Nuclear reprocessing-related radiocarbon (¹⁴C) uptake into UK marine mammals

To evaluate the transfer of Sellafield-derived radiocarbon (¹⁴C) to top predators in the UK marine environment, ¹⁴C activities were examined in stranded marine mammals. All samples of harbour porpoise (Phocoena phocoena) obtained from the Irish Sea showed ¹⁴C enrichment above background. Mammal samples obtained from the West of Scotland, including harbour porpoise, grey seals (Halichoerus grypus) and harbour seals (Phoca vitulina) showed ¹⁴C enrichment but to a lesser extent. This study demonstrates, for the first time, enriched ¹⁴C is transferred through the marine food web to apex predators as a consequence of ongoing nuclear reprocessing activities at Sellafield. Total Sellafield ¹⁴C discharge activity 24months prior to stranding and, in particular, distance of animal stranding site from Sellafield are significant variables affecting individual ¹⁴C activity. ¹⁴C activities of West of Scotland harbour porpoises suggest they did not forage in the Irish Sea prior to stranding, indicating a high foraging fidelity.