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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.
11

Experimental investigation on the effects of bed slope and tailwater on dam-break flows

liu, Wenjun, Wang, Bo, Guo, Yakun, Zhang, Jianmin, Chen, Yunliang 03 July 2020 (has links)
Yes / Understanding of the characteristics of dam-break flows moving along a sloping wet bed can help to timely issue flood warning and risk mitigation. In this study, laboratory experiments are carried out in a large flume for a wide range of upstream water depth, bed slopes and tailwater depth. The water level is recorded and processed to calculate the mean velocity and wave celerity. Results show that the increase of the bed slope will significantly accelerate the wave-front celerity for the downstream dry bed, while the negative wave celerity will decrease. When water depth ratio α ≥ 0.3 (defined as the ratio of initial downstream water depth over the upstream water depth of dam), there are extra negative waves propagating towards the reservoir area after the flow has developed for a period of time. When α ≥ 0.6, there are the Favre waves propagating downstream. The water level and the mean velocity fluctuate due to the influence of the extra negative waves and the Favre waves. Such fluctuant frequency increases with the increase of the water depth ratio. The empirical formulas are obtained for the celerity of the first extra negative wave and the first downstream wave. The variation of wave-front height is very similar under three bed slopes investigated in this study, while the maximum wave-front height occurs when α = 0.2. The present study broadens the understanding of the effects of the bed slope and the tailwater level on the movement of the dam-break flows. Furthermore, experimental results are also compared with some analytical solutions. The validity of the assumptions made during the development of these analytical solutions and their limitations are discussed by comparing with the experimental measurements. / The National Natural Science Foundation of China (Grant No: 51879179), the Open Fund from the State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University (SKHL1809) and Sichuan Science and Technology Program (No. 2019JDTD0007).
12

Contribution to Sustainable Water Management in oligotrophic mountainous rivers : Sunlight induced inactivation of Escherichia coli under the influence of physicochemical parameters water-color and water depth

Student 1, efternamn:Szépfalusi, Béla January 2022 (has links)
Water is essential for life on earth. Human society is challenged to sustain sufficient water quantity of good quality. This objective is reflected in sustainable development goal 6, “clean water and sanitation”. Water monitoring is part of sustainable water management and aims to evaluate the physical, chemical and biological status of a water body. Regular monitoring in the catchment area of Indalsälven (Sweden) is conducted by the Indalsälven Water Conservation Association (IWCA). In this area counts of Escherichia coli (E. coli) between 0 and 500 colony forming units (CFU) were monitored from 1993 – 2022 at the closest monitoring station Enkroken. This implies that drinking water quality standards were exceeded during many occasions (≥10 E. coli CFU/100ml). It is known that survival of E. coli in aquatic environments is dependent on nutrient levels, turbidity, sedimentation, pH level, predation, microbial community composition, temperature, and solar radiation. Low water depth and clear water with poor nutrient level in Enan and Handölan, tributaries to Indalsälven, are believed to cause solar radiation to be the main driver for inactivation of E. coli. Inactivation behaviour of indicator bacteria for faecal contamination such as E. col, is assumed to reflect on other bacteria that were excreted in the same way. The objective of the research was to investigate to which extent river color and river depth under the influence of sunlight affected E. coli inactivation in pristine like conditions such as the upper catchment area of Indalsälven. In this study, conditions from the research area were mimicked in 4 laboratory experiments. Results showed that neither 10 nor 35µW/cm2 led to additional inactivation due to sunlight. In a following experiment the liquid depth was reduced, with as a result that the inactivation of bacteria started to be influenced by sunlight when the depth was reduced to 14.4cm or lower. A fourth experiment was conducted at 14.4cm depth and additional color concentration 50 and 100 mg/l Pt. Results indicated that inactivation influenced by sunlight was reduced at color level 50 or more to a level that was equal to no sunlight radiation. A median depth of 0.2 cm and median color level of 15 mg/l Pt in the catchment area of Indalsälven suggests that inactivation of E. coli is very likely influenced by the sun, upstream the measuring point Enkroken and at points where the river is as shallow 14.4cm or less. Sunlight radiation might be underestimated in the conducted laboratory experiments, therefore continuous on-site research is suggested. / <p>2022-06-19</p>
13

Abiotic and biotic factors affecting size-dependent crayfish (<i>Orconectes obscurus</i>) distribution, density, and survival

Clark, Jennifer Marie 13 April 2009 (has links)
No description available.
14

Derivation of Coastal Bathymetry and Stream Habitat Attributes Using Remote Sensing Images and Airborne LiDAR

Su, Haibin 26 September 2011 (has links)
No description available.
15

Produção e trocas gasosas do capim-mombaça (Panicum maximum Jacq. cv. Mombaça) cultivado sob diferentes níveis de depleção de água no solo / Yield and gas exchanges of mombaca grass (Panicum maximum Jacq. cv. Mombaca) under different levels of soil water depletion

Brandão, Diego 11 December 2015 (has links)
O Brasil é o maior exportador mundial de carne e possui o maior rebanho comercial de bovinos do mundo. As pastagens, por apresentarem baixo custo de produção em relação aos alimentos concentrados, constituem-se na base da alimentação do rebanho bovino brasileiro. Com isso, grande parte da carne e do leite produzidos no país provêm de rebanhos mantidos a pasto. Dentre as espécies forrageiras destacam-se as cultivares de Panicum maximum por apresentarem elevada produtividade, qualidade e valor nutritivo, embora sejam exigentes em água, radiação solar e nutrientes. São escassas as informações na literatura sobre o manejo da irrigação para as espécies forrageiras. Objetivou-se neste trabalho avaliar a influência do manejo da irrigação nas trocas gasosas, na altura, na produção de fitomassa fresca e seca da parte aérea, e na área foliar do capim-mombaça. Adotou-se o delineamento de blocos aleatorizados em um experimento com dois solos de texturas distintas: Latossolo Vermelho Amarelo distrófico (série \"Sertãozinho\") franco-arenoso e Nitossolo Vermelho (série \"Luiz de Queiroz\") franco-argiloso. Aplicaram-se quatro níveis de depleção da capacidade de água disponível do solo (15, 30, 45 e 60% da CAD) com quatro repetições. A pesquisa foi realizada em casa de vegetação na Escola Superior de Agricultura \"Luiz de Queiroz\" - ESALQ/USP, no município de Piracicaba-SP. A umidade dos solos foi controlada por meio de pesagens diárias dos vasos; foram realizados três cortes da parte aérea do capim. Determinaram-se a produtividade da água, as lâminas de irrigação aplicadas, os turnos de rega médios e a sensibilidade do capim-mombaça ao déficit hídrico. A taxa líquida de assimilação de CO2, a altura das plantas e a fitomassa fresca e seca foram afetadas pela condição hídrica do solo; a produtividade da água foi maior conforme o incremento do nível de água no Nitossolo; o capim foi sensível ao déficit hídrico, apresentando produção superior de massa seca quando cultivado sob o nível de 30% de depleção de água para ambos os solos. / Brazil is the world\'s largest meat exporter and has the largest commercial cattle herd in the world. Pastures, because they have low production costs in relation to food concentrates, constitute the staple diet of the Brazilian cattle herd. Thus, much of the meat and milk produced in the country comes from cattle kept at pasture. Among the forage species, there are the cultivars of Panicum maximum for presenting high productivity, quality and nutritional value, although they are demanding in water, light and nutrients. The information in the literature on irrigation management for forage species is scarce. The aim of this study was to evaluate the influence of irrigation management in gas exchange, in the yield of fresh and dry weight of canopy, and leaf area of mombaca grass; and to determine the productivity of water, irrigation depths applied, the average irrigation frequency and sensitivity of mombaca grass to water deficit. The research was carried at \"Escola Superior de Agricultura Luiz de Queiroz\" - ESALQ/USP in greenhouse at Piracicaba-SP city. The experiement was set up in randomized blocks consisted by four levels of depletion of soil water availability (15, 30, 45 and 60%) applied to two soils - a Sandy loam Distrofic Yellow Red Latosol and a Clay loam Red Nitosol with four replications. Soil moisture was controlled by the weight of the experimental plots and the grass was cropped three times. The photosynthesis rate, the height and the weight of fresh and dry canopy of the plants was affected by soil moisture; water productivity increases as soil moisture was increased in Nitosol. Mombaca grass has shown sensible to drought and about thirty per cent of soil water depletion proportioned the better yield response for both soils.
16

Utilização de hidroretentor em substrato semi-saturado na produção de mudas de eucalipto / Hidroretentor use of semi-saturated substrate in the production of eucalyptus

Vervloet Filho, Radagasio Hugo 08 July 2011 (has links)
Made available in DSpace on 2016-12-23T13:51:44Z (GMT). No. of bitstreams: 1 Radagasio Hugo Vervloet Filho.pdf: 1995458 bytes, checksum: 8f95e786f617039b867e07b47cdc201c (MD5) Previous issue date: 2011-07-08 / This study aimed at testing the addition of three different doses of gel (soil Hydroretainer) in the production of hybrid seedlings of E. grandis X E. urophylla in two different water samples. Four clones were used (6437, 6466, 11420 and 11436). The study was conducted in nurseries at Fibria S.A., in the municipality of Aracruz - Espírito Santo. The parameters for assessing the development of seedlings occurred in four main phases of production: rooting, acclimation, growth and rustication. During these phases were monitored the moisture content of the substrate, cuttings rooting, plant survival, height growth of the bud, diameter growth of the base of the stem, nutritional status, water potential of plants leaves and ratings of the quality standard of the plants produced. With these results, it was not possible to conclude what the optimal dosage of the polymer hidroretentor to be used because the experiment was conducted in semi-saturated substrate. It was concluded that reducing the water level did not impair plant development. In addition, we evaluated the quality of the seedlings at the time of shipment and found that the better performance of clones 6437 and 6466 / Este estudo teve como objetivo testar a adição de três doses diferentes de gel (Hidroretentor de solo) na produção de mudas clonais do híbrido E. grandis vs. E .urophylla em duas lâminas d água diferentes. Foram utilizados quatro clones (6437, 6466, 11420 e 11436). O estudo foi realizado no viveiro da Fibria S.A., no município de Aracruz - Espírito Santo. Os parâmetros para avaliação do desenvolvimento das mudas ocorreram em quatro fases principais de produção: enraizamento, aclimatação, crescimento e rustificação. Durante estas fases ocorreram o monitoramento do teor de umidade do substrato, do enraizamento de estacas, da sobrevivência de plantas, do crescimento em altura do broto, do crescimento em diâmetro do coleto, do estado nutricional, do potencial hídrico foliar das plantas, e a classificações do padrão de qualidade das plantas produzidas. Com os resultados obtidos, não foi possível concluir qual a dosagem ideal do polímero hidroretentor a ser utilizada, pois todo o experimento foi conduzido em substrato semi-saturado. Concluiu-se que a redução da lâmina d água não prejudicou o desenvolvimento das plantas. Além disso, avaliou-se a qualidade das mudas no momento da expedição e constatou-se o melhor desempenho dos clones 6437 e 6466
17

PRODUÇÃO DE BIOMASSA, TEOR DE ÓLEO ESSENCIAL E TROCAS GASOSAS EM Aloysia triphylla SUBMETIDA A DIFERENTES DISPONIBILIDADES HÍDRICAS / BIOMASS PRODUCTION, ESSENTIAL OIL CONTENT AND GAS EXCHANGE IN Aloysia triphylla SUBMITTED TO DIFFERENT WATER AVAILABILITY

Schwerz, Luciano 16 January 2013 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The increasing demand for drugs in Brazil brings us to the improvement in cultivation of medicinal plants, that amount plus the quality is recommended. This study aimed to evaluate the growth, development, essential oil production as well as gas exchange and physiological parameters in Aloysia triphylla under different water availability throughout the four seasons. The experiment was conducted in greenhouse belonging to the agroclimatology laboratory of the UFSM campus of Frederico Westphalen - RS, in a randomized complete block design with four replications. Evaluations were made on the day that marked the half of each season (summer, autumn, winter and spring), and all plant material collected 20 cm above ground. The water availability (DH) was based on the reference evapotranspiration to the external environment being applied 125, 100, 75 and 50% of ETo in an irrigation interval of two days, totaling a blade 1620.06, 1304.05; 988 , 03 and 672.02 mm. year-1, respectively. The production of biomass, height and indirect measurement of chlorophyll (SPAD) had linear and cubic responses to water availability, being negative to reduce it. The effect of seasonality reveals that the spring season has growth and biomass production stronger, surpassing all other stations, while the winter was responsible for lower growth and production. The essential oil content was positively affected by water availability, being the depth of the highest yield of 75 and 50% of ETo respectively. The seasons summer and winter detained the highest content of essential oil in the leaves. And the variables which comprise plant gas exchange with the atmosphere, perspiration was lower due to the reduction of DH, thus promoting a greater stomatal resistance and increased temperature of the sheet, and the abaxial responsible for most of the total transpiration plant. / A crescente demanda por fármacos no Brasil nos remete ao aperfeiçoamento nas práticas de cultivo de plantas medicinais, para que além de quantidade a qualidade seja preconizada. O presente trabalho teve como objetivo avaliar o crescimento, desenvolvimento, produção de óleo essencial, bem como trocas gasosas e parâmetros fisiológicos em Aloysia triphylla submetida a diferentes disponibilidades hídricas ao longo das quatro estações do ano. O experimento foi conduzido em estufa plástica pertencente ao laboratório de agroclimatologia da UFSM campus de Frederico Westphalen RS, sob um delineamento experimental de blocos completos casualizados com quatro repetições. As avaliações foram realizadas no dia que marcou a metade de cada estação do ano (verão, outono, inverno e primavera), sendo coletado todo o material vegetativo 20 cm acima do solo. A disponibilidade hídrica (DH) foi baseada na evapotranspiração de referência para o ambiente externo sendo aplicados 125, 100, 75 e 50% da ETo em um turno de rega de dois dias, totalizando uma lâmina de 1620,06; 1304,05; 988,03 e 672,02 mm. ano-1, respectivamente. A produção de biomassa, a altura e a medida indireta de clorofila (SPAD) apresentaram respostas lineares e cúbicas a disponibilidade hídrica, sendo negativo para redução da mesma. O efeito da sazonalidade nos revela que a estação primavera apresenta crescimento e produção de biomassa mais vigorosa, superando as demais estações, ao passo que o inverno foi responsável pelo menor crescimento e produção. O teor de óleo essencial foi afetado positivamente pela disponibilidade hídrica, sendo a lâmina de maior rendimento a de 75 e 50 % da ETo respectivamente. As estações do ano verão e inverno detiveram os maiores teores de óleo essencial nas folhas. Quanto as variáveis que compreendem as trocas gasosas da planta com a atmosfera, a transpiração foi menor em função da redução da DH, promovendo consequentemente uma maior resistência estomática e aumento da temperatura da folha, sendo a face abaxial responsável pela maior parte da transpiração total da planta.
18

Produção e trocas gasosas do capim-mombaça (Panicum maximum Jacq. cv. Mombaça) cultivado sob diferentes níveis de depleção de água no solo / Yield and gas exchanges of mombaca grass (Panicum maximum Jacq. cv. Mombaca) under different levels of soil water depletion

Diego Brandão 11 December 2015 (has links)
O Brasil é o maior exportador mundial de carne e possui o maior rebanho comercial de bovinos do mundo. As pastagens, por apresentarem baixo custo de produção em relação aos alimentos concentrados, constituem-se na base da alimentação do rebanho bovino brasileiro. Com isso, grande parte da carne e do leite produzidos no país provêm de rebanhos mantidos a pasto. Dentre as espécies forrageiras destacam-se as cultivares de Panicum maximum por apresentarem elevada produtividade, qualidade e valor nutritivo, embora sejam exigentes em água, radiação solar e nutrientes. São escassas as informações na literatura sobre o manejo da irrigação para as espécies forrageiras. Objetivou-se neste trabalho avaliar a influência do manejo da irrigação nas trocas gasosas, na altura, na produção de fitomassa fresca e seca da parte aérea, e na área foliar do capim-mombaça. Adotou-se o delineamento de blocos aleatorizados em um experimento com dois solos de texturas distintas: Latossolo Vermelho Amarelo distrófico (série \"Sertãozinho\") franco-arenoso e Nitossolo Vermelho (série \"Luiz de Queiroz\") franco-argiloso. Aplicaram-se quatro níveis de depleção da capacidade de água disponível do solo (15, 30, 45 e 60% da CAD) com quatro repetições. A pesquisa foi realizada em casa de vegetação na Escola Superior de Agricultura \"Luiz de Queiroz\" - ESALQ/USP, no município de Piracicaba-SP. A umidade dos solos foi controlada por meio de pesagens diárias dos vasos; foram realizados três cortes da parte aérea do capim. Determinaram-se a produtividade da água, as lâminas de irrigação aplicadas, os turnos de rega médios e a sensibilidade do capim-mombaça ao déficit hídrico. A taxa líquida de assimilação de CO2, a altura das plantas e a fitomassa fresca e seca foram afetadas pela condição hídrica do solo; a produtividade da água foi maior conforme o incremento do nível de água no Nitossolo; o capim foi sensível ao déficit hídrico, apresentando produção superior de massa seca quando cultivado sob o nível de 30% de depleção de água para ambos os solos. / Brazil is the world\'s largest meat exporter and has the largest commercial cattle herd in the world. Pastures, because they have low production costs in relation to food concentrates, constitute the staple diet of the Brazilian cattle herd. Thus, much of the meat and milk produced in the country comes from cattle kept at pasture. Among the forage species, there are the cultivars of Panicum maximum for presenting high productivity, quality and nutritional value, although they are demanding in water, light and nutrients. The information in the literature on irrigation management for forage species is scarce. The aim of this study was to evaluate the influence of irrigation management in gas exchange, in the yield of fresh and dry weight of canopy, and leaf area of mombaca grass; and to determine the productivity of water, irrigation depths applied, the average irrigation frequency and sensitivity of mombaca grass to water deficit. The research was carried at \"Escola Superior de Agricultura Luiz de Queiroz\" - ESALQ/USP in greenhouse at Piracicaba-SP city. The experiement was set up in randomized blocks consisted by four levels of depletion of soil water availability (15, 30, 45 and 60%) applied to two soils - a Sandy loam Distrofic Yellow Red Latosol and a Clay loam Red Nitosol with four replications. Soil moisture was controlled by the weight of the experimental plots and the grass was cropped three times. The photosynthesis rate, the height and the weight of fresh and dry canopy of the plants was affected by soil moisture; water productivity increases as soil moisture was increased in Nitosol. Mombaca grass has shown sensible to drought and about thirty per cent of soil water depletion proportioned the better yield response for both soils.
19

Absorção de nutrientes pelo arroz em resposta ao manejo da água de irrigação / Absorption of nutrients by rice in response to the management of irrigation water.

Gonçalves, Daiana Ribeiro Nunes 29 March 2010 (has links)
Made available in DSpace on 2014-08-20T14:36:59Z (GMT). No. of bitstreams: 1 Dissertacao_Daiana_Ribeiro_Nunes_goncalves.pdf: 2494025 bytes, checksum: 6caf230533bad41b363da9fbc1a96ad0 (MD5) Previous issue date: 2010-03-29 / Currently, the rationalization of the water use by flooded rice is one of the priorities of the rice productive sector. Consequently, some alternative water managements have been proposed aiming to the reduction of water use by rice crop. However, changes in water management can affect nutrient availability for rice. For this reason, a work was carried out with the objective of evaluating the effects of the flood timing and the flood depth on nutritional status and nutrient uptake by rice. The work comprised two field experiments which were conducted in a Typic Albaqualf, at the Lowland Experimental Station of the Embrapa Clima Temperado, in Capão do Leão, State of Rio Grande do Sul, Brazil, during the growing seasons of 2007/08 and 2008/09. In the first experiment, three flood timings (2- to 3-leaf stage, 4- to 5-leaf stage, and 7- to 8-leaf stage or 6- to 7-leaf stage) were tested, and in the second experiment, it was compared the effects of three flood depths (<1cm saturated soil, 5cm, and 10cm). Both experiments were implanted in conventional system, using the cultivar BRS Querência . Rice nutritional status was determinated at the active tillering, panicle differentiation, and anthesis. On the other hand, rice nutrient uptake was determinated at the grain maturation. At the active tillering, leaf N, P, Ca, Mg, S, Mn, and Zn concentrations increased with delaying of flood timing. At the panicle differentiation, rice subjected to early flooding (2- to 3-leaf stage) presented lowest leaf K, Mg, and S concentrations and greatest leaf B concentration. Delay flooding promoted increase in leaf Mg, and Fe concentrations, and reduction in leaf P, B, and Zn concentrations at the anthesis. Flooding delay beyond the 4- to 5-leaf stage decreased N, P, K, Ca, Mg, S, B, Fe, and Mn uptake by rice. Flood depth effect on rice nutritional status was minor than the effect of flood timing. The presence of floodwater resulted in higher leaf potassium concentration and lower leaf copper, manganese, and zinc concentrations than in satured soil, at the active tillering. At the panicle differentiation, the maintenance of floodwater provided the highest leaf K concentrations and the lowest leaf Cu, and Mn concentrations. At the anthesis, the leaf K concentration increased with the thickness of the water depth; an opposite effect was determinated for leaf calcium, boron, and manganese concentrations. Changes in the thickness of water depth practically did not influence rice nutrient uptake, following the stability in the production of dry matter. The effects of flooding time on rice nutrition were greater than those of the water depth. Changes in rice 9 nutrition due to alterations on water management do not justify the revision on the indications of fertilization for flooded rice. / Atualmente, a racionalização do uso da água pelo arroz é uma das prioridades do setor produtivo. Em decorrência, a pesquisa tem proposto alternativas de manejo da água para a cultura, visando à redução no uso. Porém, as alterações no manejo da água podem alterar a disponibilidade de nutrientes para o arroz. Este trabalho teve por objetivo avaliar a influência da época de início de irrigação e da espessura da lâmina de água sobre o estado nutricional e absorção de nutrientes pelo arroz. Para tanto, realizaram-se dois experimentos, nas safras agrícolas 2007/08 e 2008/09, em Planossolo Háplico, na Estação Experimental Terras Baixas, da Embrapa Clima Temperado, em Capão do Leão, RS. No primeiro experimento, compararam-se o efeito de três épocas de início de irrigação (estádio V2-V3, V4-V5 e V7-V8 ou V6-V7) e no segundo, de três espessuras de lâmina de água (<1cm solo saturado, 5cm e 10cm). Ambos os experimentos foram implantados em sistema convencional de cultivo, utilizando a cultivar BRS Querência. Avaliou-se o estado nutricional da cultura no perfilhamento pleno, diferenciação da panícula e floração e a absorção de nutrientes pelo arroz na maturação. No perfilhamento pleno, os teores foliares de N, P, Ca, Mg, S, Mn e Zn no arroz aumentaram com o atraso no início da irrigação. Na diferenciação da panícula, a antecipação do início da irrigação para V2-V3 proporcionou menores concentrações de K, Mg e S e maior concentração de boro no tecido foliar do arroz. O atraso na irrigação promoveu aumento nas concentrações de Mg e Fe e diminuição nas de P, B, Zn na floração. O atraso da irrigação além do início do perfilhamento diminuiu a absorção de N, P, K, Ca, Mg, S, B, Fe e Mn. A espessura da lâmina de água exerceu efeito mais discreto sobre o estado nutricional do arroz. A presença de lâmina de água propiciou maior teor foliar de potássio e menores de cobre, manganês e zinco, no perfilhamento pleno. Na diferenciação da panícula, a manutenção de lâmina de água proporcionou maiores concentrações de fósforo e potássio no tecido foliar do arroz, mas promoveu redução nos teores de cobre e manganês. Na floração, a concentração foliar de potássio aumentou com a espessura da lâmina de água, sendo o efeito contrário para cálcio, boro e manganês. A variação na espessura da lâmina de água praticamente não influenciou a absorção de nutrientes pelo arroz irrigado, acompanhando a estabilidade na produção de matéria seca da planta. A época de início de irrigação exerce efeito mais marcante sobre a nutrição do arroz, comparativamente à espessura da lâmina de água. As alterações nutricionais decorrentes de mudanças no manejo da água não justificam revisão nas indicações de adubação para o arroz irrigado.
20

Volatilernas påverkan på marina vulkanutbrott / The Impact of Volatiles on Submarine Eruptions

Khadhem, Laith January 2017 (has links)
The Cape Verde archipelago is located 2000 km east of the Atlantic oceanic ridge and 500 km west of the western part of Africa. The plateau of the archipelago rises on average 2 km above the seafloor, which makes it one of the highest oceanic plateaus on Earth. Cape Verde originates from hotspot formation, a geological phenomenon which takes place beyond the tectonic plate boundaries where magma rises to the surface. In this thesis, volcanic material taken from the Charles Darwin volcanic field at a depth of more than 3000 meter and made up by four basaltic rocks and one agglomerate will be investigated. The agglomerate and vesicles in the rock shows that explosive volcanism occurs in high water depths, which is generally not common. Therefore, the material will be investigated to find out how explosive volcanism can occur at high water depths. The investigation will be based on quantifying the number of vesicles to able to calculate their area and analyze the magmatic water content in clinopyroxene crystals taken from the agglomerate by FTIR spectroscopy. Water is a volatile substance in the composition of magma and has a huge effect on its behavior at eruption. The results of quantification show that the area taken by vesicles varies from 7- 54 % which shows that magmatic products with high number of vesicles are common. The FTIR analysis shows that the magmatic water content can be high enough to cause an oversaturated magma system, which creates explosive eruptions. This statement is based on only one clinopyroxene crystal that had a magmatic water content of 3,87 ± 0,77 %. Other possible reasons for explosive eruptions at high water depth are the CO2 content in the magma and the size of volcanic vent. / Kap Verde är en arkipelag, situerad cirka 2000 km öster om den mittatlantiska spridningsryggen och 500 km väster om det afrikanska fastlandet. Arkipelagens platå har en genomsnittlig höjd på 2 km, vilket gör den till en av världens högsta oceaniska platåer. Arkipelagen har uppkommit av hetfläcksbildning, ett geologiskt fenomen baserad på att magma erupteras till ytan där jordskorpan är förtunnad och inte har någon anknytning till de tektoniska plattgränserna. Det som undersöks i detta kandidatarbete är vulkaniskt material, taget från den vulkaniska undervattensön Charles Darwin vulkanfält som ligger i den västra del Kap Verdes norra ö-grupp på över 3000 meterdjup. Materialet består av ett agglomerat och fyra stenstuffer av basaltisk komposition. Agglomeratet tyder på att explosiva vulkanutbrott förekommer, vilket även bekräftas av stenstufferna som har rikligt förekomst av luftbubblor. Explosiva vulkanutbrott är generellt inte förekomliga vid höga vattendjup, därav undersöks materialet för att kunna reda ut orsakerna som ger upphov till förekomsten av explosiva vulkanutbrott. Undersökningen baseras på att kvantifiera luftbubblor hos stenstufferna för att kunna räkna ut arean som upptas och analysera vattenhalten i klinopyroxenkristaller i agglomeratet med hjälp av FTIR spektroskopi. Vatten tillhör de flyktiga beståndsdelar i magmas sammansättning som kallas för volatiler och utgör en viktig parameter för magmans uppträdande vid eruption. Resultatet kvantifiering av luftbubblor visar att arean som upptas av luftbubblor varierar mellan 7–54 % av stenstufferna total area, vilket understryker att magmatiska produkter med hög andel luftbubblor är förkomliga. FTIR analysen visar att det finns tillräckliga höga vattenhalter för ett övermättat magmasystem som ger upphov till vulkanutbrott med explosiva förlopp, baserat på vattenhalten 3,87 ± 0,77 % av en klinopyroxenkristall. Andra möjliga orsaker till uppkomsten av magmatiska produkter med hög andel luftbubblor är koldioxidhalten i magman och storleken på vulkanrören.

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