Spatial and temporal distribution of metals in soils in warsaw, poland

Abstract

Concentrations of surface soil Cd, Cr, Cu, Mn, Pb and Zn were measured along parallel transects within Warsaw in 1996. Data were compared with that from a 1976 sampling, and soil metals were fractionated by sequential extraction for distribution of reactive species. Many soils in the city center and in industrial districts contain Cd, Cr, Cu, Mn, Pb, and Zn in concentrations well above background levels, indicating significant anthropogenic inputs. Levels have mostly increased for soil Cr, Cu, and Pb compared to the 1976 sampling. Lead contamination has extended to the city outskirts and well beyond the city limits. Soil Pb has declined in some areas of the city, which may be a result of leaching of the combined soluble, exchangeable, and organic forms, which total 25% of soil Pb. Manganese and Zn values have remained relatively constant since 1976. Plant turnover and leaching may be balancing atmospheric inputs. Large proportions of Cd exist in the exchangeable form, and substantial soil Pb occurs as carbonate-bound, plus other potentially bioavailable soil fractions. For Cd, Cr, Cu, and Zn the predominant form is the residual metal, which may become an eventual concern, as changing conditions (e.g. long-term soil acidification) may mobilize this fraction. These data, plus the hazards of Cd, Cr and Pb to human health and the biosphere, suggests that more frequent examination of their levels in soil is necessary to determine potential hazards to residents living near contaminated areas. Results are consistent with findings of earlier studies that metals from anthropogenic sources are relatively mobile in soil.