Thesis (Professional Degree)--University of Missouri, School of Mines and Metallurgy, 1938. / The entire thesis text is included in file. Typescript. Title from title screen of thesis/dissertation PDF file (viewed April 27, 2010) Includes bibliographical references (p. 40) and index (p. 41-45).

This study investigates depth and temporal variability of organic carbon (POC), total nitrogen (TN) and their isotopic compositions in sinking particulate organic matter collected at station KK (18¢X15¡¦N; 115¢X5¡¦E), northern South China Sea. Sinking particles collected from two separate sediment trap moorings conducted from August 8, 2004 to February 16, 2005 (KK-3) and from April 1, 2005 to October 10, 2005 (KK-4). Results show that their variations respond closely to the strong seasonality in the surface layer, but are modified considerably by subsequent remineralization and large terrigeneous input in the deep water. The highest of Al concentrations at 3500m is equivalent approximately to 58% of lithogenic material. Sinking particles of terrestrial origins has lower £_13C values of POM. Terrigeneous input should make the £_13C values increase but decrease from 600m to 3500m. Based upon data measured in this study, a C/N increase rate of 0.21 unit per 1 km of water depth. The C/N ratio of POM collected in the winter is significantly higher than those collected in the rest of the year (9.05 vs. 7.02). With this regard, cyanobacteria, which have been reported as an important N2-fixer may attribute to the insufficiency in new production sources. The £_15N values prove the occurrence of nitrogen fixation in the surface water of the South China Sea in summer.

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<p>This thesis uses results of systematic numerical models to argue that externally inactive salt structures, which are potential targets for radioactive waste disposal, might be internally active due to the presence of dense layers or blocks within a salt layer.</p><p>The three papers that support this thesis use the Gorleben salt diapir (NW Germany), which was targeted as a future final repository for high-grade radioactive waste, as a general guideline.</p><p>The first two papers present systematic studies of the parameters that control the development of a salt diapir and how it entrains a dense anhydrite layer. Results from these numerical models show that the entrainment of a dense anhydrite layer within a salt diapir depends on four parameters: sedimentation rate, viscosity of salt, perturbation width and the stratigraphic location of the dense layer. The combined effect of these four parameters, which has a direct impact on the rate of salt supply (volume/area of the salt that is supplied to the diapir with time), shape a diapir and the mode of entrainment. Salt diapirs down-built with sedimentary units of high viscosity can potentially grow with an embedded anhydrite layer and deplete their source layer (salt supply ceases). However, when salt supply decreases dramatically or ceases entirely, the entrained anhydrite layer/segments start to sink within the diapir. In inactive diapirs, sinking of the entrained anhydrite layer is inevitable and strongly depends on the rheology of the salt, which is in direct contact with the anhydrite layer. During the post-depositional stage, if the effective viscosity of salt falls below the threshold value of around 10¹⁸-10¹⁹ Pa s, the mobility of anhydrite blocks might influence any repository within the diapir. However, the internal deformation of the salt diapir by the descending blocks decreases with increase in effective viscosity of salt.</p><p>The results presented in this thesis suggest that it is highly likely that salt structures where dense and viscous layer/blocks are present undergo an internal deformation processes when these dense blocks start sinking within the diapir. Depending on size and orientation of these blocks, deformation pattern is significantly different within the diapir. Furthermore, model results applied to the Gorleben diapir show that the rate of descent of the entrained anhydrite blocks differs on different sides of the diapir. This suggests that if the anhydrite blocks descent within the Gorleben diapir, they initiate an asymmetric internal flow within it.</p>

This thesis uses results of systematic numerical models to argue that externally inactive salt structures, which are potential targets for radioactive waste disposal, might be internally active due to the presence of dense layers or blocks within a salt layer. The three papers that support this thesis use the Gorleben salt diapir (NW Germany), which was targeted as a future final repository for high-grade radioactive waste, as a general guideline. The first two papers present systematic studies of the parameters that control the development of a salt diapir and how it entrains a dense anhydrite layer. Results from these numerical models show that the entrainment of a dense anhydrite layer within a salt diapir depends on four parameters: sedimentation rate, viscosity of salt, perturbation width and the stratigraphic location of the dense layer. The combined effect of these four parameters, which has a direct impact on the rate of salt supply (volume/area of the salt that is supplied to the diapir with time), shape a diapir and the mode of entrainment. Salt diapirs down-built with sedimentary units of high viscosity can potentially grow with an embedded anhydrite layer and deplete their source layer (salt supply ceases). However, when salt supply decreases dramatically or ceases entirely, the entrained anhydrite layer/segments start to sink within the diapir. In inactive diapirs, sinking of the entrained anhydrite layer is inevitable and strongly depends on the rheology of the salt, which is in direct contact with the anhydrite layer. During the post-depositional stage, if the effective viscosity of salt falls below the threshold value of around 1018-1019 Pa s, the mobility of anhydrite blocks might influence any repository within the diapir. However, the internal deformation of the salt diapir by the descending blocks decreases with increase in effective viscosity of salt. The results presented in this thesis suggest that it is highly likely that salt structures where dense and viscous layer/blocks are present undergo an internal deformation processes when these dense blocks start sinking within the diapir. Depending on size and orientation of these blocks, deformation pattern is significantly different within the diapir. Furthermore, model results applied to the Gorleben diapir show that the rate of descent of the entrained anhydrite blocks differs on different sides of the diapir. This suggests that if the anhydrite blocks descent within the Gorleben diapir, they initiate an asymmetric internal flow within it.

Diatom-diazotroph associations contribute extensively to vertical flux in the modern ocean, and are linked to extensive sedimentary layers in the paleo-record formed either by rapidly sinking aggregates or more slowly sinking cells and chains. Although diatom sinking rates have been extensively studied, the sinking rates of these diatom symbioses are poorly documented. The effect of silicate and phosphate limitation on the sinking rate of Hemiaulus hauckii and its symbiont Richelia intracellularis were determined in semi-continuous cultures using a SETCOL. TEP (transparent exopolymer particle) was measured concurrently for linkages to aggregate formation. Although cells occurred in chains of 1-20 cells long, aggregate formation did not occur in semi-continuous cultures. There was no significant effect of P or Si limitation on sinking rates compared to controls. Although H. hauckii possess a symbiont that lacks gas vesicles, sinking rates (0.04-0.72 m/day) were within the range predicted by size-rate relationships. A portion of each H. hauckii experimental measurement ascended as well with significant differences found between the lowered P 80% exchange and the lowered Si with 80% exchange (p=0.05) and between the lowered Si with 80% exchange and the Si control batch culture (p=0.039). TEP production did not change significantly between treatments. However, a fraction of TEP in each population was positively buoyant as well, with ascent rates between 0.32-0.49 m/day. This study confirms an earlier report of positive buoyancy in TEP as well as noting that a significant fraction of the Hemiaulus symbiosis can be ascending within the population. / text

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Thesis (D. Min.)--Trinity Evangelical Divinity School, 1996. / Abstract. Includes bibliographical references (leaves 242-249).

Thesis (M.S.)--Brigham Young University. Dept. of Civil and Environmental Engineering, 2006. / Includes bibliographical references (p. 227-231).

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