Temporal changes in radionuclide transfer to biota in Canadian Shield lakes receiving chronic inputs: Reconstruction of radionuclide exposure to non-human biota in Perch Lake over a 40 year period

Temporal changes in radionuclide transfer factors were evaluated in forage fishes over a 40- to 50-year period. In general, 90Sr, 60Co and 137Cs transfer factors fairly consistent over time, as indicated by strong correlations between measured and estimated values. This conclusion was further strengthened by comparing radionuclide transfer factors measured in Perch Lake biota relative to those reported for other Canadian Shield lakes, since similar values were found. Despite these similarities, however, within-lake differences of up to an order of magnitude were observed for a given species collected in a given year, suggesting that within lakes, there may be factors influencing biota exposure to radionuclides and/or bioavailability.