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

Kieran M Tierney,Graham K.P Muir,Gordon T Cook,Johanna J Heymans,Gillian Mackinnon,John A Howe,Sheng Xu,Andrew Brownlow,Nicholas J Davison,Mariel Ten Doeschate,Rob Deaville

doi:10.1016/j.marpolbul.2017.07.002

Abstract

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.

Highlights

During reprocessing of nuclear materials at the Sellafield Ltd. facility (Fig. 1A), low-level radioactive waste, including 14C, is discharged to the Northeast Irish Sea, primarily as dissolved inorganic carbon (DIC; Begg et al, 1992, Cook et al, 1995)
Analytical results for samples obtained from Cetacean Stranding Investigation Programme (CSIP) and Scottish Marine Animal Stranding Scheme (SMASS) are listed in Tables 1 and 2, respectively
Two young male harbour porpoises that stranded at Porth Dafarch (North Wales) on the Southern Irish Sea coastline at a similar time had a relatively large difference in measured activity (524 ± 2 Bq kg−1C and 315 ± 2 Bq kg−1C)

Summary

Introduction

During reprocessing of nuclear materials at the Sellafield Ltd. facility (Fig. 1A), low-level radioactive waste, including 14C (half-life 5730 years), is discharged to the Northeast Irish Sea, primarily as dissolved inorganic carbon (DIC; Begg et al, 1992, Cook et al, 1995). In the UK, Sellafield discharges of 14C have dominated enriched activities in the marine environment. Since the early 1990s there have been significant changes in Sellafield 14C discharges to the Irish Sea as described in detail by Muir et al (2017). The average discharged 14C activity from 1984 to 1993 was 1.78 Tera Becquerels per year (TBq year− 1). An increase in the volume of waste reprocessed and a change in discharge policy in

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Discussion

Conclusion