Plutonium and americium in soil organic matter

A gley soil from west Cumbria, with specific activities in its surface horizon of 5–10 kBq kg−1 239,240 Pu and comparable 241Am levels, has been used as a source of actinide-enriched organic fractions. Humic and fulvic acids were isolated by conventional alkali extraction and investigation by gel filtration, treatment with organic solvents and differential flocculation procedures. All these technique are capable of resolving the organics into two or more fractions, with specific activities up to 80 kBq kg−1 239,240 Pu. There is evidence for differentiation of plutonium and americium, with americium being concentrated, to some extent, in the lower molecular weight fractions from gel filtration.