SREL Reprint #2490

Long-term studies of radionuclide contamination of migratory waterfowl at the Savannah River Site: implications for habitat management and nuclear waste site remediation

I. Lehr Brisbin, Jr. and Robert A. Kennamer

Abstract: Past nuclear industrial activities at the U.S. Department of Energy's Savannah River Site (SRS) have resulted in low-level radionuclide contamination of a variety of the site's wetlands, including a series of abandoned reactor cooling reservoirs. As a result of their long-term stable water levels and protection from public hunting and disturbance, these reservoirs have come to serve as a regionally important inland wintering site for diving ducks (Anatidae: Aythyinae) and other waterfowl species. These birds have been studied to determine the rates and patterns by which radionuclide levels in their whole body and muscle tissue have changed over time. Studies have focused particularly on the American Coot (Fulica americans) as a sentinel species. Coots have proved to consistently have the highest levels of contamination with the long-lived gamma-emitting radioisotope radiocesium (137Cs), the most ubiquitous of the radioactive contaminants accumulating in biota on the SRS. From 1971 through 1986, radiocesium body burdens of 311 coots decreased in a negative-exponential pattern, with an ecological half-life of about four years. Radiocesium levels were initially higher in two of the reservoir's three arms where contaminated effluent had entered the watershed in the late 1950s to mid-1960s. Differing rates of decline of coot radiocesium burdens among arms of the reservoir reflected histories of reactor effluent flow that caused differential movement of this contaminant within the system. For the past two decades, average radiocesium levels in wintering coots have been well below those generally considered to be of concern for human consumption. However, our findings suggest the importance of continuing these contaminant monitoring programs while also maintaining a thorough understanding of the ecology and natural history of these birds on the SRS. Future options under consideration by the Department of Energy for its former reactor cooling reservoirs, intended as either cost-saving or remediation activities, include the cessation of make-up water pumping (leading to widely fluctuating reservoir water levels) and permanent partial or complete reservoir drawdown. Our long-term information together with continued monitoring programs will be necessary to predict some of the possible radiological consequences of any such reservoir management activities.

Keywords: American Coot, contamination, Fulica americans, long-term study, radiocesium, radionuclide, risk assessment, Savannah River Site, U.S. Department of Energy, waterfowl

SREL Reprint #2490

Brisbin, I. L., Jr., and R. A. Kennamer. 2000. Long-term studies of radionuclide contamination of migratory waterfowl at the Savannah River Site: implications for habitat management and nuclear waste site remediation. Studies in Avian Biology 21:57-64.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).