Numerous studies have shown that coal ash contains high levels of trace metals such as arsenic, boron, and mercury that can potentially harm the environment. The December 22, 2008 coal ash spill at Kingston coal-burning power plant of Tennessee Valley Authority (TVA) Plant has provided a unique opportunity to study different environmental impacts of coal-ash derived metals on a regional scale. A preliminary investigation by Duke team has revealed that trace metals such as arsenic, strontium, and boron are easily mobilized from coal ash sludge and dissolved in ambient surface water. Furthermore, it was found that mercury is enriched in the downstream river sediments, reflecting transport and mixing of the ash sludge with river sediments. This RAPID proposal seeks to further investigate the environmental impacts of the coal ash spill and the remediation activities (e.g., sludge dredging) proposed by TVA. In particular, this study will focus on: (1) the critical water/sediment ratio at which the content trace metals from ash leaching begin to impact water quality; (2) the transport and accumulation of ash in downstream river sediments; (3) the potential of sulfate-reducing bacteria to generate methylmercury in the downstream anaerobic river sediments; and (4) the suitability of boron and strontium isotopes as geochemical tools for elucidating coal ash metals in aquatic systems.
The potential impact of coal ash storage on the environment is an emerging issue due to the magnitude of the problem. Currently about five hundred power plants in the USA generate approximately 130 million tons of coal ash, of which more than half is stored in landfills and ponds, such as in the Kingston coal plant. One of the major potential hazards of coal ash storage in ponds is the continuous leaching of contaminants and their transport to the hydrological system. Yet, the impact of this continuous leaching on water and ecological quality is unknown. As such, the TVA coal ash spill provides an ?opportunity? to investigate these processes on a larger scale and to define biogeochemical tools for investigating the impact of coal ash on the environment. This project will form the basis for two PhD theses at Division of Earth and Ocean Sciences and Department of Civil and Environmental Engineering at Duke University.
