GEOCHEMICAL DISTRIBUTION OF HEAVY-METALS IN SOILS OF PYROCLASTIC-ROCKFROM THE VICO VOLCANIC SYSTEM WITH RESPECT TO DOMINANT SOIL FORMATIONPROCESSES

A study on the geochemical distribution of some major and trace elemen ts in selected volcanic soils of Vico volcano (Central Italy) has been carried out. The geochemical characteristics of parent material and t he pedological evolution of soil appear strictly related. Total and ED TA-extractable contents generally decrease with depth. The topsoils di splay a moderate enrichment in those elements related to the organic m atter such as: Mn, Cd, Co, Ni, Pb, Zn and V, conforming that they ente r the biogeochemical cycle. The bottom soils maintain many of the char acteristics of the parent material, especially with regard to major el ements such as Al, K, and Fe. With the exception of Pb and Mn, whose h igh concentrations are inherited from parent material, heavy metals co ntents in these soils never reach the levels that are considered toxic to plants.