Remote sensing of intertidal sediment bound radionuclide storage, remobilization and deposition: Case study in the Ribble Estuary

Full text: Intertidal environments of the Irish Sea are spatially complex and dynamic systems. The ability to understand and monitor these environments is fundamental to a variety of industrial, regulatory and government bodies. Intertidal estuarine environments often represent sinks and sources for industrial discharges. The ability to map the fate of these discharges through remote sensing provides a powerful tool in environmental monitoring and is critical in understanding their redistribution. This study focuses on the Ribble estuary, Lancashire, UK, which is accumulating elevated radionuclide concentrations discharged under license from BNFL Sellafield and Springfields. This paper presents the results from a series of investigations which demonstrate: i) that conventional airborne remote sensing using the Airborne Thematic Mapper (flown by the UK's Natural Environment Research Council) combined with sophisticated image analysis and ground truthing could be used to quantitatively map intertidal specific activity concentrations of anthropogenic radionuclides derived from BNFL Sellafield (r2>0.8); and ii) that time series imagery flown over tidal sequences can be used to identify sources of radionuclide bearing sediments, characterise the hydrodynamic features of the estuary and quantify fluxes of sediment and radionuclides over tidal cycles. (author)