EM - Escola de Minas
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/6
Notícias
A Escola de Minas de Ouro Preto foi fundada pelo cientista Claude Henri Gorceix e inaugurada em 12 de outubro de 1876.
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56 resultados
Resultados da Pesquisa
Item Metabarcoding of soil fungal communities in rupestrian grassland areas preserved and degraded by mining : implications for restoration.(2023) Figueiredo, Maurílio Assis; Silva, Thamar Holanda da; Pinto, Otavio Henrique Bezerra; Leite, Mariangela Garcia Praça; Oliveira, Fábio Soares de; Messias, Maria Cristina Teixeira Braga; Rosa, Luiz Henrique; Câmara, Eduardo Aguiar Saraiva; Lopes, Fabyano Alvares Cardoso; Kozovits, Alessandra RodriguesRupestrian grasslands are vegetation complexes of the Cerrado biome (Brazilian savanna), exhibiting simultaneously great biodiversity and important open-pit mining areas. There is a strong demand for the conservation of remaining areas and restoration of degraded. This study evaluated, using next-generation sequencing, the diversity and ecological aspects of soil fungal communities in ferruginous rupestrian grassland areas preserved and degraded by bauxite mining in Brazil. In the preserved and degraded area, respectively, 565 and 478 amplicon sequence variants (ASVs) were detected. Basidiomycota and Ascomycota comprised nearly 72% of the DNA, but Ascomycota showed greater abundance than Basidiomycota in the degraded area (64% and 10%, respectively). In the preserved area, taxa of different hierarchical levels (Agaromycetes, Agaricales, Mortierelaceae, and Mortierella) associated with symbiosis and decomposition were predominant. However, taxa that colonize environments under extreme conditions and pathogens (Dothideomycetes, Pleoporales, Pleosporaceae, and Curvularia) prevailed in the degraded area. The degradation reduced the diversity, and modified the composition of taxa and predominant ecological functions in the community. The lack of fungi that facilitate plant establishment and development in the degraded area suggests the importance of seeking the restoration of this community to ensure the success of the ecological restoration of the environment. The topsoil of preserved area can be a source of inocula of several groups of fungi important for the restoration process but which occur in low abundance or are absent in the degraded area.Item Native grass sod and plug production as an alternative technique to restore neotropical rupestrian grassland after mining.(2023) Figueiredo, Maurílio Assis; Messias, Maria Cristina Teixeira Braga; Leite, Mariangela Garcia Praça; Kozovits, Alessandra RodriguesDespite the importance of grasses in the structure and functioning of tropical grasslands, there is still a lack of efficient and economically viable techniques to produce and introduce grasses in restoration projects. Here, we evaluated the sod and plug-plant production and planting of a native grass from Brazilian rupestrian grasslands, Sporobolus metallicolus, in a post-bauxite mining. To produce the sod, we used post-mining substrate and its mixture with commercial substrate. Then, we sowed 270 seeds of S. metallicolus on a 4-cm layer of substrate in 144-cm2 trays. Eighty days after sowing, we subdivided the contents of each tray (substrate + plant) into 4 × 3–cm plug-plants. Plug-plants were planted in the degraded area with and without the incorporation of litter from an adjacent conserved rupestrian grassland. We also evaluated the cost of production of each plug-plant. The mixture of substrates provided greater plant growth and rooting, obtaining plug-plants with an average of 13 individuals, dry mass of 270 mg, and estimated cost of US$ 0.0045. In the degraded area, the addition of litter increased shoot biomass gain. Plant survival was 100% with and without litter addition and the plants started seed dispersal at 7 months after planting. The production of S. metallicolus plugs with the mixed substrate and the growth of plants in the post-mined area showed promising results and reduced costs, indicating technical and financial feasibility. The presented techniques can be an option for introducing grasses in degraded areas and optimize the use of seeds.Item Soil-chronosequence and quaternary landscape evolution at the marine terraces of Harmony Point, Nelson Island, Maritime Antarctica.(2022) Rodrigues, William Fortes; Machado, Mariana de Resende; Oliveira, Fábio Soares de; Schaefer, Carlos Ernesto Gonçalves Reynaud; Leite, Mariangela Garcia Praça; Michel, Roberto Ferreira Machado; Araújo, Teodoro Gauzzi Rodrigues deThis study characterized the physical, chemical, macro- and micromorphological soil properties from three successive marine terrace levels from Harmony Point (Nelson Island, Maritime Antarctica) in order to understand the pedological signatures of Quaternary coastal landscape evolution of Maritime Antarctica. Soils were sampled on the Late Holocene beach (current beach) and Mid Holocene marine terraces higher up, at 3, 8, and 12 m a.s.l. At the lower levels, the predominant soils were Gelorthents, whereas Haplogelepts dominate the higher terraces. Soil properties are mostly influenced by parent material and faunal activity, in which cryoclastic (thermal weathering) and phosphatization are the main soil-forming processes. Soils from the upper levels are more developed, deeper with reddish colors, granular structures and incipient formation B horizon. These horizonation features highlight that soils vary according with age of glacier-isostatic terrace uplift, representing a Quaternary soil chronosequence. All marine terrace levels are Ornithogenic soils, at varying degrees. However, the presence of old bird nesting sites for long periods led to formation of phosphatic horizons, stable Fe-phosphate minerals and abundant vegetation in the highest terraces of this part of Maritime Antarctica.Item Permian mixed carbonate–siliciclastic lagoon coastal system in West-Central Gondwana.(2021) Silva, Rafael Oliveira; Leite, Mariangela Garcia Praça; Rudnitzki, Isaac Daniel; Lima, Wagner SouzaAlthough in recent years mixed carbonate–siliciclastic platforms have been increasingly recognized in the Perm- ian of Western Gondwana, there is no detailed description of these mixed systems in West-Central Gondwana. This study focuses on the Permian of the Sergipe–Alagoas Basin (NE Brazil), with the aim of filling this knowledge gap. Based on sedimentological data and microfacies analysis, six facies associations (FA) were identified: FA1 is an eolian–fluvial system, composed of stratified sandstones, FA2 and FA3 represent a mixed tidal flat–lagoon sys- tem composed of microbialites, pelitic/micritic sediments and intraclastic packstones, FA4 represents shoreface wave deposits composed of laminated sandstones and silicified grainstones, and FA5 and FA6 are interpreted as a barrier–tidal inlet system, composed of oolitic/intraclastic grainstones, subtidal microbialites, and mixed rudstones. Facies associations reflect the paleoenvironmental conditions of a coastal environment, with dunes and small rivers adjacent to a mixed carbonate–siliciclastic ramp. This is defined as a lagoon system associated with tidal flats protected from the high-energy region by carbonate shoals and microbial constructions. These de- posits represent the eastern portion of a shallow epicontinental sea that covered lowlands inWest-Central Gond- wana within the arid–semiarid belt, whose climate characteristics are reflected in eolian deposits, desiccation structures, mixed carbonate–siliciclastic facies, and fossil records. The main diagenetic feature observed in petro- graphic analyses was an early diagenetic silicification. Although the absence of spiculites and shelf configuration did not allow a correlation with the Permian glass ramp model, similarities were observed with Eocene glass ramps of Australia, and a relationship with the Permian Chert Event is suggested.Item Phosphatization under birds’ activity : ornithogenesis at different scales on Antarctic Soilscapes.(2021) Rodrigues, William Fortes; Oliveira, Fábio Soares de; Schaefer, Carlos Ernesto Gonçalves Reynaud; Leite, Mariangela Garcia Praça; Pavinato, Paulo SérgioExtensive areas of penguins’ nesting (Pygoscelis sp.), on ice-free areas, account for vast deposits of organic matter- rich guano in maritime Antarctica. One such area, at Harmony Point, currently houses different penguin colonies with extensive and unique ornithogenic soils, where phosphatization is the key soil-forming process. We sought to enhance the knowledge of phosphatization process, products, cycles, and phosphorus (P) forms in these un- usual soils. We compared ornithogenic and non-ornithogenic soils, based on advanced chemical, micromor- phological and mineralogical analyses of samples of guano and phosphate biocrusts, complete with P and OM fractionation. Ornithogenic soils have the organic P-pool as the largest phosphorous compartment, followed by varying P-Ca forms. In contrast, soils unaffected by phosphatization showed a high inorganic P-pool. Penguin guano is enriched with P, Ca, K, Cu, Zn, C and N. The phosphatic biocrusts are composed of struvite and hy- droxyapatite, forming a gradient of phosphate forms. We recognized three different phosphatization environ- ments, namely (i) present-day marine birds’ rookeries, (ii) adjacent zone of rookeries and (iii) abandoned rookeries. Geomorphological evolution of the coastal areas, by Holocene glacier retreat, resulted in the changing location of penguin colonies, resulting in a larger area and varying ages of phosphatization, forming ornithogenic soils with contrasting evolution degrees. Abandoned areas have greater vegetation growth, with higher diversity.Item A hydroelectric dam borrow pit rehabilitation. Two decades after the project, what went wrong?(2021) Souza, Yuri Andrade Figueiredo de; Leite, Mariangela Garcia Praça; Fujaco, Maria Augusta GonçalvesAlthough environmental rehabilitation projects that did not succeed are not uncommon, there are few research papers that deal with the subject. Works on the rehabilitation of borrow pits are even more rare. In an attempt to fulfill some gaps, the present study sought to evaluate the effectiveness of a program for the restoration of a clay borrow pit used for the construction of a hydroelectric plant, twenty years after its execution. In order to assess the current degradation stage and to identify the possible errors of this intervention, the area was mapped using an unmanned aerial vehicle, which allowed the identification of the remaining physical structures, dimensioning of the actual degraded area and characterization of vegetation cover and types of exposed soil. Physical and chemical parameters of the degraded area soils were compared to those of a contiguous preserved area, which was used as a control. Soils of the degraded area are significantly more compacted (with significant reduction in macroporosity) and depleted in organic matter and nutrients. The results showed that the methodologies used in the rehabilitation project were not sufficient to recover the resilience of a deeply degraded ecosystem. The long- term success of a rehabilitation project is only possible with the guarantee of the ecological sustainability of the area, which is largely related to the restoration of soil ecological processes. Most of the time, this cannot be achieved with the simple use of classical erosion control and revegetation techniques and without the addition of sediment material to aid the process.Item Geochemistry of Antarctic periglacial soils from Harmony Point, Nelson Island.(2021) Rodrigues, William Fortes; Oliveira, Fábio Soares de; Schaefer, Carlos Ernesto Gonçalves Reynaud; Araújo, Teodoro Gauzzi Rodrigues de; Leite, Mariangela Garcia PraçaLittle is known about the geochemical baseline of Antarctic soils in diferent environments. We investigated the soil geo- chemistry of the two main landscape units of Harmony Point (Nelson Island, Maritime Antarctica): the coastal domain and the upper platform. Fourteen soil samples (seven in each landscape unit) were divided according to depth (hA for surface and hC for subsurface horizons) and characterized by their major, trace elements and REE concentrations. The concentration of major elements (SiO2, TiO2, Al2O3, Fe2O3, MgO, CaO, MnO, and K2O) were determined by X-ray fuorescence, whereas trace elements were quantifed by inductively coupled plasma-optical emission spectrometry (Co, Ni, As, Cd, Pb, Ba, Cr, Cu, V, Zn, and Zr) and REE by inductively coupled plasma mass spectrometry. The results showed geochemical variation with depth, either related to pedological processes (phosphatization, humifcation, podzolization, and cryoturbation), and parent material constitution (andesitic basalt in upper platform and mixed volcanic sediments in coastal domain). The main chemical aspects distinguishing Harmony Point soils from other Maritime Antarctic soils from the vicinity are: (i) higher CIA index; (ii) P2O5 enrichment due to bird guano and enhanced pedogenesis; (iii) REE retention; (iv) enrichment in Fe2O3 and S concentrations. The REE concentration was infuenced by weathering processes combined with allochthonous inputs, such as volcanic ashes and iceberg-transported granitic boulders at the coastal domain. The Harmony Point soils are little subjected to anthropic impacts, so they can be used as a basis for environmental monitoring programs in the Maritime Antarctica region.Item Distribution and assessment of trace elements contamination in sediments of Conceição River Basin, Brazil.(2021) Leão, Lucas Pereira; Costa, Raphael de Vicq Ferreira da; Leite, Mariangela Garcia Praça; Nalini Júnior, Hermínio Arias; Fonseca, Rita Maria FerreiraThe Conceição river basin, in Quadrilátero Ferrífero (Iron Quadrangle), Brazil, has a long mining history which dates back to the late 17th century, with large gold and iron mines. These activities may be associated with river sediment contamination by trace elements, which were evaluated in this paper by the enrichment factor (EF) and contamination factor (CF). Potential ecological risks, assessed by combining sediment quality control guidelines (SQCG) and potential ecological risk indexes (Er and RI), are presented. Anomalous values for As (92.5 mg·kg−1 ), Cd (22.49 mg·kg−1 ), Cr (2582 mg·kg−1 ), Cu (65.9 mg·kg−1 ), Pb (58.6 mg·kg−1 ) and Zn (133.4 mg·kg−1 ) are observed. The EF and CF indexes indicate contamination by Cd, Cr, Fe, Mn, Ni and Zn in at least one site, with the highest values for Fe and Mn downstream of the iron mines, and Cr and Ni close to the gold mines. According to the SQGC and Er, As, Cd, Cr, and Ni are the most probable to result in adverse effects on sediment-dwelling organisms in this study. The results of principal component analysis (PCA) indicate distinct lithological units as sources of the analyzed elements, which, associated with the indexes, made it possible for the first time to delimit and classify the high concentrations of some analyzed elements as contamination in the Conceição river basin.Item Influência de projetos de reflorestamento de matas ciliares no controle/mitigação da erosão por ondas em reservatórios.(2021) Silva, Paola de Oliveira; Leite, Mariangela Garcia Praça; Costa, Adivane Terezinha; Fujaco, Maria Augusta GonçalvesA erosão por ondas em reservatórios está entre os processos que mais remodelam suas margens e promovem seu assorea- mento. A continuidade destes processos causa inúmeros problemas não só ambientais, mas também econômicos. Infeliz- mente, poucos são os trabalhos e modelos que tratam do assunto e a maioria deles usa um número restrito de parâmetros em suas análises. Uma das variáveis menos utilizada é a presença/tipo de vegetação, provavelmente pela dificuldade em se estimar seu impacto direto. Para se avaliar a influência da existência de matas ciliares em diferentes estágios sucessionais sobre a erosão por ondas em reservatórios, quatro áreas com diferentes usos e idades de reflorestamento tiveram ventos e ondas monitorados durante um ano e meio, incluindo feições erosivas e recuos de margens medidos, além de solos e se- dimentos caracterizados. Os dados obtidos apontaram para um processo complexo, com muitas variáveis correlacionadas. Os resultados mostraram que a área com projeto de revegetação mais antigo (29 anos), cuja mata ciliar já se encontra bem estabelecida, apresenta características de solo e erosão semelhantes à área com vegetação nativa preservada, o que ajudou a preservar suas margens da ação erosiva das ondas. Já a área com projeto de revegetação recente (19 anos), ainda sem uma mata ciliar plenamente desenvolvida, se assemelha às áreas de pastagem, apenas com gramíneas, com intensa perda de material das margens para o reservatório. Esforços devem ser feitos no sentido de modificar legislações e ampliar o número de projetos de reflorestamento no intuito de reduzir os problemas causados pela erosão por ondas em reservatórios e, desta forma, melhorar a qualidade de suas águas e aumentar seu tempo de vida útil.Item Seed covering and dry periods in the rainy season interfere with direct seeding success in the restoration of post-mined grasslands.(2021) Figueiredo, Maurílio Assis; Messias, Maria Cristina Teixeira Braga; Leite, Mariangela Garcia Praça; Kozovits, Alessandra RodriguesAmong the limitations for the use of direct seeding in the ecological restoration of severely degraded areas in tropical grasslands, the association between dry periods and an inhospitable substrate stands out. This work evaluated whether covering seed with a soil layer and the addition of a thin topsoil layer to the degraded substrate interferes with native plant establishment in degraded areas. The effect of rainfall variations on direct seeding results was also measured. The establishment of seven native species was evaluated under four different conditions: 1) seeding on degraded substrate, 2) seeding covered by 1 cm degraded substrate layer, 3) seeding on 1cm topsoil layer, and 4) seeding covered by 1 cm topsoil layer. In general, species with smaller seeds showed higher establishment percentages in treatments in which seeds were deposited on the substrate. Legume species, which have larger seeds, achieved better establishment percentage when seeds were covered by the substrate. The addition of topsoil was beneficial for Bulbostylis fimbriata (Cyperaceae), while for the other species, the effect was null or harmful. Data also showed that rainfall amount and distribution affected the establishment rate. Direct seeding is an advantageous alternative for the ecological restoration of tropical grassland degraded by mining. Better knowledge on sowing management and behavior of native species can contribute to improving the efficiency of this technique.