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ENVIRONMENTAL RISK ASSESSMENT AND CLEANUP ON DOE LANDS: Using Tissue Banks and Turtles as Biodetectors of Contamination


J. Whitfield Gibbons and Judy Greene

 

To achieve DOE's stated goal of protecting the SRS environment, understanding threats to ecological processes is essential. Contaminants must be detected and the boundaries of impact delimited. To accomplish the further goal of restoring viability and quality to altered ecosystems, the success of cleanup, measured biologically, must be validated.

RESEARCH BACKGROUND:

yellow-bellied slider

Slider (Trachemys scripta)

DOE is heir to a major biological resource on the SRS--long-term research on freshwater turtles, involving virtually all aspects of their ecology and genetics, as well as application of the findings to evaluating environmental impacts of SRS operations. SREL studies using turtles as bioindicators have served DOE well: (1) initially as environmental assessors of reactor effluents; (2) by revealing the presence of open-access sites of radioactive contamination; (3) by predicting the presence and finding radioactive turtles on private lands (preemptive of potential lawsuits); (4) by discovering altered genetic structure in turtles from contaminated sites.

Turtles can be effective biological monitors and environmental indicators with wide-ranging applicability by facilitating biodetection of contaminants occurring at low levels. Preliminary data suggest that turtles amplify environmental signals through biomagnification, thus making them extremely sensitive biomonitors. Turtles are effective, long-term bioaccumulators that can function as sentinels of the chemical makeup of a region. We have previously documented biological half-lives for radionuclides and can do likewise with other chemical contaminants. Preliminary analyses have revealed the localization of selenium and arsenic in the bone of SRS turtles, the presence of lead, mercury, and cadmium in the eggs and of cesium and strontium in the muscles and bone. These and other toxic materials, widespread on the SRS, are the focus of environmental cleanup efforts.

PROJECT GOAL:

The ultimate goal is to develop techniques and storage facilities for a tissue bank (bone, blood, and muscle) from SRS turtles useful for biological assessment of chemical presence and biological response that would be significantly more costly using other risk assessment procedures. The accumulated biological material will permit analysis of a broad spectrum of heavy metal and other contaminants and enable examination of genetic responses using individuals of a variety of species. We will sample turtles from all aquatic habitat types on the SRS, including uncontaminated Set-Aside Areas and areas with introductions of radionuclides, heavy metals, or other toxic materials. Tissue samples will be available for analysis by any group with pertinent questions related to environmental cleanup.

COST-SAVING ADVANTAGES TO DOE:

Development of biological indicators, biomonitors, or sentinels is a costly but necessary exercise for many aspects of environmental cleanup. The cost-saving advantages of using SRS turtles for biodetectors of contaminants are that (1) field sampling techniques have been standardized and (2) a 30-year biological history of marked populations of more than 10,000 freshwater turtles from numerous aquatic habitats on the SRS is already available as a data base. Thus, a suitable biomonitoring system is confirmed. The approach offers opportunity for future cost reductions on a major scale including (1) early detection and initiation of environmental cleanup efforts of contaminants, (2) reducing the time and cost of achieving EM's environmental cleanup goals by determining that environmental risk levels are minimal for prescribed areas of the SRS (based on absence of contaminants in the turtles), and (3) comparative use of the same individual turtles as benchmarks (based on biological half-lives of contaminants) to document the success of cleanup and efficacy of a remediation/ restoration effort in reclaimed ecosystems.

 
 
 
 
 
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