The rupture of the Brumadinho mining tailings dam in Brazil is considered one of the largest mining disasters in the world, resulting in 244 deaths and 26 missing people, in addition to the ...environmental consequences. The present study aims to evaluate the concentrations of multiple elements and the biological effects on water and sediments of the Paraopeba River after the Brumadinho Dam rupture. The tailings are formed by fine particulate material with large amounts of Fe, Al, Mn, Ti, rare earth metals and toxic metals. In the water, the levels of Fe, Al, Mn, Zn, Cu, Pb, Cd and U were higher than those allowed by Brazilian legislation. In the sediments, Cr, Ni, Cu and Cd levels were higher than the established sediment quality guidelines (TEL-NOAA). The differences in metal concentrations in the water and sediments between the upstream and downstream sides of the dam illustrate the effect of the tailings in the Paraopeba River. Toxicological tests demonstrated that the water and sediments were toxic to different trophic levels, from algae to microcrustaceans and fish. The fish exposed to water and sediments containing mine ore also accumulated metals in muscle tissue. This evaluation emphasizes the necessity of long-term monitoring in the affected area.
The present study performed geochemical fractioning of major and minor elements in a cross-shelf gradient of the Abrolhos Bank, where the largest and most diverse coral reefs in the South Atlantic ...are concentrated. The fractioning was performed using sequential extractions to determine the degree of availability and toxicity of the elements. The mobility pattern of the elements investigated were in the following order: Ca > Mn > Pb > Cr > Zn > Fe > V > Cu > Ba>Al > Ni > Ti. For elements, such as (Ti, Ni, Al, Ba, Cu, V, Fe, Zn, Cr, Pb), the highest concentrations were in the residual phase at some sampling sites. As established by Environment Canada (Threshold Effect Level - TEL and Probable Effect Level - PEL), Ba, Cr, and Ni produced values higher than the limits, associated with higher concentrations of other elements. In addition, significant proportions of these elements were found in mobile phases in the same sites. Thus, more rigorous measures are critical to avoid alarming levels of chronic environmental pollution inside and outside protected areas of the region. To enhance the sustainability of the region, more effective enforcement is crucial to prevent anthropic contamination that may threaten its biodiversity. The results provide the baseline for future studies regarding the potential impacts of the breach of the tailings dam in the region of Mariana, Minas Gerais.
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•Metals were evaluated in surface sediments before the impact of ore tailings dams.•Oxidizable phase elements were related with Corg indicating potential bioavailability.•Mobility levels of metals were in the order of Ca > Mn > Pb > Cr > Zn > Fe > V > Cu > Ba>Al > Ni > Ti.•The concentrations of Ba, Ni, and Cr were above the TEL in three conservation units.•Antropogenic sources increase metal concentration in Santa Barbara Island.
•A novel method for detection and identification of energy theft is proposed for advanced metering infrastructures.•The energy theft detection is made by making comparisons of estimated loads, using ...a three phase static state estimation, with the consumer loads at the transformers level, considering the estimated daily load curve.•Self-Organizing Map and Multilayer Perceptron Artificial Neural Networks are used for identification step.•A comparative analysis with existing methodologies in the literature is presented.•The proposed methodology achieved best results.
This paper presents a novel approach for detection and identification of energy theft in distribution systems considering advanced metering infrastructure. For the energy theft detection stage, a three phase state estimator based on phasor measurement units is used to detect the transformers which have evidence of energy theft. The next step is to identify consumers which are stealing energy. A Self-Organizing Map (SOM) was trained for clustering consumers according to similar consumption patterns. For each class defined by the SOM, a Multilayer Perceptron Artificial Neural Network (MP-ANN) for classification of consumers into two classes, either honest or fraudulent, was created. The main contribution of the energy theft detection step is the reduction of the number of transformers which have suspect consumers without the need to install measurement units on all transformers. The use of ANN allows to identify the fraudulent users considering either cyber or physical attacks. Tests were conducted for energy theft detection step on the IEEE 70 busbar test system. Real data from 5000 consumers were used for identification of fraudulent users. The results show the effectiveness and robustness of the proposed technique, presenting a detection rate close to 93% with a false positive rate less than 2%.
The rupture of Fundão Dam is considered one of the largest environmental disasters in Brazilian history and one of the largest in the world involving tailings dams. The present study analyzed the ...changes in metal concentrations in the dissolved, suspended particulate matter (SPM) and sediment in the period just after (15 days) and six months after the dam rupture, together with the biological and cytogenotoxic effects, from the collapse site until the Doce River mouth in the Atlantic Ocean. After the dam rupture, the tailings were mainly transported as SPM. After six months, with the deposition, there was a decrease in metal concentrations in dissolved and SPM and increased levels were observed in the sediment. Cr, Ni, Cd and Hg levels in sediment were higher than the threshold effects level (TEL/NOAA), especially six months after the dam rupture. The water induced immediate negative biological effects at different levels of the trophic chain, together with Al, Fe, Mn and Zn accumulation in fish muscle. Both water and sediment also showed cytotoxic, genotoxic and mutagenic effects. These data demonstrate the importance of long-term monitoring with abiotic and biotic parameters to clarify the impacts of mining tailings and can help to direct future monitoring programs.
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•The Fundão dam failure is one of the largest environmental disasters in the world.•Immediately the tailings were mainly transported as suspended particulate matter.•After 6 months, with the deposition, the metal levels increased in the sediment.•Water and sediment induced negative biological and toxicogenetic effects.•This joint of abiotic and biotic indicators can direct other monitoring programs.
The present study evaluated the toxicogenetic potential of the water and sediment from Paraopeba River, five days after the rupture of the mining tailings dam at Brumadinho (Minas Gerais, Brazil), on ...January 2019, by Allium cepa test. Water samples collected at sites closest to the collapsed dam caused a higher frequency of genetic damage and lower cell division rate compared to the upstream site. In sediment it was observed a decrease in the cell division rate and genetic damage in the sampling sites closest to the dam. The frequency of aberrations and the mitotic index in A. cepa cells exposed to sediments were negatively associated with the levels of most elements in total and bioavailable fractions. A negative association between some metal concentrations in total and dissolved water with the mitotic index was also observed. Otherwise, the genotoxic effects were positively correlated with the concentrations of most metals. The results demonstrate the potential of the tailings to cause cytogenotoxic effects due the higher metal concentrations released in water column and in sediments. This is the first report highlighting the toxicogenetic potential of the released tailings and reinforce the need for a long-term monitoring of the watershed due the advance of the tailings plume through Paraopeba River over time.
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•After dam rupture, 12 million m3 of mining tailings reached the Paraopeba River.•Water and sediment from river promoted genotoxic effects in Allium cepa.•Cytogenotoxicity was inversely associated with the metals in sediment.•Genotoxic effects were positively associated with toxic metals in water.•Genotoxicity in sites yet not reached by tailing indicates previous contamination.
To evaluate the impacts of the Fundão tailings dam failure (Minas Gerais, Brazil) on water quality of the Doce River, we analyzed metagenomics and physicochemical parameters during the month of the ...disaster and again 6 and 10 months after the disaster. To compare dam conditions before and after the failure, we performed a meta-analysis of physicochemical data from a public database. Immediately after the failure, suspended particulate matter (SPM) in the Doce River was 225–1877 mg L−1. Turbidity and dissolved aluminum and iron concentrations were extremely high, whereas dissolved oxygen was below Brazilian legislation norm (<5 mg L−1) in several locations. Six months later, physicochemical values were below thresholds set by Brazilian guidelines (e.g., SPM = 8–166 mg L−1). Short-term impacts on microbial communities included an increase in Actinobacteria and Bacteroidetes and gene sequences related to microbial virulence, motility, respiration, membrane transport, iron and nitrogen metabolism, suggesting changes in microbial metabolic profiles. The 11 recovered partial genomes from metagenomes (MAGs) had genes related to Fe cycle and metal resistance.
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•Possible effects of pollutants in Doce River after Fundão dam rupture were evaluated.•Fundão tailing induced short-term alterations in the Doce River microbiota.•Streptomycetaceae was detected as useful biomarker of environmental contamination.•Fe cycling genes were found among the 11 metagenome-assembled genomes.•1 year post-disaster, in the wet season, Doce River still showed abnormal turbidity.
On November 5th, 2015, the Fundão dam rupture released >50 million m3 of ore tailings into the Doce River, Minas Gerais State, Brazil. The huge volume of mud spread along the river and reached the ...sea, 17 days after the disaster, in Regência, Espírito Santo State (ES). In 2018, after three years of the disaster, the impacts of the ore tailings in the marine environment are still unclear. This study aims to investigate possible short-term impacts in marine biodiversity caused by the ore tailings' mud over the reef ecosystems that are closest to the disaster area: i.e. recently discovered reefs in the southern Abrolhos Bank. A remote sensing surveillance including winds, sea surface temperature, total suspended material and watercolor (MODIS Aqua data) indicated that the iron tailings plume reached the southern portion of Abrolhos Bank on June 16th, 2016. Subsequently, to obtain further evidence of the presence of the tailings in the coral reefs, water samples were collected in a gradient spanning from the river estuary to the reefs in southern Abrolhos Bank, we also analyzed the isotopic and microbial composition of the samples, as well as the reef benthic composition. Despite no clues of negative impact on benthic (coral) communities, isotopic analysis confirmed the presence of the plume over the reefs area. This study serves as a baseline for future long-term impact assessments of the health of coral reefs in the Abrolhos Bank.
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•The Doce River iron tailings plume reached the Abrolhos Bank on June 16th, 2016.•Analyses of SPM confirmed the presence of the tailing plume over the reef area.•Southerly winds may cause new arrivals of the iron tailing plume to the reefs.•Abrolhos reefs may be suffering with a nutrient enrichment.
Large rivers create major gaps in reef distribution along tropical shelves. The Amazon River represents 20% of the global riverine discharge to the ocean, generating up to a 1.3 × 10(6)-km(2) plume, ...and extensive muddy bottoms in the equatorial margin of South America. As a result, a wide area of the tropical North Atlantic is heavily affected in terms of salinity, pH, light penetration, and sedimentation. Such unfavorable conditions were thought to imprint a major gap in Western Atlantic reefs. We present an extensive carbonate system off the Amazon mouth, underneath the river plume. Significant carbonate sedimentation occurred during lowstand sea level, and still occurs in the outer shelf, resulting in complex hard-bottom topography. A permanent near-bottom wedge of ocean water, together with the seasonal nature of the plume's eastward retroflection, conditions the existence of this extensive (~9500 km(2)) hard-bottom mosaic. The Amazon reefs transition from accretive to erosional structures and encompass extensive rhodolith beds. Carbonate structures function as a connectivity corridor for wide depth-ranging reef-associated species, being heavily colonized by large sponges and other structure-forming filter feeders that dwell under low light and high levels of particulates. The oxycline between the plume and subplume is associated with chemoautotrophic and anaerobic microbial metabolisms. The system described here provides several insights about the responses of tropical reefs to suboptimal and marginal reef-building conditions, which are accelerating worldwide due to global changes.
Recent reports of illegal small-scale alluvial gold mining activities (locally called
garimpo
) by miners working on rafts in the Paraíba do Sul River (PSR) and in one of its tributaries (Muriaé ...River (MR)) have raised concerns about Hg contamination. This study aimed to evaluate the impact of
garimpo
activities on Hg contamination in three environmental compartments. Water, sediment, and aquatic macrophytes (
Pistia stratiotes
) were sampled during the rainy season in PSR, forming a 106-km transect from the point where
garimpo
rafts were seen and/or seized by the Federal Police. They were also sampled in the MR. Total and dissolved mercury (Hg) concentrations in water and total Hg in the suspended particulate matter (SPM) sampled in the PSR increased by 1.7, 1.5, and 2.1 times at the points where the rafts were seen compared to the point immediately upstream. In the MR, Hg concentrations were higher than those in the PSR, but most values in the environmental compartments were below the safe limits (174–486 ng∙g
−1
, threshold and probable effect level, respectively), with the exception of Hg in the SPM of one of the MR sampling points (256 ng∙g
−1
) and the mining tailings (197 ng∙g
−1
). Sediment granulometry was exponentially associated with Hg concentrations in the sediment (
R
2
= 0.75,
p
< 0.0001) and is also essential to understand the physical impacts of
garimpo
on PSR. Future studies should focus on assessing the seasonal variability of Hg concentrations in the studied compartments, especially if
garimpo
is identified during the dry season.
Modal analysis has been widely used for voltage stability assessment based on the sensitivities of reactive powers with respect to voltage magnitudes obtained from the traditional power flow ...Jacobian. It provides a relative measure of proximity to voltage instability and determines participation factors to find the critical areas of the system. However, in practice, the most probable state of the system is determined by state estimation techniques. In this case, the number of measurements gathered from the network is greater than state variables to be estimated, resulting in a non-square Jacobian matrix. In the estimation process, a gain matrix is formed based on the non-square Jacobian and the covariances of the measurements. In this paper, a novel methodology is presented for voltage stability assessment. The properties of the eigenvalues and eigenvectors of a reduced gain matrix are exploited to evaluate the sensitivities of voltage magnitudes with respect to measurements obtained from phasor measurement units, proving that the proposed method is capable of determining the weakest buses related to voltage instability. Tests are conducted using IEEE 14 and 30 bus test systems to show the applicability and efficiency of the proposed methodology.
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