Mobilization conditions of lead in forest soils from the Cserhát Mts., NE Hungary

The possible mobilization conditions of lead compared to other heavy metals (Zn and Cr) in four forest soil profiles was studied by sequential extraction to verify the relatively high lability of lead in soils at the woodlands of an undisturbed area (Cserhát Mts., NE Hungary). The results show that lead can be mobilized in a wide range of environmental conditions. The most significant amount of lead can be bound to the residual fraction (26-57%), but the role of organically bound fraction (16-49%) and amorphous oxide bound fraction (11-28%) is also important in binding Pb. Contrarily, the mobilization of the other studied metals is restricted in these profiles. Metal/Ti ratios show that lead has been significantly redistributed during the soil formation and it is presented in more labile form as compared to the other studied metals in the profiles. These differences can be resulted by the different source minerals of the studied metals on one hand, or by an external lead source on the othe