Leaching of nickel and copper from soil contaminated by metallurgical dust.

The paper presents the results of the laboratory percolation experiment simulated soil contamination by emissions from a Ni-Cu smelter. Humus (Ao horizon) columns were transferred to lysimeters from an illuvial, humic, ferriferous forest podzol site. Fine metallurgical dust containing Ni and Cu was layered on the columns and irrigated with sulphuric acid solutions at pH 3, 4, 5, and 6. Irrigation for 19 months indicated that the leaching of metals down the humus column was greatest at pH 6. Calculations indicated that it would take 160-270 years for complete leaching of Ni from the Ao layer, and 100-200 years for Cu, depending on the dust composition. Natural decontamination of affected soils will take centuries.