Remote sensing of contaminated land

The overall aim of this research is to investigate the potential of imaging spectrometry for the remote sensing of contaminated land. There were three objectives. First, to investigate the relationships between canopy reflectance measured using a field spectroradiometer, the concentration of five key canopy biochemicals (chlorophyll, water, nitrogen, lignin and cellulose) and land contamination. Second, to assess the utility of field reflectance data to estimate canopy chlorophyll, water, nitrogen, lignin and cellulose concentration that had been depleted selectively as a result of land contamination. Third, to investigate the potential of airborne imaging spectrometry to estimate, spatially, canopy biochemical concentration in order to infer levels of land contamination.Canopy reflectance data were collected using a field spectroradiometer in conjunction with ground based measurements of canopy biochemical concentration and leaf area index data across a contaminated grassland site. Spectral wavebands that were strongly and causally related with the canopy biochemical concentrations of chlorophyll, lignin, nitrogen, cellulose and water were used to develop predictive regression equations to estimate those canopy biochemicals that had been depleted selectively as a result of land contamination. Research demonstrated that estimates of canopy biochemical concentration decreased in error in the order of water, lignin, cellulose and nitrogen, with chlorophyll estimated the most accurately. Estimates of canopy chlorophyll concentration were determined using both the depth and the spectral position of the wings of one of the absorption features (the red edge). A red edge-chlorophyll concentration-land contamination relationship provided a novel link between reflectance and the biochemical results of land contamination. Spectral mixture modelling demonstrated the effects of variable canopy cover and background reflectance on the position of the red edge and provided an understanding of a double-peaked maximum present in first derivative field spectra.