Geochemical and Isotopic Characterization of Coal Combustion Residuals: Implications for Potential Environmental Impacts
Coal fired power plants are ubiquitous in the United States and most developed countries around the world, providing affordable electricity to consumers. In the US, approximately six hundred power plants generate 136 million tons of Coal Combustion Residuals (CCRs) annually, encompassing fly ash, bottom ash, and flue gas desulfurization materials. The range and blends of CCRs varies substantially across coal-fired plants and depends on a unique set of circumstances for each plant and coal source. Current U.S. regulations mandate the installation of advanced capture technologies to reduce atmospheric pollution, but do not address the transfer and storage, or the potential impacts to water resources. Thus improved air quality is traded for significant enrichments of contaminants in the solid waste and effluent discharged from power plants.
This work examines the geochemical and isotopic characteristics of CCRs, as well as potential environmental impacts from CCRs. This investigation looks at several different aspects of CCR and environmental interactions from 1) the immediate impacts of the 2008 TVA coal ash spill in Kingston, TN, 2) the long-term (18-month) exposure of the spilled ash in the Emory and Clinch rivers, 3) impacts on waterways in North Carolina that receive CCR effluent from coal fired power plants, and 4) examination of boron and strontium isotopes of CCRs from leaching experiments and their application as tracers in the environment of the TVA spill and NC waterways. These investigations have illuminated several conclusions, including contact of surface water with CCRs leach high concentrations of leachable CCR contaminants, such as As, Se, B, Sr, Mo, and V in the surface waters; the dilution effect is critical in determining the concentration of contaminants from the CCRs in surface water (both at the spill and in waterways receiving CCR effluent); recycling of trace elements (such as As) through adsorption/desorption can impact water quality; and elevated boron and strontium concentrations, in addition to their isotopes, can trace CCR effluent in the environment. Combining the geochemical behavior and isotopic characteristics provides a novel tool for the identification CCR effluents in the environment.
coal combustion residuals
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