Spatial and temporal variations in concentration factors in NW European Seas - secondary use of monitoring data

¹ The Centre for Environment, Fisheries & Aquaculture Science (CEFAS), NR33 0HT Lowestoft, UK
² Radiological Protection Institute of Ireland (RPII), Dublin, Ireland
³ Norwegian Radiological Protection Authority (NRPA)

Abstract

This paper presents new data on concentration factors (CFs: concentration kg^-1 biota/concentration l^-1 seawater) for several marine species-radionuclide pairs, in three regions: coastal waters of Ireland, eastern Irish Sea and coastal waters of Norway. The CFs were estimated using data from long-term monitoring programmes, obtained for radiological protection purposes. The practical constraints of using such data sources are discussed. CFs were obtained for a range of fin fish, crustaceans, molluscs and brown seaweed, for one or more of the following radionuclides: ⁹⁹Tc, ¹³⁷Cs, Pu and ²⁴¹Am. In general, there was a relatively high degree of variability in the values obtained, and it was not possible to discern systematic regional or time-dependent differences. However, for two datasets in the eastern Irish Sea (¹³⁷Cs in winkles and crabs) and a number of datasets (137Cs in various species of fish) in the western Irish Sea there was a statistically significant increase in the CF over the monitoring periods. Significant gender differences were found for ⁹⁹Tc in lobster. The results are compared with current IAEA recommendations and are discussed in relation to the influence of contemporaneous discharges and the possible impact of remobilised radionuclides on bioavailability.