Fractionation and mobility of Copper, lead, and zinc in soil profiles in the vicinity of a copper smelter

Four soil profiles located near a copper smelter in Poland were investigate d for the distribution and chemical fractions of Cu, Pb, and Zn and their m obility in relation to soil properties. Contamination with heavy metals was primarily restricted to surface horizons and the extent of contamination w as 7- to 115-fold for Cu, 30-fold for Pb, and 6-fold for Zn as compared wit h subsurface horizons. In the less-contaminated fine-textured soil, the met als were distributed in the order: residual > > Fe-Mn oxides occluded > org anically complexed > exchangeable and specifically adsorbed, while the orde r for sandy soils was: residual > organically complexed > Fe-Mn oxides occl uded > exchangeable and specifically adsorbed. The contaminated surface hor izons of these profiles showed no consistent pattern of metal distribution. However, the common features of highly contaminated soils were very low pe rcentage of residual fraction and the dominance of the NH4OAc extractable f raction. The sum of mobile metal fractions was generally < 10% in subsurfac e horizons, while in the contaminated surface horizons these fractions made up 50% of the total metal contents. Soil properties contributed more to th e relative distribution of the metal fractions in the studied profiles than did the distance and direction to the source of pollution. The amounts of metal extracted by 0.01 M CaCl, accounted for only a small part of the same metals extracted by NH4OAc The mobility indexes of metals correlated posit ively and significantly with the total content of metals and negatively wit h the clay content.