Application of a kinetic fractionation of trace elements (Cd, Cu & Pb) in unpolluted soil samples

The hazard due to the presence of large amounts of trace metals in some soils is strongly related to the speciation of these metals. The aim of this work was to apply an operationally defined fractionation based on kinetics which could distinguish "labile" (quickly extracted) and "non labile or slowly labile i.e. slowly extracted) cations, using the extraction kinetics of trace metals by EDTA. This kinetic fractionation has been applied to ten soil samples from Burgundy (France), which are known to be unpolluted. Copper, lead and cadmium were determined using this fractionation procedure. According to this fractionation, cadmium was found to be more mobile than copper or lead, both in terms of the labile concentration and the kinetic constants.