ANTHROPOGENIC RADIOCARBON IN THE EASTERN IRISH SEA AND SCOTTISH COASTAL WATERS

C-14 is produced as an activation product in nuclear reactors, and may be discharged to both the atmosphere and the marine environment during nuclear fuel reprocessing. In the UK, C-14 is discharged, under license, into the Eastern Irish Sea by the British Nuclear Fuels plc (BNFL) reprocessing plant at Sellafield, Cumbria, northwest England, and is then transported into Scottish coastal waters. We analyzed intertidal biota samples to determine the effect of these discharges. The specific activities of C-14 found in these samples indicate that the uptake and bioaccumulation of C-14 is dependent on the type of organism and its feeding behavior. Measured C-14 concentrations in mussels (Mytilus edulis) were higher than those in winkles (Littorina littorea), which were greater than those found in seaweed (Fucus spp.); maximum observed activities were ca. 7, 5 and 3.5 times the accepted current ambient level of 260 Bq kg-1 C, respectively. Annual Nori (Porphyra umbilicalis) samples were analyzed for their Cs-137, Am-241 and C-14 contents; both the Cs-137 and Am-241 results correlated well with published Sellafield discharge data (r = 0.877 and 0.918, respectively), whereas there was no significant correlation between measured C-14 activities and the discharge record, indicating increased complexity in the chemical and biological behavior of C-14 or some discrepancy in the estimated discharge records.