Sequential extraction of 226Ra in sediments from an estuary affected historically by anthropogenic inputs of natural radionuclides

Riverbed'sediments from an estuary historically affected by wastes discharged by several phosphate fertiliser plants and enriched in uranium-series radionuclides were operationally speciated using a Tessier-based method. In each selective fraction the Ra-226 content was determined by-alpha-particle spectrometry after radiochemical isolation and electrodeposition onto stainless steel planchets. These studies were performed in Ra-226-polluted estuarine sediments collected one year after anthropogenic discharges had ceased in order to obtain useful information about the operational forms in which this radionuclide remains associated with the sediments at this time. The results obtained revealed, that one year after Ra-226 inputs had stopped, the radionuclide was associated mostly with the more refractory forms. Consequently, it is possible to foresee little potential remobilisation of Ra-226 contamination from sediments to the aqueous. phase in the future under normal environmental conditions. (C) 2004 Elsevier Ltd. All rights reserved.