Ecological half-life of ¹³⁷Cs in plants associated with a contaminated stream

Ecological half-life (T_e) is a useful measure for studying the long-term decline of contaminants, such as radionuclides, in natural systems. The current investigation determined levels of radiocesium (¹³⁷Cs) in two aquatic (Polygonum punctatum, Sagittaria latifolia) and three terrestrial (Alnus serrulata, Myrica cerifera, Salix nigra) plant species from a contaminated stream and floodplain on the U.S. Department of Energy's Savannah River Site. Current ¹³⁷Cs levels in plants were used in conjunction with historical data to determine T_e of ¹³⁷Cs in each species. Median concentrations of ¹³⁷Cs were highest in S. latifolia (0.84Bqg^-1) and lowest in M. cerifera (0.10Bqg^-1). T_e's ranged from 4.85yr in M. cerifera to 8.35yr in S. nigra, both terrestrial species. T_e's for all aquatic (6.30yr) and all terrestrial (5.87) species combined were very similar. The T_e's of the two aquatic primary producers (P. punctatum and S. latifolia) in the Steel Creek ecosystem were somewhat longer than T_e values previously reported for some consumers from this ecosystem.