Four soil samples highly contaminated with metals of urban and mine origin
(SE1, SE2, SM1, SM2) and having different physico-chemical proprieties were
selected to study copper complexation capacity (LT) of soil solution The e
ffect of Lumbricus terrestris on copper complexation capacity of soil solut
ion was investigated on SE1 and SE2. The complexation capacity was estimate
d by amperometric titration of soil solution by copper. Free hydrated catio
n and labile complexes of copper were determined by DPASV. The results show
that the copper complexation capacity variation depends on the physico-che
mical caracteristics of soils, particulary pH. Thus, the values of copper c
omplexation capacity are 0; 0.6x10(-7); 1.8x10(-7) and 5.5x10(-7) mol l(-1)
respectively for SM2; SM1; SE1 and SE2 which are pH 5; 5.4; 6.5 and 7.4. B
ased on these results, the bioavailability levels of heavy metals show the
following pool ranking: ShM2 > SM1 > SE1 > SE2. The copper complexation cap
acity of soil solution increases with the soil disturbance by Lumbricus ter
restris. This is more obvious when the time of disturbance by lumbrics is l
onger. Indeed, average values determined for 1 month and 3 months are 3.8x1
0(-7) and 7.8x10(-7) mol l(-1) for SE1; 7.7x10-7 and 15.2x10(-7)mol l(-1) f
or SE2 respectively. It seems that the action of earthworm on soil can cont
ribute to the decrease of bioavailability of heavy metals, particulary copp
er.