A PRELIMINARY INVESTIGATION INTO THE SPECTRAL CHARACTERISTICS OF INTER-TIDAL ESTUARINE SEDIMENTS

In the Ribble Estuary, Lancashire, U.K., systematic associations betwe en discharge of radionuclides from the British Nuclear Fuels pie (BNFL ) plants at Sellafield and Springfields and sediment size-fractions ex ist. The ability to map these associations through in situ spectroscop y (0.4-2.5 mu m) of sediments at low tide was investigated. Laboratory spectra of inter-tidal sediment samples collected from the Ribble sho w a strong negative correlation (-0.7 to -0.8) between their radionucl ide-associated clay content and reflectance within the 0.4 - 2.5 mu m range. Field spectra of the same samples showed a less distinct relati onship as a result of the presence of surface moisture, cyanobacteria, and halite within the intertidal zone. Methods are proposed to accoun t for these problems.