Paller, M.H., J.W. Littrell, and E.L. Peters. 1999. Ecological half-lives of 137Cs in fishes ffrom the Savannah River Site. Health Physics 77:392-402.
Abstract Ecological half-lives (Te's) were estimated for 137Cs in largemouth bass, sunfishes, and bullheads from two reservoirs and three streams on the Savannah River Site, a nuclear weapons material production facility in South Carolina. Ecological half-life is the time required for a given contaminant concentration to decrease by 50% as a result of physical, chemical, and/or biological processes that remove it from and ecosystem or render it biologically unavailable. Te's were estimated from whole-fish 137Cs concentrations in samples collected during 1972-1996, following radionuclide releases that occurred primarily during the 1960's and 1970's. Te's ranged from 3.2 to 16.7 y, and all were shorter than expected from the half-life for radioactive decay (Tp = 30.2 y) alone. Fish taxa from the same locations differed in mean 137Cs concentrations (highest in largemouth bass and lowest in sunfishes) but, in most cases, exhibited similar Te's. Rates of 137Cs removal in fishes were strongly correlated with rates of 137Cs removal in water. The shortest Te's occurred in the upper portions of streams. Te's in lower portions of streams were longer, as were Te's in one of the reservoirs. Te's in the second reservoir, which had a much shorter water residence time, were nearly comparable to those in the upper portions of the streams until 1991. At that time, 137Cs concentrations in fishes began to increase following drainage and refilling of the reservoir, which apparently resuspended 137Cs buried in the sediments.