Water column monitoring near oil installations in the North Sea 2001-2004

Fisheries have been vital to coastal communities around the North Sea for centuries, but this semi-enclosed sea also receives large amounts of waste. It is therefore important to monitor and control inputs of contaminants into the North Sea. Inputs of effluents from offshore oil and gas production platforms (produced water) in the Norwegian sector have been monitored through an integrated chemical and biological effects programme since 2001. The programme has used caged Atlantic cod and blue mussels. PAH tissue residues in blue mussels and PAH bile metabolites in cod have confirmed exposure to effluents, but there was variation between years. Results for a range of biological effects methods reflected exposure gradients and indicated that exposure levels were low and caused minor environmental impact at the deployment locations. There is a need to develop methods that are sufficiently sensitive to components in produced water at levels found in marine ecosystems.     

Evidence of early deglaciation (18 000 cal a bp) and a postglacial relative sea‐level curve from southern Karmøy,south‐west Norway

Based on six consistent radiocarbon dates from the isolation basins Grødheimsvatnet and Kringlemyr, we estimate a minimum deglaciation age for southern Karmøy, an island in outer Boknafjorden (south‐west Norway), of around 18 000 calibrated years before present (18k cal a bp ). We use microscopic phytoplankton, macrofossils, lithostratigraphic evidence and X‐ray fluorescence data to identify the isolation contacts in the basins, and date them to 17.52–17.18k cal a bp in Grødheimsvatnet [15.57 m above present mean sea level (MSL)] and 16.19–15.80k cal a bp in Kringlemyr (11.99 m above MSL). Combining these data with previous studies, we construct a relative sea‐level (RSL) curve from 18k cal a bp until the present, which is ~3 ka longer than any previous RSL reconstruction from southern Norway. Following deglaciation, southern Karmøy has experienced a net emergence of around 16–19 m, although with significant RSL fluctuations. This includes two RSL minima well below present MSL around ~13.8 and ~10k cal a bp , and two maxima that culminated around 5–7 m above MSL during the Younger Dryas and early to mid‐Holocene, respectively. Considering eustatic sea level and modelled gravitational deformation of the geoid, we estimate a net postglacial isostatic uplift of ~120 m. © 2019 John Wiley & Sons, Ltd     

An erosional origin for drumlins of NW Poland

Drumlins are landforms essential to understanding of ice sheet movement over soft beds, sediment transport along the ice/bed interface, and the formation of a wide range of glacial deposits. Although investigated more than any other glacial landform, the origin of drumlins remains contentious. Using high-resolution LiDAR imagery and field data, we investigate the geomorphology and internal composition of one of the biggest drumlin fields in the North European Lowland. The Stargard drumlin field consists of over 1300 drumlins and related streamlined subglacial bedforms in a terminal part of a major Weichselian palaeo-ice stream of the southern Scandinavian Ice Sheet. The drumlins are typically 600-800 m long, 200-250 m wide, 3-6 m high and have axial elongation ratios ~2 but in some cases exceeding 15. Several subzones inferred from drumlin morphometry exist reflecting different ice flow dynamics. The most elongated drumlins occur in areas where ice moved down-slope and where thick fine-grained deposits of low hydraulic conductivity occur in the substratum. The largest portion of land occupied by drumlins and the greatest frequency density of drumlins occur where the ice moved up-slope. Stargard drumlins are composed of a wide variety of glacial deposits including various types of tills and meltwater sediments, which range from undisturbed to heavily deformed. There is no correlation between the deposits in the drumlins and the drumlin forms indicating that the deposits pre-date the drumlinizing process. It is suggested that the drumlin field was generated by a combination of direct glacial erosion and subglacial meltwater erosion by removing antecedent material from the inter-drumlin areas and streamlining the resultant bumps. Our data support the search for a unifying theory of drumlin formation and suggest erosion as the most plausible single mechanism generating drumlin landscapes. © 2019 John Wiley & Sons, Ltd.     

Paraxial ray theory in general coordinates

Summary Principles of an alternative approach to the ray theory and paraxial ray approximation (PRA) theory are discussed. Invariant equations for the ray, the eikonal equation and basic equations of the PRA-theory are derived on the basis of Riemannian geometry. Paraxial rays and paraxial time field equations in general curvilinear coordinates are shown as an example of application.     

Interaction between sulphide and H2O in silicate melts

Reaction between dissolved water and sulphide was experimentally investigated in soda-lime-silicate (NCS) and sodium trisilicate (NS3) melts at temperatures from 1000 to 1200 °C and pressures of 100 or 200 MPa in internally heated gas pressure vessels. Diffusion couple experiments were conducted at water-undersaturated conditions with one half of the couple being doped with sulphide (added as FeS or Na₂S; 1500-2000 ppm S by weight) and the other with H₂O (∼3.0 wt.%). Additionally, two experiments were performed using a dry NCS glass cylinder and a free H₂O fluid. Here, the melt was water-saturated at least at the melt/fluid interface. Profiling by electron microprobe (sulphur) and infrared microscopy (H₂O) demonstrate that H₂O diffusion in the melts is faster by 1.5-2.3 orders of magnitude than sulphur diffusion and, hence, H₂O can be considered as a rapidly diffusing oxidant while sulphur is quasi immobile in these experiments.In Raman spectra a band at 2576 cm⁻¹ appears in the sulphide - H₂O transition zone which is attributed to fundamental S-H stretching vibrations. Formation of new IR absorption bands at 5025 cm⁻¹ (on expense of the combination band of molecular H₂O at 5225 cm⁻¹) and at 3400 cm⁻¹ was observed at the front of the in-diffusing water in the sulphide bearing melt. The appearance and intensity of these two IR bands is correlated with systematic changes in S K-edge XANES spectra. A pre-edge excitation at 2466.5 eV grows with increasing H₂O concentration while the sulphide peak at 2474.0 eV decreases in intensity relative to the peak at 2477.0 eV and the feature at 2472.3 eV becomes more pronounced (all energies are relative to the sulphate excitation, calibrated to 2482.5 eV). The observations by Raman, IR and XANES spectroscopy indicate a well coordinated S²⁻ - H₂O complex which was probably formed in the glasses during cooling at the glass transition. No oxidation of sulphide was observed in any of the diffusion couple experiments. On the contrary, XANES spectra from experiments conducted with a free H₂O fluid show complete transformation of sulphide to sulphate near the melt surface and coexistence of sulphate and sulphide in the center of the melt. This can be explained by a lower H₂O activity in the diffusion couple experiments or by the need of a sink for hydrogen (e.g., a fluid which can dissolve high concentration of hydrogen) to promote oxidation of sulphide by H₂O via the reaction S²⁻ + 4H₂O = SO₄²⁻ + 4H₂. Sulphite could not be detected in any of the XANES spectra implying that this species, if it exists in the melt, it is a subordinate or transient species only.     

Impact of climate change on zooplankton communities, seabird populations and arctic terrestrial ecosystem—A scenario

Many arctic terrestrial ecosystems suffer from a permanent deficiency of nutrients. Marine birds that forage at sea and breed on land can transport organic matter from the sea to land, and thus help to initiate and sustain terrestrial ecosystems. This organic matter initiates the emergence of local tundra communities, increasing primary and secondary production and species diversity. Climate change will influence ocean circulation and the hydrologic regime, which will consequently lead to a restructuring of zooplankton communities between cold arctic waters, with a dominance of large zooplankton species, and Atlantic waters in which small species predominate. The dominance of large zooplankton favours plankton-eating seabirds, such as the little auk (Alle alle), while the presence of small zooplankton redirects the food chain to plankton-eating fish, up through to fish-eating birds (e.g., guillemots Uria sp.). Thus, in regions where the two water masses compete for dominance, such as in the Barents Sea, plankton-eating birds should dominate the avifauna in cold periods and recess in warmer periods, when fish-eaters should prevail. Therefore under future anthropogenic climate scenarios, there could be serious consequences for the structure and functioning of the terrestrial part of arctic ecosystems, due in part to changes in the arctic marine avifauna. Large colonies of plankton-eating little auks are located on mild mountain slopes, usually a few kilometres from the shore, whereas colonies of fish-eating guillemots are situated on rocky cliffs at the coast. The impact of guillemots on the terrestrial ecosystems is therefore much smaller than for little auks because of the rapid washing-out to sea of the guano deposited on the seabird cliffs. These characteristics of seabird nesting sites dramatically limit the range of occurrence of ornithogenic soils, and the accompanying flora and fauna, to locations where talus-breeding species occur. As a result of climate warming favoring the increase of ichthyiofagous cliff-nesting seabirds, we can expect that large areas of ornithogenic tundra around the colonies of plankton-eating seabirds situated far from the sea may disappear, while areas of tundra in the vicinity of cliffs inhabited by fish-eating seabirds, with low total production and supporting few large herbivores, will likely increase, but only imperceptibly. This may lead to habitat fragmentation with negative consequences for populations of tundra-dependent birds and mammals, and the possibility of a substantial decrease in biodiversity of tundra plant and animal communities.     

Numerical and experimental studies of a floating and liquid-filled membrane structure in waves

Linear theories to analyse a floating and liquid-filled membrane structure in head- and beam-sea waves have been presented. The dynamic solutions are based on a small perturbation of the static solution, and the hydroelastic deformation has been taken care of correctly to the first order of the incident wave amplitude. A new experiment has been carried out for measuring the dynamic tensions of a membrane. A comparison between the theories and experiment are presented for the dynamic hoop tension.     

Latest Caledonian to Present tectonomorphological development of southern Norway

The regional resultant stress field of the northeastern North Atlantic has shifted significantly throughout the Phanerozoic. In Fennoscandian parts of the Caledonian orogen, mountain building, which was characterized by NW-SE contraction (reference to present North), was followed by a collapse with transport both parallel and transverse to the mountain chain. The Late Palaeozoic – Mesozoic saw several stages of E-W to NW-SE extension, varying in time and position. Local episodes of inversion are traceable in some cases, particularly in connection with deep-seated and long-lived zones of weakness. The Cenozoic has to a larger degree been affected by compression, including folding and basin inversion. Again some of the more pronounced effects of local inversion are related to pre-existing fault systems. Neogene uplift of the western mountainous area in Scandinavia can be unravelled by potential field study, AFT data and reflection seismic sections. Assuming that the region is close to isostatic equilibrium, the uplifted areas must be supported at depth by substantial volumes of low-density material within the crust or the mantle, close to the crust/mantle interface or close to the lithosphere/asthenosphere interfaces.