Significance of soil properties for content and distribution of cadmium and lead in natural calcareous soils

The total content of Cd and Pb in 30 natural (uncultivated and unpolluted) calcareous soils from the province of Valladolid (Spain) were determined. The ranges of total Cd and Pb were 0.05–0.43 μg g−1 and 4.44–50.34 μg g−1, respectively. Significant correlations were found between total Cd and carbonate contents (P<0.05), between total Pb and organic matter (P<0.01) and between total Pb and clay contents (P<0.01). The mean contents of both elements were higher in the less developed soils (leptosols, regosols, fluvisols, solonchaks) than in the more developed ones (acrisols, cambisols, luvisols, solonetzs). This distribution is parallel to that of soil components for the accumulation of Cd and Pb in the soils studied. In the distribution of both metals and the other soil components in the soil profiles only there were similarities between the distribution patterns of Pb and clay.