Profile distributions of lead, zinc, and copper in dystric cambisols developed from granite and gneiss of the Sudetes Mountains, Poland

Total contents of Pb, Zn and Cu were examined in twenty-five soil profiles of forested Dystric Cambisols developed from granite and gneiss in the area of the Sudetes Mountains (SW Poland). Sequential extraction of heavy metals was also carried out to study relations between metal content and soil compounds. Profile distribution differed among the metals examined: Pb concentrations decreased gradually from surface with depth, whereas those of Zn increased with depth of soil profile, obtaining their maximum in the bedrock horizon. Cu was found to accumulate in topsoil and decrease with depth, but showed secondary increase of the concentration in bedrock. Organic matter was found to be a crucial factor of Pb binding and distribution, while iron oxides played the most important role in Zn binding. Both organic matter and oxides were important factors of Cu distribution. The results of sequential extraction show that all studied elements are mobile under strong acidic conditions in investigated Cambisols. Thus, total contents of Zn and Cu in bedrock cannot be used as geochemical background or as reference levels for assessing the contamination of soil surface with these metals.