A research report submitted to the Faculty of Health Sciences, University of the Witwatersrand, in partial fulfilment of the requirements for the degree of Master of Science in Medicine (Pharmaceutical Affairs). Johannesburg 2012 / Global warming has stimulated research into alternative energy carries and fuels. Hydrogen is one of these alternative fuels that are recognized as a promising future energy source. Historically, it is produced by water electrolysis and the gasification of coal. Hydrogen is a natural though transient by-product of several microbial driven biochemical reactions, including anaerobic digestion and fermentation. Microorganisms degrade complex molecules to produce butyrate and alcohols with CO2 and hydrogen as the only by- products. Hydrogen produced by microorganisms is known as biohydrogen. This study aimed to identify biohydrogen- producing bacteria in three Anaerobic Fluidised Bed Bioreactors (AFBRs), which are capable of producing hydrogen under anaerobic and thermophilic conditions, by using PCR-DGGE analysis of the 16 S rDNA genes. Sewage sludge from anaerobic digester and cow- dung were used as inoculum to isolate potential H2- producing organisms. The operational conditions were manipulated to removing mesophilic bacteria and non- spore forming bacteria by gradually increasing the temperature to thermophilic conditions and the pH maintained at acid conditions to allow acidotolerant bacteria to survive. The bioreactors were operated for a period of forty days for each research cycle. Bioreactor One was operated at 55°C for eight days and then the temperature kept at a constant 65°C for the remainder of the research cycle. Bioreactor Two was operated for 8 days at each temperature ranging from 45°C - 65°C, with increments of 5 °C. Bioreactor Three was operated at each temperature for ten days ranging from 55- 70°C, also with increments of 5°C. Samples for microbial community identification were taken at 55°C and 65°C. The bacterial morphologies and structural properties were evaluated by examining the hydrogen- producing granules, isolated at 65°C, using scanning electron microscopy. Species of the families Bacillus, Enterobacteria, Actinomyces, Clostridium and Veillonella were identified. Clostridium thermopalmarium, Bacillus coagulans and Bacillus thermoamylovorans were the culturable species at the desired operational temperature of 65°C. C. thermopalmarium and B. coagulans are major H2 producers with theoretical values of 4mol H2/ g glucose and 3mol H2/ mol sugar, respectively. Sewage sludge is the best source of biohydrogen producing bacteria in comparison to cow dung as an inoculum in AFBRs. Bioreactor 1 with a constant operational temperature of 65°C and at a HRT of 6.5 allowed for the desired Clostridium sp. to be the predominant H2 producer.

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This dissertation explores two aspects of interdecadal climate variability: the predictability of variability in the tropical Pacific region on longer-than-interannual timescales, and changes to subsurface heat content in the tropical Atlantic Ocean over a decade. Chapter 1 assesses the ability of a general circulation model (GCM) and an intermediate- complexity model (ICM) to simulate persistent cool states of the Tropical Pacific. These states, which are La Niña-like on average, last from seven to ten years and induce prolonged droughts in many parts of the world. We find that these models produce analogs to real-world examples of these states and that they are modestly predictable in the ICM. We also find some predictability of the interdecadal shifts in the mean state in this model. In Chapter 2, an attractor reconstruction technique is used to investigate the predictability of interdecadal variability in the ICM further. We find that the interdecadal regimes of the ICM emerge as a pair of distinct orbits in a three-dimensional state space, and that the observed system possesses some comparable characteristics. The ICM is found to spend over a third of the time in states from which the regime of the following fifteen years is predictable with high confidence. The implications for developing an interdecadal prediction scheme are discussed. Chapter 3 examines changes in the heat content of the tropical Atlantic below the thermocline during the recent global warming hiatus. We use simulated Lagrangian particles in an ocean reanalysis dataset to analyze the changes to the circulation of the upper tropical Atlantic Ocean that occurred between the hiatus decade and the decade prior to it; and develop a testable hypothesis for how variability in the tropical Pacific region may have influenced the subsurface heat content of the Atlantic.

Mechanisms of tropical Pacific climate variability and change are studied in numerical experiments of future anthropogenic global warming (AGW), the Last Glacial Maximum (LGM) 21,000 years ago, and decadal variability (PDV). According to these mechanisms the equatorial Pacific does not become either El Niño- or La Niña-like as the tropics warm up in response to increasing greenhouse gases. Because humidity increases much faster than precipitation as the tropical atmosphere warms up, theory and models anticipate a slowing-down of the Walker circulation in order to keep a balanced flow of water vapor into areas of convection. On long time scales characteristic of climate change, ocean dynamics oppose these changes in the Walker circulation. First, equatorial adjustment theory indicates that changes in the Walker circulation are not amplified via the Bjerknes feedback, as during El Niño or La Niña events. Second, during AGW, the ocean becomes more thermally stratified resulting in enhanced cooling of the equatorial cold tongue opposing the warming there. These ideas can be applied to interpret proxies of the LGM for which El Niño and La Niña analogies have been made. However, the LGM tropics are not an opposite analogue to future AGW because the Walker circulation is also sensitive to changes in the geography of the Maritime continent associated with lower sea level. Models simulate a stronger Walker circulation when the tropics cool in order to compensate for the decrease in moisture due to a cooler/drier atmosphere. However, this response is opposed by a weakening of the ascending branch of the Walker circulation because convection is suppressed over vast areas of the Maritime Continent exposed due to lower sea level. In general, the patterns of warming or cooling for AGW and LGM are not El Niño- or La Niña-like because of the opposing mechanisms presented here. As such, adherence to an ENSO analogy for interpreting tropical Pacific climate change can lead to serious misconceptions. However, proxies of the thermocline tilt can provide unequivocal evidence of changes in the Walker circulation because the pressure gradient associated with the thermocline tilt has to be in balance with the trade winds at all timescales.

Thesis (M. Sc.)--University of Alberta, 2009. / Title from pdf file main screen (viewed on Dec. 2, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science, Department of Earth and Atmospheric Science, University of Alberta." Includes bibliographical references.