SREL Reprint #3145

Contrasting cesium dynamics in neighboring deep and shallow warm-water reservoirs

John E. Pinder III1, T.G. Hinton2, F.W. Whicker3

1Department of Biology, Texas Christian University, Ft. Worth, TX 76129, USA
2Institute for Radiation Protection and Nuclear Safety, Cadarache, 13115 France
3Department of Environmental and Radiological Health Sciences, Colorado State University,
Fort Collins, CO 80523-1618, USA

Abstract: To measure the long term retention and seasonal dynamics of an initial 4 kg addition of 133Cs into an 11.4-ha, 157,000 m3 reservoir (Pond 4, near Aiken, South Carolina, USA), the concentrations and inventories of 133Cs in the water column were measured at periodical intervals for 522 days following the 1 August, 1999 release. After rapid declines in concentrations and inventories during the first 90 days, the 133Cs concentrations in the water column declined at an average proportional rate of 0.004 d-1. However, there were periods of less rapid and more rapid rates of declines, and these were correlated with periods of increasing and decreasing K concentrations in the water column. The decline rates were less and the K concentrations greater in the winter than in the summer. In the deeper, neighboring monomictic reservoirs of Par Pond and Pond B, a yearly cycle of increasing and decreasing 137Cs concentrations in the water column is driven by anoxic remobilization of Cs from the sediments into a persistent summer hypolimnion. In Pond 4, whose mean depth of 1.6 m is too shallow to support a persistent anoxic hypolimnion, the pattern of yearly dynamics for K and Cs appear to be related to the accumulation and release of these elements from the extensive, seasonal macrophyte communities. The contrasting results between Pond 4 and Pond B suggest that a full appreciation of the relative importance of 1) anoxic remobilization and 2) accumulation and release by macrophytes in these systems remains to be established.

Keywords: 137Cs, 133Cs, Reservoir, Water column, Sediments, Macrophytes, Remobilization, Typha latifolia, Nymphaea odorata

SREL Reprint #3145

Pinder III, J. E., T. G. Hinton, and F. W. Whicker. 2010. Contrasting cesium dynamics in neighboring deep and shallow warm-water reservoirs. Journal of Environmental Radioactivity 101(2010): 659-669.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).