PLUTONIUM AND AMERICIUM CONCENTRATIONS AND VERTICAL PROFILES IN SOME ITALIAN MOSSES USED AS BIOINDICATORS

We have examined the uptake of actinide elements Am and Pu by differen t species of lichen and moss collected in two locations (Urbino, Centr al Italy; Alps region, North-east Italy). Plutonium and americium were separated and determined by extraction chromatography, electrodeposit ion and alpha-spectrometry. This paper summarizes our results with a s pecial emphasis on the vertical profiles of these actinides in two dif ferent species of mosses. Several 1-2 cm depth sections were obtained and dated by Pb-210 method. A typical peak for Pu-239,Pu-240 and Am-24 1 was found in the very old moss species (''Sphagnum Compactum'') at a depth corresponding to the period 1960-1970 which was the period char acterized by the maximum nuclear weapon tests. In a younger moss speci es (''Neckeria Crispa'') no peak was observed and the regression curve s showed that Am is more mobile than Pu-239,Pu-240 and Pu-238.