in the underlying vents for the sustenance of theBeggiatoa mats. 相似文献