Activity concentration measurements of selected radionuclides in seals from Canadian Arctic.

The activity concentrations of naturally occurring radionuclides (such as 226 Ra, 210 Pb and 210 Po) and long lived 137 Cs were measured in a total of 119 tissue samples (43 blubber, 43 liver, and 33 muscle samples) from 40 ringed seals and 4 bearded seals collected in the Arviat area of Canada during the fall of 2014. Activity concentration of 210 Po was measured in all seal liver and muscle samples individually. The average 210 Po activity concentrations were 25 ± 7.6 Bq/kg fresh weight (fw) in muscle and 211 ± 58 Bq/kg fw in liver for ringed seals, and 20 ± 6.1 Bq/kg fw in muscle and 231 ± 150 Bq/kg fw in liver for bearded seals. Due to insufficient sample material for most samples collected, gamma counting for radioactive caesium and radiochemical analysis for 226 Ra and 210 Pb were performed for pooled samples. Activity concentrations of 210 Pb and 226 Ra were generally below detection limits. While 134 Cs activity concentration was not detectable, 137 Cs activity concentration was detected in muscle and liver samples. On average, the 137 Cs activity concentrations were 0.25 ± 0.05 and 0.12 ± 0.04 Bq/kg fw in muscle and liver samples of ringed seals, and 0.11 ± 0.02 and 0.10 ± 0.03 Bq/kg fw in muscle and liver samples of bearded seals, respectively. Neither 210 Po nor 137 Cs were detected in the blubber samples. This study confirmed that 210 Po is the dominant contributor to radiation doses resulting from seal consumption. Man-made contaminant 137 Cs only contributes less than 0.01% of the total ingestion dose obtained from Arviat seals.