Radionuclides in the terrestrial ecosystem near a Canadian uranium mill--Part I: Distribution and doses

Soils, vegetation, small mammals, and birds were measured for uranium series radionuclides at three sites near the operating Key Lake uranium mill in northern Saskatchewan. Sites, impacted by windblown tailings and mill dust, had significantly higher concentrations of uranium, 226Ra, 210Pb, and 210Po in soils, litter, vegetation, tree needles and twigs, small mammals, and birds, compared to a control site. Samples were collected from both upland jackpine and black spruce bog habitats in triplicate at each site. Both habitats were similar in radionuclide accumulation. Absorbed doses averaged 0.92, 8.4, and 4.9 mGy y(-1) to small mammals and 2.0, 5.8, and 2.8 mGy y(-1) to Lincoln's sparrows at the control, tailings, and mill sites, respectively. These doses do not include doses from short-lived radon progeny. The majority of the dose increment at the tailings and mill sites was due to 226Ra, whereas it was 210Po at the control site. Thus, use of a radiation weighting factor of 20 for alpha radiation raised equivalent doses (in mSv y(-1)) by nearly a factor of 20.