Gypsum crusts and fly ash particles on carbonatic outcrops     

Marco Del Monte  Cristina Sabbioni 《Meteorology and Atmospheric Physics》1984,35(1-2):105-111

Summary A study of the alterations caused by chemical weathering on carbonatic outcrops in the South of France (near Marseille) has revealed the presence of gypsum crusts. An analogy with carbonatic surfaces (marbles and limestones) located in urban areas (monuments and buildings) has therefore been evidenced. An analytical investigation of the morphology, typology and inner structure of the crusts found is presented in this paper.Furthermore, reference is also made to the identification of fly ash particles embedded in the altered layer: this occurrence enables a limitation of the crust-growth period to the present century. Some hypotheses as to the role played by these particles in the formation of the altered layer have also been advanced. In this regard, the study of particles emitted by coal combustion, one of the major sources of energy, as far as their environment impact is concerned, is of unquestionable importance.

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Gipskrusten und Flugascheteilchen auf Carbonat-Schichtköpfen

Zusammenfassung Die Untersuchung der durch chemische Verwitterung verursachten Änderungen an Carbonat-Schichtköpfen im Süden von Frankreich (bei Marseille) hat das Vorhandensein von Gipskrusten gezeigt. Eine Analogie zu carbonaten Oberflächen (Marmor und Kalkstein) in Stadtgebieten (Monumente und Gebäude) ist damit erwiesen. Eine analytische Erforschung der Morphologie, Typologie und inneren Struktur der gefundenen Krusten wird in dieser Arbeit vorgelegt.Ferner wird auch Bezug genommen auf die Identifizierung der in die geänderte Schicht eingelagerten Flugascheteilchen. Dieses Vorkommen ermöglichte eine Begrenzung der Periode des Krustenwachstums auf das gegenwärtige Jahrhundert. Einige Hypothesen über die Rolle, die von diesen Teilchen bei der Bildung der geänderten Schicht gespielt wird, werden auch vorgebracht. In dieser Hinsicht ist die Untersuchung der bei der Kohleverbrennung — das ist eine der größten Energiequellen — ermittelten Teilchen, insofern ihr Einfluß auf die Umgebung betrachtet wird, unzweifelhaft von Bedeutung.

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With 4 Figures  相似文献   

Globalising Swedish countrysides? A relational approach to rural immigrant restaurateurs with refugee backgrounds     

Marco Eimermann  Svante Karlsson 《Norsk geografisk tidsskrift. Norwegian journal of geography》2018,72(2):82-96

The main purpose of the article is to connect rural immigrants’ business ventures and development in Sweden to relational perspectives on their proximate and distant family and co-ethnic networks at structural and individual levels. Accordingly, the authors employ a relational approach and draw on in-depth interviews. In the context of urban–rural relationships’ meanings for the restaurateurs’ business benefits and constraints, they address two questions: (1) What does embeddedness in proximate and distant family and co-ethnic networks mean for the interviewed restaurateurs and for their businesses? and (2) How do previous and anticipated transitions in the restaurateurs’ families influence their business decisions and migration trajectories? The results suggest that the interviewees employed transnational dimensions in their social embeddedness and that they maintained material and emotional relationships with their countries of origin. This relational approach thus contributes to a better understanding of what the studied businesses mean for the entrepreneurs and the selected localities. The restaurateurs contribute to a globalisation of Swedish countrysides, but their socio-economic potential for countering rural depopulation in Sweden is not fully realised. Additionally, the study illuminates how individuals influence, and are influenced by, place-to-place mobilities on a daily basis and during their life course.  相似文献   

Early succession of micro‐periphyton communities in kelp bed and barren ground ecological systems          下载免费PDF全文

Roberto A. Uribe  Marco Ortiz  Aldo S. Pacheco  Rubén Araya 《Marine Ecology》2015,36(4):1415-1427

In shallow sublittoral rocky habitats of the Southeast Pacific, two conspicuous ecological systems exist; kelp beds dominated by large Laminariales algae, and barren grounds dominated by crustose coralline algae and sea urchins. The aim of this study was to examine the successional development of micro‐periphyton communities in both ecological systems using a colonization experiment conducted in Northern Chile. In both ecological systems, we installed replicated ceramic plates at 10 m depth and samples were taken after 1, 2, 4, 6, 8 and 14 days of exposure. Bacteria, diatoms, protozoans and small eukaryotes were identified, quantified and analysed. The succession of micro‐periphyton communities in both ecological systems followed a common pattern consisting of a net accumulation of functional groups and taxa over time; however, the total density of all groups was significantly higher in the kelp beds. In addition, the community structure of the developing micro‐periphytons was different and specific for each ecological system. Although previous studies have suggested that kelp beds and barren grounds are capable of switching from one state to the other without substantial changes in biodiversity, our results show that each of these ecological systems promotes its own successional development, suggesting that they are unique, self‐organized entities. This study is the first step towards an understanding of these ecological systems operating independently at this scale of organization.  相似文献   

Vertical structure,physical properties,and energy exchange of the East Asian trough in boreal winter     

Leung  Marco Yu-Ting  Zhou  Wen 《Climate Dynamics》2015,45(5-6):1635-1656

Climate Dynamics - The relation between the intensity of the East Asian trough and the strength of the East Asian winter monsoon is documented. A prominent dipole of the available potential energy...  相似文献   

Effective stability around the Cassini state in the spin-orbit problem     

Marco Sansottera  Christoph Lhotka  Anne Lemaître 《Celestial Mechanics and Dynamical Astronomy》2014,119(1):75-89

We investigate the long-time stability in the neighborhood of the Cassini state in the conservative spin-orbit problem. Starting with an expansion of the Hamiltonian in the canonical Andoyer-Delaunay variables, we construct a high-order Birkhoff normal form and give an estimate of the effective stability time in the Nekhoroshev sense. By extensively using algebraic manipulations on a computer, we explicitly apply our method to the rotation of Titan. We obtain physical bounds of Titan’s latitudinal and longitudinal librations, finding a stability time greatly exceeding the estimated age of the Universe. In addition, we study the dependence of the effective stability time on three relevant physical parameters: the orbital inclination, $i$ , the mean precession of the ascending node of Titan orbit, $\dot{\varOmega }$ , and the polar moment of inertia, $C$ .  相似文献   

Motion of particles on a z=2 Lifshitz black hole background in 3+1 dimensions     

Marco Olivares  Yerko Vásquez  J. R. Villanueva  Felipe Moncada 《Celestial Mechanics and Dynamical Astronomy》2014,119(2):207-217

The object of study is the geodesic structure of a \(z=2\) Lifshitz black hole in 3+1 space–time dimensions, which is an exact solution to the Einstein-scalar-Maxwell theory. The motion of massless and massive particles in this background is researched using the standard Lagrangian procedure. Analytical expressions are obtained for radial and angular motions of the test particles, where the polar trajectories are given in terms of the \(\wp \) -Weierstraß elliptic function. It will be demonstrated that an external observer can see that photons with radial motion arrive at spatial infinity in a finite coordinate time. For particles with non-vanished angular momentum, the motion is studied on the invariant plane \(\phi = \pi /2\) and, it is shown that bounded orbits are not allowed for this space–time on this plane. These results are consistent with other recent studies on Lifshitz black holes.  相似文献   

Large biases and inconsistent climate change signals in ENSEMBLES regional projections   总被引：1，自引：1，他引：0  

Marco Turco  Antonella Sanna  Sixto Herrera  Maria-Carmen Llasat  José Manuel Gutiérrez 《Climatic change》2013,120(4):859-869

In this paper we analyze some caveats found in the state-of-the-art ENSEMBLES regional projections dataset focusing on precipitation over Spain, and highlight the need of a task-oriented validation of the GCM-driven control runs. In particular, we compare the performance of the GCM-driven control runs (20C3M scenario) with the ERA40-driven ones (“perfect” boundary conditions) in a common period (1961–2000). Large deviations between the results indicate a large uncertainty/bias for the particular RCM-GCM combinations and, hence, a small confidence for the corresponding transient simulations due to the potential nonlinear amplification of biases. Specifically, we found large biases for some RCM-GCM combinations attributable to RCM in-house problems with the particular GCM coupling. These biases are shown to distort the corresponding climate change signal, or “delta”, in the last decades of the 21st century, considering the A1B scenario. Moreover, we analyze how to best combine the available RCMs to obtain more reliable projections.  相似文献   

Carbon tariffs for financing clean development     

Marco Springmann 《Climate Policy》2013,13(1):20-42

In order to address carbon leakage and preserve the competitiveness of domestic industries, some industrialized Annex I countries have proposed to implement carbon tariffs. These tariffs would be levied on energy-intensive imports from developing non-Annex I countries that have not agreed to binding emissions reductions. This action could have detrimental welfare impacts, especially on those developing countries, and may not lead to significant reductions in leakage. A recent proposal is to use the revenues generated from carbon tariffs to finance clean development in the relevant exporting non-Annex I countries. This proposal is evaluated using an energy-economic model of the global economy. The model is supplemented by marginal abatement cost curves and bottom-up information on abatement potentials in order to represent how clean development financing affects emissions reductions. The results indicate that carbon tariffs could raise US$3.5–24.5 billion (with a central value of $9.8 billion) for clean development financing. This could reduce the emissions of non-Annex I countries by 5–15% and still leave funds available for other purposes, such as adaptation. Furthermore, recycling the revenues generated from carbon tariffs back to the exporting country itself could alleviate some of the negative welfare impacts associated with them. However, a net negative impact especially on the welfare and gross domestic product of developing countries would remain.  相似文献   

Waterflood management using two-stage optimization with streamline simulation   总被引：1，自引：0，他引：1  

Tailai Wen  Marco R. Thiele  David Echeverría Ciaurri  Khalid Aziz  Yinyu Ye 《Computational Geosciences》2014,18(3-4):483-504

Waterflooding is a common secondary oil recovery process. Performance of waterfloods in mature fields with a significant number of wells can be improved with minimal infrastructure investment by optimizing injection/production rates of individual wells. However, a major bottleneck in the optimization framework is the large number of reservoir flow simulations often required. In this work, we propose a new method based on streamline-derived information that significantly reduces these computational costs in addition to making use of the computational efficiency of streamline simulation itself. We seek to maximize the long-term net present value of a waterflood by determining optimal individual well rates, given an expected albeit uncertain oil price and a total fluid injection volume. We approach the optimization problem by decomposing it into two stages which can be implemented in a computationally efficient manner. We show that the two-stage streamline-based optimization approach can be an effective technique when applied to reservoirs with a large number of wells in need of an efficient waterflooding strategy over a 5 to 15-year period.  相似文献   

Hydrological Regime and Renewal Capacity of the Micro-tidal Lesina Lagoon,Italy   总被引：1，自引：0，他引：1  

Christian Ferrarin  Luca Zaggia  Elio Paschini  Tommaso Scirocco  Giuliano Lorenzetti  Marco Bajo  Pierluigi Penna  Matteo Francavilla  Raffaele D’Adamo  Stefano Guerzoni 《Estuaries and Coasts》2014,37(1):79-93

A multidisciplinary approach that combines field measurements, artificial neural networks, water balance analyses and hydrodynamic modelling was developed to investigate the water budget and renewal capacity of semi-closed coastal systems. The method was applied to the Lesina Lagoon, a micro-tidal lagoon in the southern Adriatic Sea (Italy). Surface water flux between the lagoon and the sea was determined by neural network prediction and used as input in the analysis. Strong seasonal variations in the water budget equation were predicted. Fresh water inputs estimated by the water balance analysis were used as forcing by a calibrated finite element model to describe the water circulation and transport time scale of the lagoon’s surface waters. The model highlighted the spatial heterogeneity of the renewal behaviour of the system, with a strong east–west water renewal time gradient. Knowledge of spatial distribution of water renewal times is crucial for understanding the lagoon’s renewal capacity and explaining the high spatial variability of the biogeochemistry of the Lesina Lagoon.  相似文献