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IP11 Investigations of the Columbia River and Estuary (USA)
(IP089) Assessing Onsite Ecological Impacts of Legacy Materials from the Hanford Site, Washington State During the 21st Century.
Tiller, B1, Turner, G1, Patton, G1, 1 Pacific Northwest National Laboratory, Richland, WA, USA
ABSTRACT- Contaminants in biota that inhabit the Hanford Reach of the Columbia River have been monitored by the U.S. Department of Energy (DOE) since about 1945. Site missions have changed over the past 50 years, from plutonium production to the Department of Energy’s present mission of waste management, environmental clean-up, and restoration. In support of restoration and clean-up activities, selected contaminant monitoring efforts and biological assessments have been integrated and directed to better support the ecological assessment requirements that DOE faces during site closure. Under this strategy, contaminant monitoring of biota is targeted to include ecological receptors possessing life-history characteristics that best meet criteria of an ideal sentinel organism. The general approach includes measurement of the tissue burden of legacy materials from the Hanford Site, in addition to evaluations of a suite of biological health metrics for selected organisms. Using this target receptor approach, concentrations of uranium were examined in the water and in potential receptor organisms having different pathways of contaminant uptake. Most trace-metal uptake was associated with the benthic organisms including macrophytes, clams, crayfish and deep-rooted trees. Sampling and analysis of Asiatic clams (Corbicula fluminea) were particularly effective in assessing areas of contaminant releases along the Hanford Reach. Uranium concentrations measured in clams were highly correlated (r2=0.55, p<0.001) with uranium concentrations measured in river water samples. Concentrations of both metals (chromium) and radionuclides (strontium-90, uranium isotopes) in clams also provided signatures to known groundwater discharges into the river. These monitoring results support assessments of site conditions and assist with closing out waste sites found on the Hanford Site.
Key words: radionuclides, trace metals, tissue burdens, biological health
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