| Popis: |
A number of caribou and muskoxen samples from the western Alaskan Arctic and fish samples from the Aleutian Islands were collected between 1998 and 2006 and analyzed for anthropogenic ( 90 Sr and 137 Cs) and natural radionculides ( 40 K, 210 Pb and 226 Ra), as part of the radiological assessment for the regional subsistence hunting communities in the first half of 2000s. We examined the relationship between the activities of these nuclides with the size of the fish. In caribou samples, concentration of 90 Sr in muscle was below the detection limit of 0.14 Bq kg − 1 and 137 Cs concentration in bones was below the detection limit of 0.15 Bq kg − 1 . 137 Cs activity varied over an order of magnitude in caribou muscle samples with an average value of 2.5 Bq/kg wet wt. Average 137 Cs activity in muskoxen muscle was found to be 9.7 Bq/kg wet wt. However, there were a little variation (less than 60%) in 210 Pb, 40 K, and 226 Ra in both muscle and bone of both caribou and muskoxen. The activities of total 210 Pb in caribou and muskox bones were found to be 1–2 orders of magnitude higher than that of parent-supported 210 Pb indicating the potential for dating of bones of terrestrial mammals (time elapsed since the death of the animal) based on the excess 210 Pb method exists. In fish muscle samples, 137 Cs activity varied from below detection limit to 154 mBq/kg wet wt. and its content increased with the size of the fish due to its transfer through the food chain. Among the seven fish species investigated, 210 Pb activities varied almost an order of magnitude; however, 40 K and 226 Ra activities varied less than a factor of two. Total annual effective dose due to 90 Sr and 137 Cs from the ingestion of those terrestrial and marine meats was estimated to be negligible (ca. 9 μSV/a) compared to the natural radionuclides present thus posing negligible radiological threat to humans. |
Full Text from ScienceDirect