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Rehabilitation Proposal for a Rural Settlement Affected By the Fundão Dam Tailings (Mariana-Brazil): A Study Case
... Indeed, the wave of tailings destroyed the Doce River floodplains, causing the death of native riparian forests (Santos et al., 2019;Silva, Ferreira, & Scotti, 2015) and damage to cropping areas (Fortes, Scotti, Villefort, & Alvarenga, 2020). Plant mortality was not only attributed to the nutrient deficiency of the sediment but also to the presence of toxic compounds, such as ether amine and sodium, in the sediments (Santos et al., 2019), which were derived from the reverse cationic flotation process used in iron ore processing (Araujo, Viana, & Peres, 2005;Samarco, 2013). ...
... Plant mortality was not only attributed to the nutrient deficiency of the sediment but also to the presence of toxic compounds, such as ether amine and sodium, in the sediments (Santos et al., 2019), which were derived from the reverse cationic flotation process used in iron ore processing (Araujo, Viana, & Peres, 2005;Samarco, 2013). In contrast, metal levels found in the Fundão tailings did not differ from those in the preserved sites of the region that were not reached by the tailings (Gomes et al., 2021;Santos et al., 2019;Scotti et al., 2020) nor from the background soils in the region, either before (Santolin, Cimielli, Nascentes, & Windmöller, 2015) or after the dam rupture (Santos et al., 2019). Therefore, ether amine and sodium were the only toxic contaminants identified in the dam tailings and have been shown to cause not only plant mortality but also the depletion of microbial communities (Santos et al., 2019). ...
... Therefore, ether amine and sodium were the only toxic contaminants identified in the dam tailings and have been shown to cause not only plant mortality but also the depletion of microbial communities (Santos et al., 2019). However, Scotti et al. (2020) proved that the remediation of ether amine and sodium contamination using phyto, physical and chemical remediation strategies facilitated the establishment of a riparian forest fragment with native species from the Atlantic Forest, as well as the recovery of microbial communities. Therefore, the rehabilitation of the contaminated riparian sites may be feasible if soil remediation is performed (Gomes et al., 2021;Scotti et al., 2020). ...
Five years after the failure of the Fundão Dam in Brazil, no scientific report has been published regarding the rehabilitation interventions performed by the Renova Foundation, which is solely responsible for the rehabilitation of the Doce River Basin. This study aimed to assess the fluvial and riparian rehabilitation efforts performed by Renova, as well as to test and propose alternatives, when appropriate. Before the dam rupture, the fluvial system showed a single-thread morphology that was sinuous and meandering. After the rupture, changes occurred in the river dynamics with strong sediment deposition in riparian areas, resulting in the loss of several meandering streams, oxbow-lakes, lagoons, and fluvial islands. There was also a loss of the riparian vegetation, from 61% to 6%, as estimated by the Normalized Difference Vegetation Index (NDVI). Renova subjected nearly 61% of the study area to fluvial rehabilitation techniques, particularly using rip-rap or larssen sheet piling (37%) and erosion control fibre blankets (17%). However, 50% of these interventions have been unsuccessful because the rip-rap was poorly positioned and the biodegradable fibre blankets decomposed rapidly. We recommend changing the position of the rip-rap from convex to concave banks and to avoid using biodegradable fibre blankets. Instead, we encourage the planting of riparian forests with native species to form buffer zone systems. Renova' riparian rehabilitation attempts were found to have low success rates, which was attributed to the unaddressed presence of toxic compounds, such as sodium and ether amine. However, our results proved that riparian rehabilitation using native species is feasible, if physical, chemical, biological, and phyto-remediation strategies are adopted, to alleviate the ether amine and sodium toxicity.
The failure of the Fundão dam in Brazil spilled alkaline contaminated sediments (pH~ 8) into the Doce River basin. The contaminated sediments had high levels of ether amine (6 mg/kg) and sodium (54 mg/kg) in relation to those in preserved sites. In the present study, a riparian forest was established over contaminated sediment using two main remediation strategies: phytoremediation with species native to the Atlantic forest and previously selected for their tolerance to sediment toxicity, and physico‐chemical remediation by incorporating organic matter (OM) into the sediment. In the experimental site (ES), the tolerant native woody species were cultivated in two treatments: T1–scraping of the sediments and incorporation of the OM and T2–non‐managed sediment and superficial deposition of the OM. The results were compared with the findings from a degraded site (DS), which was reached by the contaminated sediments but lacked vegetation, and a preserved site (PS), which was composed of a fragment of preserved Atlantic forest. Six months after transplanting, the plants from T1 showed a better height growth performance and survival index in relation to those from T2. Furthermore, T1 showed a significant decline in the pH (to approximately 6) concomitant with a reduction in the ether amine and sodium contents (to approximately 0.4 mg/kg and 23 mg/kg, respectively). There was an improvement in the soil fertility and total microbial biomass in both treatments, especially in T1. Therefore, the adopted phyto‐ and physico‐chemical remediation procedures are recommended to reclaim zones reached by dam tailings containing sodium and ether amine. This article is protected by copyright. All rights reserved.
The rupture of the Fundão mine dam in Mariana municipality,
Minas Gerais State, Brazil, spilled the tailings across the Doce
River basin. These tailings, composed of residues discarded from
the beneficiation of iron ore, are rich in SiO2 and Al2O3, as well as
some ether amine compounds and NaOH. The aim of this study
was to assess the distribution of these sediments, as well as their
effect on the riparian zones reached, as compared with preserved
sites. Sediment deposition in the river resulted in a morphological
change from a meandering profile to a braided aspect. The
nutrient and mineral content (P, K, Ca, Mg, Cu, Fe, Mn, Zn, and
NO3
−) and soil organic matter of the sediments were depleted,
whereas NH4
+, Na, and pH increased. A random presence of ether
amines in the sediments was confirmed by quantitative and
chromatographic analyses, with concentrations ranging from 0
to 57.8 mg kg−1; Na reached values as high as 150 mg kg−1. The
impact of the dam tailings on biota was assessed by estimating
total microbial biomass (phospholipid fatty acids), which were
depleted in sediments relative to soils from preserved sites.
Overall plant mortality, as well as a low resilience capacity, were
also observed. Ether amines and Na present in the sediments had
a strong toxic effect in the environment. Identification of these
substances as the main impact factors will help guide future
remediation efforts.
On November 5, 2015, after the collapse of the Fundão tailings dam, a massive amount of iron mine waste was released into the Doce River system in southeast Brazil. The aim of our study was to determine the mass fractions of potentially toxic elements in soil affected by the deposition of material by the waste wave. A preliminary screening was performed with portable X-ray fluorescence spectrometry (PXRF) and principal component analysis (PCA). The EPA 3050B method was further applied to digest the samples for quantitative determination of As, Ba, Cr, Cu, Mn, Ni, Pb, V, and Zn by inductively coupled plasma mass spectrometry. PCA was useful to classify the mine waste samples based on the Fe signal from the PXRF spectra, in spite of the heterogeneous nature of the material discharged into the Doce River system. The anomalous levels of As (up to 164 mg kg−1) and Mn (as high as 2410 mg kg−1) found in some mine waste and affected soil samples are within the background ranges typically observed in the soils of the Iron Quadrangle region. The toxicity characteristic leaching procedure shows no evidence of hazards regarding As, but a high natural background level of Mn was found in the mobile fraction. This preliminary environmental assessment highlights the importance of evaluation of long-term effects on soil directly impacted, as well as on the aquatic biota of the Doce River system and adjacent coastal environment given the large affected area, which includes regions with varying background levels of toxic elements.
The Doce River Basin (DRB) is located in the southeastern region of Brazil and is home to the largest steel complex in Latin America, including the largest open pit mining industry in the world. Several economic activities are performed along the DRB, including mining, agriculture, and food industry activities. The mining activities involve the exploration of a range of minerals and gold on a smaller scale. The quality of water in the basin has been monitored since 1997 by the state agency for environmental control; however, there are no reports about metals in sediments of the basin. There is insufficient information for an assessment of metal distribution in the DRB, especially for the most toxic metals, such as mercury. Therefore, the aim of this work is to quantify Al, Cr, Co, Cu, Fe, Hg, Mn, Pb, and Zn levels and the physico-chemical parameters in sediment from the basin and to statistically analyze these variables. The results are also discussed using the geoaccumulation index (I
geo) and enrichment factor (EF), which contribute to the knowledge of the metal geochemistry in this basin. The results for Cr, Cu, Hg, Pb, and Zn indicate that 41 % of the sediment samples analyzed were above the sediment quality guideline value (SQG), and the use of geochemical parameters indicated that eight points of the basin were considered the most contaminated. Therefore, this study revealed that an implementation of a sediment monitoring program is of great value.
O presente trabalho tem por objetivo investigar a possibilidade de reutilização de aminas residuais provenientes do processo de flotação de minério de ferro. Os testes de flotação em bancada foram realizados em pH 10,5, tendo o amido como depressor dos óxidos de ferro e as aminas Flotigam EDA 3B e F2835 como coletores para a sílica. Cada rejeito desses ensaios foi submetido à separação sólido/líquido através de filtração a vácuo. O líquido contendo amina residual foi reutilizado em um segundo ensaio de flotação, onde foi investigada a dosagem de reagente novo. Utilizando-se a água contendo amina residual, juntamente com quantidades novas dos coletores, observou-se que há a possibilidade de diminuir o consumo desse reagente em até 50%. Foi realizado também teste de dessorção das aminas contidas em rejeitos sólidos, adicionando-se água ao resíduo em diferentes valores de pH e massa do resíduo. Os resultados revelaram que mais de 95 % da amina adicionada pode ser recuperada.The present work has the objective of investigating the possibility of the reuse of residual amines resulting from the process of reverse flotation of iron ore. Bench-scale flotation tests were performed at pH 10.5 with starch as the depressant of iron oxides and the amines Flotigam EDA 3B and F 2835 as silica collectors. Each waste effluent from these trials was submitted to solid/liquid separation via vacuum filtration. The liquid containing residual amine was reutilized in a second flotation trial where the concentration of the new reagent was determined. Utilizing the water containing the residual amine together with new quantities of collectors, it was observed that it was possible to reduce the consumption of this reagent by as much as 50%. A desorption test of the amines contained in the solid waste was performed by putting different masses of the residual in contact with water of different pH values. The results revealed that more than 95% of the amine added could be recovered.
The role of reagents utilised in iron ores flotation is reviewed. Desliming and flotation stages should be performed at pH levels as low as possible to reduce the expenses with caustic soda. Ether amines are by far the mostly utilised class of collector. The degree of neutralisation of the ether amine is an important process parameter. The partial substitution of amine by non-polar oils seems to be an attractive route. Part of the amine may be also replaced by polyglycols in its frother role. Starches still represent the most important class of iron oxides depressant. Very pure corn starch may be successfully replaced by products from the food industry containing proteins. Oil grades in the starch higher than 1.8% may act as froth inhibitors. Cassava starch may be an economically attractive option since the production capacity meets the required demand level.
A degraded riparian forest that has lost vegetation and has suffered periodic flooding was rehabilitated using native species under buffer zone system which was stratified according to the distance from the river (Zones I, II, III). To restore the soil stabilisation and water flow we compared the soil aggregation, porosity and soil humic substances of the experimental site (ES) with those of a disturbed site (DS) and a preserved site (PS). Six years post-transplantation, soil aggregation and micro-porosity were improved in the ES relative to the DS, but only micro-porosity achieved a pattern similar to that of the PS in Zone III. Differences in soil aggregation between ES and PS were correlated with the negative effect promoted by a high aliphatic-humic acid composition in Zone I and by an undifferentiated distribution of fulvic acid among sites which were attributed to the flooding effect. Similarities among ES and PS were related to aromatic:vinylhumic acid ratio, allowing for the clustering of samples from Zones II and III of both the PS and the ES, via a principal component analysis. Samples from Zones I of ES and PS were separated driven by aliphatic and fulvic acid contributions, while all of the DS samples formed an isolated group under the influence of aliphatic species and macro-porosity. Based on these attributes, the ES is evolving towards the PS, and the rehabilitation process has attained an intermediate phase of restoration. The zones system adopted for riparian forest restoration allowed the use of soil humic substances, aggregates and micro-porosity as indicators of restoration.
On November 5th, 2015, Samarco's iron mine dam – called Fundão – spilled 50–60 million m3 of mud into Gualaxo do Norte, a river that belongs to Rio Doce Basin. Approximately 15 km2 were flooded along the rivers Gualaxo do Norte, Carmo and Doce, reaching the Atlantic Ocean on November 22nd, 2015. Six days after, our group collected mud, soil and water samples in Bento Rodrigues (Minas Gerais, Brazil), which was the first impacted area. Overall, the results, water samples – potable and surface water from river – presented chemical elements concentration according to Brazilian environmental legislations, except silver concentration in surface water that ranged from 1.5 to 1087 μg L−1. In addition, water mud-containing presented Fe and Mn concentrations approximately 4-fold higher than the maximum limit for water bodies quality assessment, according to Brazilian laws. Mud particle size ranged from 1 to 200 μm. SEM-EDS spot provided us some semi quantitative data. Leaching/extraction tests suggested that Ba, Pb, As, Sr, Fe, Mn and Al have high potential mobilization from mud to water. Low microbial diversity in mud samples compared to background soil samples. Toxicological bioassays (HepG2 and Allium cepa) indicated potential risks of cytotoxicity and DNA damage in mud and soil samples used in both assays. The present study provides preliminary information aiming to collaborate to the development of future works for monitoring and risk assessment.
Ammonium (NH4+) toxicity is an issue of global ecological and economic importance. In this review, we discuss the major themes of NH4+ toxicity, including the occurrence of NH4+ in the biosphere, response differences to NH4+ nutrition among wild and domesticated species, symptoms and proposed mechanisms underlying toxicity, and means by which it can be alleviated. Where possible, nitrate (NO3-) nutrition is used as point of comparison. Particular emphasis is placed on issues of cellular pH, ionic balance, relationships with carbon biochemistry, and bioenergetics of primary NH4+ transport. Throughout, we attempt to identify areas that are controversial, and areas that are in need of further examination.
Soil salinity is a major abiotic stress in plant agriculture worldwide. This has led to research into salt tolerance with the aim of improving crop plants. However, salt tolerance might have much wider implications because transgenic salt-tolerant plants often also tolerate other stresses including chilling, freezing, heat and drought. Unfortunately, suitable genetic model systems have been hard to find. A recently discovered halophytic plant species, Thellungiella halophila, now promises to help in the detection of new tolerance determinants and operating pathways in a model system that is not limited to Arabidopsis traits or ecotype variations.
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