Eight years after the coal ash spill – Fate of trace metals in the contaminated river sediments near Kingston, eastern Tennessee

Abstract

Abstract In December 2008, the failure of a coal ash retention pond at the Kingston Fossil Plant in eastern Tennessee, United States contaminated the Emory River and Clinch River located upstream of the Watts Bar Reservoir on the Tennessee River. Despite an extensive cleanup effort, further leaching of metals to river water from residual coal ash remains a cause of concern. Also, it is unknown whether coal ash has undergone substantial burial by younger river sediments. In order to address these uncertainties, in spring 2016 we collected six 30\u202fcm long sediment cores from five contaminated and one uncontaminated portions of the river systems. The cores were subdivided into ∼2–3\u202fcm sediment layers, which were exposed to water and acid leaching for metal and metalloid analyses. The measured concentrations of arsenic are 10 times higher in the river sediments near the Kingston Plant compared to downstream locations. Using ratios of various metals (e.g., cadmium, chromium, selenium, vanadium) to arsenic, we have established that only arsenic and selenium in downstream sediments are predominantly sourced by coal ash (80–100%). For other metals (e.g., cadmium, chromium, vanadium) coal ash-derived contamination comprises