Implications of Sedimentological and Hydrological Processes on the Distribution of Radionuclides in a Salt Marsh Near Sellafield

摘要

The report examines sedimentological and hydrological processes affecting a salt marsh in the Ravenglass estuary, which is situated S of the Sellafield nuclear fuel reprocessing plant. The results are discussed in the context of the distribution of low-level radioactive effluent at the site. Detailed elevational measurements on sections across a subsidiary creek show mainly seasonal variations attributed to expansion of clay minerals. Transducers deployed at a range of depths in the marsh sediment point to rapid changes in pore water pressure in response to the tidal cycle and suggest infiltration of both water and radionuclides from the coarse sediments below, especially during neap tides. Desiccation cracking of the marsh clays provides preferential pathways from the surface. These, and other factors, imply distribution of radionuclides by other mechanisms than simply accretion and emphasize the environmental diversity at this location. (ERA citation 11:033847)