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Search Results: 1 - 10 of 374580 matches for " K. B. F?llmi "
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Phosphorus burial in the ocean over glacial-interglacial time scales
F. Tamburini,K. B. F llmi
Biogeosciences (BG) & Discussions (BGD) , 2009,
Abstract: The role of nutrients, such as phosphorus (P), and their impact on primary productivity and the fluctuations in atmospheric CO2 over glacial-interglacial periods are intensely debated. Suggestions as to the importance of P evolved from an earlier proposal that P actively participated in changing productivity rates and therefore climate change, to most recent ones that changes in the glacial ocean inventory of phosphorus were important but not influential if compared to other macronutrients, such as nitrate. Using new data coming from a selection of ODP sites, we analyzed the distribution of oceanic P sedimentary phases and calculate reactive P burial fluxes, and we show how P burial fluxes changed over the last glacial-interglacial period at these sites. Concentrations of reactive P are generally lower during glacial times, while mass accumulation rates (MAR) of reactive P show higher variability. If we extrapolate for the analyzed sites, we may assume that in general glacial burial fluxes of reactive P are lower than those during interglacial periods by about 8%, because the lack of burial of reactive P on the glacial shelf reduced in size, was apparently not compensated by burial in other regions of the ocean. Using the calculated changes in P burial, we evaluate their possible impact on the phosphate inventory in the world oceans. Using a simple mathematical approach, we find that these changes alone could have increased the phosphate inventory of glacial ocean waters by 17–40% compared to interglacial stages. Variations in the distribution of sedimentary P phases at the investigated sites seem to indicate that at the onset of interglacial stages, shallower sites experienced an increase in reactive P concentrations, which seems to point to P-richer waters at glacial terminations. All these findings would support the Shelf-Nutrient Hypothesis, which assumes that during glacial low stands nutrients are transferred from shallow sites to deep sea with possible feedback on the carbon cycle.
Phosphorus burial in the ocean over glacial-interglacial time scales
F. Tamburini,K. B. Fllmi
Biogeosciences Discussions , 2008,
Abstract: The role of nutrients and their impact on primary productivity and the fluctuations in atmospheric CO2 over glacial-interglacial periods are intensely debated. One of the cornerstones is the role of phosphorus (P; in the form of phosphate). Suggestions as to the importance of P evolved from an earlier proposal that P actively participated in changing productivity rates and therefore climate change, to the most recent one that changes in the glacial ocean inventory of phosphorus were small and not influential if compared to other macronutrients, such as nitrogen. Using new data coming from a selection of ODP sites, we illustrate oceanic P sedimentary phases distribution and reactive P burial fluxes, and we show how P burial fluxes changed over the last glacial-interglacial period. Concentrations of reactive P are generally lower during glacial times, while mass accumulation rates (MAR) show higher variability. On a global scale, glacial burial fluxes of reactive P are lower than those during interglacial periods by 7–10%, because lack of burial of reactive P on the glacial reduced shelf was apparently not compensated by burial in other regions of the ocean. Using the calculated changes in P burial, we try to infer their possible impact on the phosphate inventory in the world oceans. Using a simple mathematical approach, we find that these changes alone could have increased the phosphate inventory of glacial ocean waters by 20–40% compared to interglacial stages. Variations in the C/P reactive ratios and in the P sedimentary phases distribution at the investigated sites seem to indicate that at the onset of interglacial stages, shallower sites experienced an increase in reactive P concentrations. This seems to point to P-richer waters at glacial terminations, supporting the shelf-nutrient hypothesis and giving phosphorus a role as a potential player in climate change.
Bridging the Faraoni and Selli oceanic anoxic events: short and repetitive dys- and anaerobic episodes during the late Hauterivian to early Aptian in the central Tethys
K. B. Fllmi,M. B?le,N. Jammet,P. Froidevaux
Climate of the Past Discussions , 2011, DOI: 10.5194/cpd-7-2021-2011
Abstract: A detailed stratigraphical and geochemical analysis was performed on the upper part of the Maiolica Formation outcropping in the Breggia (southern Switzerland) and Capriolo sections (northern Italy). In these localities, the Maiolica Formation consists of well-bedded, partly siliceous, pelagic, micritic carbonate, which lodges numerous thin, dark and organic-rich layers. Stable-isotope, phosphorus, organic-carbon and a suite of redox-sensitive trace-metal contents (RSTE: Mo, U, Co, V and As) were measured. Higher densities of organic-rich layers were identified in the uppermost Hauterivian, lower Barremian and the Barremian-Aptian boundary intervals, whereas the upper Barremian interval and the interval immediately following the Barremian-Aptian boundary interval are characterized by lower densities of organic-rich layers. TOC contents, RSTE pattern and Corg:Ptot ratios indicate that most layers were deposited under dysaerobic rather than anaerobic conditions and that latter conditions were likely restricted to short intervals in the latest Hauterivian, the early Barremian and the pre-Selli early Aptian. Correlations are possible with organic-rich intervals in central Italy (the Gorgo a Cerbara section) and the Boreal northwest German Basin, and with the facies and drowning pattern in the evolution of the Helvetic segment of the northern Tethyan carbonate platform. Our data and correlations suggest that the latest Hauterivian witnessed the progressive installation of dysaerobic conditions in the Tethys, which went along with the onset in sediment condensation, phosphogenesis and platform drowning on the northern Tethyan margin, and which culminated in the Faraoni anoxic episode. This brief episode is followed by further episodes of dysaerobic conditions in the Tethys and the northwest German Basin, which became more frequent and progressively stronger in the late early Barremian. Platform drowning persisted and did not halt before the latest early Barremian. The late Barremian witnessed diminishing frequencies and intensities in dysaerobic conditions, which went along with the progressive installation of the Urgonian carbonate platform. Near the Barremian-Aptian boundary, the increasing density in dysaerobic episodes in the Tethyan and northwest German Basins is paralleled by a change towards heterozoan carbonate production on the northern Tethyan shelf. The following return to more oxygenated conditions is correlated with the second phase of Urgonian platform growth and the period immediately preceding and corresponding to the Selli anoxic episode is c
Bridging the Faraoni and Selli oceanic anoxic events: late Hauterivian to early Aptian dysaerobic to anaerobic phases in the Tethys
K. B. F llmi, M. B le, N. Jammet, P. Froidevaux, A. Godet, S. Bodin, T. Adatte, V. Matera, D. Fleitmann,J. E. Spangenberg
Climate of the Past (CP) & Discussions (CPD) , 2012,
Abstract: A detailed geochemical analysis was performed on the upper part of the Maiolica Formation in the Breggia (southern Switzerland) and Capriolo sections (northern Italy). The analysed sediments consist of well-bedded, partly siliceous, pelagic carbonate, which lodges numerous thin, dark and organic-rich layers. Stable-isotope, phosphorus, organic-carbon and a suite of redox-sensitive trace-element contents (RSTE: Mo, U, Co, V and As) were measured. The RSTE pattern and Corg:Ptot ratios indicate that most organic-rich layers were deposited under dysaerobic rather than anaerobic conditions and that latter conditions were likely restricted to short intervals in the latest Hauterivian, the early Barremian and the pre-Selli early Aptian. Correlations are both possible with organic-rich intervals in central Italy (the Gorgo a Cerbara section) and the Boreal Lower Saxony Basin, as well as with the facies and drowning pattern in the Helvetic segment of the northern Tethyan carbonate platform. Our data and correlations suggest that the latest Hauterivian witnessed the progressive installation of dysaerobic conditions in the Tethys, which went along with the onset in sediment condensation, phosphogenesis and platform drowning on the northern Tethyan margin, and which culminated in the Faraoni anoxic episode. This episode is followed by further episodes of dysaerobic conditions in the Tethys and the Lower Saxony Basin, which became more frequent and progressively stronger in the late early Barremian. Platform drowning persisted and did not halt before the latest early Barremian. The late Barremian witnessed diminishing frequencies and intensities in dysaerobic conditions, which went along with the progressive installation of the Urgonian carbonate platform. Near the Barremian-Aptian boundary, the increasing density in dysaerobic episodes in the Tethyan and Lower Saxony Basins is paralleled by a change towards heterozoan carbonate production on the northern Tethyan shelf. The following return to more oxygenated conditions is correlated with the second phase of Urgonian platform growth and the period immediately preceding and corresponding to the Selli anoxic episode is characterised by renewed platform drowning and the change to heterozoan carbonate production. Changes towards more humid climate conditions were the likely cause for the repetitive installation of dys- to anaerobic conditions in the Tethyan and Boreal basins and the accompanying changes in the evolution of the carbonate platform towards heterozoan carbonate-producing ecosystems and platform drowning.
Phosphorus and trace-metal records during Cretaceous oceanic anoxic events: Example of the Early Aptian OAE in the western Tethys
Westermann Stéphane,Fllmi Karl B.,Matera Virginie,Adatte Thierry
Carnets de Géologie , 2007,
Abstract:
Base-transesterification process for biodiesel fuel production from spent frying oils  [PDF]
B. K. Abdalla, F. O. A. Oshaik
Agricultural Sciences (AS) , 2013, DOI: 10.4236/as.2013.49B015
Abstract:

The concept of converting recycled oils to clean biodiesel aims towards reducing the amount of waste oils to be treated and lowering the cost of biodiesel production. Samples of waste oils were prepared from Spent Frying oil collected from local hotels and restaurants in Khartoum, Sudan. Selected methods to achieve maximum yield of biodiesel using the waste feedstock were presented and compared. Some properties of the feedstock, such as free fatty acid content and moisture content, were measured and evaluated. Biodiesel yield recovery obtained, from Base-transesterification process about 92%. Produced Biodiesel specifications were also analyzed and discussed in Base-transesterification process. Kinematic viscosity of biodiesel was found to be 5.51 mm2·s?1 at 40?C, the flash point was 174.2?C and Cetane No of 48.19. Biodiesel was characterized by its physical and fuel properties according to ASTM and DIN V 51606 standards.

GIS Data Integration to Manage Waterlogging Problem on the Eastern Nile Delta of Egypt  [PDF]
M. F. Kaiser, A. El Rayes, K. Ghodeif, B. Geriesh
International Journal of Geosciences (IJG) , 2013, DOI: 10.4236/ijg.2013.44063
Abstract:

Three sets of satellite data were utilized to outline and monitor the waterlogging problems along the Wadi El Tumilate basin. These data include Thematic Mapper image for year 1984, Enhanced Landsat Thematic Mapper image for year 2000 and SPOT-4 image for year 2008. Supervised classification using the maximum likelihood approach has been performed. A number of 6 classes were observed at the study sites including, Niledeposits and cultivated areas, surface water and water logged areas, salt crust, Quaternary playa deposits, fluviatile and lacustrine deposits and Miocene (gypsum and carbonate) deposits. Water logged areas expanded from9.1 km2 inyear 1984 to18.8 km2 inyear 2000 to25.3 km2 inyear 2008, with a rate of0.7 km2/year. At the same time, vegetation cover shows an increase from453 km2 inyear 1984 to719 km2 inyear 2008. The integrated data used by Geographic Information Systems specified factors controlling waterlogging problems, which are: topography, drainage pattern and water flow direction, excess of irrigation water, deficiency of drainage system, presence of impermeable clay lenses and lineaments direction. Groundwater modeling including GMS and MODFLOW programs were processed to manage waterlogging problem. Using of underground tile drain along the eastern portion of Wadi El Tumilate basin and dewatering wells along the western side was recommended to obtain the highest monetary return from the drainage investment.

Galaxy evolution: the effect of dark matter on the chemical evolution of ellipticals and galaxy clusters
F. Matteucci,B. K. Gibson
Physics , 1996,
Abstract: In this paper we discuss the chemical evolution of elliptical galaxies and its consequences on the evolution of the intracluster medium (ICM). We use chemical evolution models taking into account dark matter halos and compare the results with previous models where dark matter was not considered. In particular, we examine the evolution of the abundances of some relevant heavy elements such as oxygen, magnesium and iron and conclude that models including dark matter halos and an initial mass function (IMF) containing more massive stars than the Salpeter (1955) IMF, better reproduce the observed abundances of Mg and Fe both in the stellar populations and in the ICM (ASCA results). We also discuss the origin of gas in galaxy clusters and conclude that most of it should have a primordial origin.
Towards a Microscopic Theory for Metallic Heavy-Fermion Point Contacts
F. B. Anders,K. Gloos
Physics , 1996, DOI: 10.1016/S0921-4526(96)00604-7
Abstract: The bias-dependent resistance R(V) of NS-junctions is calculated using the Keldysh formalism in all orders of the transfer matrix element. We present a compact and simple formula for the Andreev current, that results from the coupling of electrons and holes on the normal side via the anomalous Green's function on the superconducting side. Using simple BCS Nambu-Green's functions the well known Blonder-Tinkam-Klapwijk theory can be recovered. Incorporating the energy-dependent quasi-particle lifetime of the heavy fermions strongly reduces the Andreev-reflection signal.
Iterative Fluiddynamics
F. Wunderlich,B. K?mpfer
Physics , 2012, DOI: 10.1140/epja/i2012-12169-3
Abstract: An iterative scheme is presented to solve analytically the relativistic fluid dynamics equations. The scheme is applied to longitudinal expansion, transversal symmetric and transversal asymmetric (triaxial) expansion as well. Within this scheme it is possible to describe the dynamics of a strongly coupled (i.e. conformal) medium for parameters referring to heavy-ion collisions at LHC.
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