THE TERRESTRIAL DISTRIBUTION OF ARTIFICIAL RADIOACTIVITY IN SOUTH-WEST SCOTLAND

This investigation extends the data base on dispersion of Sellafield-derived radionuclides to the northern Solway coastal zone of south-west Scotland. Results of a 10 x 10 km grid soil survey indicate that the predominant source of Pu-239 + 240 to the area has been weapons fallout, Chernobyl fallout having greatly modified Cs-134 and Cs-137 inventories. Inland transects reveal little evidence of airborne sea-to-land transfer of Sellafield-derived radionuclides, but riverine systems exhibit regions of significant on-land input from Sellafield via tidal inundation and deposition of particles. Sequential chemical leaching of soil and sediment samples suggests a change in chemical association of plutonium between marine and terrestrial systems. In radiological terms, airborne on-land transfer of Sellafield radionuclides is of negligible significance. Radionuclide inventories in Solway soils are generally well below the limiting values implied by the recommended generalised derived limits (GDL). In some tidally inundated riverbank areas, however, Cs-137, Pu-alpha and Am-241 levels occasionally exceed 25% of the appropriate GDL values.