MIGRATION RATES OF Cd, Cu AND Pb IN DIFFERENT SOIL PROFILES

This paper proposes complementary indices of heavy metal retention and loss that allow all horizons to be taken into account when comparing soils in regard to their response to heavy metal exposure. The proposed indices, I-R and I-L, were applied to the migration of Cd, Cu and Pb, separately or together, through the profiles of ten soils that differed in their characteristics and number of horizons: an Umbric Acrisol (UA), two Humic Umbrisols (HU1 and HU2), an Umbric Cambisol (UC), an Endoleptic Luvisol (EL), a Mollic Cambisol (MC), a Mollic Leptosol (ML), a Humic Cambisol (HC), and two Anthropic Regosols (AR1 and AR2). Those with greatest retention capacity, as measured by I-R, were MC, EL, AR2 and ML, which as well as having relatively high organic matter contents were also those with the greatest cation exchange capacities and Mn oxides contents.