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Soil colloid mobilization and metal transport Shea Buettner

Summary: Soil colloid mobilization and metal transport
Shea Buettner
Crop and Soil Sciences Seminar
Wednesday, March 30, 2011 at 3:35 pm
Room 2401, Miller Plant Sciences Building
Following construction of the Department of Energy's Savannah River Site (SRS) 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 effect of this landcover shift on U and Ni mobilization is currently unknown.
Preliminary monitoring efforts below Steed Pond suggest that during base flow, mobilized Ni
predominately occurs in soluble or nanoparticulate (<0.2 Ám) form, while significant portions of U are
mobilized as filterable particulates (>0.2 Ám). To evaluate the current impact of rainfall events more
systematically, we will install an automated stream monitoring system below the outlet of Steed Pond.
This monitoring system will be triggered by turbidity measurements to capture peaks in suspended
particulates during episodic rain events. We are also investigating the mechanisms responsible for
generating the suspended particles. Erosive mobilization of wetland sediment is likely responsible for
the largest suspended particles, but other mechanisms may drive mobilization of particles in the colloid
or nanoparticle size range (1 nm to 1Ám). Changes in pH are well known to affect the dispersion of


Source: Arnold, Jonathan - Nanoscale Science and Engineering Center & Department of Genetics, University of Georgia


Collections: Biotechnology