Low pH detection in SPECIM EAGLE-HAWK using field spectra at S. Domingos Mine, SE Portugal: Preliminary results

To detect the Acid Mine Drainage (AMD) in Imaging Spectroscopy (IS) data, field spectral measurements gathered contemporaneously were selected in function of their high correlation with relevant minerals of standard spectral libraries. Working as a spectra selector, the high correlation values at threshold ≥0.8 are inputted to a full pixel based classifier measuring the angle between spectra (Spectral Angle Mapper, SAM). This methodology is applied to SPECIM EAGLE-HAWK captured over old S. Domingos mine area in 2007. Field measurements were undertaken with an ASDFieldSpecPro spectroradiometer for calibration and on materials previously known as AMD indicators. The mining history dates back to pre-roman times, with an intensive exploitation of Volcanogenic Massive Sulphide deposits, leading to a significant environmental footprint. The isolation of mineralogical assemblages of pH<;3 delineates the hot spots at threshold ≥ 0.8, mostly confined to acidic ponds and specific waste piles.