99Tc in seawater in the West Spitsbergen Current and adjacent areas

99Tc levels were measured in seawater samples collected between 2000 and 2002 in the West Spitsbergen Current (WSC) and along the western coast of Svalbard or Spitzbergen and compared with available oceanographic 3-D modelling results for the late 1990s. Additional data from related regions are also presented in order to support the data interpretation. The seawater in the Arctic fjord Kongsfjorden on the western coast of Svalbard is influenced by the WSC, as shown by the 99Tc levels in surface water. By means of the WSC, 99Tc reaches the Eastern Fram Strait, where one branch of the WSC turns west into the East Greenland Current (EGC), and another branch continues northwards into the Arctic Ocean. Surface seawater collected in the central part of the WSC during a cruise on board the R/V "Polarstern" in the summer of 2000, showed higher levels of (99)Tc than samples measured in Kongsfjorden in the spring of 2000. However, all levels measured in surface water are of the same order of magnitude. Data from sampling of deeper water in the WSC and EGC provide information pertaining to the lateral distribution of 99Tc. In all vertical profiling surveys (conducted in spring and summer), the highest levels of 99Tc were found in surface water. Comparison with oceanographic 3-D modelling indicates both significant seasonal variations in the lateral stratification of the WSC and variations with depth over shorter vertical distances. This information can be applied in sampling strategies, environmental monitoring, long-range transport of pollutants and physical oceanography.     

Shine a light: Under-ice light and its ecological implications in a changing Arctic Ocean

The Arctic marine ecosystem is shaped by the seasonality of the solar cycle, spanning from 24-h light at the sea surface in summer to 24-h darkness in winter. The amount of light available for under-ice ecosystems is the result of different physical and biological processes that affect its path through atmosphere, snow, sea ice and water. In this article, we review the present state of knowledge of the abiotic (clouds, sea ice, snow, suspended matter) and biotic (sea ice algae and phytoplankton) controls on the underwater light field. We focus on how the available light affects the seasonal cycle of primary production (sympagic and pelagic) and discuss the sensitivity of ecosystems to changes in the light field based on model simulations. Lastly, we discuss predicted future changes in under-ice light as a consequence of climate change and their potential ecological implications, with the aim of providing a guide for future research.     

The dispersion of 99Tc in the Nordic Seas and the Arctic Ocean: a comparison of model results and observations

The radionuclide (99)Tc had been discharged from the nuclear reprocessing facility in Sellafield (UK) into the Irish Sea in increased amounts in the 1990s. We compare the simulated dispersion of (99)Tc in surface water as calculated by a hydrodynamic model and an assessment box model with field-observations from 1996 to 1999 to study concentrations, pathways and travel times. The model results are consistent with the observations and show the typical pathway of dissolved radionuclides from the Irish Sea via the North Sea along the Norwegian Coast. Subsequently the contaminated water separates into three branches of which the two Arctic branches bear the potential for future monitoring of the signal in the next decades. The results of the hydrodynamic model indicate a large variability of surface concentrations in the West Spitsbergen Current which has implications for future monitoring strategies. According to the observed and simulated distributions we suggest an improved box model structure to better capture the pattern for concentrations at the surface.     

Arctic Climate Change,Economy and Society (ACCESS): Integrated perspectives

This introduction to the special issue presents an overview of the wide range of results produced during the European Union project Arctic Climate Change, Economy and Society (ACCESS). This project assessed the main impacts of climate change on Arctic Ocean’s geophysical variables and how these impending changes could be expected to impact directly and indirectly on socio-economic activities like transportation, marine sea food production and resource exploitation. Related governance issues were examined. These results were used to develop several management tools that can live on beyond ACCESS. In this article, we synthesize most of the project results in the form of tentative responses to questions raised during the project. By doing so, we put the findings of the project in a broader perspective and introduce the contributions made in the different articles published in this special issue.     

Optimisation of sampling for the temporal monitoring of technetium-99 in the Arctic marine environment

Monitoring of the marine environment for radioactivity, for both radiological protection and oceanographic purposes, remains an expensive and labour intensive activity due to the large sample volumes needed and the complex and lengthy analytical procedures required to measure low levels of contamination. Because of this, some consideration must be given to the design of sampling plans to ensure effective and efficient sampling that can be defended on the basis of scientific rationale. This article tests the hypothesis that geostatistical techniques may prove of use in the optimisation and design of sampling regimes for the monitoring of temporal fluctuations in the levels of technetium at a location in the Norwegian Arctic marine environment. The level of temporal correlation exhibited by two relevant time series was investigated and the information used to observe the effect of sampling frequency on the production of monthly estimates of activity of technetium in both seawater and seaweed. The results indicate that reduced sampling frequency allows production of estimates that acceptably replicate the actual data and that use of geostatistical procedures may offer advantages in the planning of monitoring systems for marine radioactivity. The use of an oceanographic model was also investigated as a means of assessing the temporal correlation prior to actual sampling, an approach that may offer significant advantages by reducing the need to have lengthy time series prior to designing sampling regimes.     

Future sea ice conditions and weather forecasts in the Arctic: Implications for Arctic shipping

The ability to forecast sea ice (both extent and thickness) and weather conditions are the major factors when it comes to safe marine transportation in the Arctic Ocean. This paper presents findings focusing on sea ice and weather prediction in the Arctic Ocean for navigation purposes, in particular along the Northeast Passage. Based on comparison with the observed sea ice concentrations for validation, the best performing Earth system models from the Intergovernmental Panel on Climate Change (IPCC) program (CMIP5—Coupled Model Intercomparison Project phase 5) were selected to provide ranges of potential future sea ice conditions. Our results showed that, despite a general tendency toward less sea ice cover in summer, internal variability will still be large and shipping along the Northeast Passage might still be hampered by sea ice blocking narrow passages. This will make sea ice forecasts on shorter time and space scales and Arctic weather prediction even more important.