Vectors for Metal Transport in the Tim Branch/Steed Pond Watershed on the Savannah River Site
Seaman, John C.
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Following construction of the Department of Energy's Savannah River Site (SRC) near Aiken, SC in 1954, over 44,000 kg of depleted uranium (U), a similar amount of nickel (Ni), and other metal contaminants were released into the Tims Branch-Steed Pond (TBSP) System. Failure of the Steed Pond dam in the 1990s facilitated significant transfer of U to downstream ecosystems largely in association with particulates suspended during rainfall events. Since that time Steed Pond has become much more densely vegetated and the affect of this landcover shift on U and Ni mobilization is currently unknown. Recent monitoring efforts below Steed Pond suggest that during base flow mobilized Ni predominately occurs in soluble or nanoparticulate (<0.2µm) form, while significant portions of U are mobilized as filterable particulates (<0.2µm). To evaluate the current impact of rainfall events, we have installed an automated stream monitoring systems below the outlet of Steed Pond. This Monitoring system is triggered by turbidity measurements to capture peaks in suspended particulates during episodic rain events. In addition, we are conduction laboratory studies that probe the influence of pH, ionic strength and redox status on the remobilization of colloid-bound U within the TBSP system.