Assessment of environmental pollution and human health risks of mine tailings in soil: after dam failure of the Córrego do Feijão Mine (in Brumadinho, Brazil).

The dam failure of the Córrego do Feijão Mine (CFM) located in Minas Gerais State, Brazil, killed at least 278 people. In addition, large extensions of aquatic and terrestrial ecosystems were destroyed, directly compromising the environmental and socioeconomic quality of the region. This study assessed the pollution and human health risks of soils impacted by the tailing spill of the CFM dam, along a sample perimeter of approximately 200 km. Based on potential ecological risk and pollution load indices, the enrichments of Cd, As, Hg, Cu, Pb and Ni in soils indicated that the Brumadinho, Mário Campos, Betim and São Joaquim de Bicas municipalities were the most affected areas by the broken dam. Restorative and reparative actions must be urgently carried out in these areas. For all contaminated areas, the children's group indicated an exacerbated propensity to the development of carcinogenic and non-carcinogenic diseases, mainly through the ingestion pathway. Toxicological risk assessments, including acute, chronic and genotoxic effects, on people living and working in mining areas should be a priority for public management and mining companies to ensure effective environmental measures that do not harm human health and well-being over time.

Changes in the surface water quality of a tropical watershed in the southeastern amazon due to the environmental impacts of artisanal mining.

The expansion of areas of human occupation and the increase in economic activity and deforestation are negatively impacting the Amazon ecosystem. Situated in the Carajás Mineral Province in the southeastern Amazon, the Itacaiúnas River Watershed (IRW) encompasses several active mines and has a historical record of intense deforestation primarily linked with the expansion of pasturelands, but also of urban areas, and mining activities. Industrial mining projects are subjected to strict environmental control, but artisanal mining (ASM; 'garimpos') sites have not been controlled, despite their known environmental impacts. In recent years, the opening and expansion of ASM in the IRW for the exploitation of mineral resources (Au, Mn, and Cu) have been remarkable. This study presents evidence of anthropogenic impacts, mainly caused by ASM, on the quality and hydrogeochemical characteristics of the IRW surface water. The hydrogeochemical data sets of two projects carried out in the IRW, during 2017 and from 2020 until present, were used to evaluate these impacts within the region. Water quality indices were calculated for the surface water samples. For the whole IRW, water collected during the dry season tended to yield better quality indicators in comparison to those collected during the rainy season. Two sampling sites at Sereno Creek showed very poor water quality and extremely high concentrations of Fe, Al, and potentially toxic elements over time. From 2016 to 2022, ASM sites increased markedly. Moreover, there are indications that Mn exploitation via ASM in Sereno hill is the main source of contamination in the area. New trends of ASM expansion were observed along the main watercourses, related to the exploitation of Au from alluvial deposits. Similar anthropogenic impacts are registered in other regions of the Amazon and environmental monitoring should be encouraged to assess the chemical safety of strategic areas.

Seasonal geochemical trends and pollution assessment of bottom sediments in the São Francisco hydrographic basin, Brazil: the Três Marias Reservoir.

The Três Marias Reservoir is the ninth largest reservoir in Brazil, becoming crucial for national strategic development. However, many anthropic activities may affect the sediment quality, promoting the need for a proper environmental assessment. This research appraised the seasonal influences on the Três Marias Reservoir's sediment geochemistry, elucidating possible anthropogenic impacts. The concentrations of Mg, Al, Ca, Cr, Fe, Co, Cu, Cd, Ti, Mn, Ni, Zn, Ba, and Pb were measured in 78 samples of bottom sediments regarding the two seasons of the area, a dry winter and rainy summer. The median ± 2 median absolute deviation (MAD) settled the geochemical background and environmental thresholds for the two seasons. The sediment quality guidelines CONAMA 344/12 highlight the possible adverse ecological effects of pollutants. The hierarchical clustering analysis, the geoaccumulation index, and the pollution load index delineated the polluted zones. The pollution load index ranges from 0.25 to 2.28 in the dry season and 0.56 to 2.11 in the rainy season, defining three affected zones in the reservoir. Forestry and agriculture are the probable pollution sources, reaching warning levels that should be considered in further environmental strategies.

Geochemical signature and environmental background of bottom sediments in a tropical aquatic system: the Três Marias Reservoir, Brazil.

Understanding geochemical provenances and their respective geochemical background values is crucial to sustain a proper comprehension of a tropical ecosystem and provides a compatible evaluation for further environmental policy and monitoring. In this research, the concentrations of Mg, Al, Ca, Cr, Fe, Co, Cu, Cd, Ti, Mn, Ni, Zn, Ba, Pb, and organic matter were measured in 78 samples of bottom sediments in order to evaluate the influence of geogenic and anthropogenic chemical sources in the Três Marias reservoir. Data exploration analysis, multivariate techniques using compositional data, multielemental mapping, geochemical background based on land-use management and geological domains, and enrichment factors were applied to understand the environmental dynamics. Geochemical signatures highlight three pronounced geological structures that control the sediment supply in the Três Marias reservoir: ultramafic rocks from the Mata da Corda Formation, carbonates from the Três Marias Formation, and pedogenic cover formed by tropical Latossoils. The median values of Cu, Ti, and Pb are 28.83 mg/kg, 20.36 mg/kg, and 24.92 mg/kg, respectively, all of which exceed the average upper continental crust concentrations. Pb and Cu ratios reach the threshold effect level, whereas Cr reaches the probable effect level proposed in the CONAMA 454/2012 (Brazilian environmental guidelines). This research conjugates multielemental mapping, background evaluation, and enrichment factors to elucidate the geochemistry dynamics of the Três Marias reservoir in the sense of understanding the behavior of the bottom sediments and to define geochemical reference values for the upper São Francisco basin.

Ecological risk assessment of trace metals in soils affected by mine tailings.

Environmental impacts caused by mine dam ruptures or inappropriate tailing depositions represent a global concern. An ecological risk assessment was performed in 18 areas affected by the collapse of a major mining dam in southeastern Brazil, in two monitoring periods (2015 and 2018). In these areas, pedogeochemical surveys, and ecological risk levels were determinate. In addition, ecotoxicological assays with Proisotoma minuta (Collembola) were carried out in laboratory. Soil screening values indicated that all contaminated areas were above regional reference values for soil quality for at least one metal (As, Cd, Cr, Cu, Hg, Ni, Pb and Zn), likewise exceeding threshold values for potential ecological and human health risks. In two monitoring years, significant ecotoxicity in the avoidance and reproduction of P. minuta (> 60 % and >80 %, respectively) were evidenced in most soils; and lethal responses in some areas like Córrego Novo, Governador Valadares and Tumiritinga. Results suggest changes in soil physical-chemical properties due to tailing deposition, thus affecting soil dwellers. This study can elucidate the use of appropriate tools to ecological risk assessments, helping to identify the priority areas for defining remediation and monitoring strategies.

Ecotoxicological assessment after the world's largest tailing dam collapse (Fundão dam, Mariana, Brazil): effects on oribatid mites.

Worldwide, environmental tragedies involving mining dam ruptures have become more frequent. As occurred a few years ago in Brazil (on 5 November 2015, in Minas Gerais state) the Fundão Dam rupture released 60 million m3 of tailings into terrestrial and aquatic ecosystems. Since then, little information on the ecotoxicity of these tailings has been disclosed. In the laboratory, the acute, chronic and bioaccumulation effects of increased Fundão tailing concentrations on oribatid mites (Scheloribates praeincisus) were assessed. Additionally, the bioaccumulation of 11 trace metals (Al, As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb and Zn) and the total density of oribatid mites found in the areas contaminated by the Fundão tailings were determined. The percentages of mite survival and reproductive inhibition were higher than 60% and 80%, respectively, in all contaminated areas with the highest concentration (100% mine tailings). Field studies showed an expressive reduction in the total density of oribatids per m-2 (up to 54 times) in the contaminated areas compared with the reference area. Metal accumulations in the field were 5.4 and 3.2 higher (for Ni and Hg, respectively) and up to two times higher (for most metals) than those in the laboratory for 42 days. The mite responses to the Fundão tailings found in this study suggest long-term interference in their biological development. In this sense, we can conclude that the introduction of mine tailings onto soils tended to compromise the functionality of the mites in the ecosystem, which causes imbalances to cascade other organisms of the trophic web.

First assessment of trace metal concentration in mangrove crab eggs and other tissues, SE Brazil.

The mangrove crab Ucides cordatus is widespread in the Brazilian coast, which has an important role in nutrient cycling. This species reproduces in summer and females carry eggs about a month, when they maintain contact with water and sediments. It remains unclear if trace metals can be absorbed or adsorbed by the eggs during development. The present study aims to investigate, for the first time, trace metal concentrations in ovigerous female tissues and eggs of U. cordatus in two areas with different metal pollution levels in the Southeastern Brazil. Samples were collected in two different mangroves, Guanabara Bay (GB) highly polluted environment and Paraíba do Sul River (PSR). In both populations, we observed significant increase of V, Cr, and Mn concentrations along eggs maturation. The higher metals averages were found in PSR population. This trend was reported since the 1990s and lower concentrations in GB marine organisms were attributed to reducing conditions, high organic load, and the presence of sulfide ions. These conditions restrict the bioavailability of metals in the bay, with exception of Mn. No significant differences were observed in gills and muscles. In both populations of the present study, V, Zn, As, and Pb were higher in eggs of initial stage, whereas Mn, Ni, Cu, and Cd were higher in hepatopancreas. Beside this, V, Cr, Mn, As, and Pb showed an increase concerning egg development. Thus, V, As, and Pb in eggs come from two sources previous discussed: females and environment. Zinc came mainly from females due to essential function. Those new information should be considered as one of the mechanisms of trace metal transfer to the trophic chain, between benthonic and pelagic environment.