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Disturbed site before transplantation (A), experimental site 6 mo after transplantation (B), and experimental site 12 mo after transplantation (C); sodium spots on the sediment surface in Paracatu de Baixo (DS, degraded site) (D); qualitative flame test to confirm the presence of Na on the sediment surface (E). In (E), 1 = sodium hydroxide (Sigma Aldrich); 2 = soil from the preserved site; 3 = sediment sample 1; 4 = sediment sample 2; and 5 and 6 = sediment samples 3 and 4. All samples (1-6) were moistened with alcohol before fire. The orange flame indicates the presence of Na.
Source publication
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 remedi...
Contexts in source publication
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... and 3) an experimental site (ES) located near the Gualaxo River in Paracatu de Baixo municipality, where the remediation procedures were installed over a 2 m sediment layer ( Figure 1A). ...
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... the best of our knowledge, this is the first effort to effectively remediate and rehabilitate a contaminated area reached by the tailings of the collapsed Fundão dam using native woody species of the Brazilian Atlantic forest. The trees from T1 (scraping + OM incorporation) showed better growth performance than those from T2 (superficial OM deposition), and some species exhibited an increase in height of as much as 3 m after 6 mo ( Figures 1B and 1C). The mean survival index was greater in T1 (84%) than that in T2 (61%), and the mean height increase in T1 was nearly twice that observed in T2 (Figures 2A and 2B). ...
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... there are very few examples of field phytoremediation using woody species either for salt-affected soils ( Abbas et al. 2014) or, specifically, for alkaline tailings, such as the red mud derived from the rupture of a dam in Hungary ( Alshaal et al. 2013). Given that most phytoremediation efforts performed thus far have tested a single or few tree species, the establishment of a forest fragment with different native woody species, which exhibited rampant growth after 6 mo ( Figure 1C), is a novel and successful strategy for land rehabilitation. This strategy may be applied not only to the vast area affected by the Fundão tailings but also to other dam tailings or soil contaminated with Na and ammonium. ...
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... particular, the scraping procedure favored the Na reduction in the ES after 6 mo. In fact, the presence of Na in the superficial layers of the affected sites (DS) can be observed visually ( Figure 1D), as a consequence of soil water evaporation during the dry winter season. Such superficial Na deposition may be easily assessed by land managers and farmers by using the Na flame test (Figure 1E), which is an easy method that allows the qualitative detection of Na in the sediment. ...
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... fact, the presence of Na in the superficial layers of the affected sites (DS) can be observed visually ( Figure 1D), as a consequence of soil water evaporation during the dry winter season. Such superficial Na deposition may be easily assessed by land managers and farmers by using the Na flame test (Figure 1E), which is an easy method that allows the qualitative detection of Na in the sediment. The fire on the alcohol-moistened sediment will show an orange flame if Na is present, as observed in Figure 1E. ...
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... superficial Na deposition may be easily assessed by land managers and farmers by using the Na flame test (Figure 1E), which is an easy method that allows the qualitative detection of Na in the sediment. The fire on the alcohol-moistened sediment will show an orange flame if Na is present, as observed in Figure 1E. Such a simple method may help guide land managers to perform the scraping procedure prior to planting. ...
Citations
... These toxic compounds affect the plant survival (Halliwell et al., 2001;Britto and Kronzucker, 2002) as observed in the field after the disaster (Santos et al., 2019). By contrast, the metal levels found in the dam tailings were not considered toxic to plants since similar levels were found in the preserved Atlantic Forest soils Santos et al., 2019;Scotti et al., 2020) as well as in the soils found in the region before the disaster (Santolin et al., 2015). ...
... However, the toxicity of these compounds may be reduced by using phytoremediation associated with physico-chemical remediation strategies (sediment scrapping and organic matter amendment), enabling the establishment of a riparian forest with native species of the Atlantic Forest over 2 m dam tailings (Scotti et al., 2020;Gomes et al., 2021). Besides allowing plant survival and growth, these remediation procedures resulted in an amelioration of soil fertility and structure as well as the improvement of soil microbial communities . ...
... Accordingly, in Brazil, Kimura et al. (2017) created a successful rehabilitation model under a buffer zone system to rehabilitate a degraded riparian forest under periodic flooding using native species, which may be replicated in Ipaba. Such NBS may be a useful strategy for the Doce River rehabilitation in addition to the sodium and ether-amine remediation technology recommended by Scotti et al. (2020) and Gomes et al. (2021). ...
The Fundão Dam rupture in Mariana, Brazil spilled contaminated tailings across the Doce River basin reaching several towns such as Ipaba. Ibapa's agricultural and fishing activities declined by 50% due to the toxicity of sodium and ether-amine, followed by a reduction of nitrate resulting in inhibition of plant growth and biota. A settler's community in Ipaba composed of 51 families whose main sources of income were agriculture and fishing activities have abandoned their properties because the land became unproductive after the Fundão dam rupture, and the rural exodus is a current concern in the town. However, previous research has demonstrated that the remediation of sodium and ether-amine, as well as the recovery of soil fertility is feasible, enabling the establishment of the native Atlantic Forest and crop species. Such procedures are recommended to recover the agricultural production in Ipaba. Aiming at protecting these cropping areas against flooding, we propose the creation of riparian forests in the floodplains. In order to make the settlers able to properly manage their lands in a post-disaster scenario, a recovery plan for Ipaba may be implemented via nature based solutions supported by social capital actions such as agroforestry technical training schools and social association, which are shown through schemes and three-dimensional modelling.
... With the aim of remediating ether amine and Na toxicities as well as alkaline and infertility conditions, we established a remediation model to rehabilitate a riparian area reached by the contaminated tailings using the following 3 costrategies: phytoremediation, physical remediation, and chemical remediation. The early results showed that this model was effective in remediating the tailings that were contaminated with Na and ether amine, and also had high pH and low organic matter and fertility; the model also showed success in creating a forest fragment with native species of the Brazilian Atlantic Forest (Scotti et al. 2020). Therefore, the aims of the present study were to evaluate the effectiveness of this functional remediation model over 1 yr to remove the contaminants and to assess the success of the land rehabilitation through biotic and abiotic indicators. ...
... Twelve woody species of the Brazilian Atlantic Forest previously screened for tolerance to the contaminated sediment (Scotti et al. 2020) and belonging to the Anacardiaceae, Bignoniaceae, Fabaceae, and Malvaceae families were transplanted to the field (Table 1). Plants were assessed in relation to survival and height growth after 6 and 12 mo after transplantation. ...
... Under field conditions, the woody species selected for tolerance to the sediment toxicity showed the highest plant survival and better growth performance in T1 than in T2, at both 6 (Scotti et al. 2020) and 12 mo after planting ( Figure 1D and E and Supplemental Data, Figure S1D). Although the plant growth in T2 was worse in the first 6 mo of planting compared with that in T1, at 12 mo there was some growth recovery in T2, reaching a similar height to T1 at 6 mo (Supplemental Data, Figure S2). ...
The tailings spilled by the Fundão dam rupture in the Doce River basin (Brazil) presented high pH, elevated sodium and ether‐amine contents as well as low soil organic matter. Aiming at alleviating these toxic compounds, we established two remediations strategies: T1‐phytoremediation with tolerant native species of the Atlantic Forest cultivated on scraped sediment plus the incorporation of organic matter (OM) and T2‐phytoremediation with native species plus superficial deposition of OM. The experimental site (ES) was compared with a degraded site (DS) reached by dam tailings and a preserved site (PS), a fragment of preserved Atlantic Forest. After twelve months, plants showed an outstanding growth, especially in T1(~ 4 m) and the remediation procedures resulted in a significant decrease of pH (from 8.0 to ~ 6.0), sodium (from 154 mg/kg to 22–35 mg/kg) and electrical conductivity as well as ether‐amine (from 6.0 mg/kg to 0.5 mg/kg) in both treatments. By contrast, ammonium, a product of ether‐amine degradation, showed a significant increase in ES, followed by a significant increase of nitrate and improvement of soil microbial populations assessed by phospholipid fatty acid analysis. The treatments also improved the soil fertility in ES, as estimated by soil nutrients, cation exchange capacity (CEC) and soil aggregation. Based on the analysed parameters, a principal component analysis (PCA) showed that samples from DS and PS clustered in an opposed position and those from ES grouped in an intermediate position but closer to PS. Overall, our results demonstrated that the remediation procedures adopted were effective and allowed the rehabilitation of a riparian forest reached by dam tailings contaminated with sodium and ether‐amine. This article is protected by copyright. All rights reserved.
... Metals in the sediments were registered at the same levels as preserved sites not affected by the dam tailings [2] and the regional background, both before [6] and after [7] the disaster. Despite the great impact of these contaminants over such a vast area [2], [8], [9] were able to establish a pioneer remediation model to reduce the ether-amine and sodium in a riparian area affected by contaminated sediment by using phyto-and physical-chemical co-strategies. These strategies were able to remediate and reclaim the affected site. ...
... The N-NH4 content was also found to be elevated in the settler properties (ES), but similar to the PS. In contrast, N-NO3 was strongly inhibited (Table 1), a finding also reported by [2] and [9] in dam tailing sediments. Higher levels of N-NH4 probably derive from ether-amine, but the low N-NO3 contents suggest a lack of soil-nitrifying bacteria as a result of a decline of microbial communities and diversity due to the dam tailings [2], [9], [13]. ...
... In contrast, N-NO3 was strongly inhibited (Table 1), a finding also reported by [2] and [9] in dam tailing sediments. Higher levels of N-NH4 probably derive from ether-amine, but the low N-NO3 contents suggest a lack of soil-nitrifying bacteria as a result of a decline of microbial communities and diversity due to the dam tailings [2], [9], [13]. Sodium toxicity may inhibit plant growth, induce senescence and cause plant mortality [14] and ammonium may be toxic to native and agronomic species [15]. ...
Mining causes extreme forms of soil degradation and creates new surfaces and topography. The new landforms have increased average slopes with implications for increased run-off and erosion, while mine pits and tailing dams may alter groundwater as well as surface water. Soil biota is removed or otherwise hampered, and in addition, nutrient cycling, biodiversity and resilience of vegetation are all altered by mine site disturbance. The process of rehabilitation involves the reduction of excessively steep slopes and requires significant earth movement using large machinery, which in turn causes subsoil compaction. Deep ripping to improve soil aeration and water infiltration is usually required to create suitable conditions for root growth and development in the subsurface layers. Capping the area with the original surface and/or subsoil, which supplies organic matter, microorganisms and a seedbank from the original ecosystem, will greatly support root growth and plant development. The subsoil conditions control the growth and development of the root system, which is specifically affected by high bulk density, pans, hardsetting, compaction layers, extreme texture (sandy, silty or clayey) and adverse chemical properties (high sodicity, alkalinity, salinity, acidity and other possible toxic ions and materials). The limitations of the subsoil of mined land and tailings are discussed, and case studies of rehabilitation after bauxite and iron ore mining are described to demonstrate the main practices applied and results. Overall, the types and intensity of soil constraints are site specific, and consequently the practices adopted to restore or rehabilitate each area must consider the local conditions to achieve the best outcomes. .
In the process of recovering degraded areas, the establishment of succession of arboreal plants after the planting of herbs is an efficient strategy for diversifying vegetation cover and improving soil quality. In this sense, the objective of this research was to evaluate, in microcosm, the effect of herbaceous pre-cultivation on the initial development of Enterolobium contortisiliquum and on the rehabilitation of the physical, chemical, and biological characteristics of the iron mining tailings from the Fundão dam, Mariana, Brazil. Five different herbaceous pre-cultivation systems were applied: control without pre-cultivation (T/E); Urochloa ruziziensis (U/E); U. ruziziensis + Crotalaria spectabilis (U + C/E); U. ruziziensis + Guizotia abyssinica (U + G/E); and U. ruziziensis + C. spectabilis + G. abyssinica (U + C + G/E). After 120 days of cultivation, we evaluated the tree development and the physical, chemical, and biological attributes of the tailings. The dry mass of the total shoot and the stem of E. contortisiliquum did not differ between the pre-cultures, whereas the dry mass of the leaf was lower in U + C/E. In general, the biological attributes of the tailings were the most sensitive to the changes that occurred due to the different herbaceous pre-cultivation arrangements. In the treatments U/E, U + C/E, and U + G/E, greater efficiency was observed in the production of microbial biomass carbon and in the total enzymatic activity of the soil. E. contortisiliquum proved to be efficient in the absorption of sodium (Na), copper (Cu), zinc (Zn), chromium (Cr), and nickel (Ni), demonstrating that this tree species has the potential to be used in the revegetation of tailings. The use of fast-growing plants activates the soil microbiota and favors the arboreal being an efficient strategy for the tailings rehabilitation process.
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 disaster caused by the rupture of the Samarco tailings dam affected several Brazilian cities and created environmental and economic problems for the Doce River basin. For this reason, the aim of this study was to investigate the use of Pleurotus strains in the removal of toxic metals from the water of the Doce River. Aluminium, arsenic, barium, beryllium, bismuth, cadmium, caesium, lead, cobalt, copper, chromium, indium, iron, lithium, magnesium, manganese, mercury, nickel, silver, selenium, strontium, thallium, uranium, vanadium and zinc in Doce River water samples were quantified by inductively coupled plasma mass spectrometry. Three Pleurotus strains were tested for their capacity to remove potentially toxic metals from these water samples. In addition, Ames test was performed to verify the mutagenic potentials of these samples. Initially, the Doce River water samples showed high concentrations of aluminium, arsenic, barium, lead, iron, magnesium and manganese. But, the analyses from the batch system indicated that Pleurotus efficiently reduced lead (97%), iron (96%), aluminium (95%), manganese (92%), arsenic (87%) and barium (61%). The Ames test indicated that water samples treated with the fungal strains showed decreased mutagenicity. Studies on the contact time effect showed that the peak metal elimination was achieved between 12 and 24 h after fungal inoculation for most of the metals evaluated with a tendency to stabilize during the subsequent period for the elements aluminium, arsenic, barium, iron and lead. Thus, the results indicate that these Pleurotus strains have a biotechnological potential in bioremediation of contaminated or degraded sites.
The objective of this research was to evaluate a soil recovery strategy in soils that were affected by iron mining tailing using herbaceous species inoculated with Acaulospora morrowiae (arbuscular mycorrhizal fungus (AMF)). Tailings were collected on the banks of the Gualaxo do Norte river, one of the places impacted by the Fundão Dam rupture, where tailing layers that were more than one meter were deposited. The experiment was carried out in a greenhouse, using 6 kg pots of non-sterile reject, in a randomized block design in a 4 × 2 factorial scheme, with four cropping systems (Urochloa ruziziensis single crop–RS; and intercropping cultivation: U. ruziziensis with Crotalaria spectabilis–R + C; U. ruziziensis with Guizotia abyssinica–R + G and U. ruziziensis with C. spectabilis and G. abyssinica–R + C + G), with two AMF inoculation conditions (with 200 A. morrowiae spores per pot, and no inoculation), with three replications and 100 days duration. The R + C and R + C + G systems presented the highest shoot dry matter (SDM) yields. Regarding root dry matter production (RDM), a variation of 9.2 g of pot⁻¹ roots was observed between the R + C and R + G systems. Mycorrhizal colonization (MC) was higher in the cultivation system with the three herbaceous species, being the R + C + G system 52% higher than RS system. Spore density did not vary among treatments. Microbial carbon biomass was higher in the RS and R + G treatments when not inoculated. Basal respiration was also higher when not inoculated. Overall, the R + C + G system was more efficient than other systems in the accumulation of elements. The cultivation system with three herbaceous plants proved to be efficient in establishing itself initially in the iron mining tailings, being a viable alternative for the rehabilitation process.
