Background radiation dose-rates to non-human biota in a high mountain habitat in Norway

Determination of background radiation dose-rates is important in the process of assessing risks to the environment from exposure to human activities both in terms of deriving the incremental dose-rate and as a point of reference for evaluating the significance of the exposure level. A consideration of the available literature on naturally occurring radionuclides in wild plants and animals quickly illustrates a paucity of data coverage in numerous cases. Most notable is the lack of comprehensive information for the important dose-forming radionuclides such as 210Po and 210Pb. In order to collate data concerning these radioisotopes for components of the ecosystem, field work was conducted in a semi-natural, mountainous location in central Norway. Preliminary (since no correction was made for ingrowth from 210Pb) whole-body activity concentrations of 210Po in 2 species of small mammal were commensurate with activity concentrations reported for reindeer muscle sampled at proximate locations, falling at a level of some 10s of Bq kg-1 by fresh weight. Statistical analyses of the data showed that bank vole and shrew 210Po data constitute different populations with different mean ranks. Unweighted dose-rates attributable to the presence of internally distributed 210Po were calculated to be 0.07 μGy h-1 for Bank vole.