Aquatic chemistry of plutonium in seasonally anoxic lake waters

We present here data on the distribution of the fallout radionuclides ⁵⁵Fe, ^239,240Pu, ¹³⁷Cs and ⁹⁰Sr and the natural radionuclides ²³⁸U and ²³⁴U in a seasonally anoxic lake in an effort to determine their biogeochemical behaviour. Results from Gull Pond, Massachusetts show that the oxygen-depleted and iron-and manganese-rich bottom waters contain five times more dissolved ^239,240Pu than oxygenated surface waters. This feature, also observed in anoxic hypolimnia of other lakes, indicates that the concentration of plutonium is significantly influenced by anoxicity and redox cycles. Such observations are important in understanding the fate of artificial radionuclides which are released^1-4 to the aquatic environment through global fallout, planned disposal and localized accidents.