Source: Dissertation Abstracts International, Volume: 40-06, Section: B, page: 2568. / Thesis (Ph.D.)--The Florida State University, 1979.

Source: Dissertation Abstracts International, Volume: 37-10, Section: B, page: 4935. / Thesis (Ph.D.)--The Florida State University, 1976.

Software packages that model geochemical speciation and complexation are useful for predicting how different materials such as heavy metals and organic matter interact with the environment. The East Fork Poplar Creek (EFPC) in Oak Ridge, Tennessee suffers from extensive mercury pollution as a result of post-WWII activities to develop thermonuclear weapons. A current model that predicts the speciation of mercury and methylmercury species treats dissolved organic matter (DOM) as a single entity instead of a multidimensional and multisite molecule. The Humic-Ion Binding Model VII is a discrete multisite model implemented by default in the WHAM7 software that represents binding behavior between protons, metal cations, and humic substances. Implementing Model VII into the current EFPC model using the PHREEQC speciation program can predict site interactions of organic matter with mercury and methylmercury. Adding surface complexation to the model shows a substantial increase in the amount of methylmercury bound to DOM compared to the original model. Thus, when appropriate, employing a surface complexation model in geochemical simulations should be considered. / A Thesis submitted to the Department of Scientific Computing in partial fulfillment of the requirements for the degree of Master of Science. / Fall Semester 2017. / November 14, 2017. / Includes bibliographical references. / Ming Ye, Professor Directing Thesis; Sachin Shanbhag, Committee Member; Chen Huang, Committee Member.

As part of the assessment of the potential risk posed by contaminated sediments to the environment and human health, the United States Environmental Protection Agency (USEPA) is developing a set of sediment quality criteria (SQC) that are based on equilibrium partitioning (EqP). While EqP theory has often been used to predict contaminant concentrations within a factor of two for a range of sediment types, substantial deviations from predicted values have also been documented. The objective of this research was to evaluate the influence of PAH source on PAH sediment-pore water partitioning and distribution in sediments. The Elizabeth River is one of three Regions of Concern identified by the USEPA Chesapeake Bay Program. Sediment PAH concentrations, particularly those collected in the vicinity of two former wood-treatment facilities, are elevated in comparison to other regions in the Chesapeake Bay and around the world. Based on an examination of the contaminant levels in the main stem and southern branch of the Elizabeth River using established criteria, the river remains a clear hazard to benthic and pelagic species. A large number of potential sources of PAHs exist in this highly industrialized urban estuary. Employing a combination of principal component analysis (PCA) along with identification of source-specific isomer ratios, contributions from two former wood-treatment facilities were differentiated. Additionally, a significant coal contribution was determined by also incorporating compound-specific carbon isotope ratio analysis (CSIA). Use of CSIA successfully isolated and separated the coal signature from a coal gasification signature, which could not be distinguished using only PCA and isomer ratios. Elizabeth River sediments exhibited a wide range in partitioning patterns indicative of partitioning dominated by different sedimentary fractions including organic carbon, soot carbon, a heterogeneous mixture of sorbents, or dissolved organic carbon. For samples located in the vicinity of former wood-treatment facilities, the presence of non-aqueous phase liquids appeared to strongly influence PAH partitioning despite relatively high levels of soot carbon in the sediments. Outside of localized areas, soot carbon appears to play a dominant role in controlling PAH partitioning, limiting the influence of other factors such as dissolved organic carbon.

Source: Dissertation Abstracts International, Volume: 40-02, Section: B, page: 0640. / Thesis (Ph.D.)--The Florida State University, 1978.

Source: Dissertation Abstracts International, Volume: 39-06, Section: B, page: 2707. / Thesis (Ph.D.)--The Florida State University, 1978.

The major elements, trace elements, and isotopic composition of clinopyroxene and garnet fractions from mantle xenoliths from Colorado Plateau area were analyzed in this study to examine the sources of the xenoliths and their role in fractionation of Nb from Ta during the subduction process. Unlike most of the other elemental ratios, Nb/Ta ratio in the earth's crust and depleted mantle do not add up to the chondritic ratio (~19). This discrepancy has led to the assumption of existence of a "hidden" reservoir enriched in Nb content in the Earth's interior (core or mantle). Studies show that Nb/Ta ratio is controlled predominantly by Ta mobility in hydrous fluid. Subduction related hydration, therefore has the potential to fractionate Ta from Nb, resulting in a reservoir high in Nb in the subducted crust. In order to test this hypothesis and to find out the sources of the xenoliths, clinopyroxene and garnet fractions of eclogites and garnet pyroxenites from Moses Rock and Garnet Ridge, and clinopyroxene fractions of high MgO and low MgO clinopyroxenes from Moses Rock have been analyzed. These xenoliths are emplaced in the serpentinized ultramafic microbreccia and minnette diatreme hosts, that erupted during Laramide Orogeny (80-40 Ma) when Farallon plate subducted beneath the Navajo Volcanic Field (NVF) at a low angle. Elemental and isotope signature of the eclogites, garnet pyroxenites, and high MgO pyroxenites suggest that they are derived from the primitive mantle that underwent subsequent metasomatism followed by multiple stages of melting before and during Laramide Orogeny. In contrast, low MgO pyroxenites are from the melt metasomatized lower crust. Presence of fragments of lower crust in the minnette diatremes is a result of scraping off part of the lower crust that was dragged along by the flat-subducting Farallon plate. Reconstructed bulk rock Nb/Ta ratio of the eclogites and garnet pyroxenites suggest that they are not a potential reservoir for high Nb. The lowest Nb/Ta ratio in the high MgO pyroxenites indicates that fluid induced metasomatism has fractionated Nb from Ta due to mobility of Ta in fluid resulting in a low Nb/Ta ratio in the rocks. Therefore, subduction zone processes can fractionate Nb from Ta. The near chondritic Nb/Ta ratio in the low MgO pyroxenites emphasizes their melt metasomatized lower crustal origin. Fossil mollusk shells are widely distributed in the geologic records and their oxygen isotopic compositions have been used to reconstruct the seasonal changes in temperature, local climatic and elevation conditions. However, interpretation of isotope data from fossil shells in terms of past climate and elevation is often ambiguous. This study examines the stable isotopic systematics in the carbonate shells of modern freshwater gastropods Bellamya and Radix along an elevation/climate transect in the Asian monsoon region in China in order to improve the accuracy of paleoclimate and paleoelevation reconstruction based on stable isotopes in fossil shells. The results from sclerochronological stable isotopic analyses of the shells show that the intra-shell oxygen isotopic pattern in a shell is determined by seasonal variations in lake water temperature and water isotopic composition as well as the life history (time of birth and life span) of the organism. The data suggest that both Bellamya and Radix are able to reproduce at any time from early spring to the fall and grow all year in the low to mid altitude/latitude lakes. Bellamya is not found in high altitude Tibetan lakes. Radix in the high elevation cold habitat, although prefers to grow in the summer months, can survive through the freezing temperature. The δ18O patterns in the gastropod shells are similar across the elevation/climate transect, showing high δ18O values in the winter months and low δ18O values in the summer months, which is consistent with the expected pattern in the Asian summer monsoon region. The average growth rates of the snails analyzed in this study were highest at the lowest elevation site characterized by warm and humid climatic conditions but were similar at the mid to high elevation sites. The growth rate of Radix appears to decrease towards the late ontogeny. The serial isotope data suggest that both Bellamya and Radix shells, if they are full-sized or nearly full-sized, are excellent archives of lake environmental conditions and most suitable for paleo-environmental studies. Smaller sized shells (<1.5 cm for Radix and >2.1cm for Bellamya), on the other hand, are not ideal for paleo-environmental reconstruction as they represent short periods (<1 year) of growth and would yield biased information about paleoenvironment towards the times of their shell formation. The oxygen isotopic compositions of bulk shells from these lakes vary widely and are in part controlled by life histories of the individual snails, reflecting the average environmental conditions during the shell formation. Although the δ18O values of the shells do not show a clear relationship with elevation, the temperatures calculated from the measured δ18O values of bulk shells and lake water δ18O decrease with increasing elevation. The average calculated temperature for each lake is similar to the mean annual water temperature (MAWT) within the analytical uncertainty. Based on the isotopic variability observed in these modern shells, it was estimated that a minimum of 12 individual shells would be needed in order to provide a reliable estimate of the MAWT for a given location. The carbon isotope variations in the shells appear to be mainly controlled by variations in the carbon isotopic composition of dissolved inorganic carbon (DIC), with higher values indicating either increased primary productivity in the lake or increased fraction of DIC derived from dissolution of limestone (relative to that originated from the decomposition of organic matter). Shells from the low altitude lake (in a warm climate) are more depleted in heavy carbon isotope 13C compared to those from higher elevation lakes, due to higher rates of organic matter decomposition contributing a greater amount of 13C-depleted carbon to the DIC and resulting in lower δ13C values of the shells. Radiocarbon analyses of modern shells from the studied lakes confirm the previous observation that lake radiocarbon reservoir effect varies greatly among lakes depending on local hydrology and bedrock lithology. The reservoir effect also varies in space and time within a lake. / A Dissertation submitted to the Department of Earth, Ocean & Atmospheric Science in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Summer Semester 2017. / July 20, 2017. / Includes bibliographical references. / Yang Wang, Professor Directing Dissertation; Vincent Salters, Professor Co-Directing Dissertation; Tom Miller, University Representative; Leroy Odom, Committee Member; Munir Humayun, Committee Member.

No description available.

No description available.

No description available.