241Am and 137Cs activity in fine grained saltmarsh sediments from parts of the N.E. Irish sea shoreline

241Am and 137Cs activities in surface and core samples of saltmarsh sediment from parts of the Galloway and south Cumbria coastlines are reported. The study concentrates on areas of saltmarsh which have been colonised by Spartina anglica Hubbard., in view of its ability to trap fine grained sediments and to colonise previously bare mudflats beyond the outer edge of pre-existing marsh. At each site downprofile variations of 241Am and 137Cs are presented, and most appear to show a more or less complete record of the history of discharges from Sellafield. The total inventories of the radionuclides are calculated for core samples and compared with published results from previous studies of intertidal sediments in the immediate vicinity. The relationship between particle size and radionuclide activity and the use of magnetic measurements as a relatively simple way of normalizing for this effect are examined.

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