Spatial and temporal trends in contaminant concentrations in Hexagenia nymphs following a coal ash spill at the Tennessee Valley Authority's Kingston Fossil Plant

Abstract

A dike failure at the Tennessee Valley Authority Kingston Fossil Plant in East Tennessee, United States, in December 2008, released approximately 4.1 million m(3) of coal ash into the Emory River. From 2009 through 2012, samples of mayfly nymphs (Hexagenia bilineata) were collected each spring from sites in the Emory, Clinch, and Tennessee Rivers upstream and downstream of the spill. Samples were analyzed for 17 metals. Concentrations of metals were generally highest the first 2 miles downstream of the spill, and then decreased with increasing distance from the spill. Arsenic, B, Ba, Be, Mo, Sb, Se, Sr, and V appeared to have strong ash signatures, whereas Co, Cr, Cu, Ni, and Pb appeared to be associated with ash and other sources. However, the concentrations for most of these contaminants were modest and are unlikely to cause widespread negative ecological effects. Trends in Hg, Cd, and Zn suggested little (Hg) or no (Cd, Zn) association with ash. Temporal trends suggested that concentrations of ash-related contaminants began to subside after 2010, but because of the limited time period of that analysis (4 yr), further monitoring is needed to verify this trend. The present study provides important information on the magnitude of contaminant exposure to aquatic receptors from a major coal ash spill, as well as spatial and temporal trends for transport of the associated contaminants in a large open watershed.

Bioaccumulation Dynamics of Arsenate at the Base of Aquatic Food Webs

“…In addition, gut contents of larvae were not purged prior to analysis. Thus, As adsorption to the exoskeleton − and As associated with gut contents could have contributed greatly to measured radioactivity in larvae.…”

Comparing Trace Element Bioaccumulation and Depuration in Snails and Mayfly Nymphs at a Coal Ash–Contaminated Site

“…Although our study showed that concentrations of the coal ash–associated contaminants As and Se were higher in all the sample matrices including snails and mayflies at ash‐affected sites than at the reference sites, major remediation activities removed much of the spilled ash from the site in 2010 and 2011; and as a result, trace element concentrations in mayfly nymphs were shown to decrease in the 4 yr following the spill (Smith et al 2016). Overall, concentrations of trace elements associated with coal ash measured in mayfly nymphs in the present study remained similar to the ones reported in mayflies in other sites (Cid et al 2010; Opfer et al 2011; Fletcher et al 2014, 2017).…”

“…Although our study showed that concentrations of the coal ash-associated contaminants As and Se were higher in all the sample matrices including snails and mayflies at ash-affected 2: Biomagnification factors (BMFs) calculated as the ratio between the average concentrations of each trace element (expressed as parts per million dry wt) in the biota (i.e., mayfly nymphs and adult snails) and the average concentration of each trace element (expressed as parts per million dry wt) in their respective food resources (i.e., sediment and periphyton) a sites than at the reference sites, major remediation activities removed much of the spilled ash from the site in 2010 and 2011; and as a result, trace element concentrations in mayfly nymphs were shown to decrease in the 4 yr following the spill (Smith et al 2016). Overall, concentrations of trace elements associated with coal ash measured in mayfly nymphs in the present study remained similar to the ones reported in mayflies in other sites (Cid et al 2010;Opfer et al 2011;Fletcher et al 2014Fletcher et al , 2017.…”

Valuable Secondary Habitats or Hazardous Ecological Traps? Environmental Risk Assessment of Minor and Trace Elements in Fly Ash Deposits across the Czech Republic

“…Although Hg also belongs to the commonly analysed heavy metals, our methods were unable to reliably determine its content in our samples (cf. [30]). Nevertheless, Hg is almost completely volatilised during the combustion of coal and its proportion in ash particles is extremely low [31].…”