Po and Pb activity concentrations in Greenlandic seabirds and dose assessment.

Naturally occurring radionuclides, in particular, polonium-210 (Po), have a greater contribution than anthropogenic radionuclides to the annual effective dose received by the general public due to consumption of seafood. Knowledge of potential trophic sources and transfer of Po to seabird species and subsequently to the Greenlandic people is, however, still poor. Here, we assess the transfer of Po and Pb to seabirds sampled during autumn and winter 2017 and 2018 in Greenland and provide a dose assessment. The activity concentrations of Po in muscle and liver, respectively, ranged from 0.2 ± 0.1 Bq kg w.w. in glaucous gull (Larus hyperboreus) to 21.2 ± 22.6 Bq kg w.w. in thick-billed murre (Uria lomvia) and from 32.0 ± 9.4 Bq kg w.w. in common eider (Somateria mollissima) to 40.5 ± 49.0 Bq kg w.w. in thick-billed murre. Po was non-uniformly distributed in the body of thick-billed murre. Kidneys and feathers showed higher Po activity concentrations than heart and bone. The Po/Pb activity concentration ratios are higher than unity, indicating that Po is preferentially taken up by seabirds compared to its progenitor Pb. The derived annual absorbed dose from Po to the whole body of thick-billed murre was 6.4 × 10 ± 3.0 × 10 μGy. The annual effective dose to the average adult and representative person in Greenland due to ingestion of Po in seabirds was estimated to 13.0 μSv and 57.0 μSv, respectively. This derived dose is low and poses a slight risk, and risk communication is therefore deemed unnecessary.