Jp. Ghestem et A. Bermond, EDTA EXTRACTABILITY OF TRACE-METALS IN POLLUTED SOILS - A CHEMICAL-PHYSICAL STUDY, Environmental technology, 19(4), 1998, pp. 409-416
The reactivity of a few trace metals (Cd, Pb, Zn,Cu) present in three
polluted soils was studied using a classical extractant: EDTA. The eff
ects of the concentration of this reagent (from 0.0001 M to 0.05 M) as
well as those of the pH of the extracting solution (from 2 to 8) on t
he extracted amounts of metals have been determined. The behaviour of
the cations seems to depend heavily on an excess or a lack of EDTA. In
the case of an excess, concentrations of cations extracted are most o
f time pH-independent. On the contrary, when using a lack of EDTA, amo
unts of extracted cations show a complex behaviour versus pH which cha
nges with the type of cation and with the degree of soil pollution A c
ompetition phenomenon between minor and major cations of the soil seem
s to be revealed. These major cations seen to be Fe3+ in acidic media
and Ca2+ in neutral media. However, when in excess, this reagent revea
ls a powerful extractant of trace metals in soils: recovery rates grea
ter than 60 % have often been observed.