Thesis. 1977. Sc.D.--Massachusetts Institute of Technology. Dept. of Earth and Planetary Sciences. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND LINDGREN. / Vita. / Includes bibliographies. / Sc.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1981. / Microfiche copy available in Archives and Science. / Bibliography: leaves 40-43. / by James Raymond Wingo. / M.S.

Thesis. 1976. M.S.--Massachusetts Institute of Technology. Dept. of Earth and Planetary Sciences. / Microfiche copy available in Archives and Science. / Bibliography: leaves 55-58. / M.S.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1980. / Microfiche copy available in Archives and Science. / Vita. / Bibliography: leaves 231-243. / by Susan Margaret Henrichs. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Science, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND LINDGREN. / Bibliography: leaves 99-110. / by David Samuel Goldberg. / M.S.

Methanogenesis is the predominant terminal process of polymer degradation in anaerobic marine sediments depleted of sulfate; however, characterization of a marine consortium has not been previously reported. A marine methanogenic consortium consisting of fermentative, hydrogen-producing acetogenic and methanogenic bacteria is described. An acetotrophic methane-producing strain of bacteria was isolated. This isolate expresses three distinct morphovars: individual cocci, cell aggregates and communal cysts. Individual cocci are 1.9 µm in diameter and are nonmotile, but have fimbria-like structures. Cells have a thin protein cell wall. Acetate, methanol, methylamine, dimethylamine and trimethylamine are substrates for growth; formate and hydrogen are not. Sodium chloride and magnesium concentrations found in seawater are required for optimum growth. RNA homology values indicated that this isolate is a new species. Methanosarcina acetivorans is the proposed specific epithet. This is the first report of an acetotrophic methane-producing species indigenous to marine sediments. A method is described for mass culturing this and other acetotrophic methanogens using a pH auxostat. A strictly methylotrophic methane-producing strain was also isolated and is described. Only trimethylamine, dimethylamine, methylamine and methanol were substrates for growth. Cells were nonmotile, irregular cocci 1 µm in diameter and had a thin protein cell wall. Sodium chloride and magnesium concentrations found in seawater were required for optimum growth. Biotin was the only organic supplement required for growth in mineral medium. Fe was required for growth; Ni and Co were stimulatory. This isolate is a new genus based on RNA homology. Methanococcoides is the proposed genus and Methanococcoides methylutens is the specific epithet. Population studies suggest that this species is uniquely adapted for methylated amine degradation in marine sediments. The phylogenetic relationships of M. acetivorans, M. methylutens and other acetotrophic and methylotrophic species were determined by RNA and DNA homology techniques. Phylogenetic and physiological results in this study indicated that the population of methanogenic bacteria in marine sediments is both unique and equally diverse as the population of freshwater methanogenic species. / Ph. D.

Gas hydrate consists of guest gas molecules encaged in water molecules. Methane is the most common guest molecule in natural hydrates. Methane hydrate forms under high fluid pressure and low temperature and is found in marine sediments or in permafrost region. Methane hydrate can be an energy resource (world reserves are estimated in 20,000 trillion m3 of CH4), contribute to global warming, or cause seafloor instability. Research documented in this thesis starts with an investigation of hydrate formation and growth in the pores, and the assessment of formation rate, tensile/adhesive strength and their impact on sediment-scale properties, including volume change during hydrate formation and dissociation. Then, emphasis is placed on identifying the advantages and limitations of different gas production strategies with emphasis on a detailed study of CH4-CO2 exchange as a unique alternative to recover CH4 gas while sequestering CO2. The research methodology combines experimental studies, particle-scale numerical simulations, and macro-scale analyses of coupled processes.

Submarine topographic features of the channels, sounds, fiords, and bays can best be explained as the products of extensive glacial excavation of a pre-existing drainage system. Troughs, hanging troughs, strings of deeps or basins, terminal sills, linear rises and depressions, and oversteepened deltas are considered direct or indirect evidence of glacial scour. Following glaciation, a negative movement of the Sverdrup Basin was accompanied by flooding of the northern part of the Archipelago. Only the upper portions of former interfluvial areas remained above sea level. These topographic highs are the present-day islands of the Canadian Arctic Archipelago. Statistical analyses of beach, fluvial, deltaic, and offshore marine sediments reveal characteristics that may be unique to polar deserts and ice-covered seas. Textures of beach and fluvial sediments are a function of associated relief and parent material. The deltaic environment is defined as that portion of the sea floor extending from the mouth of a river to approximately 3,200 feet from shore. Deltaic sediments show a progressive decrease in grain size seaward. Size distribution is related to the settling velocities of particles of different diameters. Offshore sediments have uniform textural properties. They are a combination of silt and clay (settled from suspension), and a minor but significant portion of sand- to granule-sized sediment (ice-rafted). An increase in mean grain size on the crests of submarine topographic highs suggests that winnowing by currents is taking place over these features. Two large areas of the sea floor lack a cover of Recent sediment. Organic carbon constitutes 0.84 to 2.14% of the offshore sediments. A dual source, terrigenous and phytoplanktonic, may explain the relatively high percentage of organic carbon. There is a positive correlation between percent organic carbon and amount of clay in the samples. Results of semiquantitative clay-mineral analyses of source rock, fluvial, deltaic, and offshore marine sediments indicate that montmorillonite, kaolinite, and illite are the dominant clay minerals. In this northern region, there is no change in clay mineralogy during weathering and transport. It is suggested that this may be characteristic of weathering under polar desert conditions. The mineralogy of parent materials on the islands controls the clay mineral distribution in offshore areas. In Louise Fiord, well-crystallized kaolinite is differentially flocculated close to shore. A study of the roundness of quartz grains of sand, silt, and clay size reveals that the distribution of this property is bimodal. Coarse and medium sands are well rounded, fine sands through coarse silts are angular, and fine silt and clay-sized particles are well rounded. High roundness of grains in the medium to coarse sand grades is attributed to abrasion. Well rounded quartz in the silt-clay size range is considered to be a product of solution. / text

Thesis (Ph. D.)--Oregon State University, 2009. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Thesis (Ph.D.)--Mississippi State University. Dave C. Swalm School of Chemical Engineering. / Title from title screen. Includes bibliographical references.