Mercury (Hg) is a toxic element which bioaccumulates in the food chain when methylated and poses a health risk to the human population mainly through fish consumption. It is released into the environment through both natural and anthropogenic processes. Remediation of river systems contaminated with Hg presents challenges due to complexities associated with dynamic transport and deposition processes and cyclic methylation. The South River watershed in Virginia, USA contains elevated concentrations of Hg within sediment and floodplain soils as a result of historical releases from a textile manufacturing plant from 1929-1950. Methylation of Hg is a bacterially mediated process which is controlled by the availability of electron donors, electron acceptors and Hg, amongst other factors. To evaluate the factors controlling Hg methylation at the South River site, four column experiments were conducted that involved saturating site sediments with South River water, followed by subjecting the columns to influent solution containing differing organic carbon and sulfate amendments. These amendments included acetate, lactate, and lactate combined with excess SO42- and the production of MeHg relative to a control was monitored both spatially and temporally. Production of MeHg was observed in all four columns, with the lowest mass found in the effluent generated by the control column (8.7 ng L-1), and a slightly higher mass in the acetate and lactate amended column effluents (53.7 ng L-1 and 30.1 ng L-1 reached respectively). The aqueous MeHg in the column amended with lactate and SO42- reached a maximum of 4910 ng L-1 near the output of the column. The results from these column experiments suggest that excess SO42- did not inhibit methylation under saturated flow conditions in the South River sediments. The bacterial species Desulfovibrio putealis, Geobacter spp., Desulfobacterium and Desulfosporosinus were identified in the column sediments and are potential contributors to the observed Hg methylation. Experiments were conducted to evaluate the potential removal of Hg and MeHg from sediment pore water. The experiments consisted of two columns connected in series. The first column contained Hg-bearing sediment with South River water as an influent solution to provide a source of Hg for the treatment column. The effluent from the first column was then connected to a treatment column which contained 1:1 volume ratio of biochar and silica sand. This treatment column was loaded with Hg for 182 pore volumes, disconnected, and then subjected to new influent solutions consisting of first background river water and then simulated acid rain water. The purpose was to determine the potential of the biochar material to retain Hg under saturated flow conditions. No significant release of Hg was observed in the column effluent with the South River water. After the influent was switched to simulated acid rain water (pH ~ 4.6), there was an increase in Hg concentrations in the column effluent for one sampling period, but then the unfiltered and 0.45 ???m filtered Hg concentrations returned to < 8.5 ng L-1. Total Hg extractions on the biochar column material at four locations suggested that the majority of the Hg in the column resided in the first 5 cm of material even after influent perturbations, with a maximum of 0.26 ???g g-1 dry weight in the 2 cm closest to the influent. Mercury sequential extraction results on the biochar material at the termination of the column revealed the majority (67%) of the Hg on the biochar material was removed with 12 M HNO3 (F4 fraction), followed by 0.1 M KOH (F3 fraction) at 31%. Less than 1.2% of the THg was removed after subjecting the biochar material to deionized water (F1 fraction) and 0.01M HCl + 0.1M CH3COOH (F2 fraction). A solid-phase analysis of MeHg on the same biochar material resulted in a concentration of 0.20 ng g-1 dry weight, or <0.08% of total solid-phase Hg. These results suggest that application of biochar may represent an effective approach for treating Hg in passive flow through systems.

There is no abstract available for this thesis. / Department of Physics and Astronomy

This work is concerned with the characterisation of epitaxial (Hg,Mn)Te, and in particular the assessment of the structural and transport properties of the layers. Direct alloy growth (DAG) of (Hg,Mn)Te on buffered GaAs and unbuffered (Cd,Zn)Te substrates in a horizontal MOVPE reactor resulted in poor surface compositional and thickness uniformity. This was attributed to the differences in the pyrolysis rates of the Te and Mn precursors. Double crystal x-ray diffraction was used to determine accurately layer thickness, composition and quality. Analysis of the symmetric and asymmetric rocking curves revealed that for thickness over lµm (Hg,Mn)Te was almost 100% relaxed. A reduction in the dislocation density, as inferred from the x-ray rocking curve width, was observed with increasing layer thickness and was considered in terms of the Gay model. A sub-grain structure was seen using double crystal x-ray topography, where grain diameter decreased in a linear manner with inverse layer thickness. Triple axis x- ray diffraction revealed that tilts between the sub-grains were the primary cause of the rocking curve broadening. Hall and resistivity measurements were made in the temperature range 4K to 290K. The majority of the layers exhibited n-type behaviour, with carrier concentrations and mobilities dependent on layer thickness. Modelling of the temperature dependence of the carrier mobility was attempted for various lattice and impurity scattering mechanisms. Attempts were also made to explain the temperature dependence of the carrier concentration using a two band model and estimates for the bandgaps obtained from intrinsic Hall data. The interdiffused multilayer process (IMP) was then employed, resulting in layers with superior lateral compositional and thickness uniformities. Improved crystalline quality to that seen in comparable DAG layers was also obtained. The electron mobilities were higher in IMP lasers than incomparable DAG ones and analysis of the mobility data indicated that several scattering mechanisms were operative, including ionised and neutral impurity, optical phonon and piezoelectric (in Mn rich layers) scattering. Layers grown by IMP appeared to be more stable and changes in transport properties over a period of a few months were less pronounced than for comparable DAG layers.

No description available.

This thesis investigates the life and work of Edward Baines, editor of the Leeds Mercury from 1801 to 1848 and Member of Parliament for Leeds from 1834 to 1841. It considers his political, journalistic and literary achievements and it investigates why no authoritative complete study of his life has been carried out since his son's filial biography written in 1851. The thesis examines the confusion which has arisen because Edward Baines Senior and Junior were both journalists editing the Leeds Mercury, both campaigning Dissenters, both Members of Parliament for Leeds and that much of their political and journalistic lives ran concurrently and not consecutively. Consideration is given to Baines's antecedents, his early years and the influences that helped shape his thinking. Baines's philosophy is examined, particularly as it was expressed in both his newspaper editorials and his academic writings. It shows that his fundamental beliefs were rooted in Protestant Christianity and how this was reflected in his views by his opposition to war and slavery, his lifelong support for individual freedom as expressed through Whig-Liberalism and the cause of Nonconformism. The thesis then follows a chronological approach. The years 1801 to 1815 witnessed his campaign on behalf of the merchants and manufacturers of the West Riding and the active political role he adopted from the election of 1807 onwards. The years 1815 to 1829 revealed Baines at the apotheosis of his journalistic career, with the revelations of the Government Spy scandal, his involvement in the campaigns for Parliamentary Reform, the commencement of his literary career and the launch of his strategy to establish a Whig power base in Leeds by taking control of the Parish Church vestry. The years 1830 to 1841 demonstrated Baines as an active politician, becoming the Member for Leeds and using his parliamentary position to campaign for the rights of the Dissenters. His final years 1841 to 1848 showed him still active in politics locally; an examination is also made of his final commitment to evangelical Congregationalism. Primary source material has been used throughout to illustrate Baines, his beliefs and the views his contemporaries held of him. Although few manuscript primary sources are available a considerable amount of printed primary source material is to be found in Baines's books and almost fifty years of his LessisMercury. The newspapers of his opponents, which cover the same period, offer a diverse range of views on the man and these enable a more balanced view of him to be reached than that found in his son's biography.

As Mercury orbits the Sun, solar induced gravitational torques give rise to a planetary libration. While undergoing this 88 day period libration, the axes of minimum moment of inertia of the mantle and solid core, if present, become misaligned, leading to a gravitational torque which initiates a free-mode of axial oscillation between the inner core and mantle. For a large gravitational torque, the free-mode period approaches the period of the libration forcing, and should participate in the planets libration response. The goal of this work is to determine whether Mercurys observed librations can be used to place constraints on the inner core structure. Perturbations in Mercurys rotation rate are simulated for a range of interior structures. For models where the free-mode interferes with the libration signature, a marginally better fit between model response and observations is obtained, compared to models which exhibit the libration signature alone. / Geophysics

Saturated solutions of mercuric chloride in different methanol-water and hydrochloric acid solvent mixtures were equilibrated at 25.00 ± 0.01°C. Total mercury and free chloride concentrations were determined by analytical procedures and the data were analyzed with the aid of the computer. Tabulated below are the results of this study: [--see thesis for table--]

Thesis (Ph.D.)--Tennessee Technological University, 2007. / Bibliography: leaves 172-182.

Thesis (Ph. D.)--Oregon Graduate Center, 1989.

Thesis (M.Env.St. 1979) from the Department of Physical and Inorganic Chemistry, University of Adelaide.