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

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• 作者：John E. Pinder III ; T.G. Hinton ; F.W. Whicker
• 关键词：137Cs ; 133Cs ; Reservoir ; Water column ; Sediments ; Macrophytes ; Remobilization ; Typha latifolia ; Nymphaea odorata
• 刊名：Journal of Environmental Radioactivity
• 出版年：2010
• 出版时间：September 2010
• 年：2010
• 卷：101
• 期：9
• 页码：659-669
• 全文大小：993 K

文摘

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.