Effects of Coal Combustion Wastes on Reproduction

Background

The coal ash spill on December 22, 2008 at the TVA Kingston Fossil Plant in Roane County, TN poses potential health risks to a wide variety of fish and wildlife. A dike from a coal fly ash slurry pond failed releasing approximately 5.4 million cubic yards of coal ash into the nearby Emory, Clinch and Tennessee Rivers and covering approximately 300 acres of land. Coal ash contains elevated concentrations of a variety of trace elements including As, Cd, Se, Sr and V. The immediate physical disturbance was obvious, but the potential long-term ecological consequences of this spill remain a concern.  Thus, a site-specific assessment of these effects, or lack thereof, is critical for understanding the consequences of the spill.

This project is examining the effects of the spill on both aquatic (turtles) and terrestrial (tree swallows) consumers. We are studying the additive and/or interactive (synergistic and antagonistic) impacts that complex mixtures of contaminants have on exposed wildlife.

This research is directly applicable to both ecological and human risk assessments along the Emory River because the project will determine 1) whether reproductive injury exists in turtles and tree swallows, and what tissue trace element concentrations provoke these injuries and 2) whether tissue concentrations in animal tissues exceed those known to adversely affect human consumers.

One objective of this project is to identify the spatial extent of trace element exposure in turtles and tree swallows, providing the basis for practical management solutions and risk assessments if deemed necessary. This research project is scheduled to occur over three years, with the first field research season initiated in March 2011.

For more information on the Kingston, TN coal ash spill visit the TVA website.

Why Study Turtles?

Turtles are excellent model organisms for aquatic consumer studies because of their unique suite of ecological and life history attributes. Important characteristics include their wide distribution, variation in the habitat types they occupy, and the range of trophic levels in which they feed. In addition, turtles are long-lived, allowing for long-term exposure to contaminants. The ectothermic physiology of turtles allows them to reach higher biomasses in a system than endotherms occupying similar trophic levels and their eggs and young are often important as prey items for other organisms. Importantly, turtles also have relatively small home ranges. This aspect of their natural history is particularly important for studies attempting to assess the extent of exposure along downstream gradients in river systems such as the Emory River. Finally, large numbers of turtles can be collected for rigorous assessment of reproductive effects, where eggs are incubated under controlled, laboratory conditions.

Why Study Tree Swallows?

Understanding the influence of contaminant exports on terrestrial consumers is also crucial to determining the overall impact of aquatic contamination events such as the Kingston ash spill. Ideally, the species selected for study would be easily sampled in large numbers, be available for repeated sampling of contaminant exposure over various stages of ontogeny, and be tractable for ecologically relevant effects-based studies at predictable spatial and temporal scales. The tree swallow (Tachycineta bicolor) meets all of these criteria and is ideally suited for evaluating the short- and long-term impact of aquatic contamination events. Tree swallows will be used to determine whether trace elements are being exported by aquatic insects from aquatic sites associated with the ash spill near Kingston, TN.