The Environmental Impacts of the Coal Ash Spill in Kingston, Tennessee: An Eighteen-Month Survey

A year and a half investigation of the environmental impacts of the Tennessee Valley Authority (TVA) coal ash spill in Kingston, Tennessee has revealed that leachable coal ash contaminants (LCACs), particularly arsenic, selenium, boron, strontium, and barium, which originated from the spilled coal combustion products (CCPs) have different effects on the quality of impacted environments. While LCAC levels in downstream river waters are relatively low and below the EPA drinking water and ecological thresholds, elevated levels were found in surface water with restricted water exchange and in pore water extracted from the river sediments downstream from the spill. The high concentrations of LCACs in pore water are associated with anoxic conditions and predominance of the reduced arsenic species (arsenite) in the pore water. Geochemical analysis shows systematic differences in LCAC mobilization from the spilled CCPs: strontium and boron concentrations are equally high in anoxic and oxygenated waters, inferring that their reactivity with CCPs is independent of the redox state. In contrast, the mobilization of arsenic, selenium and barium depends on the redox condition present in the water with significant enrichment of arsenic (up to 2000 μg/L) and barium, and relative depletion of selenium in anoxic conditions. Based on direct measurements and species modeling, we postulate that the reduced arsenic species (arsenite) is highly mobile while reduced selenium (selenite) is highly retained in the reducing river sediments. These results have important implications for the prediction of the fate and migration of LCACs in the environment, particularly for the storage of CCPs in holding ponds and landfills, and any potential CCP leakage into lakes, rivers, and other aquatic systems.

Duke Scholars

Author Avner Vengosh Earth and Climate Sciences

Author Heileen Hsu-Kim Civil and Environmental Engineering