Comparative analysis of reflectance spectroscopy and laboratory based assessment of asbestos pollution in the rehabilitated mining environment, South Africa

Asbestos minerals (Amosite, Crocidolite, Chrysotile, Tremolite, Anthophylite) were mined extensively in South Africa for more than ninety years. The mines were later closed because of the negative health and environmental impacts, thereafter commissioning the mine rehabilitation process in 1986. Since then, there has not been an effectively coordinated monitoring procedure to assess the progress of mine rehabilitation in mitigating asbestos pollution. Field evidence shows that traces of different asbestos minerals appear scattered even after the rehabilitation process has been conducted. This study uses remote sensing techniques to spectrally distinguish different types of asbestos minerals in the post-mining environment for use in pollution monitoring. Laboratory based techniques (X-Ray diffraction and scanning electron microscopy) were performed to detect the presence of asbestos minerals in soil and water of the rehabilitated environments. Analytical spectral devices (ASD) field spectrometer was used to collect spectra of asbestos minerals and that of soil and water samples analyzed in the laboratory in order to detect the presence of these minerals using spectral characteristics, and to compare the output with laboratory results. Results show that very low quantities of asbestos in water (<1 ppm) cannot be clearly detected using spectral data. The results were correlated to examine the potential use of remote sensing techniques in monitoring the asbestos polluted environment.