On lipid surface films on the sea. I. A simple method for sampling and studies of composition

A method for collection of surface films on the sea has been developed and tested at various places along the Swedish West Coast. Considerable amounts of lipids on the sea surface were found even when no seaslicks were observed. Triglycerides, free fatty acids, and wax esters are the dominating constituents, and there are characteristic deviations in the fatty-acid patterns compared to the corresponding lipids dissolved in the sub-surface water. Organochlorine residues, phthalic acid esters and heavy metals also occur in considerable amounts.     

Remedial measures against radioactive Caesium in Swedish lake fish after Chernobyl

The aim of this work is to give a summary of the work on Cs-137 in Swedish lakes carried out mainly by our group (the Liming-mercury-caesium project) between 1986 and 1990. The focus is on results from extensive field experiments carried out in 41 lakes testing various remedial measures to speed up the natural recovery of Cs-137 in lakes: Lake liming and wet land liming with primary rock lime, sedimentary rock lime and so-called mixed lime, which also contains nutrients; potash treatment and intensive fishing. Selected results: The remedies have given the intended water-chemical response. None of the methods used works effectively as cure, i.e., no rapid and clear reduction in the concentrations of radioactive caesium in fish is obtained in comparison with lakes where the waterchemical or biological conditions are not changed. In lakes with long water turnover time and with low values of, foremost, conductivity, hardness and potassium, the fish had relatively higher concentrations at the same fallout levels. The differences present between the lakes as regards the continued magnitude of the change in concentration in fish can foremost be linked to factors controlling the secondary load (i.e., the internal loading and the input from the catchment). A successful potash treatment (in oligotrophic lakes) may imply that the natural recovery will be at the most 5% faster compared to no treatment. This would give quite positive implications in the long run since the ecological half-life for Cs-137 in pike (the top predator in these lake types) is very long. The time interval between the remedies and the latest fish analyses (about 2 years on average) is not sufficient to obtain (statistically) clear-cut results on these the small effects of the remedies. A longer time series of data is required for this.     

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.     

The importance and limitations of social networks and social identities for labour market integration: The case of Ghanaian immigrants in Bergen,Norway

Whereas refugees and larger immigrant groups’ integration in the Norwegian labour market has received considerable research attention, less is known about the labour market integration of small, non-refugee immigrant groups from West African countries such as Ghana. The purpose of the article is to examine the role of social networks and social identities for the differentiated labour market integration outcomes among Ghanaian immigrants in the city of Bergen. Based on data produced through in-depth interviews, participant observation and informal conversations, the authors argue that Ghanaian immigrants’ ability to obtain jobs is determined by more than simply having the appropriate educational and language qualifications, and largely depends on having favourable social identities and being embedded in social networks beyond the Ghanaian immigrant community. They find that those who mainly relied on Ghanaian networks found it difficult to circumvent labour market hindrances and they predominantly obtained menial jobs. The authors conclude that Norwegian job-seekers networks played a crucial role in the immigrants’ opportunities and for potential Norwegian employers’ perception of their employability, especially in professional and semi-professional jobs.     

A comparison of MODIS and NOHRSC snow‐cover products for simulating streamflow using the Snowmelt Runoff Model

Remote sensing is an important source of snow‐cover extent for input into the Snowmelt Runoff Model (SRM) and other snowmelt models. Since February 2000, daily global snow‐cover maps have been produced from data collected by the Moderate Resolution Imaging Spectroradiometer (MODIS). The usefulness of this snow‐cover product for streamflow prediction is assessed by comparing SRM simulated streamflow using the MODIS snow‐cover product with streamflow simulated using snow maps from the National Operational Hydrologic Remote Sensing Center (NOHRSC). Simulations were conducted for two tributary watersheds of the Upper Rio Grande basin during the 2001 snowmelt season using representative SRM parameter values. Snow depletion curves developed from MODIS and NOHRSC snow maps were generally comparable in both watersheds: satisfactory streamflow simulations were obtained using both snow‐cover products in larger watershed (volume difference: MODIS, 2·6%; NOHRSC, 14·0%) and less satisfactory streamflow simulations in smaller watershed (volume difference: MODIS, −33·1%; NOHRSC, −18·6%). The snow water equivalent (SWE) on 1 April in the third zone of each basin was computed using the modified depletion curve produced by the SRM and was compared with in situ SWE measured at Snowpack Telemetry sites located in the third zone of each basin. The SRM‐calculated SWEs using both snow products agree with the measured SWEs in both watersheds. Based on these results, the MODIS snow‐cover product appears to be of sufficient quality for streamflow prediction using the SRM in the snowmelt‐dominated basins. Copyright © 2005 John Wiley & Sons, Ltd.     

Quaternary denudation of southern Fennoscandia – evidence from the marine realm

Throughout the last 1.1 million years repeated glaciations have modified the southern Fennoscandian landscape and the neighbouring continental shelf into their present form. The glacigenic erosion products derived from the Fennoscandian landmasses were transported to the northern North Sea and the SE Nordic Seas continental margin. The prominent sub‐marine Norwegian Channel trough, along the south coast of Norway, was the main transport route for the erosion products between 1.1 and 0.0 Ma. Most of these erosion products were deposited in the North Sea Fan, which reaches a maximum thickness of 1500 m and has nearly 40 000 km³ of sediments. About 90% of the North Sea Fan sediments have been deposited during the last 500 000 years, in a time period when fast‐moving ice streams occupied the Norwegian Channel during each glacial stage. Back‐stripping the sediment volumes in the northern North Sea and SE Nordic Seas sink areas, including the North Sea Fan, to their assumed Fennoscandian source area gives an average vertical erosion of 164 m for the 1.1–0.0 Ma time period. The average 1.1–0.0 Ma erosion rate in the Fennoscandian source area is estimated to be 0.15 mm a^?1. We suggest, however, that large variations in erosion rates have existed through time and that the most intense Fennoscandian landscape denudation occurred during the time period of repeated shelf edge ice advances, namely from Marine Isotope Stage 12 (c. 0.5 Ma) onwards.     

Design Methodology for Grout Curtains Under Dams Founded on Rock

Geotechnical and Geological Engineering - Grout curtains are commonly constructed under dams to reduce the seepage through the rock foundation. In the design of grout curtains, empirical methods...     

Conditioning geological surfaces to horizontal wells

Computational Geosciences - Kriging is a standard method for conditioning surfaces to observations. Kriging works for vertical wells, but may produce surfaces that cross horizontal wells between...     

A dated volcano-tectonic deformation event in Jan Mayen causing landlocking of Arctic charr

We provide the first documentation of tectonic deformation resulting from a volcanic eruption on the island of Jan Mayen. Vertical displacement of about 14 m southwest of the stratovolcano Beerenberg is associated with an eruption in ad 1732 on its southeastern flank. The age of the uplift event is bracketed by radiocarbon-dated driftwood buried by material deposited due to uplift, and by tephra from this eruption. Constraints, inferred from radiocarbon ages alone, allow for the possibility that uplift was completed prior to the ad 1732 eruption. However, the occurrence of tephra in the sediment column indicates that some displacement was ongoing during the eruption but ceased before the eruption terminated. We attribute the tectonic deformation to intrusion of shallow magma associated with the volcanic eruption. Our results complement previous studies of volcanic activity on Jan Mayan by providing precise age constraints for past volcanic activity. Also, it raises new hypotheses regarding the nature, timing and prevalence of precursor tectonic events to Jan Mayan eruptions. The uplift caused the complete isolation of a coastal lake by closing its outlet to the sea, thus landlocking the facultative migratory fish species Arctic charr (Salvelinus alpinus).     

A GIS-based approach to compare economic damages of fluvial flooding in the Neckar River basin under current conditions and future scenarios

Natural Hazards - Fluvial floods can cause significant damages and are expected to increase in magnitude and frequency throughout the twenty-first century due to global warming. Alongside hazard...