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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
101

Respostas fisiológicas a dessecação e a re-hidratação em quatro espécies de pteridófitas epifíticas

Schlindwein, Carolina Casco Duarte January 2012 (has links)
As plantas que possuem hábito epifítico estão mais sujeitas as variações ambientais do que as de hábito terrestre, principalmente em relação à disponibilidade hídrica. A água, então, destaca-se como um dos fatores restritivos mais importantes. Entretanto, algumas espécies desenvolveram a capacidade de tolerar a dessecação, apresentando uma significante vantagem adaptativa na ocupação de habitats. O objetivo deste estudo foi verificar o grau e os mecanismos de tolerância à dessecação de quatro espécies de pteridófitas epifíticas que comumente co-ocorrem sobre mesmo forófito. Frondes expandidas e hidratadas foram coletadas para a quantificação e comparação do conteúdo relativo de água, integridade de membrana, pigmentos fotossintéticos, flavonóides, fenóis, açúcares solúveis e fluorescência da clorofila ao longo dos processos de dessecação e re-hidratação. Estas avaliações fisiológicas nos permitiram inferir que as espécies com características de tolerância à dessecação apresentam mais adaptações fisiológicas durante períodos de dessecação e rehidratação do que àquelas que não apresentam este comportamento. Os resultados obtidos também revelaram a existência de diferentes graus de tolerância nas três espécies consideradas tolerantes à dessecação. Polypodium polypodioides var. minimum foi a mais tolerante, seguida de Pleopletis pleopeltifolia e Polypodium hirsutissimum. Enquanto Microgramma squamulosa demonstrou evitar à dessecação. Assim, concluímos que estas espécies apresentam diferentes estratégias ecofisiológicas em relação ao estresse hídrico, minimizando possíveis danos irreversíveis às membranas celulares. Desta forma, otimizam a captura de luz durante períodos de re-hidratação, diminuem a competição inter-específica e facilitam a co-ocorrência destas quatro espécies. / Epiphytic plants are more sensible to environmental variations than terrestrial plants, especially in relation to water availability. The water then stands out as one of the most important limiting factors. However, some species have evolved the ability to tolerate desiccation, showing a significant adaptive advantage in the occupation of habitats. The aim of this study was to determine the degree and mechanisms of drought tolerance of four species of epiphytic ferns that commonly co-occur on the same host tree. Expanded and hydrated fronds were collected for quantification and comparison the relative water content, membrane integrity, photosynthetic pigments, flavonoids, phenols, soluble sugars and chlorophyll fluorescence over the processes of desiccation and rehydration. The results of the present study allowed us to infer that the tolerant species have more physiological adaptations during periods of desiccation and rehydration. Thus, tolerant species showed distinct degrees of tolerance: Polypodium polypodioides var. minimum was the most tolerant, followed by Pleopletis pleopeltifolia and Polypodium hirsutissimum. While Microgramma squamulosa shown avoidance desiccation. We conclude that these species exhibit different ecophysiological strategies in relation to water stress, minimizing possible irreversible damage to cell membranes. Thus optimize capture of light during periods of rehydration, reduce inter-specific competition and facilitating the co-occurrence of these four species.
102

Respostas fisiológicas a dessecação e a re-hidratação em quatro espécies de pteridófitas epifíticas

Schlindwein, Carolina Casco Duarte January 2012 (has links)
As plantas que possuem hábito epifítico estão mais sujeitas as variações ambientais do que as de hábito terrestre, principalmente em relação à disponibilidade hídrica. A água, então, destaca-se como um dos fatores restritivos mais importantes. Entretanto, algumas espécies desenvolveram a capacidade de tolerar a dessecação, apresentando uma significante vantagem adaptativa na ocupação de habitats. O objetivo deste estudo foi verificar o grau e os mecanismos de tolerância à dessecação de quatro espécies de pteridófitas epifíticas que comumente co-ocorrem sobre mesmo forófito. Frondes expandidas e hidratadas foram coletadas para a quantificação e comparação do conteúdo relativo de água, integridade de membrana, pigmentos fotossintéticos, flavonóides, fenóis, açúcares solúveis e fluorescência da clorofila ao longo dos processos de dessecação e re-hidratação. Estas avaliações fisiológicas nos permitiram inferir que as espécies com características de tolerância à dessecação apresentam mais adaptações fisiológicas durante períodos de dessecação e rehidratação do que àquelas que não apresentam este comportamento. Os resultados obtidos também revelaram a existência de diferentes graus de tolerância nas três espécies consideradas tolerantes à dessecação. Polypodium polypodioides var. minimum foi a mais tolerante, seguida de Pleopletis pleopeltifolia e Polypodium hirsutissimum. Enquanto Microgramma squamulosa demonstrou evitar à dessecação. Assim, concluímos que estas espécies apresentam diferentes estratégias ecofisiológicas em relação ao estresse hídrico, minimizando possíveis danos irreversíveis às membranas celulares. Desta forma, otimizam a captura de luz durante períodos de re-hidratação, diminuem a competição inter-específica e facilitam a co-ocorrência destas quatro espécies. / Epiphytic plants are more sensible to environmental variations than terrestrial plants, especially in relation to water availability. The water then stands out as one of the most important limiting factors. However, some species have evolved the ability to tolerate desiccation, showing a significant adaptive advantage in the occupation of habitats. The aim of this study was to determine the degree and mechanisms of drought tolerance of four species of epiphytic ferns that commonly co-occur on the same host tree. Expanded and hydrated fronds were collected for quantification and comparison the relative water content, membrane integrity, photosynthetic pigments, flavonoids, phenols, soluble sugars and chlorophyll fluorescence over the processes of desiccation and rehydration. The results of the present study allowed us to infer that the tolerant species have more physiological adaptations during periods of desiccation and rehydration. Thus, tolerant species showed distinct degrees of tolerance: Polypodium polypodioides var. minimum was the most tolerant, followed by Pleopletis pleopeltifolia and Polypodium hirsutissimum. While Microgramma squamulosa shown avoidance desiccation. We conclude that these species exhibit different ecophysiological strategies in relation to water stress, minimizing possible irreversible damage to cell membranes. Thus optimize capture of light during periods of rehydration, reduce inter-specific competition and facilitating the co-occurrence of these four species.
103

Respostas fisiológicas a dessecação e a re-hidratação em quatro espécies de pteridófitas epifíticas

Schlindwein, Carolina Casco Duarte January 2012 (has links)
As plantas que possuem hábito epifítico estão mais sujeitas as variações ambientais do que as de hábito terrestre, principalmente em relação à disponibilidade hídrica. A água, então, destaca-se como um dos fatores restritivos mais importantes. Entretanto, algumas espécies desenvolveram a capacidade de tolerar a dessecação, apresentando uma significante vantagem adaptativa na ocupação de habitats. O objetivo deste estudo foi verificar o grau e os mecanismos de tolerância à dessecação de quatro espécies de pteridófitas epifíticas que comumente co-ocorrem sobre mesmo forófito. Frondes expandidas e hidratadas foram coletadas para a quantificação e comparação do conteúdo relativo de água, integridade de membrana, pigmentos fotossintéticos, flavonóides, fenóis, açúcares solúveis e fluorescência da clorofila ao longo dos processos de dessecação e re-hidratação. Estas avaliações fisiológicas nos permitiram inferir que as espécies com características de tolerância à dessecação apresentam mais adaptações fisiológicas durante períodos de dessecação e rehidratação do que àquelas que não apresentam este comportamento. Os resultados obtidos também revelaram a existência de diferentes graus de tolerância nas três espécies consideradas tolerantes à dessecação. Polypodium polypodioides var. minimum foi a mais tolerante, seguida de Pleopletis pleopeltifolia e Polypodium hirsutissimum. Enquanto Microgramma squamulosa demonstrou evitar à dessecação. Assim, concluímos que estas espécies apresentam diferentes estratégias ecofisiológicas em relação ao estresse hídrico, minimizando possíveis danos irreversíveis às membranas celulares. Desta forma, otimizam a captura de luz durante períodos de re-hidratação, diminuem a competição inter-específica e facilitam a co-ocorrência destas quatro espécies. / Epiphytic plants are more sensible to environmental variations than terrestrial plants, especially in relation to water availability. The water then stands out as one of the most important limiting factors. However, some species have evolved the ability to tolerate desiccation, showing a significant adaptive advantage in the occupation of habitats. The aim of this study was to determine the degree and mechanisms of drought tolerance of four species of epiphytic ferns that commonly co-occur on the same host tree. Expanded and hydrated fronds were collected for quantification and comparison the relative water content, membrane integrity, photosynthetic pigments, flavonoids, phenols, soluble sugars and chlorophyll fluorescence over the processes of desiccation and rehydration. The results of the present study allowed us to infer that the tolerant species have more physiological adaptations during periods of desiccation and rehydration. Thus, tolerant species showed distinct degrees of tolerance: Polypodium polypodioides var. minimum was the most tolerant, followed by Pleopletis pleopeltifolia and Polypodium hirsutissimum. While Microgramma squamulosa shown avoidance desiccation. We conclude that these species exhibit different ecophysiological strategies in relation to water stress, minimizing possible irreversible damage to cell membranes. Thus optimize capture of light during periods of rehydration, reduce inter-specific competition and facilitating the co-occurrence of these four species.
104

Tolerância à dessecação em Pleurostima purpurea (Velloziaceae): trocas gasosas, pigmentos fotossintéticos e conteúdo relativo de água foliar / Desiccation tolerance in Pleurostima purpurea (Velloziaceae): gas exchanges, photosynthetic pigments and leaf relative water content

Saulo de Tarso Aidar 07 December 2005 (has links)
Pleurostima purpurea (Velloziaceae) é uma espécie rupícola encontrada em afloramentos rochosos do estado do Rio de Janeiro, sudeste do Brasil. Por apresentar notável capacidade de tolerar a dessecação vegetativa, este estudo teve o intuito de esclarecer detalhes sobre a estratégia ecofisiológica utilizada por tais plantas frente à desidratação do ambiente e as vantagens associadas ao processo. Para tanto foi analisada a dinâmica de trocas gasosas, o conteúdo de pigmentos fotossintéticos e o conteúdo relativo de água de tecidos foliares durante os processos de dessecação e reidratação de indivíduos adultos cultivados. Comportaram-se como homeohídricas típicas economizadoras de água sob condição de seca moderada que, quando agravada, assumiram o comportamento de pecilohídricas e peciloclorófilas. A suspensão da irrigação provocou o fechamento estomático sob conteúdo relativo de água foliar acima de 90%, levando a restrições sobre a transpiração e assimilação líquida de carbono até o estabelecimento da anabiose. Durante este processo, houve um atraso na diminuição do CRAfoliar em relação ao CRAplanta-solo. A degradação das clorofilas acompanhou a diminuição do CRAfoliar, o qual alcançou o valor médio mínimo de 17% sem incorrer na abscisão das folhas, enquanto sua resíntese somente se iniciou após a total reidratação dos mesmos tecidos. Durante todo este processo o conteúdo de carotenóides manteve-se estável. 12 horas de reidratação do solo de cultivo foram suficientes para a retomada respiratória. Um balanço positivo de CO2 foi observado a partir da 36ª hora de reidratação quando o grau de abertura estomática passou a ser maior do que o observado para o grupo controle. Comparando-se com as condições iniciais, 84 horas de reidratação foram suficientes para a recuperação fotossintética mesmo com uma recuperação apenas parcial do conteúdo de clorofilas. Assim como os tecidos foliares, suas raízes também devem ser tolerantes à dessecação. / Pleurostima purpurea (Velloziaceae), a rupicolous flowering species found in rock outcrops in Rio de Janeiro state, southeastern Brazil, show notable capacity to endure vegetative desiccation. This study had the intent to show more details about the ecophysiological strategy used by these plants facing a drying ambient and the advantages associated with the process. For this, it was analised the gas exchanges, photosynthetic pigments content, and relative water content of leaf tissues during desiccation and rehydration of cultivated individuals. They behaved typicaly as homeohydrics water savers under moderated drought condition that, when aggravated, prosecute with poikilohydric and poikilochlorophyllous behavior. After watering suspension, stomatic closing was observed under a relative leaf water content up to 90% that resulted in gas exchanges restrictions until the anabiosis. During this process, it was observed a delay in the leaf relative water content (RWCleaf) decrease comparing to the plant-soil relative water content (RWCplant-soil). The chlorophylls degradation acompanished the RWCleaf decrease, which achived the minimum average value of 17% without incur in leaves abscission, while its resynthesis just begun after the full leaves rehydration. During all of this process, the carotenoids content remained stable. Twelve hours of soil rehydration were sufficient for the respiration retake. A positive carbon balance was observed since the 36th hour of rehydration, when the degree of stomatic opening became bigger than that observed for the control group. Comparing with inicial conditions, 84 hours of rehydration were sufficient to photosynthetic recovery, even just with a parcial recovery of chlorophyll content. As well as the leaf tissues, its roots might be desiccation tolerants.
105

Épocas de dessecação da pastagem e escarificação influenciando a atividade microbiana do solo e produtividade de grãos / Desiccation periods pasture and scarification influencing microbial activity soil and grain yields

Mazzuchelli, Rita de Cássia Lima 16 May 2017 (has links)
Submitted by Michele Mologni (mologni@unoeste.br) on 2018-05-11T18:40:49Z No. of bitstreams: 1 Rita de Cássia Lima Mazzuchelli.pdf: 967240 bytes, checksum: b50abc610a188a8f6408500562f11123 (MD5) / Made available in DSpace on 2018-05-11T18:40:49Z (GMT). No. of bitstreams: 1 Rita de Cássia Lima Mazzuchelli.pdf: 967240 bytes, checksum: b50abc610a188a8f6408500562f11123 (MD5) Previous issue date: 2017-05-16 / The objective of this study was to evaluate drying times of the previous pasture to soybean cultivation, associated with physical intervention (scarification), through impacts on soil microbial activity in soil and grain yield in the livestock farming system integration. The experiment was conducted in soil classified as Acrisol dystrophic. The experimental area was occupied by the species Urochloa brizantha (cv Marandu) with five years of implementation. The experimental design was a split tracks, onstituting a double factorial 5x2. The plots consisted of five periods of desiccation of grassland (150 DBS - days before soybean sowing; 120 DBS, 60 DBS, 30 DBS and 15 DBS) and the subplots, with and without soil scarification. Were grown two production cycles of soybean and maize, soil samples being collected at the beginning of each production cycle for biological, chemical and physical analysis of fertility. plants were collected for nodulation analysis. At the end of each production cycle crops were evaluated for productivity parameters. The longer periods of early pasture desiccation provided gains in microbial activity in the soil, the first year of cultivation of soybeans and corn. There were also improvements in soil fertility indicators. In the second year of cultivation of soybeans and corn gains in quality indicators were lower compared to the first year of cultivation. Early pasture desiccation in 150 days before the soybean crop yielded considerable nodulation and soybean yield gains. The yield of corn after the first crop of soybeans, was significantly influenced by longer periods of anticipation desiccation performed before soybean cultivation. / O objetivo do presente trabalho foi o de avaliar épocas de dessecação da pastagem anteriores ao cultivo da soja, associado com intervenção física (escarificação), através de impactos na atividade microbiana no solo e rendimento de grãos dentro do sistema de integração lavoura pecuária. O experimento foi desenvolvido em solo classificado como Argissolo Vermelho distroférrico. A área experimental estava ocupada com a espécie Urochloa brizantha (cv Marandu) com cinco anos de implantação. O delineamento experimental foi em faixas subdivididas, constituindo um fatorial duplo, 5x2. As parcelas foram constituídas por cinco épocas de dessecação da pastagem (150 DAS - dias antes da semeadura da soja; 120 DAS; 60 DAS; 30 DAS e 15 DAS) e as subparcelas, com e sem escarificação do solo. Foram cultivados dois ciclos produtivos de soja e milho, sendo coletadas amostras de solo ao início de cada ciclo produtivo para análises biológicas, químicas de fertilidade e físicas. Foram coletadas plantas para análise de nodulação. Ao final de cada ciclo produtivo as culturas foram avaliadas para os parâmetros de produtividade. Os maiores períodos de dessecação antecipada da pastagem proporcionaram ganhos na atividade microbiana no solo, no primeiro ano de cultivo da soja e milho. Ocorreram também melhorias em indicadores de fertilidade do solo. No segundo ano de cultivo da soja e milho os ganhos nos indicadores de qualidade foram menores, comparando-se ao primeiro ano de cultivo. A dessecação antecipada da pastagem em 150 dias antes do cultivo da soja proporcionou ganhos consideráveis de nodulação e rendimento da soja. O rendimento do milho, após o primeiro cultivo da soja, foi influenciado significativamente pelos maiores períodos de antecipação da dessecação efetuada antes do cultivo da soja.
106

Inhibiting Survival of Salmonella During Desiccation Through the Use of Naturally Occurring Signals

Headrick, Joseph 01 May 2023 (has links) (PDF)
A rising problem in agriculture is the increase of antibiotic-resistant Salmonella cases associated with chicken eggs, which transmit infection to humans. To counter this, new approaches to combat Salmonella in chickens and desiccated on eggshells are vital in the prevention of human foodborne illness. Disrupting signaling pathways with naturally occurring compounds provides a potential novel avenue for prevention of Salmonella infections, as this would disrupt sensing of these environments and inhibit subsequent optimal gene expression. Starting with signals identified in previous studies, salicylic acid was found to inhibit Salmonella desiccation survival on both eggshells and plastic. To expand upon this, a desiccation inhibition screen of 285 signals resulted in 9 additional potential desiccation inhibitors, including deoxyribose and guanine. By using natural signals to disrupt bacterial communication pathways, novel therapeutics that serve as viable antibacterial alternatives could be developed to prevent Salmonella contamination at a major source.
107

Effects Of Intertidal Position On The Response To Oxygen And Desiccation Stress In The Common Acorn Barnacle, Balanus Glandula

Dotterweich, Megan M 01 June 2023 (has links) (PDF)
Sessile invertebrates in the rocky intertidal experience intermittent periods of air exposure due to tidal flux, presenting risks of temperature extremes, hypoxia, nutrient limitation, and most dangerously, desiccation. Microscale variation in severity and frequency of these risks is widely dependent on vertical position within the intertidal zone. Common acorn barnacles (Balanus glandula) have a wide vertical distribution in the intertidal, creating large differences in microhabitat between the highest and lowest individuals in the population. This study set out to explore whether tidal position dependent differences exist in the response to oxygen and desiccation stress in B. glandula. We hypothesized that B. glandula from relatively high tidal heights, which are exposed to the air for a greater duration, will be better suited to tolerate anoxic and desiccation stress than conspecifics from lower tidal heights. To explore this, we compared responses of B. glandula collected from high and low intertidal positions to A) anoxia (0 mg O2/L) and hypoxia (≤ 2 mg O2/L) on survival, behavior (closed opercular plates, cirral beating, pneumostome formation), enzyme activity (lactate dehydrogenase (LDH), superoxide dismutase (SOD)), and tissue-lactate accumulation, in addition to B) the effects of humid (98% RH) and dry (32% RH) air emersion (at 17˚C) on survival, opercular behavior (open/closed), evaporative water loss (EWL) rates, and tissue-lactate accumulation. Relative to barnacles from the low intertidal, we found that barnacles from the high intertidal survive longer during anoxia and air emersion stress, close their operculum sooner in dry air, lose more water during air exposure at any humidity level, and tend to accumulate less D-lactate. We suspect that high intertidal B. glandula can survive desiccation longer by ejecting stores of mantle cavity fluid, thereby creating a moist lung-like, air-filled internal environment, then remaining largely closed and metabolically inactive when in air to avoid drying out and becoming anoxic. These differences may reflect plasticity or selective pressure in response to environmental stress during development and highlight the potential importance of microscale stress heterogeneity in influencing species climate change tolerance and potential distribution patterns.
108

DEVELOPMENTAL PLASTICITY OF STRESS TOLERANCE AND LIFE-HISTORY STRATEGY TO ARTIFICIAL LIGHT AT NIGHT

Bonfoey, Alyssa M. 01 January 2022 (has links)
Artificial light at night (ALAN), or ecological light pollution, is increasingly prevalent worldwide. Exposure to ALAN tends to negatively impact animals—particularly, nocturnal animals—but life-history strategies may mitigate these costs. Animals in many regions are also increasingly exposed to climate-related stressors, such as heat and drought. Yet, interactions among ALAN, life-history strategy, and stress tolerance are unknown. Therefore, I determined if developmental ALAN exposure (1) affects development, (2) affects adult phenotype, including heat and desiccation tolerance, and (3) affects and/or interacts with life-history strategy. To address my aims, I used the variable field cricket (Gryllus lineaticeps) because its geographic range is increasingly exposed to ALAN, heat, and drought conditions; it exhibits different life-history strategies (flight-capability vs. flight-incapability); and it is mainly nocturnal. Although developmental duration and success were not impacted by ALAN exposure, ALAN affected adult phenotype, with a positive effect on body mass, body size, and reproductive investment, and a negative effect on heat tolerance. Life-history strategy also affected stress tolerance—flight-incapable females had greater heat tolerance, and their desiccation tolerance was improved by ALAN exposure. Thus, key features of environmental change (i.e., exposure to ALAN, heat, and drought) may favor some life-history strategies over others.
109

The Effects of Vegetation on Stream Bank Erosion

Thompson, Theresa M. 17 June 2004 (has links)
Riparian buffers are promoted for water quality improvement, habitat restoration, and stream bank stabilization. While considerable research has been conducted on the effects of riparian buffers on water quality and aquatic habitat, little is known about the influence of riparian vegetation on stream bank erosion. The overall goal of this research was to evaluate the effects of woody and herbaceous riparian buffers on stream bank erosion. This goal was addressed by measuring the erodibility and critical shear stress of rooted bank soils in situ using a submerged jet test device. Additionally, several soil, vegetation, and stream chemistry factors that could potentially impact the fluvial entrainment of soils were measured. A total of 25 field sites in the Blacksburg, Virginia area were tested. Each field site consisted of a 2nd-4th order stream with a relatively homogeneous vegetated riparian buffer over a 30 m reach. Riparian vegetation ranged from short turfgrass to mature riparian forest. Multiple linear regression analysis was conducted to determine those factors that most influence stream bank erodibility and the relative impact of riparian vegetation. Results of this research indicated woody riparian vegetation reduced the susceptibility of stream bank soils to erosion by fluvial entrainment. Riparian forests had a greater density of larger diameter roots, particularly at the bank toe where the hydraulic stresses are the greatest. These larger roots (diameters > 0.5 mm) provided more resistance to erosion than the very fine roots of herbaceous plants. Due to limitations in the root sampling methodology, these results are primarily applicable to steep banks with little herbaceous vegetation on the bank face, such as those found on the outside of meander bends. In addition to reinforcing the stream banks, riparian vegetation also affected soil moisture and altered the local microclimate. While summer soil desiccation was reduced under deciduous riparian forests, as compared to herbaceous vegetation, winter freeze-thaw cycling was greater. As a result, in silty soils that were susceptible to freeze-thaw cycling, the beneficial effects of root reinforcement by woody vegetation were offset by increased freeze-thaw cycling. Using the study results in an example application, it was shown that converting a predominately herbaceous riparian buffer to a forested buffer could reduce soil erodibility by as much as 39% in soils with low silt contents. Conversely, for a stream composed primarily of silt soils that are prone to freeze-thaw cycling, afforestation could lead to localized increases in soil erodibility of as much as 38%. It should be emphasized that the riparian forests in this study were deciduous; similar results would not be expected under coniferous forests that maintain a dense canopy throughout the year. Additionally, because dense herbaceous vegetation would likely not develop in the outside of meander bends where hydraulic shear stresses are greatest, the reductions in soil erodibility afforded by the herbaceous vegetation would be limited to areas of low shear stress, such as on gently sloping banks along the inside of meander bends. As the first testing of this type, this study provided quantitative information on the effects of vegetation on subaerial processes and stream bank erosion. It also represents the first measurements of the soil erosion parameters, soil erodibility and critical shear stress, for vegetated stream banks. These parameters are crucial for modeling the effects of riparian vegetation for stream restoration design and for water quality simulation modeling. / Ph. D.
110

[pt] AVALIAÇÃO DOS PROCESSOS DE DISPOSIÇÃO E SECAGEM DE UM REJEITO DE LAVAGEM DE BAUXITA / [en] EVALUATION OF THE DISPOSAL AND DRYING PROCESSES OF A WASHED BAUXITE TAILINGS

CAIO ARAUJO MARINHO 25 April 2024 (has links)
[pt] O gerenciamento e estocagem dos residuos de mineração apresentam desafios constantes devido às crescentes demandas do setor, dessa forma, o aperfeiçoamento dos processos de gestão dos rejeitos e a otimização da capacidade de estocagem dos reservatórios são fundamentais para a viabilidade de um empreendimento de exploração de recursos minerais. O presente trabalho apresenta a metodologia utilizada para avaliação do processo de ressecamento de rejeito da lavagem de bauxita da Mineração Rio do Norte, sendo proposta a execução de dois reservatórios experimentais, em escala piloto, possibilitando o monitoramento do comportamento de ressecamento do rejeito in loco e a cxecução de ensaios em laboratório. A proposta do estudo é avaliar o comportamento do rejeito quando disposto em diferentes espessuras de camadas, incluindo aspectos de condições climáticas e tempo de secagem. O objetivo foi calibrar o modelo de enchimento e otimizar a área dos reservatórios contidos no sistema de contenção de rejeitos da MRN, aperfeiçoando a previsibilidade do final da vida útil das estruturas e maior assertividade do balanço de massas no longo prazo. Os estudos de campo e laboratório consistiram na disposição e monitoramento de camadas com 0,50 m e 0,80 m. Dessa forma, foi possível a avaliacão dos teores de sólidos ao final do periodo de secagem das camadas dispostas, avaliar as curvas de enchimento e recalque do rejeito, medir os ângulos de repouso no momento da disposição e após periodo de ressecamento e analisar a morfologia e desenvolvimento das trincas de contração. Com base nos resultados laboratoriais e de campo obtidos nesse trabalho, conclui-se que o comportamento do processo de ressecamento do rejeito é influenciado por uma série de fatores, podendo citar a permeabilidade do fiundo dos reservatórios as condições climáticas (incidência pluviométrica e taxa de evaporação) como os mais impactantes ao processo. No trabalho não foi observado uma grande diferença do comportamento de rejeito para as camadas de 0,50 cm e 0.80 cm. / [en] The management and storage of mining waste present constant challenges due tothe increasing demands of the sector. Therefore, improving waste managementprocesses and optimizing the storage capacity of reservoirs are fundamental to theviability of a mineral resource exploration project. This study presents themethodology used to evaluate the desiccation process of washed bauxite tailings atMineração Rio do Norte (MRN). The implementation of two experimentalreservoirs at a pilot scale is proposed, allowing on-site monitoring and laboratorytests for the tailings desiccation behavior. The objective of the study is to assess thetailings behavior when disposed in different layer thicknesses, considering aspectssuch as weather conditions and drying time. The aim was to calibrate the fillingmodel and optimize the area of the reservoirs within MRN s tailings storage facility,thus improving the predictability of the structures end-of-life and enhancing theaccuracy of long-term mass balance. Field and laboratory studies involved thedeposition and monitoring of layers with thicknesses of 0.50 m and 0.80 m. Thisenabled the evaluation of the solids content at the end of the drying period.assessment of filling and settlement curves, measurement of the angle of repose atthe time of deposition and after the drying period, and analysis of crack morphologyand development. Based on the field and laboratory results obtained in this study,it can be concluded that the behavior of the tailings desiccation process is influencedby several factors. The permeability of the reservoir bottom and weather conditions(rainfall and evaporation rate) are identified as the most impactful to the process.No significant difference in the behavior of the waste was observed between the 0.50 cm and 0.80 cm layers.

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