Ra-226 was measured by alpha-emission spectroscopy in water, sediments, and fish (tissues and gut contents), from five lakes in a watershed containing U mining and milling operations at Elliot Lake, Ontario, and from control lakes in an adjacent non-industrialized watershed. Ra-226 transfer parameters from lake water and sediments to fish tissues, and annual intakes by humans consuming fish, were estimated. Mean dissolved 226Ra levels ranged from approximately 76 mBq litre(-1) in water of the most affected lake, to < 10 mBq litre(-1) in control lakes.
View Article and Find Full Text PDFRadionuclides (210Pb, 210Po, 230Th, and 232Th) and chemical Th and U were measured in water, sediments, and fish tissues (bone, muscle, and gut contents of laketrout, Salvelinus namaycush, whitefish, Coregonus clupeaformis and Prosopium cylindraceum) from four lakes in a watershed affected by U mining and milling operations at Elliot Lake, Ontario, and from control lakes in an adjacent, non-industrialized, watershed. Radionuclide concentration ratios between tissue levels and sediment and water levels were calculated. Annual radionuclide intakes and resulting doses were estimated for humans consuming fish from the watershed.
View Article and Find Full Text PDFUptake of 226Ra, 232Th, 230Th, and 228Th from water, sediment, and diet sources to bone and muscle of white suckers (Catostomus commersoni) was studied in sixteen lakes in the uranium-mining district of Ontario, Canada. Fish tissues did not increase linearly with environmental concentrations. The best relationship appears to be a power function.
View Article and Find Full Text PDFEquilibrium conditions are assumed in the simple linear concentration factor model commonly used in simulations of contaminant flow through ecosystems and in dose and risk calculations. Predictions derived from a power function model have suggested that if the time scale of the food-chain transfer is less than six years in fish, radium-226 equilibrium will not be achieved in nature, thereby violating the equilibrium requirement in the concentration factor model. Our results indicate (226)Ra equilibrium is achieved in a natural population of lake herring (Coregonus artedii), contrary to predictions of the power function model.
View Article and Find Full Text PDFSnowshoe hare (Lepus americanus) trapped near U tailings had higher concentrations of (226)Ra in their bones (250 +/- 94 mBq g(-1) dry wt) than those from local control sites 3-15 km from the tailings (20-30 mBq g(-1) dry wt) and those from a distant control site 880 km away from the U mining area, which were below the detection limit (DL) (3.7 mBq g(-1) dry wt). Most chyme (stomach content) samples contained 226Ra below DL.
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