No description available.

The purpose of this work was to investigate the evaporation rates of various brines and to compare them to the evaporation rates of pure water under the same environmental conditions in the laboratory. NaCl, MgCl 2 and KCl were the salts used in the experiments, at three densities. Mixtures of the salts were also used. One set of experiments was conducted under free convection while the other was conducted under forced convection, both over pans. Temperature was relatively constant for the experiments but relative humidity was not controlled. Wind profiles were measured during the forced convection experiments and an aerodynamic equation used to calculate evaporation for comparison with the observed evaporation rates. Surface temperatures were also measured. Water activities of all the brine and brine mixtures were also measured and compared to predictions by Raoult's law. In general, it was found the evaporation rate of brines was lower than that of pure water and that the water activities and evaporation rates were density-dependent to a certain extent. More precisely, they were dependent on the actual constituents in the brine due to the different molecular weights, and the number of ions dissolving from a given weight of salt or salt mixture. Evaporation rates can better be estimated on this basis than on the basis of density alone, as one would expect from Raoult's Law.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Thesis (M. Phil.)--University of Hong Kong, 2008. / Also available in print.

Thesis (M.A.)--Guo li Taiwan da xue. / Cover title. Mimeo, copy. Includes bibliographical references.

Thesis (Ph.D.)--Aberdeen University, 2009. / Title from web page (viewed on Feb. 18, 2010). Includes bibliographical references.

No description available.

The present work investigates the inorganic nitrogenous nutrition of the phytoplanktonic community and its association with the bacterial role in the remineralisation and/or utilisation of inorganic nitrogen, in the waters of the Menai Strait. The field study lead to the recognition of four distinct phases in the seasonal cycle, based on measurements of primary plankton production and metabolism of nitrate and ammonium by the algae and bacteria. These were first the net autotrophic phase (April and May), followed by the net heterotrophic phase (June), then the secondary net autotrophic phase (July and August) and finally, the regenerative phase (remainder of the year). The phytoplankton seasonal pattern was characterised by nitrate-based production in the spring followed by ammonium-based production in summer and autumn, associated with the ambient availability of these nutrients. Bacteria accounted for up to 70% of the total inorganic nitrogen taken up with nitrate contributing heavily to bacterial production (up to 80%) early in the year. Whilst the maximum contribution of the heterotrophs to the total uptake was observed during the net heterotrophic phase, the lowest (<25%) was during the net autotrophic periods of the seasonal cycle. Calculations suggest that a maximum of 67% of algal ammonium uptake came from bacterial recycling. Only in June was there evidence of competition between algae and bacteria for nitrogen which is believed to have contributed to the sharp decline of the phytoplankton, at this time of the year. There was no evidence for nutrient limitation of the algae at other times of the season. There was also evidence for uptake of nitrate and ammonium in conditions of total darkness by both the bacteria and the algae, with bacteria accounting for a maximum of-75% the total nitrate and ammonium uptake. Ammonium was preferred over nitrate by the autotrophs and the heterotrophs. However, early in the year, when both primary and bacterial production were nitrate based, nitrate was utilised equitably with its environmental availability. For increasing concentrations of ammonium, bacteria clearly rejected the more oxidised form of inorganic nitrogen. The seasonal variation of 13C (as NaH13CO3) uptake by the populations studied was also investigated and there was strong evidence for heterotrophic uptake. Over the diel cycle, the contribution of bacteria to the total 13 C uptake amounted to a maximum of 44% during the net heterotrophic phase. In dark conditions, this percentage increased to a value of 60%, measured on the same occasion. The ambient availability of inorganic nitrogen seemed to influence the proportion of carbon fixed by the autotrophs that was inferred to be transferred to the bacteria. The assumed carbon transference from the autotrophs to the heterotrophs was highest in the spring, following a period of sufficiency of inorganic nitrogen, and lowest during summer (despite peaks of primary production), associated with conditions of ambient nitrogen depletion. It is widely hypothesised that bacteria take up inorganic nitrogen in order to be able to utilise carbon-rich, nitrogen-deficient compounds and so maintain a constant C:N cell quota. From a series of laboratory experiments, it was observed that the C:N ratio of the dissolved organic matter (DOM) used by the bacteria set the boundary on the role of these organisms as inorganic N net consumers or remineralisers. The laboratory work was interpreted as showing that when DOM was the major nitrogen source for growth, bacteria excreted the excess nitrogen as ammonium whereas at high C:N ratios, bacteria took up and conserved nitrogen. In the latter circumstances, when nitrogen was limiting, bacteria appeared to increase respiratory losses in order to dispose of the excess carbon. By contrast at low C:N ratios, carbon conservation occurred. It was concluded that if the release of DOM by the algae is the prime source of organic material for the bacteria, then this switching of the inorganic nitrogen metabolism of the bacteria, will be ultimately driven by the algae. These results were used to interpret the seasonal dynamics of the phytoplanlctonic and bacterial inorganic nitrogen metabolism in the Menai Strait.

Made available in DSpace on 2014-06-12T16:27:57Z (GMT). No. of bitstreams: 2 arquivo1918_1.pdf: 8599430 bytes, checksum: 5ff7691e1a400f323890fbfcc3e58c35 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2009 / John Waters é um diretor americano que começou a fazer filmes underground na década de sessenta. A partir de Pink Flamingos, Waters tornou-se conhecido por cenas tidas como bizarras. Protagonizadas, entre outros, pelo ator Harris Glen Milstead, mais conhecido como Divine. Um dos grandes fatores de reconhecimento para o autor foram as exibições no circuito cinematográfico Midnight Movie, dedicado à mostra de filmes que, por seu teor escatológico, não seriam bem aceitos em cinemas convencionais. Essas sessões, assim como a exploração de roteiros anti-convencionais em sua obra, geraram em torno de si um público ávido pelo consumo de filmes voltados a uma estética não canônica, o que reverbera até os dias atuais. A seguinte análise, leva em conta elementos presentes na primeira fase de John Waters (década de setenta até meados da década de 80), abordando temas como o grotesco, o feio e o camp. Na segunda parte nos propomos a analisar alguns aspectos dos Midnight Movie em busca de elementos de gosto, que formariam uma subcultura onde seus membros apresentariam em comum a preferência pelo nãocanônico. Depois nos ativemos a uma análise estética, confrontando características do cinema clássico com as teorias estudadas. Por fim, tentamos confrontar as duas premissas com base no teórico Michel Foucault, buscando descobrir a coerência entre o conceito de transgressão e o material analisado

‘Microplastics’ are pieces of plastic debris < 5mm in diameter. They are introduced into the marine environment directly for example via release of small pieces of plastics used as abrasives and indirectly through the fragmentation of larger items. The European Marine Strategy Framework Directive 2008/56/EC (MSFD) regards microplastics as an emerging issue of concern and calls for more data on the quantity, distribution and composition of this debris. This thesis examines the amount, composition and distribution of buoyant microplastic debris in marine waters using different sampling devices and methodologies. To investigate the spatial distribution, abundance and composition of microplastic debris between nearshore and offshore marine subsurface waters a subset of samples from the Continuous Plankton Recorder (CPR) survey were examined. Abundance was generally higher in nearshore coastal waters than the offshore oceanic samples, with the highest mean concentrations observed in the UK’s coastal waters of the northeast Atlantic and the southern North Sea. To validate the accuracy of the presence/absence of microplastic debris reported in the Continuous Plankton Recorder (CPR) samples by analysts at the Sir Alister Hardy Foundation for Ocean Science (SAHFOS) a subset of data was formally analysed using Fourier Transform Infrared (FTIR) spectroscopy. This analysis indicated a good level of accuracy (~66%) in the ability of the SAHFOS’ analysts to detect visually microplastic fragments during their normal processing of plankton samples. To compare quantity and composition of buoyant microplastic debris collected by two different approaches (CPR vs. Manta net) samples were collected from a similar body of coastal waters. The results showed significantly higher abundance of microplastic in samples collected by the manta net per unit of distance but no significant difference once the results were standardised per cubic volume of water. To assess the susceptibility of each method to ‘procedural contamination’, repetitive controlled tests were conducted to quantify the amount and composition of contaminants before, during and after the sampling programme. In both methods the highest number of contaminants was found on the net and prior to the deployment to sea. The semi synthetic Rayon fibres were the most abundant type of contaminants in both cases. To compare the abundance and composition of buoyant plastic debris in estuarine waters according to daily and lunar tidal cycles a mensurative experiment was conducted in a macrotidal Estuary. Microplastics comprised 82% of the debris and there was a significant difference in size frequency distribution between the spring and neap tides with more fragments of larger size observed during spring tides. In conclusion, this study shows further evidence of the spatial heterogeneity of microplastic debris distribution in marine waters and therefore also highlights the need for more comparable data from different marine habitats using standardised methodologies.