Lídia Maria Quental

Identification of materials related to acid mine drainage using multi-source spectra at S. Domingos Mine, southeast Portugal

Imaging spectroscopy (IS) can identify target materials at both mineralogical and geochemical levels. Therefore, in environmental applications, it can be used to assess contamination derived from mining activities, moving from contamination sources along pathways to receptors as acid mine drainage (AMD). This can be based on the spectra of specific assemblages of minerals from spectral libraries, which can indicate pH values at the time of their generation and the subsequent acid-generating potential. Alternatively, field spectral measurements can be used as input data for mapping algorithms. This study presents a new methodological approach to improving the results for mapping contamination sources and pathways, by combining multisource spectra from both these approaches at different scales. In addition to the mineralogical libraries and field spectra already mentioned, additional end-member spectra that are extracted from IS data are used so as to highlight particular site phenomena otherwise undetected by the two previous approaches. The highly correlated spectra are then used as input to the Spectral Angle Mapper algorithm, to establish a map of local field spectra and also one from image end-members. The intersection of the two maps results in an improved map, assigned in terms of correlation ≥0.8 of mineralogical assemblages focused on AMD indicators. This methodology was tested in the abandoned S. Domingos Mine, in southeast Portugals Iberian Pyrite Belt, with AMD caused by long-term exploitation of volcanogenic massive sulphide deposits. Data from the HyMap™ sensor covered the area, and field spectroradiometric measurements were undertaken and analysed for mineralogical and geochemical content. A flightline containing the open pit was processed according to the aforementioned methodology, focusing directly on the target of interest and minimizing errors. The final map displays the mineralogical assemblage correlations ≥0.8 of variable pH indicators, particularly isolating a low-pH combination of significance to the contamination in the area.

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.

Integration of Geohazards into Urban and Land-Use Planning. Towards a Landslide Directive. The EuroGeoSurveys Questionnaire

Exposure to hazards is expected to increase in Europe, due to rapid population growth in urban areas and the escalation of urbanization throughout many countries. In the framework of the European Geological Surveys (EGS), the Earth Observation and Geohazards Expert Group (EOEG) has carried out a survey based enquiry regarding the integration of geohazards (earthquakes, volcanoes, landslides, ground subsidence, floods and others) into urban and land-use planning. Responses from 19 European countries and 5 regions reveal heterogeneous policies across national borders. 17% of the countries have not yet implemented any legal measures to integrate geohazards into urban and land-use plans and half of the participating countries have no official methodological guides to construct geohazard maps. Additionally, there is a scarce knowledge about real social impacts of geohazards and resulting disasters in many of the countries, although they have a significant impact on their national economies. This overview stresses the need for a common legislative framework and homogenization of the national legislations as well as mutual guidelines which adopt the principles applicable to the management of geohazards and explain the process to be followed in the production of hazard documentation. This is especially relevant in case of landslide and subsidence hazards; although those are of great importance in Europe, there are no common guidelines and practices similar to Directive 2007/60/EC on the assessment and management of flood risk. Based on their expertise, EuroGeoSurveys (EGS) have the potential to coordinate this activity in European geohazard guidelines and to promote the interaction among stakeholders.