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1.
Water Sci Technol ; 82(5): 887-904, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33031068

RESUMO

The effectiveness of two Azadirachta indica bark activated carbons (ABAC) for the removal of selected toxic metals from mining wastewater and the attendant challenge of multivariate factors in the process were enhanced through optimization studies. Experimental design was carried out using adsorbent dosage, agitation rate, contact time, grain size, pH and temperature as independent variables. Batch adsorption experiments were conducted using the experimental design result, then the experimental data obtained were optimized using Design-Expert software and the results validated. Optimum values for ABAC-NaOH adsorbent were 1.999 g of adsorbent dosage, 149.73 rpm agitation rate, 119.55 min contact time, 2 mm grain size, pH of 7 and 30 °C temperature; while for ABAC-HCl adsorbent the optimum values were 3.993 g of adsorbent dosage, 150 rpm agitation rate, 120 min contact time, 2 mm grain size, pH of 7.001 and 30 °C temperature. These resulted in 100% removal efficiencies for all the selected toxic metals with standard errors of between 0.02 and 2.72%. So the optimization process is a very useful tool in adsorption studies. It has the merits of being economical, energy and time saving, and is therefore strongly recommended for the biosorption of toxic metals from mining wastewater using Azadirachta indica adsorbent.


Assuntos
Azadirachta , Águas Residuárias , Concentração de Íons de Hidrogênio , Metais , Mineração , Casca de Planta
2.
Chemosphere ; 254: 126904, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32957297

RESUMO

Estimating bioaccessible content of mercury in soils is essential in evaluating risks that contaminated soils pose. In this study, soil samples spiked with HgCl2 through adsorption were used to test the effects of liming, soil organic matter, soil depth, and Hg concentration on the following bioaccessibility tests: dilute nitric acid at room temperature, dilute nitric acid at body temperature, Simplified Bioaccessibility Extraction Test (SBET) method, and gastric phase of the In vitro Gastrointestinal (IVG) protocol. Soil and sediment samples from Descoberto, Minas Gerais (Brazil), a city with a well-known record of Hg contamination from artisanal mining, were subjected to these bioaccessibility tests for the first time, and the different methods of estimating bioaccessible content were compared. Bioaccessible fractions in spiked samples ranged from 10% to 60%, and this high bioaccessibility was due to the highly soluble species of Hg and the short time under adsorption. In general, clay and organic matter decreased bioaccessible content. Although the soil in Descoberto is undoubtedly polluted, mercury bioaccessibility in that area is low. In general, dilute nitric acid estimated higher bioaccessible content in soil samples, whereas the SBET method estimated higher bioaccessible content in sediment samples. In multivariate analysis, two groups of bioaccessibility tests arise: one with the two nitric acid tests, and the other with SBET and the gastric phase of the IVG protocol. The addition of pepsin and glycine in the last two tests suggests a more reliable test for assessing mercury bioaccessibility.


Assuntos
Argila/química , Substâncias Húmicas/análise , Mercúrio/análise , Mineração , Poluentes do Solo/análise , Solo/química , Adsorção , Disponibilidade Biológica , Brasil , Cidades , Mucosa Gástrica/metabolismo , Humanos , Mucosa Intestinal/metabolismo , Mercúrio/metabolismo , Modelos Biológicos , Ácido Nítrico/química , Poluentes do Solo/metabolismo
3.
Bull Environ Contam Toxicol ; 105(4): 633-638, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32960332

RESUMO

Waste disposal, metal plating, refineries, and mining operations frequently contaminate soils with nickel (Ni). We explored the effects of artificial Ni contamination (0, 56, and 180 mg Ni kg-1) on the soil biochemical indices. The lab experiment also investigated the possible use of kunai grass (Imperata cylindrica) biochar at a 0.75% dry weight basis to alleviate contamination effects. The biochemical indices such as dehydrogenase enzyme activity, acid phosphatase enzyme activity, and soil respiration rates were monitored in three replications. High level of Ni (180 mg kg-1) suppressed soil respiration rate by 37% and dehydrogenase activity by 62% up to 15 days. The acid phosphatase activity was not affected by Ni levels and was insensitive to Ni contamination. Biochar application to the Ni contaminated soil did not improve the soil's key biological properties. The beneficial effects of biochar could be limited to improvements in soil chemical properties and not on index biological properties.


Assuntos
Níquel/análise , Poluentes do Solo/análise , Carvão Vegetal , Mineração , Poaceae , Solo/química
4.
J Environ Radioact ; 222: 106324, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32892898

RESUMO

Radium is a naturally occurring radioactive element commonly found at low levels in natural systems such as lacustrine or marine sediments. Anthropogenic activities including former uranium mining activities can lead to the dissemination of radium isotopes having high radiological toxicities, which potentially threaten the safety of nearby environments. Although radium mobility in oxidized environments is known to be largely governed by sorption/desorption onto Fe and Mn oxyhydroxides and coprecipitation with sulfate minerals (e.g. barite), little is known regarding its behavior under reducing conditions, which are the conditions typically encountered in organic-rich systems such as wetlands and lake sediments. The present study aims at understanding the behavior of long-lived radium isotopes (226Ra and 228Ra), during early diagenesis of lake sediments contaminated by former uranium mining activities. Solid and pore water concentrations of 226Ra and 228Ra were determined using ultra low background gamma spectrometry, which allowed improvement of detection limits and measurement accuracy. This study shows that the downcore distribution of radium isotopes is closely related to the reductive dissolution of iron and manganese oxyhydroxides below the sediment-water interface. The resulting diffusive fluxes of 226Ra and 228Ra (4.1 10-25 and 4.7 10-28 mol cm-2.s-1) are however significantly lower than other radium-impacted environments, such as uranium mill tailings pond and phosphate industry-impacted sediments, and are similar to those reported for natural marine environments. Hence, in the reduced lake sediments of Saint-Clement, the major fraction of radium is trapped by the solid phase, while early diagenesis only induces a slight mobility of this radioelement.


Assuntos
Mineração , Monitoramento de Radiação , Rádio (Elemento) , Urânio , Sedimentos Geológicos , Rádio (Elemento)/análise , Áreas Alagadas
5.
Waste Manag ; 118: 68-78, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32891025

RESUMO

Enhanced Landfill Mining (ELFM) is a powerful tool for the sustainable management of landfill sites, aiming at both land reclamation and material recovery/reuse. To enhance the recovery and recycling rate of excavated plastic fractions, in most cases destined to energy recovery, new convenient, effective and sustainable strategies are needed. In this study, a recovery and valorization process of ELFM excavated plastics has been validated through an integrated experimental and Life Cycle Assessment (LCA) approach, demonstrating the environmental sustainability of the secondary raw material generated, in terms of use of resources and emissions generated. In particular, the secondary granulate from ELFM was compared with a virgin product and the last one resulted to have a higher impact (more than 4.46 times greater than the first one), in particular for the use of the resource crude oil as raw material in the production of primary LDPE. The valorization process of the excavated plastic made the mechanical properties of the secondary raw material comparable to that of a primary material.


Assuntos
Petróleo , Gerenciamento de Resíduos , Mineração , Plásticos , Reciclagem , Instalações de Eliminação de Resíduos
6.
Ecotoxicol Environ Saf ; 205: 111267, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32992213

RESUMO

Arsenic is a common contaminant in gold mine soil and tailings. Microbes present an opportunity for bio-treatment of arsenic, since it is a sustainable and cost-effective approach to remove arsenic from water. However, the development of existing bio-treatment approaches depends on isolation of arsenic-resistant microbes from arsenic contaminated samples. Microbial cultures are commonly used in bio-treatment; however, it is not established whether the structure of the cultured isolates resembles the native microbial community from arsenic-contaminated soil. In this milieu, a culture-independent approach using Illumina sequencing technology was used to profile the microbial community in situ. This was coupled with a culture-dependent technique, that is, isolation using two different growth media, to analyse the microbial population in arsenic laden tailing dam sludge based on the culture-independent sequencing approach, 4 phyla and 8 genera were identified in a sample from the arsenic-rich gold mine. Firmicutes (92.23%) was the dominant phylum, followed by Proteobacteria (3.21%), Actinobacteria (2.41%), and Bacteroidetes (1.49%). The identified genera included Staphylococcus (89.8%), Pseudomonas (1.25), Corynebacterium (0.82), Prevotella (0.54%), Megamonas (0.38%) and Sphingomonas (0.36%). The Shannon index value (3.05) and Simpson index value (0.1661) indicated low diversity in arsenic laden tailing. The culture dependent method exposed significant similarities with culture independent methods at the phylum level with Firmicutes, Proteobacteria and Actinobacteria, being common, and Firmicutes was the dominant phylum whereas, at the genus level, only Pseudomonas was presented by both methods. It showed high similarities between culture independent and dependent methods at the phylum level and large differences at the genus level, highlighting the complementarity between the two methods for identification of the native population bacteria in arsenic-rich mine. As a result, the present study can be a resource on microbes for bio-treatment of arsenic in mining waste.


Assuntos
Actinobacteria/efeitos dos fármacos , Arsênico/toxicidade , Firmicutes/efeitos dos fármacos , Metagenômica/métodos , Proteobactérias/efeitos dos fármacos , Poluentes do Solo/toxicidade , Actinobacteria/citologia , Actinobacteria/genética , Arsênico/análise , Biodegradação Ambiental , Meios de Cultura/química , Farmacorresistência Bacteriana/efeitos dos fármacos , Firmicutes/citologia , Firmicutes/genética , Ouro , Testes de Sensibilidade Microbiana , Microbiota/efeitos dos fármacos , Microbiota/genética , Mineração , Proteobactérias/citologia , Proteobactérias/genética , RNA Ribossômico 16S/genética , Solo/química , Microbiologia do Solo , Poluentes do Solo/análise
7.
Nat Commun ; 11(1): 4174, 2020 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-32873789

RESUMO

Renewable energy production is necessary to halt climate change and reverse associated biodiversity losses. However, generating the required technologies and infrastructure will drive an increase in the production of many metals, creating new mining threats for biodiversity. Here, we map mining areas and assess their spatial coincidence with biodiversity conservation sites and priorities. Mining potentially influences 50 million km2 of Earth's land surface, with 8% coinciding with Protected Areas, 7% with Key Biodiversity Areas, and 16% with Remaining Wilderness. Most mining areas (82%) target materials needed for renewable energy production, and areas that overlap with Protected Areas and Remaining Wilderness contain a greater density of mines (our indicator of threat severity) compared to the overlapping mining areas that target other materials. Mining threats to biodiversity will increase as more mines target materials for renewable energy production and, without strategic planning, these new threats to biodiversity may surpass those averted by climate change mitigation.


Assuntos
Biodiversidade , Mudança Climática , Conservação dos Recursos Naturais/estatística & dados numéricos , Mineração/estatística & dados numéricos , Energia Renovável/efeitos adversos , Análise Espacial
8.
J Environ Manage ; 275: 111266, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32846359

RESUMO

Acid mine drainage (AMD) is a challenge for current and legacy mining operations worldwide given its potential to severely harm ecosystems and communities if inadequately managed. Treatment costs for AMD are amongst the highest in the industrial wastewater treatment sector, with limited sustainable options available to date. This work demonstrates a novel chemical-free approach to tackle AMD, whereby staged electrochemical neutralisation is employed to treat AMD and concomitantly recover metals as precipitates. This approach was guided by physico-chemical modelling and tested on real AMD from two different legacy mine sites in Australia, and compared against conventional chemical-dosing-based techniques using hydrated lime (Ca(OH)2) and sodium hydroxide (NaOH). The electrochemical treatment demonstrated the same capacity than Ca(OH)2 to neutralise AMD and remove sulfates, and both were significantly better than NaOH. However, the electrochemical approach produced less voluminous and more easily settleable sludge than Ca(OH)2. Moreover, the staged treatment approach demonstrated the potential to produce metal-rich powdered solids with a targeted composition, including rare earth elements and yttrium (REY). REY were recovered in concentrations up to 0.1% of the total solids composition, illustrating a new avenue for AMD remediation coupled with the recovery of critical metals.


Assuntos
Metais Terras Raras , Poluentes Químicos da Água , Austrália , Ecossistema , Metais/análise , Mineração , Poluentes Químicos da Água/análise
9.
Trends Ecol Evol ; 35(10): 853-857, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32741648

RESUMO

Scientific misconceptions are likely leading to miscalculations of the environmental impacts of deep-seabed mining. These result from underestimating mining footprints relative to habitats targeted and poor understanding of the sensitivity, biodiversity, and dynamics of deep-sea ecosystems. Addressing these misconceptions and knowledge gaps is needed for effective management of deep-seabed mining.


Assuntos
Ecossistema , Mineração , Biodiversidade
10.
Ecotoxicol Environ Saf ; 202: 110921, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800256

RESUMO

Jarosite is one of the iron oxyhydroxysulfate minerals that are commonly found in acid mine drainage (AMD) systems. In natural environments, phosphate and sulfate reducing bacteria (SRB) may be coupled to jarosite reduction and transformation. In this research, the effect of phosphate on jarosite reduction by SRB and the associated secondary mineral formation was studied using batch experiments. The results indicated that Fe3+ is mainly reduced by biogenic S2- in this experiment. The effect of PO43- on jarosite reduction by SRB involved not only a physico-chemical factor but also a microbial factor. Phosphate is an essential nutrient, which can support the activity of SRB. In the low PO43- treatment, the production of total Fe2+ was found to be slightly larger than that in the zero PO43- treatment. Sorption of PO43- effectively elevated jarosite stability via the formation of inner sphere complexes, which, therefore, inhibited the reductive dissolution of jarosite. At the end of the experiment, the amounts of total Fe2+ accumulation were determined to be 4.54 ± 0.17a mM, 4.66 ± 0.22a mM, 3.91 ± 0.04b mM and 2.51 ± 0.10c mM (p < 0.05) in the zero, low, medium and high PO43- treatments, respectively, following the order of low PO43- treatment > zero PO43- treatment > medium PO43- treatment > high PO43- treatment. PO43- loading modified the transformation pathways for the jarosite mineral, as well. In the zero PO43- treatment, the jarosite diffraction lines disappeared, and mackinawite dominated at the end of the experiment. Compared to PO43--free conditions, vivianite was found to become increasingly important at higher PO43- loading conditions. These findings indicate that PO43- loading can influence the broader biogeochemical functioning of AMD systems by impacting the reactivity and mineralization of jarosite mineral.


Assuntos
Bactérias/metabolismo , Compostos Férricos/química , Fosfatos/química , Sulfatos/química , Adsorção , Biodegradação Ambiental , Compostos Ferrosos , Ferro/química , Compostos de Ferro/química , Minerais , Mineração , Oxirredução
11.
J Environ Manage ; 273: 111139, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32768761

RESUMO

Potentially toxic elements (PTEs) present in abandoned mining wastes (AMW) are of great concern because of potential risks to human health and ecosystems. Indices of contamination (IC) applied to mining wastes are calculated using the total concentration of PTEs and comparing them with regional geochemical backgrounds. However, determining the total content of heavy metals is insufficient to assess the hazard of mining wastes. Therefore, in addition to total concentration, the potential risk is also evaluated through water mobility of elements. Accordingly, leaching procedures are useful tools for the geochemical characterization of soluble constituents that are mobilized. In this study, the solubility of PTEs from different types of mining wastes is comparatively assessed using three standard leaching methods (European; U.S. Geological Survey and; Mexican). The Hazard Average Quotient (HAQ) was calculated to assess the potential Toxicity Factor (TF). TF is an indicator of the relative potential toxicity of wastes and is the basis for the classification of AMW. A comparative assessment provides evidence that there are no statistically significant differences in PTEs solubility by the three leaching methods and it was also found that the pH of the eluates was dictated by the type of waste. Results suggest that the IC gives an indicator of the potential contamination of soils and sediments by erosive processes, or a long-term measure, whereas TF assesses the possibility of contaminating water in the short term. The most significant finding is the new ranking scale of TF, as a function of HAQ, applied to the Mexican standard leaching test. This factor, together with other considerations relating to risk-generating processes, might then be applied in places having large amounts of recorded AMW, such as the Iberian Peninsula and Latin America, where effective management is required to rank sites, based on preliminary environmental and human risk assessment.


Assuntos
Metais Pesados/análise , Poluentes do Solo/análise , Ecossistema , Monitoramento Ambiental , Humanos , México , Mineração
12.
PLoS Negl Trop Dis ; 14(8): e0008380, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32797078

RESUMO

In French Guiana, five species are associated with Cutaneous Leishmaniasis (CL). Though infections with Leishmania guyanensis, L. (V.) braziliensis and L. (L.) amazonensis have been extensively described, there are few available clinical and genetic data on L. (V.) lainsoni and L. (V.) naiffi. We determined the clinical and epidemiological features of all cases of CL due to L. (V.) naiffi and L. (V.) lainsoni diagnosed in French Guiana between 2003 and 2019. Phylogenetic analysis was performed by sequencing a portion of HSP70 and cyt b genes. Five cases of L. naiffi and 25 cases of L. lainsoni were reported. Patients infected by L. (V.) lainsoni were usually infected on gold camps, mostly along the Maroni river (60%), while L. naiffi was observed in French patients infected on the coast (100%). A high number of pediatric cases (n = 5; 20%) was observed for L. (V.) lainsoni. A mild clinical course was observed for all cases of L. (V.) naiffi. HSP70 and cyt b partial nucleotide sequence analysis revealed different geographical clusters within L. (V.) naiffi and L. (V.) lainsoni but no association were found between phylogenetic and clinical features. Our data suggest distinct socio-epidemiological features for these two Leishmania species. Patients seem to get infected with L. (V.) naiffi during leisure activities in anthropized coastal areas, while L. (V.) lainsoni shares common features with L. (V.) guyanensis and braziliensis and seems to be acquired during professional activities in primary forest regions. Phylogenetic analysis has provided information on the intraspecific genetic variability of L. (V.) naiffi and L. (V.) lainsoni and how these genotypes are distributed at the geographic level.


Assuntos
Leishmania/classificação , Leishmaniose Cutânea/tratamento farmacológico , Leishmaniose Cutânea/epidemiologia , Adolescente , Adulto , Criança , Pré-Escolar , Citocromos b/genética , Feminino , Guiana Francesa/epidemiologia , Proteínas de Choque Térmico HSP70/genética , Humanos , Lactente , Leishmania/genética , Leishmania/patogenicidade , Leishmaniose Cutânea/patologia , Atividades de Lazer , Masculino , Pessoa de Meia-Idade , Mineração , Doenças Negligenciadas , Filogenia , Estudos Retrospectivos , Análise de Sequência de DNA
13.
PLoS One ; 15(8): e0236718, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32797052

RESUMO

High-flow low-expansion backfill materials have been developed to improve difficult slurry pipeline transport and poor roof-contact effect of many filling materials. The fly ash content was fixed at 80%, with 8.5% - 9.5% mineral powder content, 8.5% - 9.5% lime, 2% - 3% desulfurized gypsum, 0.9% - 1.2% sodium carbonate, and 0.01% - 0.02% aluminum powder content. The prepared backfill material processed good fluidity, with the expansion rate of the hardened material reaching 2% - 3%, and compressive strength on 90 d reaching 4 MPa-5.5 MPa. SEM observations indicated that as the aluminum content increased, ettringite on bubble walls transformed from a fine-needle to needle-rod shape. Secondly, the hydration products of the system were mainly hydrated calcium silicate gel and ettringite, which interconnected and promoted the formation of the structure. The backfill material has extensive sources of raw materials, low cost, simple filling process, and good filling effect.


Assuntos
Cinza de Carvão/química , Mineração , Compostos de Cálcio/química , Sulfato de Cálcio/química , Óxidos/química , Água/química
14.
Chemosphere ; 260: 127582, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32758782

RESUMO

This is a systematic study of human health risk assessment (HHRA) and risk categorization for inorganic mercury (IHg) and methylmercury (MeHg) in Hg mining areas. A multi-pathway exposure model coupled with Monte Carlo simulation was constructed for the Wanshan Hg mining area (WSMM), Southwestern China, with consideration of oral ingestion (foodstuffs, water and soil), dermal contact (water and soil), and inhalation (gaseous Hg and particulate Hg). The results show that dietary intake (food and water), gaseous Hg inhalation, oral ingestion of soil particles, dermal contact, and particulate Hg inhalation comprised 88.3-96.3%, 3.49-6.14%, 0.14-5.3%, 0.02%, and <0.01% of total IHg ingestion, respectively. As expected, rice consumption contributed the highest proportion (86.3-92.7%) of MeHg. The study shows that the elevated MeHg exposure risk is the most significant issue in Hg mining areas. In addition, Hg risk categorization and prioritization in the WSMM are established for the first time based on rice-based exposure doses of IHg and MeHg. Target areas for future treatment and/or remediation are characterized according to thresholds of reference dose and provisional tolerable weekly intake for exposure doses, as well as risk screening values and risk control values for contaminated soil. The proposed multi-pathway exposure model is strongly recommended for the HHRA of Hg-contaminated sites worldwide and helps facilitate the implementation of the Minamata Convention on Mercury.


Assuntos
Mercúrio/análise , Compostos de Metilmercúrio/análise , Mineração , Medição de Risco , Poluentes do Solo/análise , China , Monitoramento Ambiental , Humanos , Modelos Teóricos , Método de Monte Carlo , Oryza/química , Projetos Piloto
15.
Sci Total Environ ; 747: 141295, 2020 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-32777513

RESUMO

Uranium mining and milling activities raise environmental concerns due to the release of radioactive and other toxic elements. Their long-term management thus requires a knowledge of past events coupled with a good understanding of the geochemical mechanisms regulating the mobility of residual radionuclides. This article presents the results on the traces of anthropic activity linked to previous uranium (U) mining activities in the vicinity of the Rophin tailings storage site (Puy de Dôme, France). Several complementary approaches were developed based on a study of the site's history and records, as well as on a radiological and chemical characterization of soil cores and a dendrochronology. Gamma survey measurements of the wetland downstream of the Rophin site revealed a level of 1050 nSv.h-1. Soil cores extracted in the wetland showed U concentrations of up to 1855 mg.kg-1, which appears to be associated with the presence of a whitish silt loam (WSL) soil layer located below an organic topsoil layer. Records, corroborated by prior aerial photographs and analyses of 137Cs and 14C activities, suggest the discharge of U mineral particles while the site was being operated. Moreover, lead isotope ratios indicate that contamination in the WSL layer can be discriminated by a larger contribution of radiogenic lead to total lead. The dendroanalysis correlate U emissions from Rophin with the site's history. Oak tree rings located downstream of the site contain uranium concentrations ten times higher than values measured on unaffected trees. Moreover, the highest U concentrations were recorded not only for the operating period, but more surprisingly for the recent site renovations as well. This integrated approach corroborates that U mineral particles were initially transported as mineral particles in Rophin's watershed and that a majority of the deposited uranium appears to have been trapped in the topsoil layer, with high organic matter content.


Assuntos
Monitoramento de Radiação , Urânio , França , Mineração , Solo , Urânio/análise
16.
Science ; 369(6506): 906-909, 2020 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-32820107
17.
PLoS One ; 15(8): e0237599, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32785287

RESUMO

The microbial oxidation of metal sulfides plays a major role in the formation of acid rock drainage (ARD). We aimed to broadly characterize the ARD at Ely Brook, which drains the Ely Copper Mine Superfund site in Vermont, USA, using metagenomics and metatranscriptomics to assess the metabolic potential and seasonal ecological roles of microorganisms in water and sediment. Using Centrifuge against the NCBI "nt" database, ~25% of reads in sediment and water samples were classified as acid-tolerant Proteobacteria (61 ± 4%) belonging to the genera Pseudomonas (2.6-3.3%), Bradyrhizobium (1.7-4.1%), and Streptomyces (2.9-5.0%). Numerous genes (12%) were differentially expressed between seasons and played significant roles in iron, sulfur, carbon, and nitrogen cycling. The most abundant RNA transcript encoded the multidrug resistance protein Stp, and most expressed KEGG-annotated transcripts were involved in amino acid metabolism. Biosynthetic gene clusters involved in secondary metabolism (BGCs, 449) as well as metal- (133) and antibiotic-resistance (8501) genes were identified across the entire dataset. Several antibiotic and metal resistance genes were colocalized and coexpressed with putative BGCs, providing insight into the protective roles of the molecules BGCs produce. Our study shows that ecological stimuli, such as metal concentrations and seasonal variations, can drive ARD taxa to produce novel bioactive metabolites.


Assuntos
Ácidos/química , Metagenoma , Microbiota , Mineração , Proteobactérias/genética , Proteobactérias/metabolismo , Transcriptoma , Cobre/química , Marcadores Genéticos , Minerais/química , Proteobactérias/crescimento & desenvolvimento
18.
Bioresour Technol ; 317: 123985, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32805482

RESUMO

A field pilot-scale passive treatment system was developed for in-situ bioremediation of acid mine drainage (AMD). The microbial community and its variation were analyzed. The data proved that 93.7% of total soluble Fe and 99% of soluble Fe(II) could be removed by the system. Principal coordinates analysis (PCoA) showed that a low pH and an elevated Fe concentration within the system created a unique microbial community that was dominated by acidophilic iron-oxidizing bacteria and iron-reducing bacteria. Canonical correlation analysis (CCA) indicated that the pH, iron content and total sulfur jointly determined the composition of the microbial communities. Species of Ferrovum, Delftia, Acinetobacter, Metallibacterium, Acidibacter and Acidiphilium were highly enriched, which promoted the removal of iron. Furthermore, the results revealed important data for the biogeochemical coupling of microbial communities and environmental parameters. These findings are beneficial for further application of in-situ field bioreactors to remediate AMD.


Assuntos
Microbiota , Mineração , Ácidos , Carvão Mineral , Concentração de Íons de Hidrogênio
19.
Water Sci Technol ; 81(12): 2568-2584, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32857744

RESUMO

Iron (Fe), zirconium (Zr) and titanium (Ti) oxides nanoparticles were each embedded onto a weak acid chelating resin for support using the precipitation method to generate three hybrid adsorbents of hydrated Fe oxide (HFO-P), hydrated Zr oxide (HZO-P) and hydrated Ti oxide (HTO-P). This paper reports on the characterization, performance and potential of these generated nanoadsorbents in the removal of toxic metal ions from acid mine drainage (AMD). The optimum contact time, adsorbent dose and pH for aluminium (Al) (III) adsorption were established using the batch equilibrium technique. The metal levels were measured using inductively coupled plasma-optical emission spectrometry. The scanning electron microscopy-energy dispersive X-ray spectroscopy results confirmed the presence of the metal oxides within the hybrid resin beads. HFO-P, HZO-P and HTO-P adsorbed Al(III) rapidly from synthetic water with maximum adsorption capacities of 54.04, 58.36 and 40.10 mg/g, respectively, at initial pH 1.80 ± 0.02. The adsorption of Al(III) is of the second-order in nature (R2 > 0.98). The nanosorbents removed ten selected metals from environmental AMD and the metal removal efficiency was in the order HTO-P > HZO-P > HFO-P. All three hybrid nanosorbents can be used to remove metals from AMD; the choice would be dependent on the pH of the water to be treated.


Assuntos
Poluentes Químicos da Água/análise , Purificação da Água , Adsorção , Concentração de Íons de Hidrogênio , Cinética , Mineração
20.
Environ Monit Assess ; 192(9): 605, 2020 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-32860151

RESUMO

Block sequencing is of great importance in an open-pit mining operation. Sequencing is usually performed to maximize the net present value (NPV). Also, from the environmental viewpoint, the sequence of dumping mined materials is of significant value in the sulfide mines. The potential acid-forming (PAF) waste rocks in these mines can seriously damage the environment due to the formation of acid mine drainage (AMD). To prevent the exposition of the PAF materials, it is essential to design suitable block sequencing. For this purpose, encapsulation of the PAF rocks by non-acid forming (NAF) rocks should be considered during waste dumping. However, this method can impose unnecessary re-handling costs. This issue is due to the determination of the waste-dump sequence based on improper block sequencing obtained from the previous models with the NPV maximization strategy. In the present study, a mixed-integer programming (MIP) model is proposed for generating proper block sequencing taking into account the composition of waste rocks. The main objective of the proposed MIP model is to maximize NPV and minimize the destructive environmental effects of PAF materials dumping. The CPLEX solver was applied to solve the proposed model in small datasets. Then, an artificial bee colony (ABC) is implemented to find out optimum block sequencing and waste dumping (BSWD) on a large scale. The proposed approach was examined employing several sets of data. The obtained results were compared with those of the CPLEX solver as a benchmark. An approximate gap of 2% demonstrates the efficiency of the proposed approach.


Assuntos
Monitoramento Ambiental , Heurística , Meio Ambiente , Mineração , Instalações de Eliminação de Resíduos
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