title: Food-chain transfer of U-series radionuclides in a northern Saskatchewan aquatic system.
abstract: Levels of TotalU, 226Ra, and 210Pb in water, sediments, insects and fish were measured in a stream and a lake affected by U mill effluents and in three uncontaminated systems (one creek and two lakes). Radionuclide levels were significantly elevated in water, sediments and biota at contaminated sites. Radionuclide concentration declined with each successive trophic level due primarily to very low assimilation efficiency. Fish radionuclide concentrations varied with season but did not vary with age or year of sampling. Distribution coefficients were high; therefore, a large proportion of radionuclides entering the systems go to the solid phase. Organisms feeding on or near sediments had higher radionuclide levels than pelagic species. There is a potential for long-term cycling of radionuclides from sediments through food chains due to low flux and sedimentation rates. With the exception of water----insects and water----fish all transfer coefficients (TC) were low, usually less than one. Control TCs were greater than TCs in contaminated areas. Radium-226 and 210Pb TCs declined dramatically at the insect-fish level. Uranium uptake from water by insects and fish was much less than 226Ra or 210Pb uptake. Uptake from sediments was similar for all nuclides in insects but 210Pb sediment-fish TCs differed from 226Ra or U TCs. The critical pathway in the contaminated area was sediments----insects----forage fish----whitefish----man. Estimated internal dose rates to large fish in the contaminated area were 1-2 rad/y. Dose to humans from consumption of one fish serving per week for 1 y was 2% of the International Commission on Radiological Protection (ICRP) annual limit for the general public.
mesh_terms: D000818:Animals; D004175:Diptera / Q000032:analysis; D005399:Fishes / Q000378:metabolism; D005507:Food Contamination, Radioactive / Q000032:analysis*; D006801:Humans; D007854:Lead / Q000032:analysis*; D011005:Plutonium / Q000032:analysis*; D011868:Radioisotopes / Q000032:analysis; D012525:Saskatchewan; D014501:Uranium / Q000032:analysis*; D014873:Water Pollutants / Q000032:analysis*; D014875:Water Pollutants, Radioactive / Q000032:analysis*
chemical_list: D011868:Radioisotopes; D014873:Water Pollutants; D014875:Water Pollutants, Radioactive; D007854:Lead; D014501:Uranium; D011005:Plutonium