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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.
1

The behaviour of trace metals in the Humber Estuary, U.K

Coffey, Michael January 1994 (has links)
No description available.
2

Re-presenting the Waterfront: revealing the intersection of human and natural processes

Geronilla, Kristina 15 December 2004 (has links)
Water and waterfronts are appealing to almost any person, as a visitor or designer. This study challenges the author's design processes and understanding of the landscape as the sculpted meeting ground, intersecting human and natural physical processes. It progresses from assumptions through collaborated ideas of others in a literature review through case studies of various waterfront situations and finally to the design project of the Jones Point waterfront in Alexandria, Virginia. Here the intermingled aspects from cultural activities over time and local, physical movement of land by water are assessed to be revealed and enhanced for the visitor's benefit, use, and connection with place. For it is the author's belief that the landscape and space can be sculpted, experienced, and imagined for the purpose of connecting us to a larger framework of living systems on this planet and beyond. The design extends the city to the waterfront and vice versa with an understanding of both physical processes and cultural choices to the point of being unable to distinguish action from reaction. / Master of Landscape Architecture
3

The Combined Effect of Ocean Acidification and Euthrophication on water pH and Aragonite Saturation State in the Northern Gulf of Mexico

Garcia Tigreros, Fenix 03 October 2013 (has links)
Rising atmospheric carbon dioxide (CO2) concentrations are increasing the rate at which anthropogenic CO2 is accumulating in the ocean, and thereby acidifying ocean water. However, accumulation of anthropogenic CO2 is not the only process affecting coastal oceans. Anthropogenic inputs of nutrients to coastal waters can result in massive algal blooms, a process known as eutrophication. Microbial consumption of this organic matter depletes bottom waters of oxygen and increases acidity through the release of CO2. This study assesses the synergistic effect of ocean acidification and eutrophication in the coastal ocean using data from six cruises to the northern Gulf of Mexico. In addition, this study investigates the effect of the 2011 Mississippi River flood on coastal pH and aragonite saturation states. Data from a model simulation using data collected from the northern Gulf of Mexico indicates that eutrophication is contributing to acidification of subsurface waters and plays a larger role than acidification from atmospheric CO2 uptake. Furthermore, results from the model simulation show that the decrease in pH since the industrial era is 0.04 units greater than expected from ocean acidification and eutrophication combined. The additional decrease was attributed to the reduced buffering capacity of the region and may be related to the uptake of atmospheric CO2 into O2-depleted and CO2-enriched waters, the addition of atmospheric CO2 into O2-rich and CO2-poor waters, the input of CO2 via respiration into waters in equilibrium with high atmospheric CO2, or a combination of all three processes.
4

Modelagem numérica da circulação de correntes de maré na Baía de Marajó e Rio Pará (PA). / Numerical modelling of the tidal currents circulation in Marajó Bay and Pará River (PA).

Souza, Rogério Riker de 17 July 2006 (has links)
A região amazônica possui uma vocação natural para a navegação, uma vez que os rios desempenham um papel preponderante, sendo em muitos casos as únicas alternativas de transporte e comunicação. O trabalho se insere nesse cenário, tendo como objetivo maior a sistematização do conhecimento a respeito da circulação de correntes de maré na Baía de Marajó e Rio Pará (PA), com foco na Área Portuária de Vila do Conde. O melhor entendimento sobre as correntes de maré será um elemento importante para o planejamento portuário e hidroviário interior, além de propiciar um incremento na segurança e otimização nas operações portuárias. A sistematização da circulação das correntes de maré na área de estudo foi implementada através de modelagem numérica com a utilização do software MIKE21 HD de autoria do DHI, consistindo basicamente em um modelo bidimensional verticalmente integrado. Como subsídio à programação numérica, foi realizada uma revisão bibliográfica a respeito dos principais temas relacionados: correntes, maré e vento, bem como foram levantadas as principais bases de dados da região, utilizados na calibração e validação do modelo numérico. Em razão da escassez de dados disponíveis a calibração foi executada com dados do Porto de Vila do Conde, por meio de medições de intensidade e direção das velocidades das correntes nos anos de 1991 e 2001. A validação foi realizada através da Carta de Correntes de Maré, com ponto específico na Baía de Marajó. O programa mostrou-se consistente e aplicável à realidade, permitindo desta forma a obtenção de Cartas de Correntes de Maré para toda a área de estudo, bem como para a área foco. / In the amazonic region, navigation is the natural and leading, in some cases the only one possibility, role in the transportation network. In this scenario, the thesis has the main purpose of consolidating the knowledge about tidal currents pattern in Marajó Bay and Pará River (PA), considering Vila do Conde Harbour as the most important study area. A best knowledge about the tidal currents will be an important factor for port and waterway planning, contributing to increase the port operation safety and development. The tidal currents pattern was consolidated through numerical modelling using DHI MIKE 21 HD software, which is a bidimensional vertically integrated model. A bibliographical review was carried out about correlated themes: currents, tides and winds, and also was made a data base research, which was used in the numerical model calibration and validation. Due to the few data obtained, calibration was performed with Vila do Conde Harbour data, using current intensity and directions obtained in 1991 and 2001 surveys. The validation was performed using the Tidal Currents Chart, for a point in the Marajó Bay. The software results showed a consistent fit to the real condition, which made possible to get a Tidal Currents Chart of the whole area and for the focus area.
5

Modelagem numérica da circulação de correntes de maré na Baía de Marajó e Rio Pará (PA). / Numerical modelling of the tidal currents circulation in Marajó Bay and Pará River (PA).

Rogério Riker de Souza 17 July 2006 (has links)
A região amazônica possui uma vocação natural para a navegação, uma vez que os rios desempenham um papel preponderante, sendo em muitos casos as únicas alternativas de transporte e comunicação. O trabalho se insere nesse cenário, tendo como objetivo maior a sistematização do conhecimento a respeito da circulação de correntes de maré na Baía de Marajó e Rio Pará (PA), com foco na Área Portuária de Vila do Conde. O melhor entendimento sobre as correntes de maré será um elemento importante para o planejamento portuário e hidroviário interior, além de propiciar um incremento na segurança e otimização nas operações portuárias. A sistematização da circulação das correntes de maré na área de estudo foi implementada através de modelagem numérica com a utilização do software MIKE21 HD de autoria do DHI, consistindo basicamente em um modelo bidimensional verticalmente integrado. Como subsídio à programação numérica, foi realizada uma revisão bibliográfica a respeito dos principais temas relacionados: correntes, maré e vento, bem como foram levantadas as principais bases de dados da região, utilizados na calibração e validação do modelo numérico. Em razão da escassez de dados disponíveis a calibração foi executada com dados do Porto de Vila do Conde, por meio de medições de intensidade e direção das velocidades das correntes nos anos de 1991 e 2001. A validação foi realizada através da Carta de Correntes de Maré, com ponto específico na Baía de Marajó. O programa mostrou-se consistente e aplicável à realidade, permitindo desta forma a obtenção de Cartas de Correntes de Maré para toda a área de estudo, bem como para a área foco. / In the amazonic region, navigation is the natural and leading, in some cases the only one possibility, role in the transportation network. In this scenario, the thesis has the main purpose of consolidating the knowledge about tidal currents pattern in Marajó Bay and Pará River (PA), considering Vila do Conde Harbour as the most important study area. A best knowledge about the tidal currents will be an important factor for port and waterway planning, contributing to increase the port operation safety and development. The tidal currents pattern was consolidated through numerical modelling using DHI MIKE 21 HD software, which is a bidimensional vertically integrated model. A bibliographical review was carried out about correlated themes: currents, tides and winds, and also was made a data base research, which was used in the numerical model calibration and validation. Due to the few data obtained, calibration was performed with Vila do Conde Harbour data, using current intensity and directions obtained in 1991 and 2001 surveys. The validation was performed using the Tidal Currents Chart, for a point in the Marajó Bay. The software results showed a consistent fit to the real condition, which made possible to get a Tidal Currents Chart of the whole area and for the focus area.
6

Environmental influences on the sustainable production of the Sydney rock oyster Saccostrea glomerata : a study in two southeastern Australian estuaries

Rubio Zuazo, Ana Maria, anarubio.zuazo@gmail.com January 2008 (has links)
There has been a continuous decline in both the production and general performance of the SRO in NSW estuaries over the past three decades. The relationship of this decline to both environmental and oyster-density related factors are assessed in this thesis. This question has been examined at different scales: a large scale that compares two different estuaries (Clyde and Shoalhaven Rivers, southern NSW); a regional scale that encompasses variations within an estuary and, at a lease scale that examines processes pertaining to individual or small groups of oysters. Levels of inorganic nutrients were in general very low potentially limiting primary production. The limiting nutrient was nitrogen or phosphorus depending on whether long term conditions were dry or wet, respectively. Only during rain events, through the input of terrestrial material, were conditions favourable for fast rates of primary production. Carbon and nitrogen isotope analysis has demonstrated that both external material and local resuspension of the benthos constitute a major proportion of the SRO diet. The uptake of the various food sources also varied considerably depending on local environmental conditions. Increases in SRO growth were strongly correlated to increases in temperature with a low temperature cut-off at ~13°C. Growth also appeared to reduce considerably when salinities lower than ~15ppt persisted for the order of a month. These factors may alter growth through changes in filtration rates. These processes were modelled in a coupled hydrodynamic-NPO (Nitrogen-Phytoplankton-Oyster) model of the Clyde River. This demonstrated that primary production was more affected by estuarine dynamics and nutrient concentrations than oyster uptake. At the current levels of oyster densities, primary production by itself could not account for the observed oyster growth, however growth became realistic with observed levels of POC added to the model. A set of environmental indices were used to complement the model and to assess the sustainability of the culture system. The combined indices indicated that while the ecological carrying capacity of the Clyde was exceeded the production capacity at an estuarine scale was not. On the lease scale, density experiments showed that while growth was not reduced as a result of current stocking densities, the condition index was significantly affected.

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