MOBILITY OF HEAVY-METALS IN SOIL PROFILES

Mobility is a concept frequently used in soil science to estimate the risk of contamination of other environmental compartments. However some confusion exists over the definition of mobility, originating from the fact that this term is used in different fields. Consequently many operational parameters have appeared in relation to mobility estimation. This leads to great difficulties in comparatively interpreting practical data obtained under different conditions, and especially the biological significance of mobility. A standardization of the definition of mobility, taking into account the time scale, should be recommended. Practical results obtained in reconstituted soil-vegetation systems are discussed, with a particular emphasis on the “mobility” of Cd, Cu and Zn. Several definitions were used to estimate the movement of heavy metals in the studied systems, i.e. the metal exports by plants or by gravitational water and the distribution of metals in the soil profile; this led to opposite conclusions about the mobility order of the three considered metals. However this apparent discrepancy can be resolved by taking into account the chemical species in the liquid phase. © 1992, Taylor & Francis Group, LLC. All rights reserved.