Activity concentration measurements of selected radionuclides in seals from Canadian Arctic

The activity concentrations of naturally occurring radionuclides (such as Ra-226, Pb-210 and Po-210) and long lived Cs-137 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 Po-210 was measured in all seal liver and muscle samples individually. The average Po-210 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 Ra-226 and Pb-210 were performed for pooled samples. Activity concentrations of Pb-210 and Ra-226 were generally below detection limits. While Cs-134 activity concentration was not detectable, Cs-137 activity concentration was detected in muscle and liver samples. On average, the Cs-137 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 Po-210 nor Cs-137 were detected in the blubber samples. This study confirmed that Po-210 is the dominant contributor to radiation doses resulting from seal consumption. Man-made contaminant Cs-137 only contributes less than 0.01% of the total ingestion dose obtained from Arviat seals. Crown Copyright (C) 2016 Published by Elsevier Ltd. All rights reserved.