M. Sickel

Radioactive contamination in the Arctic--sources, dose assessment and potential risks.

Arctic residents, whose diets comprise a large proportion of traditional terrestrial and freshwater foodstuffs, have received the highest radiation exposures to artificial radionuclides in the Arctic. Doses to members of both the average population and selected indigenous population groups in the Arctic depend on the rates of consumption of locally-derived terrestrial and freshwater foodstuffs, including reindeer/caribou meat, freshwater fish, goat cheese, berries, mushrooms and lamb. The vulnerability of arctic populations, especially indigenous peoples, to radiocaesium deposition is much greater than for temperate populations due to the importance of terrestrial, semi-natural exposure pathways where there is high radiocaesium transfer and a long ecological half-life for this radionuclide. In contrast, arctic residents with diets largely comprising marine foodstuffs have received comparatively low radiation exposures because of the lower levels of contamination of marine organisms. Using arctic-specific information, the predicted collective dose is five times higher than that estimated by UNSCEAR for temperate areas. The greatest threats to human health and the environment posed by human and industrial activities in the Arctic are associated with the potential for accidents in the civilian and military nuclear sectors. Of most concern are the consequences of potential accidents in nuclear power plant reactors, during the handling and storage of nuclear weapons, in the decommissioning of nuclear submarines and in the disposal of spent nuclear fuel from vessels. It is important to foster a close association between risk assessment and practical programmes for the purposes of improving monitoring, formulating response strategies and implementing action plans.

How to monitor semi-natural key habitats in relation to grazing preferences of cattle in mountain summer farming areas: An aerial photo and GPS method study

Summer farming was formerly an important part of Norwegian husbandry and mountain areas have been used for grazing for hundreds of years. A decline in summer farming practices, during the twentieth century, has caused a large-scale encroachment of trees and shrubs leading to extensive landscape changes and decreased biodiversity. Therefore, in order to maintain the biodiversity in summer farm mountain areas, it is now necessary to detect, map and monitor remaining species-rich fragments, i.e. key habitats. It is also important to identify still grass- and herb-rich areas that can be successfully restored for grazing because of a new interest for summer farming. Field surveys in the re-growing mountain areas are extremely time consuming, as the concomitant terrain renders movement by foot arduous. A method was thus developed for detection of key-habitats and other grass and herb-rich habitats in such areas based on interpretation of coloured infrared aerial photographs (CIR). In addition, black-and-white aerial photographs, taken nearly 40 years ago, were used to identify past open land and pastures and thus in combination with the modern ones allow the identification of areas that exhibit a continuity in grazing. Interpretation keys were developed and vegetation maps were constructed. The interpretation from the aerial photographs was compared to detailed field control and the method was found to be efficient and accurate. The method gave useful information about the landscape history and continuity of grazing. The cattle’s movements were traced by GPS equipment mounted on a collar on the leading cattle, and their movements were later transferred to a map and analysed together with the vegetation map in a GIS. The results show that the cattle preferred to graze in the areas identified as most valuable and species rich. The developed method also makes it possible to identify areas for which pasture-restoration might be successfully achieved. Furthermore, the study revealed that there is a high correspondence between key habitats in the summer farming areas and grazing preferences of the cattle.

The accidental sinking of the nuclear submarine, the Kursk: monitoring of radioactivity and the preliminary assessment of the potential impact of radioactive releases.

Measurements of samples taken from the close vicinity of the Kursk during two expeditions to the site in August and October 2000, indicate that no leakage of radionuclides from the reactors has been observed. Only background levels in the range 0.0-0.1 microSv/h have been measured by use of the remote operating vehicle (ROV) or by the divers working on and inside the submarine. Preliminary model calculations based on two different scenarios, representing short- and long-term releases of 100% of the reactors radionuclide inventory, show that the impact on man and the environment from the Kursk should not be deemed very serious. The conservative estimates indicate a maximum 137Cs activity concentration in fish in the order of about 80-100 Bq/kg and a total collective dose of 97 manSv.