210Po in Mytilus edulis in the Irish marine environment

Abstract

210Po is available to the Irish marine environment as a result of natural and anthropogenic processes. As it constitutes a significant portion of the radiation exposure of the population through the consumption of seafood, it is of interest to identify a suitable bio-indicator to monitor fluctuations of 210Po concentrations in the marine environment. Mytilus edulis was examined to assess the geographical variation in 210Po concentrations around the coast of Ireland. Temporal variations and the effect of mussel size on their 210Po contents at two sites, Sutton and Carlingford, were also examined. Chemical techniques for the separation of 210Po from mussels, seawater and suspended particulate are described. These methods use 209Po as a chemical yield monitor, microwave systems and Teflon bomb procedures for sample digestion. The concentration of 210Po in mussels around the coast was found to vary between 80±9 Bq kg -1 (dry wt.) at Seapark near Belfast and 468±32 Bq kg -1 (dry wt.) at Sutton in Dublin. The two sites at Sutton and Carlingford, which displayed similarities in terms of mussel morphology and 210Po concentration in water, exhibited significant temporal variations in mussel concentration. Furthermore, relationships derived from both sites indicate a strong linear dependency between mean 210Po content and mean mussel dry weight with higher concentrations of 210Po found in smaller mussels at a given site. Concentration ratios for mussels and water are also presented.