Influence of the Atlantic inflow on trace metal enrichments in sediments and particulate matter of the NW Alboran Sea (SW Mediterranean).

Trace metal contents and fluxes in downward particulate matter and dated sediment cores of the NW Alboran Sea are analysed in this study with the aim of assessing the role of the Atlantic inflow on their transport. Increases in Zn, Cu and Pb were detected in downward particulate matter collected by sediment traps after river flooding events and after the Aznalcollar mining spill. Their arrival coincided within the recently estimated time range for river particles discharged into the Gulf of Cádiz to reach the Alboran Sea, indicating that their transfer is enhanced during events of increased river inputs of contaminated particulate matter. This also suggests that the effects of potential tailing dam failures in the Gulf of Cádiz watersheds could reach the Alboran Sea. These trace metals also increased in the sediment cores from the continental rise since the second half of the 19th century, suggesting that contaminated particles have been continuously transferred towards the Mediterranean Sea since that time, when mining concessions and production increased in the SW Iberian Pyrite Belt.

A study on siting of emergency shelters for dam failure floods considering population distribution and weather effects.

In recent years, dam failures have occurred frequently because of extreme weather, posing a significant threat to downstream residents. The establishment of emergency shelters is crucial for reducing casualties. The selection of suitable shelters depends on key information such as the number and distribution of affected people, and the effective capacity and accessibility of the shelters. However, previous studies on siting shelters did not fully consider population distribution differences at a finer scale. This limitation hinders the accuracy of estimating the number of affected people. In addition, most studies ignored the impact of extreme rainfall on the effective capacity and accessibility of shelters, leading to a low applicability of the shelter selection results. Therefore, in this study, land-use and land-cover change (LUCC) and nighttime lighting data were used to simulate population distribution and determine the number and distribution of affected people. Qualified candidate shelters were obtained based on screening criteria, and their effective capacity and accessibility information under different weather conditions were quantified. Considering factors such as population transfer efficiency, construction cost and shelter capacity constraints, a multi-objective siting model was established and solved using the non-dominated sorting genetic algorithm II (NSGA- II) to obtain the final siting scheme. The method was applied to the Dafangying Reservoir, and the results showed the following: (1) The overall mean relative error (MRE) of the population in the 35 downstream streets was 11.16 %, with good fitting accuracy. The simulation results truly reflect the population distribution. (2) Normal weather screening generated 352 qualified candidate shelters, whereas extreme rainfall weather screening generated 266 candidate shelters. (3) Based on the population distribution and weather factors, four scenarios were set up, with 63, 106, 73, and 131 shelters selected. These two factors have a significant impact on the selection of shelters and the allocation of evacuees, and should be considered in the event of a dam-failure floods.

Has the Rio Doce "time bomb" been defused? Using a weight-of-evidence approach to determine sediment quality.

The Fundão mine tailings dam rupture of 2015, in the Rio Doce basin, Brazil, resulted in the deposition of tailings downstream of the dam. It has yet to be determined if metals associated with the tailings have contributed toxicity to organisms, burying a time bomb that could be ticking. Currently the data on toxicity to benthic and aquatic organisms have not been assessed sufficiently to allow an informed assessment using an approach based on weight-of-evidence. This study was conducted to ascertain if sediments at "hot spots" that received Fundão tailings reflected elevated concentrations of metals and if these concentrations were sufficient to result in toxicity to freshwater organisms. The lines-of-evidence considered included assessing metals concentrations in relation to sediment quality criteria, establishing biogeochemical characterizations, completing an evaluation of potential metal release upon resuspension to provide information on bioavailability, and identifying acute and chronic toxicity effects using sensitive native species for waters (water flea, Daphnia similis) and sediments (burrowing midge larvae, Chironomus sancticaroli). Only porewater concentrations of iron and manganese exceeded Brazilian surface water criteria, whereas most trace elements exhibited no enrichment or elevated environmental indexes. The concentrations of bioavailable metals were assessed to be low, and metal concentrations did not increase in the overlying water upon resuspension; rather, they decreased through time. Toxicity testing in resuspended waters and bulk sediments resulted in no acute or chronic toxicity to either benthic or aquatic species. The low metal bioavailability and absence of toxicity of the tailings-enriched sediments was attributed to the strong binding and rapid removal of potentially toxic metal ions caused by oxyhydroxides and particles in the presence of iron-rich particulates. The findings of these sediment hot-spot studies indicate the Fundão dam release of tailings more than six years ago is not causing the current release of toxic concentrations of metals into the freshwaters of the Rio Doce. Integr Environ Assess Manag 2024;20:148-158. © 2023 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Long-term impacts on estuarine benthic assemblages (2015-2020) after a mine tailing spill in SE Brazil.

The Rio Doce estuary was critically impacted in 2015 by the world's largest mining tailing spill, with still unclear long-term effects on the aquatic biota. Here we present a long-term (2015 to 2020) assessment of estuarine benthic assemblages, where we demonstrate that despite a decline in the absolute concentrations of potentially toxic elements; sediment contamination is still above pre-impact conditions. The presence of these contaminants is likely responsible for a continued low habitat quality for the benthic fauna, characterized by a reduction of 96 % of the macroinvertebrate density and persistent change in the benthic assemblage composition. Our study supports previous work indicating the long-term nature of pollution impacts in estuaries, and demonstrate that although water quality levels were quickly adequate under regulatory terms, they largely lack significance to the overall ecosystem health assessment, as they are not related to the recovery of bottom- dwelling assemblages in estuarine ecosystems.

How did a tailings spill change the distribution of legacy organochlorine compounds in a Southeast Atlantic inner shelf area: Is a hidden danger being transferred to the ocean?

Polychlorinated biphenyls (PCBs) and dichloro-diphenyl-trichloroethane (DDT) were evaluated in water and sediments from the Espírito Santo Inner Shelf (ESIS), Brazil, three years after the Fundão dam failure (FDF). We discuss the levels, sources, fate, and current environmental risks of these contaminants on temporal and spatial scales. In addition, the associated coastal dispersion patterns, water-sediment exchange trends, and environmental alterations were also discussed. Low contributions and no environmental risks were verified for PCBs after FDF. However, the low concentrations and frequency of occurrence in the samples did not allow for further reliable conclusions regarding the source of this contaminant. In contrast, hazard risk has been detected for DDTs in water and sediments. In sediments, there were a significant increase in level (up to 13.42 ng g-1; outlier = 369.6 ng g-1), inventory (maximum = 35.98 ng cm-2) and mean total mass (21.1 ± 39.4 kg) of DDTs after FDF. The integrated assessment of the spatial distribution in water and sediment suggests that DDTs was released from the Doce River, travelled south by the water column, and returned to the mouth region by northward sediment transport, where it accumulated. However, intense rainfall increased the input of DDTs to the ESIS and may have also altered its spatial distribution. Fugacity fraction analysis (ƒƒ) indicated a net flux of DDTs from water to sediment, suggesting that vertical sinking was an important transport process in this area. Finally, the findings indicate that FDF contributed to DDTs input on ESIS by remobilizing contaminated past sediments and soils from the Doce River drainage basin. This contribution is expected to continue since a large amount of tailings is still stored in the river basin and estuary. These results highlight the importance of assessing the indirect impacts of large-scale land disasters on marine environments, and may be helpful in future interpretations of additional local trends and global inventories of legacy pollutants.

A model based on a multivariate classification for assessing impacts on water quality in a DOCE river watershed after the Fundão tailings dam failure.

The main purpose of this study was to build multivariate classification models using water quality monitoring data for the hydrographic basin of the Gualaxo do Norte River, Minas Gerais state, Brazil, which was impacted in 2015 by the rupture of a containment structure for iron ore tailings. A total of 27 points were evaluated, covering areas affected and unaffected by the disaster, with monitoring of chemical, physical, and microbiological variables during the period from July 2016 to June 2017. Multivariate classification techniques were applied to the data, with the aim of developing models to determine when the impacted locations would present characteristics equivalent to those existing prior to the rupture. Classification models constructed using PLS-DA and LDA were able to predict three classes: unaffected main river, affected main river, and tributaries. The first technique was able to clearly differentiate the three classes for the data evaluated, achieving averages corresponding to 90% accuracy. The second method was consistent with the first, identifying the chloride content, conductivity, turbidity, and alkalinity as discriminatory variables, among those monitored, with the relationships among the parameters being coherent with the environmental conditions of the region. The model, with a correct classification rate of 91.67%, enabled identification of the behavior of new samples, using only these easily measured variables. In summary, application of the multivariate statistical tools allowed the development of models capable of providing information about the recovery process of an ecosystem impacted by the greatest environmental disaster to have occurred in Brazil.

Scientometric analysis on the review research evolution of tailings dam failure disasters.

As the most severe damage form of tailings ponds, dam failure causes a serious threat and damage to the surrounding lives and environment. Therefore, based on the systematic collection and consultation of relevant data at home and abroad, the literature source analysis on tailings dam failure disasters is conducted using the CiteSpace scientometric tool. The research on tailings dam failure disasters can be classified into two stages: the preliminary germination stage and rapid development stage. Based on the scientometric knowledge map, the research hotspots of tailings dam failure disasters are analyzed and summarized as three main research directions: environmental impact, risk assessment, and mechanical behavior. With the maturity of the research on ecological problems caused by tailings leakage, ecological restoration has also gradually become a hot research topic. Through the analysis of keyword bursts and co-cited bursts, the research frontier of tailings dam break disaster is explored. "Risk management," "real-time monitoring," and "tailings characteristic" represent the current research frontier. Among them, risk management is burst for the longest time and is expected to be a very important research direction in the future. Finally, a tailings pond risk management and control suggestion is proposed with risk management as the core, emphasizing risk monitor, and combined with dynamic risk control, which provides a foundation for the construction of tailings dam safety management and dynamic monitoring systems.

Health risk assessment and cost-benefit analysis of agricultural soil remediation for tailing dam failure in Jinding mining area, SW China.

The impact of the tailing dams and the economic feasibility of the remediation process is significant for future risk management for tailing dams. In this research, we develop a hypothetical failure scenario for a tailing dam in the Jinding mining area, Southwest China. We assess the exposure with the Geo-Environmental Risk Assessment System, tier-1 model, and health impact with Disability-Adjusted Life Years (DALY). Cost and benefit are also analyzed for the following clean-up process. The result shows that the exposure dose (mg/kg-BW/d) of As, Cd, and Pb right after the dam failure is 1.07 × 10-2 for As, 1.76 × 10-4 for Cd, and 5.68 × 10-3 for Pb, respectively. The DALY caused by heavy metal exposure is 2.63 × 10-2 DALY per year, which significantly exceeds the tolerable level. This indicates that the tailing dam failure will pose a high health risk to the residents, and remediation is necessary. After remediation, the DALY is 1.24 × 10-8 DALY per year, indicating the clean-up process effectively reduces the resident's health impact. From the financial point of view, the net present value of the clean-up is $- 1.02 × 107. This indicates that the clean-up process is not economically feasible. Sensitivity analysis shows that the amount of released tailing influences the output result. The time span for benefit estimation is also an important issue. This research shows that the impact of a tailing dam failure will be severe, and remediation may be effective but economically infeasible. Therefore, preventing tailing dam failure is the most crucial task for the local government.

Changes in access to water and incidence of waterborne diseases after the Vale dam collapse in Brumadinho (MG), Brazil / Alterações no acesso à água e na incidência de doenças de veiculação hídrica após o rompimento da barragem da Vale em Brumadinho (MG)

ABSTRACT Objective: To describe, within the Human Rights to Water and Sanitation (HRWS) framework, the access to water supply services and the incidence of waterborne diseases in the communities affected by the dam disaster in Brumadinho (MG), Brazil. Methods: A quantitative and qualitative methodology was used, having as variables information on access to water supply services and waterborne diseases. The primary data were extracted from the "Brumadinho Health Project", using a sample stratum with 981 people interviewed, totaling 92.5% of the eligible population in the affected communities of Córrego do Feijão and Parque da Cachoeira. The secondary data from Brumadinho was extracted from the project "Sanitation conditions and the River Basin of the B1 River Basin of Mineradora Vale between 2017 and 2020", available in public databases between 2017 and 2020, and qualitative data was collected in 2022 through individual interviews with health professional also live in the communities. Results: With regard to access to water supply services, the results of this combined data analysis indicate that the HRWS is being neglected, especially with regard to availability, accessibility, acceptability and quality of water. The study also shows a significant increase in the incidence of waterborne diseases in the region after the disaster. Conclusion: It is necessary to use the HRWS as the basis to the implementation of public policies aiming to reduce vulnerability in access to water supply services.

RESUMO Objetivo: Descrever, na ótica dos direitos humanos à água e ao esgotamento sanitário (DHAES), o acesso à água e a incidência de doenças de veiculação hídrica na região atingida pelo rompimento da barragem da Mina B1 em Brumadinho (MG). Métodos: Utilizou-se a metodologia quantitativa e qualitativa, tendo como variáveis, em ambos os métodos, informações sobre o acesso à água e as doenças de veiculação hídrica. Os dados primários foram extraídos do Projeto de Saúde Brumadinho, sendo aqui utilizado um estrato amostral com 981 pessoas entrevistadas, totalizando 92,5% da população elegível das comunidades atingidas de Córrego do Feijão e Parque da Cachoeira. Os dados secundários de Brumadinho foram coletados pelo Projeto Condições de Saneamento e Saúde da População da Bacia do Rio Paraopeba, a Jusante da Barragem B1 da Mineradora Vale, entre 2017 e 2020, em banco de dados públicos entre 2017 e 2020, e os dados qualitativos foram coletados em 2022 por meio de entrevistas individuais com profissionais de saúde residentes nas comunidades atingidas. Resultados: No tocante ao acesso à água, a análise combinada dos dados apontou que os DHAES estão sendo negligenciados na região, de maneira especial no que se refere à disponibilidade, acessibilidade física, aceitabilidade e qualidade da água. Observou-se também que houve aumento significativo na incidência das doenças de veiculação hídrica na região após o desastre. Conclusão: É necessária utilização dos DHAES como marco referencial na implementação de políticas públicas voltadas para reduzir as situações de vulnerabilidade relacionadas ao acesso à água.

Mortality patterns in municipalities of a mining region before the Brumadinho dam failure, state of Minas Gerais, Brazil / Padrões de mortalidade em municípios de uma região mineradora antes do rompimento da barragem de Brumadinho, Minas Gerais, Brasil

ABSTRACT Objective: To describe the patterns of overall mortality and mortality from external causes and the temporal evolution in the municipalities of the Paraopeba River Basin, before the socio-environmental disaster of the Brumadinho dam and, additionally, to investigate the correlation between mortality and socioeconomic deprivation in these municipalities. Methods: Global Burden of Disease Study mortality estimates for 26 municipalities in the state of Minas Gerais, Brazil, were analyzed. Rates of overall mortality and mortality from external causes were estimated in the triennia (T) T1 (2000 to 2002), T2 (2009 to 2011), and T3 (2016 to 2018). Pearson's correlation coefficient measured the association between mortality rates and socioeconomic deprivation, according to the Brazilian Deprivation Index (IBP). Results: There was a decrease in overall mortality in the Paraopeba River Basin from 717.7/100 thousand to 572.6/100 thousand inhabitants, and in most municipalities between T1-T3. Mortality from external causes increased from 73.3/100 thousand to 82.1/100 thousand, and it was higher in these municipalities compared with the mean for Brazil and Minas Gerais. Deaths from suicide and interpersonal violence increased from 29.6/100 thousand to 43.2/100 thousand in most of the 26 municipalities. Death rates due to unintentional injuries decreased during the period, and those due to transport injuries, increased. There was a positive correlation between socioeconomic deprivation and the percent change in mortality rates. Conclusion: Despite the strong presence of mining activity in the region, such did not reflect in the improvement of the sanitary situation. Death rates due to external causes increased in the period, associated with inequalities, which must be considered in the planning for the recovery of the disaster areas.

RESUMO: Objetivo: Descrever os padrões de mortalidade geral e por causas externas e a evolução temporal nos municípios da Bacia Hidrográfica do Rio Paraopeba previamente ao desastre socioambiental de Brumadinho e, adicionalmente, investigar a correlação entre a mortalidade e a privação socioeconômica nesses municípios. Métodos: Foram analisadas estimativas de mortalidade do Estudo Carga Global de Doenças referentes a 26 municípios de Minas Gerais. Calcularam-se taxas de mortalidade geral e por causas externas nos triênios (T) T1 (2000 a 2002), T2 (2009 a 2011) e T3 (2016 a 2018). O coeficiente de correlação de Pearson mediu associação entre as taxas de mortalidade e a privação socioeconômica, segundo Índice Brasileiro de Privação. Resultados: Houve declínio da mortalidade geral na Bacia Hidrográfica do Rio Paraopeba de 717,7/100.000 para 572,6/100.000 hab. e na maioria dos municípios entre T1-T3. A mortalidade por causas externas aumentou de 73,3/100.000 para 82,1/100.000 e foi mais elevada nesses municípios comparando-se com a média do Brasil e de Minas Gerais. As mortes por suicídio e violência interpessoal aumentaram de 29,6/100.000 para 43,2/100.000 na maioria dos 26 municípios. Os acidentes não intencionais reduziram-se no período, e as taxas por acidente de transporte aumentaram. Houve correlação positiva entre a privação socioeconômica e a variação percentual das taxas de mortalidade. Conclusão: Apesar da forte presença da atividade mineradora na região, isso não refletiu na melhoria do quadro sanitário, as causas externas aumentaram no período, associadas às desigualdades, o que deve ser considerado no planejamento para a recuperação das áreas do desastre.

Mortality patterns in municipalities of a mining region before the Brumadinho dam failure, Minas Gerais, Brazil / Padrões de mortalidade em municípios de uma região mineradora antes do rompimento da barragem de Brumadinho, Minas Gerais, Brasil

Objectives: to describe the patterns of general mortality and mortality from external causes and the temporal evolution, in the municipalities of the Paraopeba River Basin, before the socio-environmental disaster of Brumadinho and, additionally, to investigate the correlation between mortality and socioeconomic deprivation (PPI) in these municipalities. Methods: mortality databases from the Global Burden of Disease Study in 26 municipalities in Minas Gerais. The researches analyzed the mortality databases from the Global Burden of Disease Study in 26 municipalities in Minas Gerais. General and external causes mortality rates were calculated in the triennia (T) T1 (2000 to 2002), T2 (2009 to 2011), and T3 (2016 to 2018). Pearson's correlation coefficient measured the association between mortality rates and socioeconomic deprivation, according to the Social Deprivation Index (IBP). Results: There was a decline in overall mortality in BHRP from 717.7/100,000 to 572.6/100,000 inhab, and in most municipalities between T1-T3. Mortality from external causes increased from 73.3/100,000 to 82.1/100,000. And they were higher in these municipalities compared to the average for Brazil and Minas Gerais. Deaths from suicide and interpersonal violence increased from 29.6/100,000 to 43.2/100,000 in most of the 26 municipalities. Unintentional accidents decreased during the period, and transportation accident rates increased. The association with socioeconomic deprivation (PPI) was positive with increased mortality rates. Conclusion: Despite the strong presence of mining activity in the region, this did not reflect in the improvement of the sanitary situation, the external causes increased in the period, associated with inequalities, which must be considered in the planning for the recovery of the disaster areas.

Objetivos: descrever os padrões de mortalidade geral e por causas externas e a evolução temporal, nos municípios da Bacia Hidrográfica do Rio Paraopeba (BHRP), previamente ao desastre socioambiental de Brumadinho e, adicionalmente investigar a correlação entre a mortalidade e a privação socioeconômica (IBP) nesses municípios. Métodos: Foram analisadas bases de mortalidade do Estudo Carga Global de Doenças em 26 municípios de Minas Gerais. Foram calculadas taxas de mortalidade geral e por causas externas nos triênios (T) T1 (2000 a 2002), T2 (2009 a 2011) e T3 (2016 a 2018). O coeficiente de correlação de Pearson mediu associação entre as taxas de mortalidade e a privação socioeconômica, segundo Índice de Privação Social (IBP). Resultados: Houve declínio da mortalidade geral na BHRP de 717,7/100.000 para 572,6/100.000 hab, e na maioria dos municípios entre T1-T3. A mortalidade por causas externas aumentou de 73,3/100.000 para 82,1/100.000, e foram mais elevadas nesses municípios comparando-se com a média do Brasil e de Minas Gerais. As mortes por suicídio e violência interpessoal aumentaram de 29,6/100.000 para 43,2/100.00, na maioria dos 26 municípios. Os acidentes não intencionais reduziram no período e as taxas por acidente de transporte aumentaram. A associação com a privação socioeconômica (IBP) foi positiva com aumento das taxas de mortalidade. Conclusão:  Apesar da forte presença da atividade mineradora na região, isto não refletiu na melhoria do quadro sanitário, as causas externas aumentaram no período, associadas às desigualdades, o que deve ser considerado no planejamento para a recuperação das áreas do desastre.

Tailings dams: Assessing the long-term erosional stability of valley fill designs.

Tailings is a generic term for waste material from the extraction and processing of minerals and frequently contain mineral and chemical residues. They are usually highly erodible and transportable via fluvial processes. Tailings are commonly stored in 'tailings dams' and such dams are a feature of many mine sites. As they impound water and sediment, tailings dams can be at risk from both catastrophic and gradual failure, especially if unmanaged. A fundamental question for their management is, can tailings dams ever be walk-away structures? Catastrophic failure occurs when there is a large scale rapid structural failure of the dam wall suddenly releasing large volumes of water and sediment. However, over time, there will the increased risk of gradual failure by the slow infilling of the dam and the erosion of the dam wall. Failure can occur where water overtops the dam wall and then incises through the wall due to a loss of freeboard in the dam, a situation which is more likely in legacy tailings dams where they have been filled, vegetated and abandoned. Here, firstly, a computer based landscape evolution model (CAESAR-Lisflood) is employed to assess a hypothetical tailings dam failure by erosion. Secondly, using an idealised example, it is demonstrated that given average climate conditions a dam can be sufficiently robust to last centuries. Thirdly, and longer term it is demonstrated that the tailings can be contained if (a) maintenance is conducted to increase the dam wall height over time or (b) a more robust dam wall is constructed to manage extreme events. However, erosion and infill will continue to reduce the integrity of any structure over time. Therefore, it is highly likely that tailings dams will require continued monitoring and maintenance. The method outlined provides a new tool for assessing any tailings facility for its erosional stability.

Effect of simulated earthquake loading on radon exhalation from uranium tailings dam.

Uranium tailings sand will continuously release radon-222. When the external condition changes, the exhalation of radon will also change. Thus, radon is being recommended as a tracer for dam damage assessment. When an earthquake is simulated on the uranium tailings dam with a shaking table test and the change in radon concentration is measured, it is observed that the earthquake causes micro-fissures in the uranium tailings dam, which aggregate to form fractures. During the process, the radon concentration will climb dramatically, as will the radon exhalation rate. To verify that the radon monitoring date is accurate, the acceleration response, surface displacement, and interior displacement are all monitored. The results show that radon can be utilized as a tracer to evaluate uranium tailings dam damage.

Rupture of Brumadinho dam (Minas Gerais, Brazil): embryotoxicity in zebrafish induced by metal mixture-contaminated water.

Rupture of dam B-1 at the Córrego do Feijão mine in Brumadinho, state of Minas Gerais, Brazil (25/Jan/2019) contaminated the Paraopeba River with mine waste. To identify the adverse effects of this event on public and environmental health, we conducted the Fish Embryo Acute Toxicity (FET) test (OECD No. 236). During the tests, zebrafish embryos were exposed for 144 hours to solutions containing realistic concentrations of dissolved iron and aluminum and total manganese at the following analysis points upstream or downstream of the dam: 10 km, upstream; 19.7 km, downstream, at the point where water for consumption is collected; 24.5 km, downstream, in the city of Mário Franco; and 59 km, downstream, on the border between the towns of Juatuba and Betim. Metal concentrations were taken from September 2019 report No. 53 released by IGAM. Mortality was high at all exposure points and reached 93% at the Juatuba/Betim point. We also detected lethal, sublethal and teratogenic effects, such as non-hatching, non-inflation of the swim bladder, pericardial edema and scoliosis, affecting up to 25% of embryos at the other analysis points. The results highlight the need for continuous monitoring of the water quality of the Paraopeba River.

Numerical Simulation of Tailings Flow from Dam Failure over Complex Terrain.

A tailings dam failure can lead to disastrous impacts on people's livelihood and the surrounding ecological environment. Due to interactions among water, tailings and ground, the mechanism of a tailings flow is more complicated than that of a flood flow. In this paper, the tailings flow is regarded as a homogeneous and incompressible non-Newtonian fluid. Its rheological properties were studied through rheological tests conforming to the Bingham model. The rheological parameters were further used in a Computational Fluid Dynamics (CFD) simulation over complex terrain to explore the tailings flow characteristics. The method was validated with experimental results of a non-Newtonian dam-break flow from literature. The flow characteristics, including flow velocity, runout distance, inundation area and depth, were analyzed in the case of the Dagangding tailings dam. The results showed that the downstream railway and village would not be affected in a conservative scenario. Finally, the effects of two measures for preventing tailings flow hazards were discussed. Setting the check dam and planting grasses and trees can effectively mitigate the damage of tailings flow.

An integrated study of the plankton community after four years of Fundão dam disaster.

Mining activities can affect the environment either by the tailings releasing or dams failures. The impact of the tailings can last decades and cause chronic effects due to their toxicity. The Fundão dam collapse, a relevant environmental disaster, occurred in November 2015 in Southeastern Brazil. Tailing rich in metals reached the Doce River and arrived in the Atlantic Ocean. Previous studies revealed the acute impact of the tailings in the marine planktonic community near the Doce River mouth. The current study aims to characterize the structure of planktonic assemblages in the impacted area after four years of the disaster. Sampling occurred in November 2018, January, April, and July 2019 at 32 stations located at the marine coastal area near the Doce River mouth. Our study detected high metal concentrations in the surface waters during January 2019, when the lowest diversity and abundance of phytoplankton, lowest zooplankton diversity, and low ichthyoplankton abundance were recorded. The zooplanktonic community was structured by environmental parameters and ichthyoplankton assemblages in November 2018, January and April 2019. Nutrients and metals, mainly iron from the tailing carried by the Doce River waters to the marine environment changed the plankton community, confirming the impact of the Fundão Dam collapse in the coastal area near the Doce River mouth. The phytoplankton community, influenced by the nutrients and to a lesser extent metals concentrations, was not decisive in the zooplankton community structure. The environmental variability was driven by the meteoceanographic conditions and the Doce River flow. There was a high correlation between the zooplanktonic community and ichthyoplanktonic assemblage and the environmental factors and metals. These relations indicate the impact of the tailings from the collapse of the Fundão Dam on these communities, even after four years of the Mariana disaster.

Ecological trap for seabirds due to the contamination caused by the Fundão dam collapse, Brazil.

Human-induced rapid environmental changes can disrupt habitat quality in the short term. A decrease in quality of habitats associated with preference for these over other available higher quality is referred as ecological trap. In 2015, the Fundão dam containing iron mining tailings, eastern Brazil, collapsed and released about 50 million cubic meters of metal-rich mud composed by Fe, As, Cd, Hg, Pb in three rivers and the adjacent continental shelf. The area is a foraging site for dozens of seabird and shorebird species. In this study, we used a dataset from before and after Fundão dam collapse containing information on at-sea distribution during foraging activities (biologging), dietary aspects (stable isotopes), and trace elements concentration in feathers and blood from three seabird species known to use the area as foraging site: Phaethon aethereus, Sula leucogaster, and Pterodroma arminjoniana. In general, a substantial change in foraging strategies was not detected, as seabirds remain using areas and food resources similar to those used before the dam collapse. However, concentration of non-essential elements increased (e.g., Cd and As) while essential elements decreased (e.g., Mn and Zn), suggesting that the prey are contaminated by trace elements from tailings. This scenario represents evidence of an ecological trap as seabirds did not change habitat use, even though it had its quality reduced by contamination. The sinking-resuspension dynamics of tailings deposited on the continental shelf can temporally increase seabird exposure to contaminants, which can promote deleterious effects on populations using the region as foraging sites in medium and long terms.

Fundão tailings dam failure in Brazil: Evidence of a population exposed to high levels of Al, As, Hg, and Ni after a human biomonitoring study.

BACKGROUND: On November 5th, 2015, the Fundão mine tailings dam in Minas Gerais State, Brazil, failed, releasing more than 50 million m3 of mud, rich in toxic metals. After that, a massive environmental disaster began with the mud wave flowing more than 600 km, until the mouth of Doce River, in Espírito Santo State, and finally reaching the Atlantic Ocean. A vast area was contaminated, affecting the ecosystem and several communities. Despite the tremendous environmental disaster, little is known concerning the population's exposure to toxic elements yet. METHODS: Thus, a cross-sectional study was for the first time conducted in three communities directly affected by the disaster (Regência, Povoação, and Campo Grande) in Espírito Santo State, to evaluate the levels of 11 chemical elements (Al, As, Cd, Co, Cu, Hg, Mn, Ni, Pb, Se, and Zn) in blood. Sample analysis (n = 300) was performed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). RESULTS: Our data show high levels of exposure to Al, As, Hg, and Ni. Mean values in blood were 60 µg/L (ranging from 9 to 434 µg/L), 10.9 µg/L (ranging from 5.81 to 269 µg/L), 6.4 µg/L (ranging from 0.05 to 103 µg/L) and 2.7 µg/L (ranging from 0.08 to 21 µg/L) for Al, As, Hg and Ni, respectively. Moreover, after applying a multiple regression model, we found community, drinking water, fish, seafood consumption, and smoking habits associated with metal/metalloid levels in their body. Well and tap water intake were identified as important sources of exposure to aluminum and nickel. CONCLUSIONS: Our findings represent health risks to the groups living in the areas affected by the tailings dam failure, calling for further studies to evaluate the potential health effects of high exposure to metals and remediation actions from public health Brazilian authorities.

Conceptual model to analyze the effects caused by technological disaster on the physical-chemical state of the lower Doce River waters, Brazil.

Research has shown the effort to develop conceptual models that relate anthropic stressors to changes in aquatic environment state. Several of these models come from the structure Drivers, Pressures, State, Impact and Response (DPSIR), which has been used since the 1990s. However, there is a lack of conceptual models that consider in its structure the connection between the damages caused in the aquatic environment and technological disasters. This research develops a general conceptual model based on the DPSIR structure incorporating technological disasters. Based on the general conceptual model guidelines and the methodological procedure associated with it, a model was developed to assess the Lower Doce River waters' state, by considering Fundão's iron-ore dam failure scenario, which took place in November 2015, in the municipality of Mariana, state of Minas Gerais, Brazil. The relevant aspects of this adaptation of the DPSIR structure were: I) it considers the combined effect of drivers and pressures that already existed in the study area with those originated from the technological disaster; and II) the causal relationships among elements of the model were explicited through a systemic conceptual map, allowing a more holistic and integrated view of the problem. The application of the conceptual model to Doce River's scenario before the disaster allowed us to verify that a set of environmental pressures was already acting in a way to stress it, making the river vulnerable. For the post-disaster scenario, it was possible to determine that the already existing vulnerability condition, caused by urbanization, agriculture1 and mining, had been intensified by adding new pressures due to the tailings dam failure.

Mining dams disasters as systemic risks / Desastres em barragens de mineração como riscos sistêmicos

ABSTRACT: Between 2015 and 2019, Brazil recorded the two most serious disasters involving mining dams of the 21st century. The purpose of this article is to offer an understanding of these disasters as systemic risks. They involve from global and national processes related to social determinants that materialize in a complex system of dams distributed throughout the country with their intrinsic risks. When they occur, result in a set of impacts with potential damage and immediate effects combined with secondary and tertiary impacts that can trigger chain reactions, which promote risk factors of heterogeneous and complex occurrence. Approaching these events from the point of view of systemic risk allows for a broader understanding of both the singularity of each of these disasters and their multiple exposure, risk and disease processes, as well as the structural characteristics in which social, political processes and dynamics and economic factors reproduce in multiple territories a common pattern of disasters and their effects. We conclude that the promotion of population health and sustainable territories should guide the organization of production processes and not the opposite, with the externalization of human, environmental and social costs of mining and its disasters.

RESUMO: Entre 2015 e 2019, o Brasil registrou os dois mais graves desastres envolvendo barragens de mineração do século XXI. O objetivo deste artigo é oferecer a compreensão desses desastres como riscos sistêmicos, que envolvem desde processos globais e nacionais relacionados aos determinantes sociais que se concretizam em um complexo sistema de barragens distribuídas pelo País com seus riscos intrínsecos. Quando ocorrem, resultam em um conjunto de impactos com potencial de danos e efeitos imediatos combinados com impactos secundários e terciários que podem desencadear reações em cadeia, promovendo fatores de riscos de ocorrência heterogênea e complexa. Abordar esses eventos com base no conceito de risco sistêmico permite uma compreensão mais ampla tanto da singularidade de cada um desses desastres e seus múltiplos processos de exposição, riscos e doenças, como também das características estruturais com que os processos e dinâmicas sociais, políticas e econômicas reproduzem, em múltiplos territórios, um padrão comum de desastres e seus efeitos. Concluímos que a promoção da saúde da população e de territórios sustentáveis deve orientar a organização dos processos produtivos e não o contrário, com a externalização dos custos humanos, ambientais e sociais da mineração e seus desastres.