published_or_final_version / Earth Sciences / Doctoral / Doctor of Philosophy

Groundwater is now being considered as an alternative water supply in the Pearl River Delta (PRD) because of the increasing demand for fresh water coupled with deterioration in river water quality as a result of rapid urbanization and industrialization. There are thick aquitards in the PRD as a result of several times transgression and regression in the Holocene. This study considers this aquitards as a research object because it has a significant impact on the underneath confined aquifer. It is necessary to analyze the hydraulic properties of the aquitards. A slug-test is a reasonable method to determine the hydraulic conductivity and specific storage of the low-permeability aquitards of silt and clay in the PRD. In this study, several slug-test methods were used to determine the hydraulic parameters of aquitards in several piezometers at the key site MZ04in the PRD. The results from these methods were compared to obtain the most reasonable group of hydraulic parameters. A reasonable equivalent numerical method is applied at the key site MZ04 site after the calibration with the C-B-P solution and the KGS model. The natural groundwater regime is obtained, which is helpful for the further research. A three-dimensional numerical model using MODFLOW is carried out under some assumptions and the simplification for the sediments structure. The characteristics of regional groundwater flow and the influence of hydraulic properties of the aquifer-aquitard system on groundwater flow were analyzed. The simulated groundwater level both in the unconfined aquifer and confined aquifer agree reasonably well with the observed data. Study on the water budget of the groundwater showed that the quantity of ground water discharged from participation to participate the water exchange is very small. In the groundwater participated water exchange, 97% of them flow into rivers, while only 3% of them flow into the sea. Moreover, the vertical flow is more important than the horizontal flow to the regional ground water balance in aquitards according to the water budget obtained from the model. The research of the PRD needs numerous data due to the complicated deposition and evolution process of the sediments and the intensive river network. The modeling results are preliminary because of the complexity of the geological and hydrogeological conditions in the PRD and the limitation of the observed water level data. The hydraulic parameters calculated for this study and the model results can provide a basis for further research on groundwater in the PRD. / published_or_final_version / Earth Sciences / Master / Master of Philosophy

An aquitard is not only a confining layer in the aquifer-aquitard system, but also a functional complex for nutrient reservation and microorganism inhabitation. Geochemical characteristics and geomicrobial processes in aquitards play an important role in groundwater quality, and should be well studied. The Pearl River Delta is dominated by clay-rich aquitards and was intensively influenced by Holocene transgression. In this thesis, the aquifer-aquitard system in the PRD was studied from various perspectives including geophysics, geochemistry and geomicrobiology. Sediment and groundwater samples were taken from representative locations in the PRD at different lithological units. Particle size distribution, computed axial tomography, optically stimulated luminescence dating and scanning electron microscopy were analyzed to understand the geophysical properties. Concentrations of major ions and abundances of environmental isotopes were measured for geochemical analysis. Bacterial 16S rRNA gene clone libraries were constructed to analyze microbial identifications and community structures in different strata. Gene abundances of anammox 16S and bacteria amoA in both sediment and groundwater samples were quantitatively analyzed with 15N isotope at the same depth. The mixing process of seawater and river water was the dominant factor controlling the isotopic and chemical characterizes of groundwater in the system. Isotopic fractionation in the aquitards was majorly controlled by chemical and biological reactions other than diffusion. Chemical pattern in this system was mainly controlled by topography and sea level in the Holocene. Independent sedimentary centers of strong reducing environment were located in the depressions controlled by fault zones, and generated massive amount of pyrite minerals in the sediment and NH4+ in the groundwater. The sea level and depositional environment in the Holocene determined the physical structures of the sediment and seawater/river-water ratio in the estuary. Isotopic research also demonstrated that South Asia Monsoon was the major source of atmospheric precipitation in the PRD. Bacterial species in the PRD sediment were identified. Canonical correspondence analysis between bacterial linages and environment factors showed that community structures were significantly modified by geological conditions. High bacterial diversity was observed in samples from the Holocene aquitard M1 and aquifer T1, while in the older aquitard M2 and basal aquifer T2, the bacterial diversity was much lower. Chloroflexi, γ-proteobacteria and δ-proteobacteria were the dominant phyla in the aquitard sediment. β-proteobacteria was the dominant phylum in sediment which was strongly influenced by fresh water. Anammox was the controlling biochemical process in microbial-derived ammonium loss, as demonstrated by gene abundance coupling with 15N isotope and ammonium concentration. The 16S gene abundance of anammox bacteria ranged from approximately 105 to 106 copies/g in the aquitard sediment, and ranged from 104 to 105 copies/g in aquifers. amoA gene abundance was 1-2 orders lower than anammox bacteria 16S in aquitard sediment, but in aquifers, the gene abundances of amoA and anammox 16S were similar. Interface between aquifer and aquitard was demonstrated as biochemically enhanced zone. The results of this study significantly benefited the understanding of geochemistry and microbiology in the aquifer-aquitard system, and showed directions for future work on geomicrobiology in aquitards. / published_or_final_version / Earth Sciences / Doctoral / Doctor of Philosophy

This dissertation investigates the historical construction of the foreigner as a category of subjectivity. It does so by tracing a set of procedures and regulations devised by British imperial authorities to bring the Gulf pearl industry, which was one of the largest sources of natural pearls in the world for several millennia, under their control in the period between the signing of the first Anglo-Arab treaty at the turn of the nineteenth century and the effective demise of Gulf pearling in the early 1930s. I argue that imperial concerns about the mobility of pearl fishers shaped the production of this novel category of subject, the migrant foreigner, in three ways. In the first place, the yearly influx of scores of pearl fishers to the shaikhdoms that lined the Gulf's western littoral at the advent of the main diving season hindered British attempts to establish expansive jurisdictional claims in these polities. It was in the context of the effort to rein in the excesses of pearling labor mobility that British imperial institutions were first constructed in the Gulf shaikhdoms. In the second place, Britain also shaped the comportment of these mariners by policing their movement. Since Britain portrayed itself as a guardian of the Gulf pearl trade through the treaties and agreements it signed with Gulf shaikhs throughout the nineteenth century, it restricted behaviors that it considered detrimental to the success of that trade. Chief among these was the ability of indebted pearl fishers to run away to neighboring shaikhdoms to take on a fresh cash advance unencumbered by the debt they had accumulated elsewhere, a practice that British officials deemed absconding. In the third place, Britain eventually institutionalized the measures it took to govern migrant pearl fishers in the shaikhdom of Bahrain, which became ground zero for British operations in the region from 1900 onward. In doing so, British officials incorporated methods of governance initially devised to regulate the movement of an itinerant group of workers within the juridical scope of their jurisdiction over all foreigners in Bahrain. By demonstrating the constitutive effects of this effort, which rendered deportations and constraints on collective labor agitation a regular tool in the repertoire of imperial and shaikhly power, this dissertation presents a new way to understand the nature and legacies of British rule in the Gulf and a different set of historical coordinates to locate the origins of the foreign worker as a category of legal and political subjectivity in the region.

No description available.

Thesis (M.A.)--Trinity International University, 2001. / Abstract. Includes bibliographical references (leaves 128-132).

No description available.

Thesis (D.Phil.)(Botany)--University of Pretoria, 2006. / Includes summary. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1957. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 255-260).

Thesis (M.S.)--University of Wisconsin--Madison, 1960. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves [114]-119).