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 137Cs, 90Sr and 239,240Pu in terrestrial and fresh water environments is mainly global fallout. In addition, the Chernobyl accident gave a small contribution of 137Cs. Reindeer and lamb contain the largest observed 137Cs concentrations in the terrestrial environment—up to 80 Bq kgy1 fresh weight have been observed in reindeer. Due to special environmental conditions, 137Cs is transferred to landlocked Arctic char with extremely high efficiency in South Greenland leading to concentrations up to 100 Bq kgy1 fresh weight. In these cases very long ecological halflives are seen. Concentrations of 99Tc, 137Cs and 90Sr in seawater and in marine biota decrease in the order North- East Greenland and the coastal East Greenland current)South-West Greenland)Central West Greenland and North-West Greenland)Irmiger Sea;Faroe 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 PCBin 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 99Tc 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.