Trends in the spatial and temporal distribution of ¹²⁹I and ⁹⁹Tc in coastal waters surrounding Ireland using Fucus vesiculosus as a bio-indicator

Spatial and temporal trends in ¹²⁹I and ⁹⁹Tc concentrations around the Irish coastline have been evaluated using Fucus vesiculosus as a bio-indicator. ¹²⁹I concentrations in a recent set of seawater samples have also been recorded and reveal an identical spatial pattern. Concentrations of ¹²⁹I in Fucus from the northeast coast of Ireland proved to be at least two orders of magnitude higher than concentrations in Fucus from the west coast. The ¹²⁹I content of Fucus increased significantly between 1985 and 2003, in line with increases in discharges of ¹²⁹I from the Sellafield nuclear reprocessing plant. Similar trends were observed in the case of ⁹⁹Tc. ¹²⁹I/⁹⁹Tc ratios in Irish seawater were deduced from the Fucus data, and compared to ratios in discharges from Sellafield and from the French reprocessing plant at Cap de la Hague. Levels of ¹²⁹I and ⁹⁹Tc in Fucus from the west coast were found to be enhanced with respect to levels in seaweeds from other regions in the Northern Hemisphere unaffected by discharges from nuclear installations such as those referred to.