The influence of a whole-lake addition of stable cesium on the remobilization of aged ~(137)Cs in a contaminated reservoir

摘要

To document the short-term dynamics of Cs, 4 kg of ~(133)Cs were introduced into an 11.4-ha, 157000 m~3 reservoir previously contaminated with ~(137)Cs from past reactor operations at the US Department of Energy's Savannah River Site near Aiken, South Carolina, USA. The ~(133)Cs addition resulted in an increase of 6.1 MBq of ~(137)Cs (1.9 μg ~(137)Cs) in the water column over the following 260 days. Possible sources for the increased ~(137)Cs included release from the sediments, release from the approximately 26 000 kg of aquatic macrophytes that occupied 80% of the reservoir, and wash-in from the pond's watershed. Data are presented to indicate that release from the sediments was the principal source of the ~(137)Cs increase. The fraction of ~(137)Cs released from the sediments (0.7%) is consistent with laboratory measurements of ~(137)Cs desorption from neighboring ponds on the Savannah River Site.