Vertical distribution of Cd, Pb and Zn in soils near smelters in the Northof France

The analysis of the horizons of 12 soil profiles confirm occasionally signi ficant levels of Cd, Pb and Zn contamination in the areas surrounding two l ead and zinc smelters in the North of France. A pedological approach enable d the original Cd; Pb and Zn content of the horizons to be estimated, based on physico-chemical characteristics of soil unaffected by contamination. T he main contamination was found in the upper 20-30 cm. Traces of Cd and Zn contamination were found at a depth of around 2 m. The mobility of the meta ls may be classified in the following order: Cd >> Pb greater than or equal to Zn. The concentration profile of a metal seems insufficient to evaluate its movement as the metal could have been leached beyond the contaminated horizons. The depth reached by the metals increases with their concentratio n in the surface horizon; a decrease in pH and an increase in sand content seem to facilitate their movement. The depth reached by Zn increases with t he organic carbon content in the surface horizon. Earthworm galleries act a s paths via which metals migrate downwards (C) 2000 Elsevier Science Ltd. A ll rights reserved.