Coal and lignite mining have produced enormous amounts of mine waste usually collected and left in long term storage facilities such (tailings, waste-rock dumps, and mine-water treatment) across Europe. These deposits may cause long-term environmental and geotechnical risks (instability, acid mine drainage, vegetation and land degradation), while coexisting with opportunities for the recovery of critical raw materials (CRMs). Improving the characterization of these volumes and integrating multiple data inputs is essential to support circular economy approaches to rethink the way mine waste is managed and contribute to regional transition processes in coal regions.

In practice, understanding and giving value to waste facilities is hindered by fragmented information across satellite products (multi and hyper-spectral, thermal, radar interferometry), airborne or UAV digital maps (laser scans, hyper-clouds, geophysical surveys), in-situ sensors, geotechnical observations, geochemical and mineralogical data. As a result, sites cannot be easily compared and Earth-observation data are rarely used directly to support resource assessments and decisions.

In this contribution, we demonstrate the concept of a European data-space framework dedicated to coal waste facilities.  CRMsDataSpace intends to collect scattered data from different sources and formats in a shared digital framework, where the data can be used together and facilitate interpretation. The data is subjected to quality control respecting data ownership and access control. This framework connects Earth observation (EO) data with ground-based references and laboratory analyses at different temporal and spatial scales by using common data structures, shared terminology, and modelling workflows that turn observations into indicators useful for CRM assessment and decision-making.

Demonstration waste facilities in coal and post-mining regions of Germany, Spain, Poland, and Romania will be used as case scenarios. The project combines existing legacy, compositional and EO products with new mineralogical and geochemical analyses, hydrometallurgical recovery tests and exploration drilling to provide comprehensive characterization. This infrastructure is implemented in a Minimum Viable Data Space, allowing sites to be compared in a consistent way and helping to identify and prioritize reprocessing opportunities. While the initial focus is on coal waste streams, the CRMsDataSpace tool is intended to be transferable to other mine-waste origins, supporting circular economy strategies and business opportunity for mining operators or governmental agencies aligned with the European Green Deal and the Critical Raw Materials Act.

The presented digital framework is developed within the EU-CRMsDataSpace project funded by the Research Fund for Coal and Steel (RFCS).

How to cite: Flores, H., Dogan, T., Krzemień, A., Marquez, A., and Riesgo, P.: CRMsDataSpace: Building a European Data Space for Critical Raw Materials, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19984, https://doi.org/10.5194/egusphere-egu26-19984, 2026.

Mining generates more than 14 billion tonnes of waste each year, which must be safely stored and managed over decades. In circular-economy frameworks, mine waste is increasingly recognised not only as an environmental liability but also as a potential secondary resource, and industrial-scale valorisation initiatives are already being implemented by major mining companies and specialised start-ups. Using mining waste for CO₂ sequestration presents a particularly promising valorisation approach, as it promotes both the “zero waste” as well as the “net zero CO₂” principles. 

In this contribution, we explore integrated Earth-observation (EO) workflows to support the assessment of CO₂ sequestration potential at mine waste sites through two complementary pathways: (i) passive mineral carbonation, where atmospheric CO₂ is bound through natural weathering of reactive waste materials, and (ii) carbon sequestration through revegetation and improved stewardship of post-mining landscapes. 

Mafic and ultramafic waste materials rich in Mg-Fe-Ca-bearing silicates, including olivine, serpentine, pyroxenes, amphiboles and smectites, exhibit high carbonation potential and occur widely in waste derived from mining of e.g. asbestos, diamonds, Ni-Cr, PGM, and Pb-Zn ores. Despite their abundance in active and legacy waste facilities, identifying and quantifying these minerals at scale remains challenging, as mine waste is intrinsically heterogeneous and existing mine-waste inventories rarely include spatially explicit mineralogical information. Using resolution-enhanced satellite hyperspectral data, we derive spatially continuous maps of reactive mineral assemblages in mine waste deposits through band-ratio analysis, minimum-wavelength mapping, and spectral unmixing based on dedicated mineral libraries. These products support the screening, targeting, and design of mineral-based CO₂ sequestration strategies such as enhanced weathering or ex-situ carbonation. 

In parallel, we monitor revegetation dynamics on mine waste deposits as a proxy for vegetation-based carbon sequestration. Reclamation commonly involves the addition of topsoil or the construction of technosols from waste materials to enable plant growth and soil development. However, revegetation success is often spatially variable due to hydrology, nutrient limitations, toxicity, and surface instability. We apply decomposition and trend analysis to long-term Sentinel-2 and Landsat vegetation-index time series to quantify revegetation trajectories across multiple closed mine sites. This approach reveals fine-scale patterns in rehabilitation success, identifies erosion-affected or delayed-recovery zones and provides objective indicators for optimising reclamation strategies. Where available, LiDAR and hyperspectral data are integrated to characterise vertical vegetation structure and species composition, providing a basis for above-ground biomass estimation, for carbon accounting and crediting assessments.

The presented EO-based monitoring framework, developed within the EU-funded MOSMIN project, enables consistent comparison, prioritisation, and tracking of CO₂ sequestration potential across heterogeneous waste deposits, supporting more sustainable land-use and waste-management strategies.

How to cite: Kirsch, M., Lorenz, S., Thiele, S., Nwazelibe, V., Chakraborty, R., and Gloaguen, R.: Earth-observation for CO2 sequestration at mine waste sites, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9747, https://doi.org/10.5194/egusphere-egu26-9747, 2026.

The legacy of abandoned mining sites poses a major threat to both the environment and human health due to the possible accumulation of potentially toxic elements in soils and sediments. The São Domingos mining area, located in the Iberian Pyrite Belt, represents one such site, where mining activities ceased without the implementation of environmental control or remediation measures. As a consequence, high concentrations of potentially toxic elements have accumulated throughout the surrounding area, leading to severe environmental degradation.

In this context, to improve the understanding of ecological and human health risks in this area, sediment samples were collected from four drills carried out at spaced locations along approximately 5 km of the former mining area. The samples were separated into two grain-size fractions (<2 mm and <2 µm), the latter being particularly relevant due to its enhanced capacity to retain contaminants. Geochemical analyses were performed, and contamination levels were evaluated using several ecological risk indices, including the contamination factor, the geoaccumulation index, and the potential ecological risk index. Human health risks were assessed using the hazard quotient and cancer risk approaches, considering multiple exposure pathways, namely ingestion, inhalation, and dermal contact, for both adults and children.

The results show that potentially toxic element concentrations in most drills largely exceed background values, particularly in the <2 µm fraction. Very high ecological risk levels were identified, well above established thresholds, and the geoaccumulation index classifies several elements as extremely polluted. Human health risk assessment reveals significant non-carcinogenic and carcinogenic risks, with children identified as the most vulnerable population group. Hg, Pb, and As were the elements that contributed most significantly to the observed ecological and human health risks. The most hazardous drills are located close to former ore extraction and processing areas, with a progressive decrease in both environmental and human health risks observed with increasing distance from these zones. These findings are particularly important due to frequent tourist visits throughout the year and the presence of nearby communities, highlighting the potential for widespread human exposure.

Overall, this study demonstrates that the São Domingos mining area represents a serious ecological and public health concern, highlighting the urgent need for remediation measures and continuous environmental monitoring.

How to cite: Gomes, P. and Valente, T.: Ecological and human health risk assessment of sediments from the São Domingos old mining área, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-22613, https://doi.org/10.5194/egusphere-egu26-22613, 2026.

Water pollution by potentially toxic elements has become a growing global concern, particularly in developing countries, where rapid industrialization and mining activities often outpace environmental regulation. In Brazil, mining stands out as one of the main contributors to surface water contamination, especially in historically exploited regions such as the Iron Quadrangle. This study presents a comprehensive assessment of surface water quality in the Iron Quadrangle, one of Brazil's most important mining regions, with a focus on contamination by potentially toxic elements. A total of 487 water samples were collected from third-order drainage basins across an area of 7,000 km², resulting in a high sampling density (one point per 14.4 km²). Samples were analyzed for major, minor, and trace elements and compared with national and international water quality guidelines. Pollution levels were evaluated using the Heavy Metal Pollution Index (HPI) and the Heavy Metal Evaluation Index (HEI), complemented by high-resolution geochemical mapping. The results revealed elevated concentrations of As, Cd, Pb, Cr, and Zn, with numerous samples exceeding drinking-water standards. The highest concentrations were observed in the Doce, das Velhas, and Paraopeba river basins, particularly within the municipalities of Nova Lima, Mariana, Ouro Preto, and Brumadinho. HPI values ranged from 0.9 to 2871, with 34% of the samples classified as highly polluted. Arsenic, Pb, and Cd were the dominant contributors to HPI, with mean values of 36.8, 35.4, and 26.8, respectively, far exceeding those of other elements (0.001–2.83). Pb and As alone exceeded the pollution threshold (HPI > 100) in 14.3% and 14.1% of the sampling points, respectively.

HEI values ranged from 3.2 to 70.6, with a mean of 8.65. Overall, 22% of samples were classified as moderately polluted and 6.8% as polluted. As, Pb, and Cd again dominated HEI contributions, with average values of 2.95, 2.61, and 1.25, markedly higher than those of other elements (0.016–0.87). The comparison of the indices indicates that HPI exhibits greater variability due to its element-specific weighting, whereas HEI shows a more stable, uniform behavior. The spatial distribution of the indices highlighted severely polluted areas associated with intense mining activity, unplanned urbanization, and natural geogenic sources. The spatial patterns of both indices delineate severely contaminated zones linked to intensive mining, unplanned urbanization, and geogenic inputs. The integrated methodology proved effective in identifying critical contamination hotspots near urban areas, rural communities, and water supply intakes, offering a robust scientific basis for environmental management, monitoring programs, and public policy development in highly impacted regions.

How to cite: Valente, T., Vicq, R., Leite, M. G. P., Leão, L. P., Nalini Júnior, H. A., Gomes, P., and Fonseca, R.: Assessing Mine-Related Surface Water Contamination in the Iron Quadrangle (Brazil): A Risk-Based Spatial Analysis Using Potentially Toxic Elements Indices, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-22557, https://doi.org/10.5194/egusphere-egu26-22557, 2026.

Atmospheric aerosols are a key component of the Earth system, originating from both natural processes and human activities. Mining is a major industrial source of airborne particulate matter, particularly in open-pit operations where blasting, crushing, hauling, and waste management continuously generate dust. Mine waste facilities, such as tailings storage facilities (TSFs) and waste-rock dumps, are among the dominant anthropogenic sources of mineral dust emissions in many mining districts, due to their large exposed surface areas and limited vegetation cover. Mining aerosols typically consist of mineral particles such as silica and metal oxides, often enriched in toxic trace elements, making them relevant from both public health and environmental perspectives. While coarse particles (PM₁₀) tend to deposit near the source, fine particles (PM_2.5 and smaller) can remain suspended and be transported over tens of kilometres, contributing to regional air quality degradation and population exposure.

Monitoring strategies at mining sites primarily rely on in-situ instruments, which provide accurate point measurements but limited spatial context. These observations often do not capture the full extent of dust dispersion or identify preferential transport pathways toward populated areas, particularly in remote or topographically complex regions. Satellite-based aerosol observations offer a valuable complement by providing spatially continuous, long-term, and independent information on aerosol presence, intensity, and transport, yet their application to mining environments remains underexplored.

The MOSMIN project addresses this gap by developing a multi-sensor satellite-based framework to characterise mining-related aerosols across contrasting climatic and surface environments. Satellite products from MODIS MAIAC aerosol optical depth (AOD), Sentinel-5P aerosol index (AI), and CALIOP lidar profiles are combined with meteorological reanalysis to investigate dust emissions, transport, and vertical structure at four pilot sites: Roșia Poieni (Romania), Talabre (Chile), Trident (Zambia), and Aitik (Sweden). Sentinel-5P AI identifies absorbing aerosol hotspots, while MODIS AOD resolves local dust plumes over open pits and TSFs. CALIOP vertical profiles provide complementary information on plume height and vertical structure, improving the interpretation of satellite column measurements.

The combined satellite analysis reveals pronounced site-specific differences driven by meteorology and surface properties. The hyper-arid Talabre site exhibits persistent absorbing aerosol signals and extended plume dispersion, while the Trident mining complex shows strong seasonal contrasts, with enhanced aerosol loading during the dry season and additional contributions from regional biomass burning. At Roșia Poieni, dust emissions show a clear summer maximum linked to increased mechanical activity and boundary-layer mixing, with aerosol accumulation frequently occurring in surrounding valleys rather than directly above the open pit. At the high-latitude Aitik site, mining-related aerosol signals are primarily detectable during the snow-free summer period, when reduced surface brightness allows reliable satellite retrievals of dust transport from exposed mining surfaces.

Overall, the results demonstrate that satellite observations provide essential spatial, temporal, and vertical context for assessing mining-related aerosols, extending monitoring beyond the mine fence and supporting exposure assessment, environmental management, and mitigation planning. In addition, satellite-derived products offer a consistent and accessible basis for communicating dust impact to regulators and other stakeholders, complementing in-situ measurements.

How to cite: Deaconu, L.-T., Kerekes, A.-H., Baciu, L.-C., and Kirsch, M.: Combining MODIS, Sentinel-5P, and CALIOP to monitor dust emissions from mining activities, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6316, https://doi.org/10.5194/egusphere-egu26-6316, 2026.

Industrial mining activities have long driven the growth of civilization over the past hundred years. The large-scale mining activities, however, result in large amounts of residual waste in forms of e.g., rock waste and tailings. Engineered embankments or dams are typically used to contain these residual wastes, ensuring their long-term containment and stability. However, these dams can pose a risk of failure, and uncontrolled release of contained materials can bring harm to the environment and nearby communities.  The EU-funded project, MOSMIN (Multiscale observation services for mining related deposits), aims to integrate Earth observation techniques and in-situ geophysical survey for geotechnical and environmental monitoring, as well as the valorisation of mining-related waste. Within this framework, we explore the potential of passive seismic methods as a non-invasive approach for imaging and monitoring such mining waste deposits without the need for high impact seismic sources such as dynamite and vibroseis.

In this work, we present the first results of multidimensional imaging of a legacy Tailings Storage Facility (TSF) using a large-N passive seismic experiment to assess the geotechnical integrity of the legacy TSF, and its potential volume for valorisation. We deployed a total 200 autonomous seismic stations, consisting of 160 1-component and 40 3-components sensors on the surface of a TSF in a closed mining site in Laisvall, Sweden. The seismic stations were deployed as a grid array, with interstation distance of 20 m that covers the whole 500 x 700 m area of the TSF.

We applied the Horizontal-to-Vertical Spectral Ratio method to the 3-components seismic sensors to extract the Rayleigh wave ellipticity curves. The curves obtained were utilized to model the one-dimensional shear wave velocity (Vs) for every station. These values were subsequently interpolated to create a pseudo three-dimensional Vs model of the TSF. Additionally, we also applied Ambient Noise Tomography (ANT) to fully utilize the full coverage of the deployed large-N array. Preliminary results of this research show a robust Vs model that reveals the internal subsurface structure of the deposited tailings, highlighting areas with thicker deposits and lower Vs value. Ultimately, we discuss our results with respect to the implications for storage facilities safety and re-valorisation of the legacy deposits.

How to cite: Trichandi, R., Haberland, C., Ryberg, T., Rodríguez Tribaldos, V., Kirsch, M., and Krawczyk, C.: Multidimensional Passive Seismic Imaging of Legacy Tailings Storage Facility , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9823, https://doi.org/10.5194/egusphere-egu26-9823, 2026.

Tailings and waste rocks are residuals of industrial mining operations and their collection amounts to the world's largest human-made structures both in spatial extent and mass. The catastrophic consequences of tailings dam failures have been extensively documented, prompting the establishment of stringent regulatory frameworks to mitigate environmental and societal risks. The United Nations Environment Programme (UNEP) introduced the Global Industry Standard on Tailings Management (GISTM) in 2020, which mandates the implementation of monitoring concepts that manage risks throughout the lifecycle of a tailings facility. Addressing this requirement is a key goal of MOSMIN (Multiscale observation services for mining-related deposits), an EU-funded initiative aimed at establishing comprehensive monitoring solutions for mining-related deposits. The project integrates Earth observation technologies with ground-based geophysical measurements to create unified datasets. These datasets are then analysed using advanced computational techniques, including machine learning algorithms, to characterise spatio-temporal dynamics relevant to the safety and sustainability of mining-related deposits.

We contribute to these efforts with in situ high-resolution passive seismic measurements conducted at the tailings storage facilities of two copper mines: the FQM Sentinel mine in Kalumbila, Zambia, and the CODELCO Chuquicamata mine near Calama, Chile. Both experiments aim to seismically characterize the internal structure of the dams and to monitor subsurface processes at different scales, resolutions and depths of investigation through the creation of shear wave velocity models using ambient noise tomography (ANT). Similar array designs were implemented for both sites. Each site was equipped with a kilometers-long, trenched fiber-optic cable interrogated by a commercial Distributed Acoustic Sensing (DAS) system along with 30 conventional geophones. Both types of instrumentation were installed parallel to targeted tailings dam sectors and recorded during regular mining, disposal, and maintenance activities around the tailings facility for several months. However, the highly variable seismic wavefield generated by the active mining environment poses challenges for the ANT procedure. In order to obtain an overview of the wavefield’s spatio-temporal behaviour, we calculate the strain-rate root-mean-square (RMS) in different frequency bands across the entire recording period and fiber array, which encompasses approximately two months across 4 km and 9 months across 1.5 km of optic fiber for the Chile and Zambia sites, respectively. We present results regarding the spatio-temporal variation and stability of cross-correlations, and discuss the feasibility of performing Multi-channel Analysis of Surface Waves (MASW) to obtain high-resolution profiles of the velocity structure of the dam across space and time.

Ultimately, tracking seismic changes in the dam structure could be used as an additional tool for non-invasive, spatially and temporally continuous geotechnical monitoring of the tailings storage facility and, in joint analysis with InSAR-derived surface deformation, reduce false alarms and enable physically meaningful, surface-subsurface interpretation.

How to cite: Wollin, C., Rodríguez Tribaldos, V., Haberland, C., Ryberg, T., Trichandi, R., Krawczyk, C., and Kirsch, M.: Fiber-optic monitoring of tailings dams in the MOSMIN project, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18342, https://doi.org/10.5194/egusphere-egu26-18342, 2026.

Shield tunneling generates a large volume of shield tunnel spoil (STS). Conventional disposal practices are associated with high costs, low resource recovery efficiency, and considerable environmental burdens. Meanwhile, synchronous backfill grouting materials used during shield advancement are critical for controlling ground settlement and maintaining lining stability. To address these issues, this study proposes an Alkali-Activated Full-Component Shield Tunnel Spoil Regenerated Solid-Waste Grouting Material (AFS-RSWGM). The material is formulated through the synergistic utilization of cement, fly ash, shield-sieved sand, and spoil soil, and incorporates alkali activation together with the pozzolanic effect of fly ash to enable full-component resource utilization of STS. This approach aims to reduce spoil handling costs, improve recycling efficiency, and enhance the performance of grouting materials. Key findings include:

(1) Based on cement, fly ash, shield-sieved sand, and shield tunnel spoil soil, and coupled with NaOH solution alkali activation and the fly ash pozzolanic effect, AFS-RSWGM was developed. Response Surface Methodology (RSM) was employed to optimize three key factors, namely the water–binder ratio (A), binder–sand ratio (B), and shield tunnel spoil soil (STSS)–water ratio (C). The construction adaptability and mechanical performance were evaluated using macroscopic indices such as compressive strength, fluidity, and bleeding rate. The results indicate that, after mix optimization, the 28-day compressive strength increased by approximately 32% compared with traditional cement-based grouting materials (TCGM), while fluidity increased and bleeding decreased, demonstrating superior overall adaptability and mechanical performance.

(2) The micro-mechanism underlying the performance enhancement of the optimized mix was investigated through multi-scale characterization, including rheological tests, hydration heat analysis, and SEM/XRD/FTIR. The results show that the optimized slurry exhibits a reduced yield stress and pronounced shear-thinning behavior. The hydration heat evolution displays a bimodal exothermic profile, with a significantly intensified second exothermic peak. Microstructural analyses reveal that alkali activation promotes the dissolution of aluminosilicate components in the spoil, producing abundant amorphous C-A-S-H gel and AFt. In addition, fly ash continuously supplies reactive SiO₂ and Al₂O₃, refining the interfacial transition zone (ITZ) and reducing porosity. Accordingly, a coherent evidence chain of "performance enhancement–structural evolution–reaction mechanism" is established.

(3) In the Jinan Metro Line 4 project, the left and right lines adopted TCGM and AFS-RSWGM, respectively, for synchronous grouting. A comparative analysis of settlement monitoring data verified the engineering effectiveness of the proposed material. The results demonstrate that AFS-RSWGM limited the maximum surface settlement to approximately 12.1 mm, representing a 68.6% reduction relative to conventional slurry, and achieved settlement stabilization 65 days earlier. Moreover, no issues such as segment dislocation, cracking, or grout leakage were observed during right-line construction, indicating a marked improvement in lining integrity. Based on the above engineering verification outcomes, construction risk identification and control were carried out, highlighting the transition from material optimization to intelligent construction management and control.

How to cite: Zhou, Y., Yang, Z., and Gao, Y.: Development and Engineering Application Validation of Alkali-Activated Full-Component Shield Tunnel Spoil Regenerated Solid-Waste Grouting Material, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4393, https://doi.org/10.5194/egusphere-egu26-4393, 2026.