Levels and trends of radioactive contaminants in the Greenland environment

Levels of radioactive contaminants in various Greenland environments have been assessed during 1999-2001. The source of Cs-137 Sr-90 and Pu-239,Pu-240 in terrestrial and fresh water environments is mainly global fallout. In addition, the Chernobyl accident gave a small contribution of Cs-137. Reindeer and lamb contain the largest observed Cs-137 concentrations in the terrestrial environment-up to 80 Bq kg(-1) fresh weight have been observed in reindeer. Due to special environmental conditions, Cs-137 is transferred to landlocked Arctic char with extremely high efficiency in South Greenland leading to concentrations up to 100 Bq kg(-1) fresh weight. In these cases very long ecological half-lives are seen. Concentrations of Tc-99, Cs-137 and Sr-90 in seawater and in marine biota decrease in the order NorthEast Greenland and the coastal East Greenland current> South-West Greenland> Central West Greenland and North-West Greenland> Irmiger Seasimilar toFaroe Islands. The general large-scale oceanic circulation combined with European coastal discharges and previous contamination of the Arctic Ocean causes this. As the same tendency is seen for the persistent organic pollutants (POPs) DDT and PCB in marine biota, it is suggested that long-distance oceanic transport by coastal currents is a significant pathway also for POPs in the Greenland marine environment. The peak Tc-99 discharge from Sellafield 1994-1995 has only been slightly visible in the present survey year 2000. The concentrations are expected to increase in the future, especially in East Greenland. The Bylot Sound at the Thule Airbase (Pituffik) in North-West Greenland was contaminated with plutonium and enriched uranium in a weapons accident in 1968. Biological activity has mixed accident plutonium efficiently into the new sediments resulting in continued high surface sediment concentrations three decades after the accident. Transfer of plutonium to benthic biota is low-and lower than observed in the Irish Sea. This is supposed to be caused by the physico-chemical form of the accident plutonium. A recent study indicates that 'hot particles' hold considerably more plutonium than previously anticipated and that the Bylot Sound sediments may account for the major part of the un-recovered plutonium after the accident, i.e. approximately 3 kg. (C) 2004 Elsevier B.V. All rights reserved.