Plutonium occurrence and phase distribution in sediments of the Wyre estuary, northwest England

The occurrence of plutonium isotopes derived from the Windscale reprocessing facility discharges and weapons test fallout in intertidal sediments of the Wyre estuary, northwest England, is reported. Windscale plutonium appears to be slowly transported to the estuary in association with sedimentary material, and its distribution in surface and buried sediments is controlled by the variations in organic matter content of the sediments and/or their grain size characteristics. Results from chemical leaching experiments suggest that very little plutonium is ion exchangeable or in humic substances, but it is in other organic and Fe/Mn hydrous oxide fractions of the sediments. Plutonium shows a similar depositional behaviour to mercury which enters the Wyre directly in local industrial discharges. (author)