Cesium-137 partitioning to wetland sediments and uptake by plants
D. I. Kaplan,1 T. G. Hinton,2 A. S. Knox1
1Savannah River National Laboratory, Aiken, SC 29808, USA
2Savannah River Ecology Laboratory, Drawer E, Aiken, SC 29803,
USA
(Received April 6, 2004)
Studies were undertaken to develop a conceptual model for conducting ecological
risk assessment at the R-Canal, located on the Savannah River Site, Aiken,
South Carolina. Soil profiles collected from within the canals indicated
that the maximum 137Cs concentrations generally occurred at a depth between
2.5 and 7.5 cm. The original 137Cs deposits, the result of
accidental releases in the early 1960's, were covered by newly formed
organic and/or fluvial deposits. About 60% of the total 137Cs
inventory in each core existed at the organic matter/mineral interface.
Based on sequential extraction tests, most of the Cs in this layer was
held by either amorphous Fe-oxyhydroxides or organic matter. Sequential
extraction tests also indicated that almost half of the Cs was weakly
bound to the soil (either exchangeable or associated with amorphous Fe-oxides),
a percentage that is five times greater than reported at the Hanford Site.
137Cs distribution within the profile was controlled more when
the 137Cs was released than by the composition (organic matter
concentrations, mineralogy, particle size distribution) of the soil. Netted
chain fern had greater plant: soil concentration ratios in drier terrestrial
environments than in wetland environments. The cause may be related to
the Cs existing in a more bioavailable form or to the better oyerall health
of the plants under drier soil conditions. The average concentration ratio
was greater for the netted chain fern 2.78±2.96 than for rice cutgrass
0.18±0.13. The overall average plant: soil concentration ratio,
1.05±2.0l, was large and points out, yet again, that Cs bioavailability
is greater on the SRS than at most other sites.
SREL Reprint #2830
Kaplan, D. I., T. G. Hinton and A. S. Knox. 2005. Cesium-137 partitioning to wetland sediments and uptake by plants. Journal of Radioanalytical and Nuclear Chemistry 264:393-399.
