Behaviour and transport of radionuclides in soil and vegetation of a sand dune ecosystem

A sand dune ecosystem in the vicinity of the British Nuclear Fuels reproces sing plant at Sellafield. Cumbria, UK was used to examine the spatial, temp oral and depth distributions of Cs-134, Cs-137, Pu-238, Pu239+240 and Am-24 1 in soil and in two species of vegetation (Festuca rubra, Ammophila arenar ia). Core samples showed evidence of the accumulation of radionuclides deri ved mainly from sea-to-land transfer. Accumulated deposits of radioactivity (0-0.1 m) lie within the range: 1.1-3.4 Bq kg(-1) (Cs-134). 260-440 Bq kg( -1) (Cs-137), 31-40 Bq kg(-1) (Pu-238), 150-215 Bq kg(-1) (Pu239+240) and 1 90-240 Bq kg(-1) (Am-241). Soil profiles showed greater activity concentrat ions in their deeper regions and this is attributed to leaching of radionuc lides in percolating drainage water accentuated by the coarse texture, low organic matter and clay mineral content of coastal sands. Radionuclide acti vity concentrations in F. rubra and A. arenaria were similar, in the ranges 20-70 Bq kg(-1) (Cs-137), 1-5 Bq kg(-1) (Pu-238), 10-30 Bq kg(-1) (Pu239+2 40) and 10-65 Bq kg(-1) (Am-241). Clear temporal and spatial variations wer e observed in both species of vegetation, reflecting the weather conditions antecedent to the sampling period and the influence of sea-to-land transfe r. Concentration ratios (vegetation:soil) for activity concentrations in th e two species were similar, in the ranges: 0.05-0.14 (Cs-137), 0.025-0.097 (Pu-238), 0.022-0.057 (Pu239+240) and 0.025-0.212 (Am-241). (C) 2001 Elsevi er Science Ltd. All rights reserved.