SREL Reprint #3681

Understanding the role of biotic vectors in the accumulation and spread of radioactive contamination on the Savannah River Site - 22270

M. Chapman1, G. Dharmarajan1, A. L. Bryan Jr.1, T. L. DeVault1, L. Lee1, and O. E. Rhodes Jr.2

1University of Georgia, Savannah River Ecology Laboratory, PO Drawer E, Aiken SC 29802 USA
2University of Georgia, Odum School of Ecology, 140 E Green St, Athens, GA 30602 USA

Abstract: The H-area tank farm (HTF) is an 18-ha facility that contains liquid waste storage tanks and supporting structures that store legacy radioactive waste at the Savannah River Site (SRS), South Carolina, USA. Routine radiological surveys at the HTF detected radiocesium (Cs-137) contamination in biological samples collected at the site, specifically bird feces, a dead mouse, and a bird nest. Analysis of the fecal material revealed seeds of pokeweed (Phytolacca americana), and additional surveys of vegetation within the HTF revealed two individual plants (pokeweed and blackberry (Rubus sp.)) exhibiting elevated levels of radioactivity. We evaluated the potential sources and pathways that might be involved in the movement and transport of radiological materials within and outside of the controlled radiological areas. We assessed the extent of the biotic vector problem (i.e., birds and rodents), explored spatial risk associated with the movement of contaminants through biotic vectors within and outside of the site via VHF tracking, and identified the specific exposure pathways that led to the assimilation of radionuclides into the tissues and/or digestive tracks of the biotic vectors (vegetation and insect sampling). Of the birds and rodents evaluated for volumetric radioactivity, only 1.3% had an internal contamination level >5000dpm. Home range sizes and habitat use of birds and rodents varied widely among individuals and species, but overall we found that they tended to avoid the industrialized center of the HTF. Six pokeweed samples had contamination levels above background. None of the insect samples had elevated levels of Cs-137. Our analyses revealed relatively low levels of risk to human populations from radionuclide contamination associated with biotic vectors (i.e., birds and rodents) and their potential food sources (i.e., plants and insects) within and adjacent to the HTF. However, some pokeweed samples had low-level contamination that could accumulate in birds and rodents. We recommend vegetation control measures to reduce or eliminate pokeweed at the HTF, as well as the establishment of an integrated wildlife management program to minimize potential transport of contaminants from the HTF by birds and rodents. Our findings and methodological approaches may be useful to other accident sites and nuclear facilities facing similar environmental/industrial interactions leading to the transport of radionuclides within and outside of controlled areas.

SREL Reprint #3681

Chapman, M., G. Dharmarajan, A. L. Bryan, T. L. DeVault, L. Lee, and O. E. Rhodes Jr. 2022. Understanding the role of biotic vectors in the accumulation and spread of radioactive contamination on the Savannah River Site - 22270. Waste Management 2022 Conference, Phoenix, AZ.

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