Sulfur Dioxide (SO2) is a difficult air pollutant to characterize spatially since it is primarily emitted from a few point sources typically having tall stacks. A better comprehension of the behavior and advection of ambient SO2 in metro Atlanta will help in the interpretation of epidemiologic analyses as well as establish an understanding of the source contributions to ambient SO2 in Atlanta. The operation and SO2 emission characteristics of four coal-fired power plants and a coal-fired cement kiln, all of which lie in the vicinity of Atlanta, were examined. Data retrieved from three downtown Atlanta monitoring stations that record ambient SO2 concentrations were also examined. Trends from ambient SO2 data agree with emission trends from the four coal-fired power plants, suggesting that one or more of the power plants are contributing to the ambient SO2 in Atlanta. SO2 rose plots using concentration and wind direction data from downtown monitoring stations were developed to identify from which direction the elevated levels of ambient SO2 were originating. A strong peak in the northwest direction of Atlanta suggests that Plant Bowen, Plant McDonough, or Lafarge Building Materials may be contributing to high concentrations of ambient SO2 in Atlanta. Further analysis concluded that Lafarge was not a likely contributor to the northwest peak. The plumes of Plant Bowen and Plant McDonough were modeled using air parcel trajectories and the Gaussian dispersion model. The results suggest that, when the wind is blowing from the northwest direction, Plant McDonoughs plume is the primary contributor to the elevated levels of SO2 recorded by downtown Atlanta monitoring stations.

Immobilization and detoxification of chromium in the vadose zone is made possible by the existence of an effective reductant, SO2, that exists in a gaseous form at room temperature. Experimental studies were designed to characterize stoichiometry and kinetics of chromium reduction both in aqueous solutions at pH values near neutrality and in soil. First, batch experiments and elemental analyses were conducted to characterize the stoichiometry and kinetics of Cr(VI) reduction in water. The stoichiometric ratio of S(IV) removed to Cr(VI) removed ranged between 1.6 and 1.8. The overall reaction is believed to be the result of a linear combination of two reactions in which dithionate is an intermediate and sulfate is the stable oxidized product. The reaction was also rapid, with the half-time of about 45 minutes at pH 6 and about 16 hours at pH 7. A two-step kinetic model was developed to describe changes in concentrations of Cr(VI), S(IV), and S(V). Nonlinear regression was applied to obtain the kinetic parameters. The rate of reaction was assumed to be second-order with respect to [Cr(VI)] and first-order with respect to [S(IV)], and [S(V)]. The values for the rate coefficient for the first reaction (k1) were found to be 4.5 (?10%), 0.25 (?9.4%) (mM-2h-1) at pH 6 and 7, respectively. The values of the rate coefficient for the second reaction (k2) were 25 (?29%), 1.1 (? 30%) (mM-2h-1) at pH 6 and 7, respectively. The reaction rate decreased as pH increased. Experiments showed that the rate at pH 7 was lower than that at pH 6 by one order of magnitude. Second, batch experiments and elemental analyses were conducted to characterize the stoichiometry and kinetics of Cr(VI) reduction in soil. The stoichiometric ratio of S(IV) removed to Cr(VI) removed was almost 2, which is slightly higher than that for the reaction in water. This higher value may be due to S(IV) oxidation by soil-derived Fe(III). The reaction was rapid, with the half-time less than 2 minutes, which is faster than in water. The rate coefficients, k1 and k2, were 22 (?41%) and 13 (?77%) (M-2h-1), respectively.

Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references (leaves 76-77). Also available in electronic version. Access restricted to campus users.

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Thesis (Ph. D.)--Ohio University, March, 1991. / Title from PDF t.p.

Thesis (Ph. D.)--Ohio University, November, 1993. / Title from PDF t.p.

Thesis (M.S.)--Ohio University, November, 2000. / Title from PDF t.p.

Thesis (M.S.)--Ohio University, August, 1999. / Title from PDF t.p.