Long-term performance: strength and metal encapsulation in alkali-activated iron ore tailings.

Understanding the strength behavior and leaching characteristics of mining tailings stabilized with alkali-activated cements in the short, medium, and long term is crucial for the feasibility of material applications. In this context, this study assessed the stabilization/solidification of iron ore tailings (IOT) using alkali-activated binder (AAB) composed of sugarcane bagasse ash and eggshell lime at curing times of 7, 28, 60, 90, 180, and 365 days. Additionally, leaching tests were conducted, along with the examination of possible changes in the chemical and mineralogical composition resulting from exposure to acidic environments. Tests included unconfined compression strength (UCS), leaching, X-ray diffraction, and Fourier-transform infrared spectroscopy for the IOT-AAB mixtures. The highest increase in UCS was observed between 7 and 60 days, reaching 6.47 MPa, with minimal variation thereafter. The AAB-bonded IOT exhibited no metal toxicity over time. Elements Ba, Mn, Pb, and Zn present in IOT and ash were encapsulated in the cemented matrix, with complete encapsulation of all metals observed from 90 days of curing time. The mineralogy of the stabilized/solidified tailings showed no changes resulting from leaching tests. Characteristic bands associated with the presence of N-A-S-H gel were identified in both pre-leaching and post-leaching samples for all curing times analyzed. Exposure to acidic environments altered bands related to carbonate bonds formed in the IOT-AAB mixture.

Rare Earth Element Accumulation in Fiddler Crabs (Minuca rapax) from the Rio Doce Tropical Estuary Strongly Affected by Mine Tailings Following the Fundão Disaster.

A mining tailing dam rupture in Brazil in November 2015 released millions of tons of mining waste into the Rio Doce ecosystem, leading to long-term aquatic ecosystem impacts. Although multiple lines of evidence indicate tailings associations with potentially toxic elements in estuarine sediments and biological impact and bioaccumulation pathways in fishes, the extent of contamination in base benthic species is still largely unknown. Moreover, Rare Earth Elements (REE) have not received any attention in this regard. This study assessed REE in fiddler crabs (Minuca rapax) sampled from the Rio Doce estuary in 2017, nearly 2 years after the disaster. The ΣREE in crab hepatopancreas and muscle were high (327.83 mg kg-1 w.w. and 33.84 mg kg-1 w.w., respectively, compared to other assessments in crabs, indicating a preference for REE bioaccumulation in the hepatopancreas compared to muscle. Neodimium, La, and Ce were detected at the highest concentrations. The REE from the Rio Doce Basin were, thus, transported and deposited in the estuary with the mine tailings slurry, leading to bioaccumulation in crabs. This may lead to trophic effects and other ecological impacts not readily measured by typical impact assessment studies, revealing an invisible and not typically acknowledged damage to the Rio Doce estuary.

Assessing pollution degree and human health risks from hazardous element distribution in soils near gold mines in a Colombian Andean region: Correlation with phytotoxicity biomarkers.

The assessment of human health risk due to the presence of hazardous elements in the environment is now necessary for environmental management and legislative initiatives. This study aims to determine the contamination by As, Cd, Pb, and Cr in soils near gold mines in three municipalities located in the Andean region of Colombia. One of the main objectives of the study is to explore possible correlations between the Lifetime Cancer Risk (LCR) and phytotoxicity biomarkers using a simple and rapid-response plant model, radish (Raphanus sativus L.). In the municipality of Yalí, Puerto Berrío, and Buriticá, the hazardous elements concentrations ranged from 8.1 to 35.5, 1.7 to 892, and 5.8 to 49.8 for As, 0.1 to 4.6, 0.1 to 65.2, and 0.5 to 18.2 for Cd, 18.5 to 201.3, 13.0 to 1908, and 189 to 2345 for Pb, and 5.4 to 118.4, 65.4 to 301, and 5.4 to 102.3 for Cr, respectively. The results showed that the biomarkers intracellular H2O2 concentration, antioxidant activity, and radicle elongation exhibited significant (P < 0.05) variations associated with the concentration of hazardous elements in the soils. Significant correlations (P < 0.05, r > 0.58) were found between the biomarkers and the LCR for Cd, Pb, and Cr, but not for As. The results using biomarkers reveal that soil pH and organic matter content are important variables that control the bioavailability of these elements in the soil. The use of indicators like LCR alone has limitations and should be accompanied by the use of biomarkers that allow for a better understanding of the biological system's response to exposure to potentially toxic elements. The results obtained show the urgent need to implement public policies to minimize exposure to hazardous substances in areas near gold mining projects.

Temporal changes in metal and arsenic concentrations in blood and feathers of tropical seabirds after one of the largest environmental disasters associated with mining.

Monitoring of contaminant levels in wildlife over time is a tool for assessing the presence and persistence of environmental impacts at ecosystem, community and population levels. Tropical seabirds breeding in the Abrolhos Archipelago, 70 km off the Brazilian coast, forage in areas under the influence of the Doce River discharge. In 2015, the Fundão Dam collapsed and released ca 60 million tons of iron ore tailings into the ocean. In the present study, red-billed tropicbirds Phaethon aethereus and brown boobies Sula leucogaster breeding in Abrolhos were monitored over four years (2019-2022) for metal (Fe, Mn, Zn, Cu, Cr, Hg, Pb, Cd) and metalloid (As) concentrations in blood and feathers. Over six sampling events, metal (loid) concentrations showed strong temporal variation in both tissues. Overall, feathers showed greater element concentrations than blood, with stronger correlations between elements, especially Mn and the nonessential As, Cd, Hg and Pb. Mn is one of the major chemical markers of the Fundão Dam tailings. Metal (loid) concentrations in the tropical seabirds evaluated were above suggested threshold levels for most nonessential elements (As, Cd and Pb), especially in February 2021, when metal (loid) concentrations peaked in feathers. In this case, values were orders of magnitude higher than those observed in other sampling events. This occurred one year after a major rainy season in the Doce River basin, which increased river discharge of contaminated mud into the ocean, where contaminants are further remobilized by winds and currents, resulting in transference through the marine food web. This finding is consistent to what has been observed for other ecosystem compartments monitored in the region under the influence of the Doce River. Our findings highlight the utility of using tropical seabirds as sentinels of marine pollution, revealing strong temporal patterns in metal (loid) concentrations associated to bottom-up climatic processes.

Polycyclic aromatic hydrocarbons in estuarine sediments as a consequence of the mine tailings remobilization and transport in the Rio Doce basin.

The Fundão dam failure in 2015 severely impaired the economy, the lives of riverine communities, and the aquatic ecosystems of the Rio Doce basin in southeast Brazil. Several contaminants, including polycyclic aromatic hydrocarbons (PAHs), were transported downstream, deposited in the estuary, and released into the Atlantic Ocean. The high concentration of PAHs in estuarine sediments may pose ecological risks and deleterious effects to benthic organisms, so here we aimed at determining the source and fate of these compounds before and after the tailings' arrival. The mean concentration of the analyzed Σ16PAHs increased from 34.05 µg kg-1 in the prefailure period to 751.77 µg kg-1 one year after the arrival of the tailing. The classification of the sediment quality changed from low to moderate contamination. Our results suggest that there was PAHs remobilization by mine tailings along the Rio Doce basin. The target analytes exhibited mostly a pyrolytic profile from fossil fuel and biomass burning. In addition to other contaminants deposited in the estuary after the arrival of the tailings, this study revealed that the profile change of PAHs in the estuary region is a consequence of the mud's erosive power. Integr Environ Assess Manag 2024;20:169-178. © 2023 SETAC.

Quantifying the potential seepage from porphyry copper tailing impoundments using a multi-isotopic approach.

Porphyry-style copper deposits are characterized by low Cu grades and high tonnages, resulting in large mine tailing volumes disposed in impoundments. Due to the mining tailing sizes, waterproofing techniques cannot be applied along the dam base. Therefore, to minimize seepage towards the aquifers, pumping wells are usually installed as hydraulic barriers. Currently, there is a controversy over whether or not the water extracted from hydraulic barriers should be counted as the use of new water rights. Consequently, a growing interest to develop tools to trace and quantify the tailing impacts in groundwater and to determine the water pumped amount subjected to water rights exist. In the present study, isotope data (δ2H-H2O, δ18O-H2O, δ34S-SO42- and δ18O-SO42-) are proposed as a tool to quantify tailings seepage towards groundwater and to assess hydraulic barriers effectiveness. To illustrate this approach usefulness, the Quillayes porphyry Cu tailing impoundment (Chile) case study is presented. The multi-isotopic approach revealed that tailing waters are highly evaporated showing high SO42- content (~1900 mg L-1) derived from primary sulfate ore dissolution, whereas freshwaters, derived from recharge water, have low SO42- contents (10-400 mg L-1) resulting from the interaction with geogenic sulfides from barren host rock. The δ2H and δ18O values of groundwater samples collected downstream from the impoundment suggest a mixing at different proportions of highly evaporated water from the mine tailing waters and non-evaporated regional fresh groundwater. Cl-/SO42-, δ34S-SO42-/δ18O-SO42-, δ34S-SO42-/ln(SO42-) and δ2H-H2O/δ18O-H2O mixing models allowed to determine that groundwater located closer to the impoundment had a mine tailing water contribution from 45 to 90 %, whereas those located farther away had lower contribution (5-25 %). Results confirmed the stable isotope usefulness to determine the water origin and to calculate the hydraulic barrier efficiencies and the pumped water proportions unrelated to the mining tailing subject to the water rights.

Leaching Mechanism and Health Risk Assessment of As and Sb in Tailings of Typical Antimony Mines: A Case Study in Yunnan and Guizhou Province, Southwest China.

The weathering and leaching of mining tailings have released large amounts of antimony (Sb) and arsenic (As), causing serious pollution in the surrounding soil, water, and sediments. To understand the leaching characteristics of Sb and As in mining tailings, Zuoxiguo and Qinglong mining tailings were collected for analysis. The average content of Sb in Zuoxiguo and Qinglong tailings was 5902.77 mg/kg and 1426.43 mg/kg, respectively, while that of As was 412.53 mg/kg and 405.26 mg/kg, respectively, which exceeded the local background value. Furthermore, the concentrations of Sb in the leachate of Zuoxiguo and Qinglong increased with time; the average Sb concentration in the leachate of Zuoxiguo and Qinglong was 1470.48 µg/L and 70.20 µg/L, respectively, while that of the As concentration was 31.20 µg/L and 6.45 µg/L, respectively. This suggests that the concentrations of Sb and As in the leachate of Zuoxiguo are both higher than those in the leachate of Qinglong and that the pH of the leachate of Zuoxiguo and Qinglong significantly changed within the first day under different initial pH conditions, and tended to be between 6 and 8, after one day. The results of the average health risk index showed that As in the leachate from Zuoxiguo and Qinglong for children was 5.67 × 10-4 and 9.13 × 10-5, respectively, and 4.43 × 10-4 and 7.16 × 10-5, respectively, for adults. As in the leachate from Zuoxiguo poses serious carcinogenic risks for residents, and in the study area, As poses a serious threat to human health. Therefore, the local government must manage As in these areas.

History of tailings dam failure: Impacts on access to safe water and influence on the legislative framework.

Tailings dams have been built since 3000 BCE and despite the advancement of construction methods, mainly in the second half of the 21st century, their ruptures were still recorded. The main direct impacts are related to the loss of human lives, impairment of physical structures and changes in water quality. In this review, different dam failure events were critically analyzed considering their social and environmental impacts, besides the gaps in current regulations framework to appropriately charge the companies involved. These aspects differ the current review paper from those currently available, which also present advancements in the discussion of actions taken after the ruptures, the impacts on water quality, and the challenges related to the water supply. It has been noticed a lack of studies and methodologies capable to predict the water quality under scenarios of tailings contamination. Studies covering that aspect would be an important tool for planning emergency responses by stakeholders. With that in mind, the article discloses the pathway toward an effective strategy in scenarios of tailing dam failure that would mitigate the impacts on water quality and guarantee access to safe water.

Why is Brachiaria decumbens Stapf. a common species in the mining tailings of the Fundão dam in Minas Gerais, Brazil?

Currently, more than five years after the Fundão dam failure in Mariana, Minas Gerais, Brazil, Brachiaria decumbens Stapf. is the main grass in pasturelands affected by the mining tailings. The aim of this study was to investigate the reason for this fact as well as to determine the ecophysiological effects of mining tailings on B. decumbens and to test whether mixing the tailings with unaffected local soil enhances the affected soil properties. For the experiment, two different soils were collected, one unaffected soil without mining tailings (Ref) and the mining tailings (Tec), and we also created a mixture with 50 % of each soil type (Ref/Tec). We cultivated B. decumbens in the three soil treatments in a greenhouse for 110 days and evaluated soil physical-chemical properties and plant ecophysiology. Our results show that the tailings (Tec) compromised the normal ecophysiological state of B. decumbens. The species survived these adverse conditions due to its great efficiency in acquiring some elements. The soil management tested by this work mitigated the stress caused by tailings and can represent an alternative for the environmental recovery of the affected soils.

Leaching assessment of cemented bauxite tailings through wetting and drying cycles of durability test.

Disposal of mine tailings can cause negative environmental effects by releasing contaminants to surface and underground water. Alkali activation is a promising technique for immobilizing metals in stabilization/solidification of these wastes. This study evaluates the leaching behavior of cemented bauxite tailings (BT) submitted to weathering conditions. The alkali-activated binder was composed of sugar cane bagasse ash, carbide lime, and sodium hydroxide solution. Comparisons of the durability and leaching behavior of BT stabilized with alkali-activated binder and high initial strength Portland cement were performed. The durability results for alkali-activated were similar to the Portland cement, showing an average difference of 16%. Portland cement showed favorable results in the encapsulation of heavy metals like Cd and Hg, while the alkali-activated cement on Al, Cr, and Se. For Ba, Fe, Mn, and Zn immobilization, both types of cement presented an equal performance. The durability and leaching behavior of stabilized bauxite tailings is governed by the cement content and porosity of the blends, as well as their pH.

Aftershocks of the Samarco disaster: diminished growth and increased metal content of Raphanus sativuscultivated in soil with mining tailings

The collapse of the Fundão tailings dam of the Samarco mining complex in Mariana, Brazil, was the largest mining disaster in the world to date with many socio-economic and environmental impacts. Soil affected by mining tailings was severely altered with negative impacts for agriculture. We tested whether diluting mining tailings with organic soil would eliminate or at least attenuate the ecotoxic effects on plant development and performance. We cultivated radish, Raphanus sativus,in substrates containing different proportions of mining tailings and organic soil: pure tailings (T100%); 2) tailings75%+ soil25%(T75%); 3) tailings50%+ soil50%(T50%); 4) tailings25%+ soil75%(T25%), and 5) pure organic soil (Soil100%, control). There were large differences in soil quality parameters between the 100% tailings treatment (T100%) and the control (Soil100%), as well as for some parameters in the most diluted treatment -T25%(Ca2+, Fe, Mn) in relation to the controltreatment. Although dilution of the tailings soil improved radish development, there was lower radish productivity (leaf area, total biomass, and root/tuber biomass) than for pure soil (control). There were also significantly higher amounts of bioaccumulated metals in radish tubers grown with tailings, even when grown in T25%for Fe content and in T75%for Mn content. These results present a worrisome scenario for human communities in the region of the Doce river, as human consumption of crops produced in soil contaminated with tailingsis not recommended due to potential toxicological effects from high metal concentrations.(AU)

Cyanide treatment of mining tailings using suspended biomass and moving bed biomass reactors.

Mexico is the top producer of silver and is on the eighth place from producing gold in the world. For instance, the hydrometallurgical extraction process produces wastewater (mining tailing) characterized by being composed with varying concentrations of cyanide and heavy metals. The purpose of this research was to study the biodegradation of cyanide contained in mining tailings by means of a bacterial consortium isolated from a tailings dam. For this purpose, three types of Eckendfelder reactors were used, one with suspended biomass (BS) and two moving bed biofilter reactors, one with biomass immobilized on Kaldnes (BK) supports, and the other on polyurethane cubes (BCP). Three experimental stages were worked; in each of them, the concentrations of total cyanide were varied. In the first one, it was 26 ± 2 mg·L-1; in the second one 40 ± 4 mg·L-1; and the third one 55 ± 4 mg·L-1. During the whole operation, the pH and temperature were maintained at 9.5 units and 25 °C. After 141 days of operation, biodegradation of the total cyanide contained in the mining tailings was 69% (17 mg·L-1) in the BS reactor, while in the BK reactor, it was 93% (3.9 mg·L-1) and in the BCP reactor 95% (2.5 mg·L-1). The predominant families in each of the reactors, as well as their respective relative abundances, were for the BS and for the BK of Cyclobacteriaceae (20.65% and 24.64%) and Rhizobiaceae (18.48% and 14.01%) and Halomonadaceae (46.97%) and Hyphomonadaceae (24.94%) in the BCP.

Effects of seasonal contaminant remobilization on the community trophic dynamics in a Brazilian tropical estuary.

In tropical estuaries, wet seasons are responsible for the downstream transport of allochthonous material from the upper basin and flooded plains. Although allochthonous matter is commonly associated to nutrient and detritus input, pollutants are also transported throughout the basin or suspended from the river bottom via strong streamflow remobilization and rainfall dynamics. We assessed community and population trophic niche-based patterns using organisms' stable isotopes signatures in the wet and the dry seasons to test if estuarine trophic diversity is affected by remobilization of metal-contaminated material from a mining dam collapse that occurred in the Doce river basin, Brazil. Trophic depletion was detected community-wide and in a key consumer group (bottom-dwelling fishes) at the end of the wet season in the impacted Doce river estuary (DRE). Conversely, higher trophic diversity values were recorded in a well-preserved estuary used as control site. Stable isotopes mixing models indicated in the DRE that G. genidens, a predator fish species, presented poor-quality diet based on pollutant-tolerant tiny organisms, a finding that strongly contrasts from diet described in other, little-impacted Brazilian estuaries. Although wet seasons are expected to increase trophic, functional and taxonomic diversity in tropical estuaries, in the DRE the rainfall-driven dynamics poses a threat to the community due to the presence of ore tailings.

When destruction comes first: Two new species of Hypostomus Lacépède, 1803 (Siluriformes: Loricariidae) from a deeply-impacted river in the Rio São Francisco basin in Brazil.

Environmental disasters affecting Brazilian rivers have been frequent recently, especially involving mining activities. Two recent dam-rupture events suddenly released millions of cubic meters of iron tailings downstream into two major Brazilian watersheds. These events generated major losses to the environment and human life. Additionally, the biodiversity in both watersheds was still incompletely known. Two new species of the armoured catfish genus Hypostomus were discovered in the Rio Paraopeba and surrounding rivers of the Rio São Francisco Basin. The species share some main characteristics including a depressed body, large dark spots on a clearer background and the absence of keels on flanks. However, while one species (Hypostomus freirei sp. n.) has a large mandibular ramus and numerous slender teeth, the other (Hypostomus guajupia sp. n.) has a shorter mandibular ramus and few robust teeth. The discovery of these two new mid-sized fish species emphasizes the presumption that the effects of major environmental disasters cannot be fully estimated as local biodiversity is not completely known. This discovery in a recently devastated area also shows that tough environmental laws for the protection, supervision and mitigation of major impacts are urgently needed in developing countries.

Estudo experimental da translocação, percolação e lixiviação dos metais presentes no rejeito de mineração: rompimento de barragem em Mariana-MG / Experimental study of translocation, percolation and leaching of metals present in mining tailings: dam failure in Mariana-MG

A exploração mineral é uma relevante atividade econômica desenvolvida no Brasil, principalmente, no Estado de Minas Gerais. A região do Quadrilátero Ferrífero é considerada uma das maiores províncias poliminerais do Planeta e possui importantes reservas de minério de ferro, manganês, níquel, alumínio e ouro. Com o rompimento da barragem de Fundão em Mariana-MG, em 2015, milhões de toneladas de rejeitos extravasaram ficando depositados no solo e nos recursos hídricos. A carga de rejeitos atingiu, primeiramente, a Barragem de Santarém, provocando o seu galgamento, subsequentemente, alcançou o subdistrito de Bento Rodrigues, Rio Gualaxo do Norte, Rio Carmo, Rio Doce e Oceano Atlântico. Foram 663,2 km de corpos hídricos diretamente impactados, 41 municípios e dois estados atingidos: Minas Gerais e Espírito Santo. Diante da magnitude dos danos provocados ao ecossistema e carência de informações e de estudos na área da saúde, esta pesquisa tem por objetivo avaliar as concentrações de metais na área afetada pelo rompimento da barragem de rejeitos de mineração e simular, experimentalmente, a translocação, percolação e lixiviação desses metais no ambiente. Foram realizadas coletas de solo natural e rejeitos in loco, nos locais mais afetados pelo rompimento (Paracatu de Baixo-MG), para análise de parâmetros físicos e químicos. Avaliação do Fator de Translocação dos metais foi desenvolvida em hortaliças (alface, rúcula e rabanete), cultivada com solo natural de Mariana-MG e com rejeitos de mineração. Além disso, foram realizados ensaios de lixiviação e percolação de água em solo contaminado. Considerando os resultados desta pesquisa, foi possível realizar um diagnóstico básico sobre rotas de dispersão ambiental dos metais no solo após ruptura da Barragem do Fundão, Mariana, MG. Após analisar as amostras do solo e rejeitos, foi evidenciado que o As, Pb, Tl, Al e Fe apresentaram as maiores concentrações. Algumas amostras analisadas apresentaram Cu e Ni em concentrações superiores às recomendadas pela Resolução 420 do CONAMA e por normativas da Alemanha. Os resultados dos ensaios com hortaliças apontam amostras que apresentaram Fator de Translocação superior a 1, evidenciando o transporte de metais das raízes até a parte aérea dos vegetais, o que pode representar risco para saúde da população. De acordo com os resultados obtidos durante a simulação de percolação e lixiviação nos cilindros experimentais, verificou-se que ocorreu movimentação de metais na dimensão horizontal e vertical. Os resultados dos ensaios de translocação, percolação e lixiviação mostram, de maneira experimental, diferentes rotas de dispersão dos metais contidos nos rejeitos do minério. Esses resultados permitem inferir o que pode ter acontecido no ambiente após o rompimento da barragem na região de Mariana. Fica evidenciada a necessidade de se dar continuidade a estudos em áreas atingidas pelos rejeitos de mineração a médio e longo prazo, com foco em estratégias de remediação que objetivem a redução de efeitos adversos à saúde nas comunidades assentadas após esse tipo de desastres. Certamente, a obtenção de dados toxicológicos e de avaliações de risco à saúde da população subsidiarão a tomada de decisão e o desenvolvimento de ações intersetoriais, visando à promoção e proteção da saúde e melhoria das condições sociais e de vida da população afetada pelo desastre

Mineral exploration is an important economic activity developed in Brazil, mainly in the State of Minas Gerais. The Quadrilátero Ferrífero region is considered one of the largest polymineral provinces on the planet and has important reserves of iron ore, manganese, nickel, aluminum and gold. With the collapse of the Fundão dam in Mariana-MG in 2015, millions of tons of tailings overflowed, being deposited in the soil and in water resources. The tailings load first reached the Santarém Dam causing its overtopping, subsequently reaching the sub-district of Bento Rodrigues, Rio Gualaxo do Norte, Rio Carmo, Rio Doce and Oceano Atlântico. There were 663.2 km of water bodies directly impacted, 41 municipalities and two states affected: Minas Gerais and Espírito Santo. Given the magnitude of the damage caused to the ecosystem and the lack of information and studies in the area of health, this research aimed to evaluate the concentrations of metals in the area affected by the collapse of the mining tailings dam and to experimentally simulate translocation, percolation and leaching of these metals in the environment. Natural soil and tailings were collected in loco, in the places most affected by the rupture (Paracatu de Baixo-MG), for the analysis of physical and chemical parameters. Evaluation of the Translocation Factor of metals was developed in vegetables (lettuce, arugula and radish), cultivated with natural soil from Mariana-MG and with mining tailings. In addition, leaching and water percolation tests were carried out in contaminated soil. Considering the results of this research, it was possible to carry out a basic diagnosis of environmental dispersion routes of metals in the soil after the Fundão Dam rupture, Mariana, MG. After analyzing the soil and tailings samples, it was evidenced that As, Pb, Tl, Al and Fe had the highest concentrations. Some analyzed samples presented Cu and Ni at concentrations higher than those recommended by Res. 420 of CONAMA and German regulations. The results of the tests with vegetables indicate samples that presented a Translocation Factor greater than 1, showing the transport of metals from the roots to the aerial part of the vegetables, which may represent a risk to the health of the population. According to the results obtained during the simulation of percolation and leaching in the experimental cylinders, it was verified that metal movement occurred in the horizontal and vertical dimensions. The results of the translocation, percolation and leaching tests show, in an experimental way, different routes of dispersion of the metals contained in the ore tailings. These results allow us to infer what may have happened in the environment after the dam collapsed in the Mariana region. The need to continue studies in areas affected by mining tailings in the medium and long term is evidenced, with a focus on remediation strategies aimed at reducing adverse health effects in settled communities after this type of disaster. Certainly, obtaining toxicological data and health risk assessments for the population will support decision-making and the development of intersectoral actions, aimed at promoting and protecting health and improving the social and living conditions of the population affected by the disaster

Characterization of K6Ta10.8O30 Microrods with Tetragonal Tungsten Bronze-Like Structure Obtained from Tailings from the Penouta Sn-Ta-Nb Deposit.

In this work, a deep characterization of the properties of K6Ta10.8O30 microrods has been performed. The starting material used to grow the microrods has been recovered from mining tailings coming from the Penouta Sn-Ta-Nb deposit, located in the north of Spain. The recovered material has been submitted to a thermal treatment to grow the microrods. Then, they have been characterized by scanning electron microscopy, X-ray diffraction, micro-Raman and micro-photoluminescence. The results of our study confirm that the K6Ta10.8O30 microrods have a tetragonal tungsten bronze-like crystal structure, which can be useful for ion-batteries and photocatalysis.

Electrical resistivity imaging for detection of hydrogeological active zones in karst areas to identify the site of mining waste disposal.

Hydrogeological active zones found in mine waste (tailings) dumping sites are a major source of concern that threatens the safety of the environment and groundwater, especially in karstic areas. Therefore, detecting and identifying these regions correctly will help in selecting the appropriate sites for tailings disposal and avoid consequential environmental problems. In this study, electrical resistivity imaging (ERI) surveys with high-resolution data were carried out to detect hydrogeological active zones in an area proposed as a settling pond for mining tailings accumulated from El Mochito mine property, located in the north-western section of Honduras. Two-dimensional (2-D) inversion results of thirty-four survey lines revealed several zones of low resistivity. These zones indicate water-/clay-bearing regions that are structurally weak. However, some survey lines, the limestone beneath the surface is entirely compacted; as such, it is considered to be an ideal site for tailings pond construction. In addition, on the eastern side of the valley, there is a large chunk limestone layer that is compacted and can be considered for tailings pond construction. The ERI method provided insight and developed an informative subsurface map to detect the hydrogeological active zones, thus proving it as a beneficial tool used for selecting disposal sites for mining tailings in karstic areas.

Tailings from Fundão Tragedy: Physical-Chemical Properties of the Material That Remains by Candonga Dam.

In this work, samples of Fe mining tailings from the collapsed Fundão Dam, Brazil, which were retained by the Candonga hydroelectric power plant, were characterized by various techniques. Quartz, hematite, kaolinite, and goethite were identified as the main phases present. The composition, homogeneity, and relatively low (~1%) organic matter content indicate potential for usage of these tailings in civil constructions. The next step of this work is to investigate such applications. If their feasibility is confirmed, the goal is to use this material for construction in the areas affected by the Fundão Dam rupture. This use will lead to positive socio-environmental impacts in these regions, where tailings still need to be removed and damaged infrastructure needs to be repaired. Integr Environ Assess Manag 2020;16:636-642. © 2019 SETAC.

Neste trabalho, amostras do rejeito de mineração de ferro, proveniente do rompimento da barragem de Fundão e retidas pela usina hidroelétrica de Candonga, foram caracterizadas por diversas técnicas. Quartzo, hematita, caulinita e ghoetita foram identificadas como as principais fases presentes no rejeito. A composição, homogeneidade e teor de matéria orgânica relativamente baixo, cerca de 1%, indicam uso potencial deste material em construção civil. O próximo passo deste trabalho é investigar tais aplicações. Se a viabilidade for confirmada, o objetivo é utilizar esse material para obras nas áreas afetadas pelo rompimento da barragem de Fundão. Isso contribuirá para reduzir os impactos socioambientais nessas regiões, as quais ainda necessitam da remoção do rejeito e de reparos na infraestrutura danificada. Integr Environ Assess Manag 2020;16:636-642.

Active and legacy mining in an arid urban environment: challenges and perspectives for Copiapó, Northern Chile.

Urban expansion in areas of active and legacy mining imposes a sustainability challenge, especially in arid environments where cities compete for resources with agriculture and industry. The city of Copiapó, with 150,000 inhabitants in the Atacama Desert, reflects this challenge. More than 30 abandoned tailings from legacy mining are scattered throughout its urban and peri-urban area, which include an active copper smelter. Despite the public concern generated by the mining-related pollution, no geochemical information is currently available for Copiapó, particularly for metal concentration in environmental solid phases. A geochemical screening of soils (n = 42), street dusts (n = 71) and tailings (n = 68) was conducted in November 2014 and April 2015. Organic matter, pH and elemental composition measurements were taken. Notably, copper in soils (60-2120 mg/kg) and street dusts (110-10,200 mg/kg) consistently exceeded international guidelines for residential and industrial use, while a lower proportion of samples exceeded international guidelines for arsenic, zinc and lead. Metal enrichment occurred in residential, industrial and agricultural areas near tailings and the copper smelter. This first screening of metal contamination sets the basis for future risk assessments toward defining knowledge-based policies and urban planning. Challenges include developing: (1) adequate intervention guideline values; (2) appropriate geochemical background levels for key metals; (3) urban planning that considers contaminated areas; (4) cost-effective control strategies for abandoned tailings in water-scarce areas; and (5) scenarios and technologies for tailings reprocessing. Assessing urban geochemical risks is a critical endeavor for areas where extreme events triggered by climate change are likely, as the mud flooding that impacted Copiapó in late March 2015.