Transport and accumulation of heavy metals in undisturbed soil columns

The podzolic soils of the Kola Peninsula, Russia, have in localised areas been highly
contaminated with copper and nickel from smelting activities. Migration and retention of these
metals were investigated in undisturbed soil columns irrigated with simulated background and
polluted precipitation in order to study the temporal processes of retention and release within
the soil. The mineral layers were strongly acidified by the contaminated precipitation. Forest
floor layers demonstrated a high capacity to retain input Ni and Cu under all conditions.
Mineral layers accumulated some Cu, but released Ni. In general, Ni leached through the soil
faster than Cu. Since metals are strongly retained in the forest floor layer, even after reduction
or cessation of inputs there may be a significant long–term risk of their leaching to deeper soil
and groundwater. This risk cannot be ameliorated without remediative intervention.