Mercury is a leading concern among the air toxic metals addressed in the 1990 Clean Air Act Amendments (CAAA) because of its volatility, persistence, and bioaccumulation as methylmercury in the environment and its neurological health impacts. The Environmental Protection Agency (EPA) reports for 2001 shows that total mercury emissions from all sources in USA is about 145 tons per annum, of which coal fired power plants contribute around 33% of it, about 48 tons per annum. Unlike other trace metals that are emitted in particulate form, mercury is released in vapor phase in elemental (Hg0) or oxidized (Hg2+, mainly HgCl2) form. To date, there is no post combustion treatment which can effectively capture elemental mercury vapor, but the oxidized form of mercury can be captured in traditional emission control devices such as wet flue gas defulrization (WFGD) units, since oxidized mercury (HgCl2) is soluble in water. The chlorine concentration present during coal combustion plays a major role in mercury oxidation, which is evident from the fact that plants burning coal having high chlorine content have less elemental mercury emissions. A novel method of co-firing blends of low chlorine content coal with high chlorine content cattle manure/biomass was used in order to study its effect on mercury oxidation. For Texas Lignite and Wyoming coal the concentrations of chlorine are 139 ppm and 309 ppm on dry ash free basis, while for Low Ash Partially Composted Dairy Biomass it is 2,691 ppm. Co-firing experiments were performed in a 100,000 BTU/hr (29.3 kWt) Boiler Burner facility located in the Coal and Biomass Energy laboratory (CBEL); coal and biomass blends in proportions of 80:20, 90:10, 95:5 and 100:0 were investigated as fuels. The percentage reduction of Hg with 95:5, 90:10 and 80:20 blends were measured to be 28- 50%, 42-62% and 71-75% respectively. Though cattle biomass serves as an additive to coal, to increase the chlorine concentration, it leads to higher ash loading. Low Ash and High Ash Partially Composted Dairy Biomass have 164% and 962% more ash than Wyoming coal respectively. As the fraction of cattle biomass in blend increases in proportion, ash loading problems increase simultaneously. An optimum blend ratio is arrived and suggested as 90:10 blend with good reduction in mercury emissions without any compromise on ash loading.

Coal fired power plants will face many challenges in the near future as new regulations, such as the Clear Sky Act, are being implemented. These regulations impose much stricter limits on NOx emissions and plan to impose limits on mercury emissions from coal fired boilers. At this time no technologies are currently being implemented for control of Hg and this explains the strong interest in this area by the Department of Energy (DOE). Reburn technology is a very promising technology to reduce NOx emissions. Previous experimental research at TAMU reported that Feedlot Biomass (FB) can be a very effective reburn fuel, for reduction of NOx up to 90%-95%; however, little work has been done to model such a process with Feedlot Biomass as reburn fuel. The present work addresses the development of a reburn model to predict NOx and Hg emissions. The model accounts for finite rate of heating of solid fuel particles, mixing with NOx laden hot gases, size distribution, finite gas phase and heterogeneous chemistry, and oxidation and reduction reactions for NOx and Hg. To reduce the computational effort all the reactions, except those involved in mercury oxidation, are modeled using global reactions. Once the model was validated by comparison with experimental findings, extensive parametric studies were performed to evaluate the parameters controlling NOx reduction. From DOE research programs some experimental data regarding the capture of mercury from power plant is available, but currently no experimental data are available for Hg emission with reburn process. This model has shown a very large mercury reduction using biomass as a reburn fuel. The model recommends the following correlations for optimum reduction of NOx: Equivalence Ratio should be above 1.05; mixing time should be below 100ms (especially for biomass); pure air can be used as the carrier gas; the thermal power fraction of the reburner should be between 15% and 25%; residence time should be at least 0.5s and the Surface Mean Diameter (SMD) of the size distribution should be as small as possible, at least below 100 µm.

The major goal of this research is the development of a competitive ligand equilibration-solvent solvent extraction (CLE-SSE) method to determine organically complexed mercury species in estuarine water. The method was applied to estuarine surface waters of Galveston Bay and the water column of Offatts Bayou. Thermodynamic equilibrium modeling estimated organically complexed mercury species in estuarine water using the conditional stability constants of mercury-organic complexes and the concentrations of organic ligands determined by CLE-SSE. Two competing ligands, chloride and thiosalicylic acid (TSA), were used for CLE-SSE. Chloride ion competition determined conditional stability constants for 1 : 1 mercury-ligand complexes ranging from ~1023 to ~1024 with concentrations of organic ligands at low nM levels. TSA competition determined stronger mercury-binding ligands by manipulating the TSA concentration such that a higher binding strength was achieved than that for the mercury-chloride complex. TSA competition determined conditional stability constants for 1 : 1 mercury-ligand complexes ranging from ~1027 to ~1029, with ligand concentrations ranging from 10 to 100 pM. Mercury-organic binding strengths in these ranges are consistent with bidentate mercury complexation by low molecular weight organic thiols. A linear relationship was observed between log stability constants for the mercury-ligand complex and log ligand concentrations, supporting the hypothesis that there is a continuum of mercury binding site strengths associated with dissolved organic matter. In Galveston Bay, organically complexed mercury accounted for > 95 % of the total dissolved mercury in surface water. Organic complexation of mercury coupled with mercury dissolution from particulate phases controls the filter-passing mercury distribution in surface waters of Galveston Bay. The estuarine distributional features of mercury-complexing organic ligands were similar to those of glutathione, supporting mercury complexation by a thiol binding group. In Offatts Bayou, a seasonally anoxic bayou on Galveston Bay, thermodynamic equilibrium modeling suggests that the speciation of dissolved mercury in anoxic systems is dominated by sulfide complexation rather than organic complexation.

Thesis (Ph.D.)--University of Delaware, 2009. / Principal faculty advisor: James E. Pizzuto, Dept. of Geological Sciences. Includes bibliographical references.

Thesis (Honors)--College of William and Mary, 2009. / Includes bibliographical references (leaves 96-112). Also available via the World Wide Web.

Thesis (Ph. D.)--University of Oregon, 2000. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 169-178). Also available for download via the World Wide Web; free to University of Oregon users.

Thesis (Ph. D.)--University of Texas at Austin, 2002. / Supervisor: Gary T. Rochelle. Vita. Includes bibliographical references. Also available from UMI.

Thesis (M.S.)--University of South Florida, 2003. / Title from PDF of title page. Document formatted into pages; contains 64 pages. Includes bibliographical references.

The presence of Hg in natural gas and gas condensate is termed as a “critical severity risk”, according to health and safety regulation of the petroleum industry. Mercury affects the gas processing plants as well as refinery industries; damaging heat exchanger, poisoning the catalysts and increases the exposure risk to the field workers. Consequently, in order to establish a data base project to assess both the total mercury content and/or the dominants species for certain production field, alongside with mercury distribution within a natural gas processing plant or petrochemical industries, it is vital to develop and establish a reliable, low cost, time saving and applicable method(s) to be used in oil and gas industry as a routine method, if possible. Hence, the current study primarily aimed to follow the distribution of mercury, as a total and species, within Obaiyed plant (Egypt) as a model of natural gas processing factory. Then the second phase of this work has been devoted to conduct an environmental visibility study to develop reliable and convenient methods to measure and speciate mercury on polluted crops due to industrial waste. This part of study was followed by a screening analysis for commercial rice samples represent the product of different world regions including Egypt.

Abstract The concentration of mercury vapour in ambient air is routinely determined using specialised instruments. As an economical alternative, actively pumped Hopcalite sorbent tubes can be used to trap atmospheric mercury, which is subsequently analysed by cold vapour atomic absorption spectroscopy. Plant materials are also readily available in most regions and can be analysed to obtain information on time averaged atmospheric mercury levels. Lichen and tree bark samples were collected in the cities of Pretoria and Witbank, dried and acid digested with subsequent cold vapour atomic absorption spectroscopy. Average mercury concentrations ranging from 74 to 193 μg.kg-1 were found in lichens from three Pretoria suburbs, whilst average Hg levels of 228 μg.kg-1 were determined in lichens collected in Witbank. The average mercury concentration in tree bark was consistently lower than in lichens, with concentrations between 28 and 72 μg.kg-1 determined in samples from three Pretoria suburbs and 75 μg.kg-1 determined in samples taken in Witbank. This study is the first in South Africa to determine mercury levels in lichens and tree bark. Average total gaseous mercury concentrations in ambient air at the three Pretoria suburban sites, as determined by a semi-continuous spectroscopic method using Hopcalite sampling, ranged between 1.6 and 2.5 ng.m-3, while an average of 1.7 ng.m-3 was measured in Witbank over the sampling interval.