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

Mining waste induces oxidative stress, cell death and irreversible histopathology in the liver of Psalidodon rivularis in a contaminated Neotropical stream

In areas impacted by mining activities, waste rich in heavy metals can contaminate water bodies and aquatic biota. Metal contamination is related to several pathological triggers in key organ such as the liver. The objective of the work was to evaluate the effects of mining waste on the liver of fish species Psalidodon rivularis. For this, 57 specimens were collected in a reference stream (S1), without contamination by mining waste, and an impacted stream (S2), located downstream iron ore mines and six associated tailings dams, southeastern Brazil. Liver samples were collected and subjected to morphological, immunohistochemistry, TUNEL assay and Western blotting techniques. Water and sediment samples were collected to evaluate metal concentrations (Al, Cd, Fe, Pb, Mn, Hg). Compared to S1, Fe, Al and Mn concentrations were significantly higher in S2. In fish from S2, liver presented histopathologies such as cell and tissue alterations, hyperemia, inflammatory infiltrate, apoptosis, necrosis and fibrosis, and histopathological alteration index (HAI) significantly higher. TUNEL-positive cells were more frequent in fish at S2, and hepatocytes showing ferroptosis morphological characteristics were detected in this site. CYP1A, metallothionein (MT-1), superoxide dismutase (SOD1), glutathione peroxidase (GPx1) and catalase (CAT) were identified in the cytoplasm of hepatocytes from both sites, but MT-1 and SOD1 was also localized in the nucleus in S2. The expression of these proteins was significantly higher in S2. We concluded that exposure to mining waste rich in heavy metals induced oxidative stress, cell death and severe histopathology in the liver of chronically exposed fish.

Evaluating the surface water quality after the rupture of an iron mining tailings

The aim of this article is to assess whether the collapse of the Fundão tailings dam still impacts the surface water quality of the Doce River in the state of Minas Gerais (Brazil). The records of 15 water quality parameters were evaluated, comparing data from before and after the accident. Nine sampling points were selected, six of which corresponded to water intakes for the water supply systems. The records showed that after the collapse of the Fundão Dam, there was an increase in the percentage of non-conforming values for dissolved Fe, dissolved Al, true color, turbidity, and total suspended solids, but a reduction in total Mn and total Pb, based on the Normative Consideration COPAM/2008. The time series analysis showed no trends, with Levene's test indicating variance changes only for dissolved Fe, total dissolved solids, and dissolved Al. Mann-Whitney tests revealed no median changes in key parameters after the Fundão Dam collapse. For the seven trace metals evaluated (As, Cd, Cr, Pb, Hg, Ni and Zn), the Mann-Whitney and Pettitt tests allow us to infer that there was a change in the median concentrations and an abrupt change in the data series after the dam rupture. It is not possible to associate any plausible cause for the changes observed in some tests and monitoring stations in the records prior to the accident. For records after the accident, the prospect of the Doce River's recovery still lacks greater statistical robustness, emphasizing the relevance of maintenance of water quality monitoring stations in the Doce River channel.

Sensitivity analysis of a parameterization of coagulation in an aqueous transport model

A three-dimensional aqueous transport model, ALGE, was developed at the Savannah River National Laboratory (SRNL) as a tool for emergency response. Recently, coagulation and break-up of suspended sediment and particulate (contaminant adhered to sediment) matter has been added as a new model capability via bilinear interpolation of salinity and turbulence. A sensitivity analysis was performed by comparing time series of suspended sediment and particulate concentrations at various locations when the model's parameters (particle size and density) are altered. Concentrations produced by the model match well with the literature, producing concentrations between 0.05 and 0.25 kg/m3. Simulations of suspended sediment also show similar trends to the literature, where concentrations reach equilibrium faster in a salinity driven environment (>0.5 days) when compared to a freshwater environment (∼1 day). Sensitivity results show significant differences (P-values <0.05) between suspended sediment experiments in both freshwater and saltwater systems when all parameters (particle diameter, density, fraction of mass) vary, whereas significant differences (P-value <0.05) between particulate tracer experiments occur primarily at the source of the release.

Five years after the Brumadinho dam collapse: Evaluation of water quality based on combined analysis of land use and environmental data

The collapse of the dam in the Paraopeba River watershed in 2019 triggered significant concerns regarding water quality in the region. This study aimed to assess, five years after the disaster, the effects on water quality and understand the underlying factors of environmental pressure contributing to the observed changes. To perform the evaluation, the study utilized surface water quality data pre-disaster (2012-2018) and post-disaster (2019-2023), environmental data regarding the identification of high-polluting potential industries operating in the region of interest, and land use for the watershed as a combined evaluation. Nonparametric statistical tests Kruskal-Wallis, complemented by Dunn's, were employed to assess the significance of changes in water quality parameters post-collapse. The results indicate a relatively stable baseline scenario of land use dominated by agriculture and pasture, with minor changes observed in forest cover and urban development. However, post-collapse assessments showed significant variations in water quality parameters, with turbidity exceeding conformity levels by up to 68 % (over 100 NTU), dissolved iron (Fe) by up to 70 % (over 0.3 mg.L-1), manganese (Mn) by up to 91 % (over 0.1 mg.L-1), dissolved aluminum (Al) by up to 83 % (over 0.01 mg.L-1), and lead (Pb) by up to 26 % (over 0.01 mg.L-1). Statistical tests suggested possible effects of the dam collapse on turbidity, pH, dissolved Fe, Mn, and dissolved Al. Temporal analysis showed constant effects on water quality, with notable increases in dissolved Fe and Mn concentrations observed upstream post-disaster and persistent impacts downstream. New mining activities licensed after 2019 may have contributed to the deterioration of water quality, highlighting the relevant relationship of anthropogenic activities and the environmental disaster in the Paraopeba River watershed.

Integrating reverse osmosis to a conventional river water treatment plant as a strategy to produce drinking water after mining dam rupture events: a case study

Incidents of mining dam failure have compromised the water quality, threatening the water supply. Different strategies are sought to restore the impacted area and to guarantee the water supply. One example is water treatment plants that treat high-polluted waters within the required limits for their multiple usages. The current study assesses the integration of reverse osmosis (RO) to a river water treatment plant (RWTP) installed in Brumadinho (Minas Gerais, Brazil) to treat the water from the Ferro-Carvão stream impacted by the B1 dam rupture in 2019. The RWTP started eleven months after the mining dam rupture and is equipped with eight coagulation-flocculation tanks followed by eight pressurised filters. A pilot RO plant was installed to polish the water treated by the RWTP. Water samples were collected at different points of the water treatment plant and were characterised by their physical, chemical, and biological parameters (160 in total). The results were compared with the historical data (1997-2022) to reveal the alterations in the water quality after the rupture event. The compliance with both parameters was only achieved after the RO treatment, which acted as an additional barrier to 30 contaminants. The water quality indexes (WQI) suggested that the raw surface water, even eleven months after the incident, was unfit for consumption (WQI: 133.9) whereas the reverse osmosis permeate was ranked as excellent in the rating grid (WQI: 23.7).

Major recent failures in Brazilian mine waste containment facilities, current cases of maximum emergency level and imminent risk of rupture, and a brief sustainability analysis

Waste is the materials left over after the processing of ores. Significant disasters involving waste disposal structures have occurred in Brazil in recent years and caused severe damage by contaminating soil, rivers and coastal areas, destroying native fauna and flora, interrupting the water supply and compromising its potability, putting the population's health, livelihoods and economy at risk, as well as causing 289 irreparable human deaths. Regulatory laws have become stricter, and since 2019, after the tailings dam tragedies occurred in 2015 and 2019 in Mariana and Brumadinho, in Minas Gerais, the operation of  upstream-raised tailings dams has been prohibited in Brazil. In 2022, a waste slide from a sterile pile at the Pau Branco Mine in Nova Lima promoted a dike overflow. There was the death of five people whose car was buried by a landslide on a hillside. New strategies and technologies, such as reprocessing and recycling, can be tested to ascertain whether they can help improve practices in tailings management. Indeed, mining companies' corporate responsibility and sustainability practices need to be evaluated to verify whether they better match expectations. On the other hand, more specific and detailed regulations and resolutions are required to ensure the safe monitoring and management of sterile waste piles. This paper presents a review of the facts, a discussion of the literature (mainly on recent tailings dam disasters), the current situation of mining-containing waste structures in Brazil, a brief sustainability analysis and perspectives aimed at preventing/minimising catastrophes in the future.

Environmental pollution and human health risk due to tailings storage facilities in China

Tailings storage facilities (TSFs) represent an anthropogenic source of pollution, resulting in potential risks to both environmental integrity and human health. To date, the environmental and human health risks from TSFs in China have been under-researched. This study attempts to address this gap by developing, and geo-statistically analyzing two comprehensive databases. The first database (I) focuses on failed TSFs; we supply the statistics of environmental damages from 143 TSF failure incidents. Notably, approximately 75 % of the failure incidents involved tailings flows released into water bodies, resulting in a significant exacerbation of environmental pollution. To better inform ecological and human health risks, we present another database (II) for 147 non-failed TSFs to investigate the soil heavy metal contamination, considering 8 heavy metals. The findings reveal that (i) Cd, Pb, and Hg are the prominent pollutants across the non-failed TSF sites in China; (ii) lead‑zinc and tungsten mine tailings storage sites exhibit the most severe pollution; (iii) Pb, Cd, and Ni present noteworthy non-carcinogenic risks to human health; (iv) >85 % of TSF sites pose carcinogenic risks associated with arsenic; and (v) health risks resulting from dermal absorption surpass ingestion for the majority of heavy metals, with the exception of Pb, where ingestion presents a more pronounced route of exposure. Our study presents a comprehensive evaluation of environmental and human health risks due to TSFs, highlighting the necessity for risk assessment of >14,000 existing TSFs in China.

A conceptual model to establish preventive and corrective actions to guarantee water safety following scenarios of tailing dam failure

One of the impacts related to mining dam failures is the change in water quality downstream of the rupture and a knowledge gap is observed in terms of methodologies aimed at the prognosis of impact in water abstractions, a vulnerability that can be identified before a rupture event. Thus, the present work aims to describe a novel methodological proposal, not currently considered by control agencies, of a standard protocol that enables a comprehensive prognosis of the impacts on water quality impact in scenarios of dam failure. Initially, extensive bibliographic research was carried out on the main disruptions events since 1965 intended to better comprehend the impacts on water quality and to identify mitigatory actions proposed by the time. The information provided a framework to propose a conceptual model for the prognosis of water abstractions, with the suggestion of software and studies to comprehend the different scenarios in the event of dam failure. A protocol was prepared to obtain information on potentially affected inhabitants and a multicriteria analysis was developed using the Geographic Information System (GIS) to suggest the employment of preventive and corrective actions. The methodology was demonstrated in the Velhas River basin considering a hypothetical scenario of tailing dam failure. Changes in water quality would be observed in 274 km of its extension, mainly related to alterations in solids, metals, and metalloids' concentration, in addition to the impact on important water treatment plants. The map algebra and the results suggest the need for structuring actions in cases where the water abstraction is intended for human supply and in populations greater than 100,000 inhabitants. Populations smaller than these, or usages other than human supply, could be supplied by water tank trucks or mixed alternatives. The methodology pointed out the necessity for structuring supply actions with due notice, with the potential to prevent water shortages in scenarios of tailing dam failure and to complement the enterprise resource planning of mining companies.

Membrane technology as an emergency response against drinking water shortage in scenarios of dam failure

With dam failure events, there can be changes in water quality and difficulties in the operation of water treatment plants (WTPs) since they were not designed for water treatment under severe pollution conditions. To avoid that, it was investigated two strategies based on pre-oxidation, ultrafiltration (UF) and reverse osmosis (RO) integrated into a conventional treatment process (coagulation, flocculation, and sand filtration) or with each other, with the potential to reduce the risks of drinking water shortage and guarantee a safe drinking water supply. The study considered the context of the Velhas river basin (Brazil), where water quality is compromised by high turbidities (500-3000 NTU) and excessive arsenic (∼0.4 mg/L), iron (∼50 mg/L), and manganese (∼3 mg/L) levels. They were only partially removed by conventional treatments (removals: 74 ± 21%) and potability standards were only achieved after the membrane separation processes were considered (As: <0.01 mg/L, Mn: <0.1 mg/L, and Fe: <0.3 mg/L). The high water quality after RO enables its blend with the stream obtained after sand filters and would allow for greater flexibility during the operation of WTPs operation. Despite the susceptibility to fouling and most frequent maintenance, the pre-oxidation-UF-RO system would also guarantee a safe drinking water supply. The decision for the most adequate strategy was then based on a multicriteria analysis. A retrofit of conventional WTPs by their integration with UF-RO was classified as the best strategy for centralized facilities, whereas pre-oxidation-UF-RO better fits the reality of decentralized treatments given the lower costs and deployment time. The methodology based on multicriteria analysis and water treatment technologies, exemplified by membranes in this study, presented satisfactory results for different scenarios of critical treatment.