Incubation of air-pollution-control residues from secondary Pb smelter in deciduous and coniferous organic soil horizons: Leachability of lead, cadmium and zinc

► Pb smelter fly ash was incubated in forest soil horizons to assess metal mobility. ► The metal mobilization depends on pH and the ratio of humic/fulvic acids to SOM. ► The lowest mobilization of Pb, Zn and Cd took place in horizon H (coniferous forest). ► A huge amount of Cd was found to have leached in the horizon F (deciduous forest). ► More vulnerable to metal leaching from APC residues is soil from deciduous forest.