Pitch-angle diffusion of ring current protons caused by electrostatic ion loss-cone waves

Pitch-angle diffusion of ring current protons is investigated, assuming that the scattering is caused by resonant interaction with electrostatic ion loss-cone waves. Bounce averaged diffusion coefficients are presented for different wave energy distributions. It is found that wave amplitudes about 1 mV/m are required to give strong diffusion of protons with average energy.     

Molecular analysis of petroleum derived compounds that adsorb onto gas hydrate surfaces

Field observations have shown that some streams of water, gas and crude oil do not form gas hydrate plugs during petroleum production even when operating within thermodynamic conditions for hydrate formation. Also, when studied under controlled laboratory conditions, some oils are found to form hydrate dispersed systems whereas others form plugs. Oils with low tendency to form hydrate plugs are believed to contain natural hydrate plug inhibiting components (NICs) that adsorb onto the hydrate surface, making them less water-wet and preventing the particles from agglomerating into large hydrate clusters. The molecular structure of the NICs is currently unknown. In this work, hydrate adsorbing components were extracted from crude oils using freon hydrates as an extraction phase. The fractions were found to be enriched in polar material, and more polar material is associated with hydrates generated in biodegraded crude oils than in non-biodegraded oils. Various fractionation schemes and analytical techniques have been applied in the search for molecular characterisation. The average molecular weights were found to be approximately 500 g/mole. GC–MS chromatograms show a large UCM (Unresolved Complex Mixture). Thus, GC–MS has a limited potential for identification of compounds. A commercial biosurfactant was used as a model compound in the search for similar structures in the extracts. The results from analysis of the hydrate adsorbing components suggest that the type and structure are more important for hydrate morphology than the amount of material adsorbed.     

Validity of the Fossil Fuel Production Outlooks in the IPCC Emission Scenarios

Anthropogenic global warming caused by CO₂ emissions is strongly and fundamentally linked to future energy production. The Special Report on Emission Scenarios (SRES) from 2000 contains 40 scenarios for future fossil fuel production and is used by the IPCC to assess future climate change. Previous scenarios were withdrawn after exaggerating one or several trends. This study investigates underlying assumptions on resource availability and future production expectations to determine whether exaggerations can be found in the present set of emission scenarios as well. It is found that the SRES unnecessarily takes an overoptimistic stance and that future production expectations are leaning toward spectacular increases from present output levels. In summary, we can only encourage the IPCC to involve more resource experts and natural science in future emission scenarios. The current set, SRES, is biased toward exaggerated resource availability and unrealistic expectations on future production outputs from fossil fuels.     

Methods for locating the proper position of a planned fishway entrance near a hydropower tailrace

The spatial distribution of upstream migrating Atlantic salmon (Salmo salar) spawners was studied in 2008 and 2009 in the surroundings of the tailrace from a hydropower station in the River Umeälven. This area is problematic because the fish have difficulties finding their way into the original riverbed, which prompted an investigation on the feasibility of adding a fishway in the area. Echo sounding was used in 2008 to investigate the spatial use of fish in the tailrace channel during the time of salmon migration. Presence of other fish species was so low that all echo sounding detections were assumed to be salmon. In 2009, data on wild radio-tagged salmon (n = 94) was collected in the same tailrace by an array of underwater antennas with a detection radius of approximately 10 m, to validate the results from the echo sounding. Both types of surveys showed aggregations of fish in one part of the tailrace. As a final step, Computational Fluid Dynamics (CFD) modeling was performed to analyze hydrodynamics. This CFD modeling showed a coincidence of fish detections in areas with turbulence intensities between 0.6 and 0.8, which may be an indication that the fish are holding in these areas to reduce energy expenditure during migration. A high proportion of the radio-tagged salmon were observed in the tailrace area (a median of 21 days between their first and last detection), indicating that the salmon are delayed in their upstream migration by the attraction to the tailrace in this area. The overall data on fish behavior in the tailrace led us to suggest a location for a new fishway where the fish aggregation was most pronounced. The number of detections from either technology had similar distributions over the tailrace, suggesting that the results are comparable. Thus, the split beam echo sounder can preferably be used to investigate which location is most appropriate for locations of entrances to new fishways since many more individual fishes are covered by this method compared to telemetry. Furthermore, there is no need to handle the fish in the echo sounding studies as is required in telemetry studies.     

Sulphur isotope compositions in the Åmmeberg Zn-Pb ore deposit,south-central Sweden: Genetic implications

The distribution of sulphur isotope compositions in the Åmmeberg sulphide ore deposit is discussed. The ³⁴S values for various sulphides show a complex pattern of fluctuations between isotopic equilibrium and non-equilibrium conditions. This feature as well as the observed variations in the ³⁴S values of galena and sphalerite are interpreted to have originated from successive pulses of sulphide-forming solutions. On the basis of geological field criteria and sulphur isotope data, the Ammeberg deposit is considered to be a typical distal mineralization, belonging to the volcanic-exhalative group of ore deposits. The banded structure of the ore, the spatial separation of Pb and Zn and the presence of discrete, persistant ore layers probably relate to the type of convective system that created the mineral-forming solutions and to the various processes taking place when the brines were expelled onto the sea floor.

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Zusammenfassung Es wird die Verteilung von Schwefelisotopenzusammensetzungen in der Åmmeberg Sulfidlagerstätte diskutiert. Die ³⁴S-Werte für verschiedene Sulfide zeigt ein kompliziertes Schwankungsmuster zwischen Isotopengleichgewichts- und Isotopenungleichgewichtsbedingungen. Dieses Merkmal zusammen mit den beobachteten ³⁴S Schwankungen von Bleiglanz und Zinkblende werden dahingehend interpretiert, daß sie ihren Ursprung im anhaltenden Zustrom von sulfidhaltigen Lösungen hatten. Auf der Basis von geologischen Geländebefunden und Schwefelisotopendaten wird die Åmmeberg Lagerstätte als eine typische distale Mineralisation eingestuft, welche zur vulkanisch-exhalativen Lagerstättengruppe gehört. Die gebänderte Struktur des Erzes, die räumliche Trennung von Blei und Zink und die Anwesenheit von gesondert durchziehenden Erzlagen sind zum konvektiven System in Beziehung zu setzen, welches die mineralformenden Lösungen lieferte. Ebenfalls zeigt sich ein Zusammenhang zu den verschiedenen Prozessen, welche abliefen als die Sole auf den Meeresboden ausgestoßen wurde.

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Résumé L'auteur discute la distribution des compositions du soufre dans le gisement de sulfure d'Åmmeberg. Les valeurs de ³⁴S pour divers sulfures présentent des fluctuations complexes entre les conditions d'équilibre et de non-équilibre isotopique.Cette distribution, ainsi que les variations observées de ³⁴S de la galène et de la blende sont interprétées comme résultant d'arrivées successives de solutions sulfurantes. Sur la base de critères géologiques de terrain et des données relatives aux isotopes du soufre, le gisement d'Åmmeberg est considéré comme une minéralisation typiquement distale, appartenant au groupe volcanique exhalatif. La structure rubanée du minerai, la séparation spatiale du Pb et du Zn et la présence de couches de minerai discrètes et continues doivent vraisemblablement être mises en relation avec le type de système convectif qui a engendré les solutions minéralisantes et avec les divers processus qui sont entrés en jeu lorsque les saumures se sont répandues sur le fond de la mer.

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Åmmeberg. d³⁴S . d³⁴S, , , . Åmmeberg , , . , , . , , .

     

The border as an engine for mobility and spatial integration: A study of commuting in a Swedish–Norwegian context

The purpose of the study was to analyse how cross-border commuting differed from intranational commuting in Sweden, and how cross-border mobilities affected spatial integration. The authors analysed patterns and spatial flows of cross-border commuting by comparing them with characteristics of intranational commuting. In the article, they explore the assumption that the border constitutes an ‘engine’ for work-related mobility, which affects processes of spatial integration in cross-border areas. The empirical material comprised data from surveys of commuting from the Swedish county of Värmland to Norway and commuting within Värmland. The findings showed that cross-border commuting shared common features with intranational commuting, including how the frequency of commuting was dependent on distance. The motives for commuting differed, and the reasons for working in Norway were economic rather than professional. In terms of spatial integration, cross-border commuting was mainly one-directional, from Sweden to Norway, while leisure mobility and migration tended to be in the opposite direction. The authors conclude that the border region is characterised by integration through specialisation, which involves a permanent state of ‘transient’ mobility. Thus, a win-win situation can be distinguished, in which the border serves as a resource and an ‘engine’ for cross-border integration, mobility and economic activities.     

Intelligent ship traffic monitoring for oil spill prevention: risk based decision support building on AIS

The paper describes a model, which estimates the risk levels of individual crude oil tankers. The intended use of the model, which is ready for trial implementation at The Norwegian Coastal Administrations new Vard? VTS (Vessel Traffic Service) centre, is to facilitate the comparison of ships and to support a risk based decision on which ships to focus attention on. For a VTS operator, tasked with monitoring hundreds of ships, this is a valuable decision support tool. The model answers the question, "Which ships are likely to produce an oil spill accident, and how much is it likely to spill?".     

Prevention of oil spill from shipping by modelling of dynamic risk

This paper presents a new dynamic environmental risk model, with intended use within a new, dynamical approach for risk based ship traffic prioritisation. The philosophy behind this newly developed approach is that shipping risk can be reduced by directing efforts towards ships and areas that have been identified as high priority (high risk), prior to a potential accident. The risk model proposed in this paper separates itself from previous models by drawing on available information on dynamic factors and by focusing on the ship's surroundings. The model estimates the environmental risk of drift grounding accidents for oil tankers in real time and in forecast mode, combining the probability of grounding with oil spill impact on the coastline. Results show that the inherent dynamic risk introduced by an oil tanker sailing along the North Norwegian coast depends, not surprisingly, significantly upon wind and ocean currents, as well as tug position and cargo oil type. Results of this study indicate that the risk model is well suited for real time risk assessment, and effectively separates low risk and high risk situations. The model is well suited as a tool to prioritise oil tankers and coastal segments. This enables dynamic risk based positioning of tugs, using both real-time and projected risk, for effective support in case of a drifting ship situation.