Forms of cadmium, lead, and zinc in contaminated soils from southwest Poland

The metals Cd, Pb, and Zn occurring in Haplorthods and Haplumbrepts of both sandy and loamy textures in the vicinity of Tarnowskie Gory in southwest Poland, an area that has been subjected to severe metal contamination, were studied according to a procedure based on sequential extraction analysis. Concentrations of the metals ranged from background levels to levels well in excess of the maximum tolerable limits in agricultural soils. Thus, Cd, Pb, and Zn ranged from 0.2 to 103, 14 to 7100 and 20 to 10000 mg kg(-1) soil, respectively. Soil type, texture, organic matter, and cation exchange capacity (CEC) did not influence the relative proportions of heavy metal forms in any consistent manner. However, the influence of soil pH was clear. Soil samples of pH < 5.6 contained relatively more of all metals in the exchangeable form than in samples where pH was >5.6. The most consistent distribution patterns were found when the soil samples were grouped according to their total metal contents. The inferred relative mobility of the metals and their redistribution among the different fractions are generally consistent with the findings of previous studies of contaminated soils and support the view that metals from anthropogenic sources are more mobile than those from soil parent materials.