Continuing contamination of north Atlantic and Arctic waters by Sellafieldradionuclides

Discharges of Tc-99 and I-129 from the reprocessing plant at Sellafield hav e increased significantly since the mid-1990s, against the overall trend of most other radionuclides. The 'pulsed' release of Tc-99 has provided an op portunity to study transport pathways and transit times in UK waters, the N orth Sea and beyond. Transit times estimated from the Tc-99 data are signif icantly shorter than rates reported previously using other radiotracers. Th e possible reasons for this are discussed. A comparison is made between the response of seawater concentrations and those in the brown seaweed Fucus v esiculosus to variations in the release rates. Current discharges of pluton ium are very low compared with the 1970s and 1980s. However, the seabed sed iments of the Irish Sea represent a substantial source and remobilisation i nto the water column results in the continuing export of plutonium from the Irish Sea and its transport to Arctic waters. Crown Copyright (C) 1999 Pub lished by Elsevier Science B.V. All rights reserved.