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

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