Recognising the importance of understanding sediment dynamics to evaluate the status of a coastal lagoon environment, this work has been focused on the investigation of the hydrodynamic and sediment transport processes occurring in such basins. In order to describe the lagoon system, a modelling approach combining hydrodynamics, waves and sediment dynamics has been developed. The framework of the numerical model consists of a finite element hydrodynamic model, a third generation finite element spectral wave model and a sediment transport and morphodynamic model for both cohesive and non-cohesive sediments. The model adopts the finite element technique for spatial integration, which has the advantage to describe more accurately complicated bathymetry and irregular boundaries for shallow water areas. The developed model has been applied to test cases and to a very shallow tidal lagoon, the Venice Lagoon, Italy. Numerical results show good agreement with water level, waves and turbidity measurements collected in several monitoring stations inside the Lagoon of Venice. Such a model represents an indispensable tool in analysing coastal problems and assessing morphological impacts of human interference. 相似文献
The isotopic content of rainfall was measured in Niamey (Niger) over a period of eight years (1992–1999). Seasonal distribution of rainy events depends on the monsoon movement over the region. At the beginning and at the end of the rainy season, low rainfall, high temperatures and low relative humidity favour isotopic enrichment. In the middle of the rainy season, heavy rainfall, low temperatures and relative humidity close to saturation lead to isotopically depleted contents because of the mass effect; moreover, in the case of low rainfall, marked vertical convective development favours high altitude condensation. How far the Intertropical Front moves north, determines the quality of the rainy season and influences the isotopic contents. Thus the isotopic contents of rainfall are good climatic indicators. To cite this article: J.-D. Taupin et al., C. R. Geoscience 334 (2002) 43–50 相似文献
New radiometric ages from the Subpenninic nappes (Eclogite Zone and Rote Wand – Modereck Nappe, Tauern Window) show that phengites formed under eclogite-facies metamorphic conditions retain their initial isotopic signature, even when associated lithologies were overprinted by greenschist- to amphibolite-facies metamorphism. Different stages of the eclogite-facies evolution can be dated provided 40Ar/39Ar dating is combined with micro-structural analyses. An age of 39 Ma from the Rote Wand – Modereck Nappe is interpreted to be close to the burial age of this unit. Eclogite deformation within the Eclogite Zone started at the pressure peak along distinct shear zones, and prevailed along the exhumation path. An age of ca. 38 Ma is only observed for eclogites not affected by subsequent deformation and is interpreted as maximum age due to the possible influence of homogenously distributed excess argon. During exhumation deformation was localised along distinct mylonitic shear zones. This stage is mainly characterised by the formation of dynamically recrystallized omphacite2 and phengite. Deformation resulted in the resetting of the Ar isotopic system within the recrystallized white mica. Flat argon release spectra showing ages of 32 Ma within mylonites record the timing of cooling along the exhumation path, and the emplacement onto the Venediger Nappe. Ar-release patterns and 36Ar/40Ar vs.39Ar/40Ar isotope correlation analyses indicate no significant 40Ar-loss after initial closure, and only a negligible incorporation of excess argon. From the pressure peak onwards, eclogitic conditions prevailed for almost 8–10 Ma. 相似文献
The mandible of Homo heidelbergensis was found 1907 in the sand pit Grafenrain at Mauer in coarse fluvial sands 24 m below the surface, deposited in a former course of the Neckar River. These ‘Mauer sands’ are overlain by a series of glacial-climate loess deposits with intercalated interglacial palaeosols, which can be correlated with Quaternary climate history, thus indicating an early Middle Pleistocene age for H. heidelbergensis. The ‘Mauer sands’ are famous for their rather rich mammal fauna, which clearly indicates interglacial climate conditions. The faunal evidence – in particular the micromammals – place the ‘Mauer sands’ into MIS 15 or MIS 13 although most stratigraphic arguments favour correlation to MIS 15 and therefore to an age of ca 600 ka. 相似文献
This article provides an analysis of the EU Emissions Trading Scheme (ETS) and the harmonized benchmark-based allocation procedures by comparing two energy-intensive sectors with activities in three Member States. These sectors include the cement industry (CEI) and the pulp and paper industry (PPI) in the UK, Sweden, and France. Our results show that the new procedures are better suited for the more homogeneous CEI, in which the outcome of stricter allocation of emissions allowances is consistent between Member States. For the more heterogeneous PPI – in terms of its product portfolios, technical infrastructures, and fuel mixes – the allocation procedures lead to diverse outcomes. It is the lack of product benchmark curves, and the alternative use of benchmark values that are biased towards a fossil fuel-mix and are based on specific energy use rather than emission intensity, which leads to allocations to the PPI that do not represent the average performance of the top 10% of GHG-efficient installations. Another matter is that grandfathering is still present via the historically based production volumes. How to deal with structural change and provisions regarding capacity reductions and partial cessation is an issue that is highly relevant for the PPI but less so for the CEI.
Policy relevance
After an unprecedented amount of consultation with industrial associations and other stakeholders, a harmonized benchmark-based allocation methodology was introduced in the third trading period of the EU ETS. Establishing a reliable and robust benchmark methodology for free allocation that shields against high direct carbon costs, is perceived as fair and politically acceptable, and still incentivizes firms to take action, is a significant challenge. This article contributes to a deeper understanding of the challenges in effectively applying harmonized rules in industrial sectors that are heterogeneous. This is essential for the debate on structural reformation of the EU ETS, and for sharing experiences with other emerging emissions trading systems in the world that also consider benchmark methodologies. 相似文献