Applications of multi-season hyperspectral remote sensing for acid mine water characterization and mapping of secondary iron minerals associated with acid mine drainage

Acid mine drainage (AMD) resulting from the oxidation of sulfides in mine waste is a major environmental issue facing the mining industry today. Open pit mines, tailings ponds, ore stockpiles, and waste rock dumps can all be significant sources of pollution, primarily heavy metals. These large mining-induced footprints are often located across vast geographic expanses and are difficult to access. With the continuing advancement of imaging satellites, remote sensing may provide a useful monitoring tool for pit lake water quality and the rapid assessment of abandoned mine sites. This study explored the applications of laboratory spectroscopy and multi-season hyperspectral remote sensing for environmental monitoring of mine waste environments. Laboratory spectral experiments were first performed on acid mine waters and synthetic ferric iron solutions to identify and isolate the unique spectral properties of mine waters. These spectral characterizations were then applied to airborne hyperspectral imagery for identification of poor water quality in AMD ponds at the Leviathan Mine Superfund site, CA. Finally, imagery varying in temporal and spatial resolutions were used to identify changes in mineralogy over weathering overburden piles and on dry AMD pond liner surfaces at the Leviathan Mine. Results show the utility of hyperspectral remote sensing for monitoring a diverse range of surfaces associated with AMD

Applied Geochemistry with Case Studies on Geological Formations, Exploration Techniques and Environmental Issues

Geochemistry has become an essential subject to understand our origins and face the challenges that humanity will meet in the near future. This book presents several studies that have geochemistry as their central theme, from the description of different geological formations, through its use for the characterization of contaminated sites and their possible impact on ecosystems and human health, as well as the importance of geochemical techniques as a complement to other current scientific disciplines. Through the different chapters, the reader will be able to approach the world of geochemistry in several of its subfields (e.g. environmental, isotope, or biogeochemistry) and learn through practical cases

Multispectral and Hyperspectral Remote Sensing Data for Mineral Exploration and Environmental Monitoring of Mined Areas

In recent decades, remote sensing technology has been incorporated in numerous mineral exploration projects in metallogenic provinces around the world. Multispectral and hyperspectral sensors play a significant role in affording unique data for mineral exploration and environmental hazard monitoring. This book covers the advances of remote sensing data processing algorithms in mineral exploration, and the technology can be used in monitoring and decision-making in relation to environmental mining hazard. This book presents state-of-the-art approaches on recent remote sensing and GIS-based mineral prospectivity modeling, offering excellent information to professional earth scientists, researchers, mineral exploration communities and mining companies

Application of hyper-spectral remote sensing to assess contamination associated with gold mining in the Witwatersrand Gold Basin, South Africa

A research report submitted to the Faculty of Science, University of the Witwatersrand in fulfilment of the requirements for the degree of Master of Science, Johannesburg, August, 2014.Efflorescent minerals are a common feature of the soil surface in seasonal environments where evapotranspiration (ET) exceeds precipitation (P), and are formed by the evaporation of salt solutions from the soil during periods of drying. On the Highveld gold fields, ET exceeds rainfall by approximately two-and-a-half times during the dry season, and soils overlying acid mine drainage and along polluted stream banks can become covered by distinctively coloured mineral efflorescent crusts. Whereas some efflorescent minerals are relatively insoluble and present a negligible environmental hazard (for example, gypsum), others may be readily soluble and contain high concentrations of potentially toxic metals (for example, copiapite, jarosite and uranyl sulphate). During periods of rainfall, such salts are washed further afield and into surface water bodies and act as sources of episodic pollution. The presence of some efflorescent minerals can be detected from their characteristic reflectance signatures using remote-sensing (RS) of the electromagnetic spectrum. The species of efflorescent minerals present is a useful indication of the spatial extent of sub-surface contamination, and also of the chemical conditions of the substrate, in particular the concentration of total dissolved solids, pH and redox conditions. The aim of this study was therefore to assess the use of remote-sensing on indicator efflorescent minerals as a cost-effective aid in the spatial mapping of acid rock-drainage polluted soils and water-bodies. This study describes the range of efflorescent crusts identified on different land-use areas and soil classes in a Highveld gold-mining region. Crusts were first measured in-situ under natural sunlight using a portable analytical spectral radiometer (ASD) as well as using X-ray diffraction (XRD). They were then dissolved in deionized water and the resulting salt solutions allowed to evaporate prior to analysis under controlled lighting conditions. Spectra were post-processed and compared with iv geological spectral reference libraries. The salt solutions were also analyzed for metal and sulphate content and the results were used to establish evaporation models from which mineral precipitation could be predicted. Minerals identified in the visible near-infra red (VNIR) region included iron oxides (hematite and goethite), and the sulphate mineral jarosite. In the short wave infra-red (SWIR) region clay minerals of the smectite group were dominant. Gypsum and Al-Mn-Mg-Na sulphate salts were identified in the SWIR region as mixtures occurring with clay minerals. Minerals identified in the VNIR-SWIR region were all confirmed by X-Ray diffraction (XRD). Upon dissolution, geochemical modeling revealed that gypsum and jarosite are the most common minerals expected to precipitate. The precipitation of gypsum and jarosite indicates persistent acidic conditions after dissolution of mineral salts. Gypsum and jarosite were also accurately identified by hyper-spectral spectroscopy and confirmed by XRD and geochemical modeling. Agreement between spectral interpreted minerals and geochemically precipitated mineral phases demonstrated the ability of hyper-spectral data in detecting efflorescence minerals on the soil surface. Using partial least squares regression (PLSR) combined with bootstrapping, reflectance spectrum was significantly correlated with geochemical variables

MINEO Southern Europe environment test site : contamination impact mapping and modelling : final Report

Relatório final do projeto MINEO: Assessing and monitoring the environmental impact of mining activities in Europe using advanced Earth Observation techniques. Project funded by the European Community under the “Information Society Technology” Programme (1998-2002)ABSTRACT: Under the framework of the MINEO project, the abandoned S.Domingos mining area as been selected as representative of Southern Europe Environment to test methods and tools for assessing and monitoring the environmental impact of mining activities using hyperspectral data and other relevant data sets. The S.Domingos mining area, is characterised by a long-term mining activity, since pre-roman times till the 1960’s, and is included in the group of Volcanogenic Massive Sulphide deposits of the Iberian Pyrite Belt. The orebody contained Cu, and also Zn and Pb. Several facilities were developed for mining works and ore transportation, covering an area of 50km2, facilitating dispersion of related pollutants. The main environmental problems can be summarised as related to waste material and their pollutant content (Zn, Pb, Sb, Cu, As, Hg and Cd), acid waters (minimum pH value of 1.7) and associated dispersion, as well as landscape disruption. Hyperspectral images were able to identify mineralogical/chemical dispersion of waste material related to Acid Mine Drainage (AMD) following two approaches: one related to AMD waste material field spectra and the other based on AMD minerals, using standard spectral libraries. The processing techniques used were mainly based on the Spectral Angle Mapper classifier and Mixture Tunned Matched Filtering. Globally, both mapping results obtained, either in AMD waste material either in AMD minerals, were able to detect mineralogical/chemical characteristics of imaged ground data, which were validated by field data. The GIS geochemical modelling allowed the determination of effective AMD area of influence, based in water pH values, using geostatistical methods. The Indicator “Collocate-Cokriging” of the water pH using the distance to the highest correlated AMD waste material (mixed sulphur materials from hyperspectral classification) predicts the AMD dispersion in the area related to that material. This methodology achieved good results and could be applied in new areas using waste material hyperspectral image classification for AMD delimitation area.N/

Monitoring sedimentary areas from mine waste products with Sentinel‐2 satellite images: A case study in the SE of Spain

[EN] Torrential rainfall regimes, among others, are the origin of accelerated soil erosion. The Spanish southeastern Mediterranean region is characterised by an arid climate regime affected by extreme erosion episodes with an important loss of sediments. Soil erosion effects are even more noticeable in areas where soil has been anthropically degraded, as in the mining district of Sierra Minera de Cartagena. The present research focuses on monitoring and mapping the changes in the sediment distribution of iron oxides and hydroxyl (OH−) bearing minerals caused by a cold drop known in Spanish as 'DANA' in September 2019 on the Rambla del Beal. This short rambla is fed by sediments from its drainage basin and by mining residues, irrigating a wide agricultural area. When discharges overflow the rambla channel, residues spread over its floodplain and reach the ecological protected coastal lagoon Mar Menor. The objective of the study was mapping the mineral distribution of the mining materials eroded from the source areas and sedimented in Rambla del Beal during a DANA. The study was carried out using a pre- and a post-DANA image from the Sentinel-2 satellite. After masking vegetation, urban areas and water bodies, different band ratios (B4/B3, B11/B12, B8A/B6) and a Spectral Angle Mapper (SAM) classification were applied. Sediment deposits were identified in wider areas after the DANA. Iron oxides increased their extension by 11.08% in the central area (B3/B4 with R2 of 0.84) and hydroxyl-bearing minerals increased by 8.95% in the Rambla del Beal's headwaters (B11/B12 with R2 of 0.71). The SAM classification (with a 0.1 rad threshold and an overall accuracy of 87.33%) allowed the differentiation and classification of two ferric iron oxides (haematite and goethite) and one iron hydrous sulphate mineral (jarosite). Additionally, band ratio images were spatially overlaid with the soil land uses map layer of the cadastre in order to plot the land uses most affected by the transported sediments during the DANA. These results highlighted agricultural land as the areas (land uses) most affected by iron oxides deposition, as oxidation processes occur more rapidly in these areas. However, grassland and scrubland were the areas with the highest content of hydroxyl-bearing minerals, as water is accumulated in these places, which favours hydrolysis reactions.S