Index cations and anions. The anion which can contribute
in reducing heavy metal adsorption by the possible
formation of negatively charged or neutral species like:
MCl2, Mcl–
3, and Mcl–
4. In particular Cd is known to form
relatively stable Cl– complexes, which greatly influences the
mobility of metals in soils. This fact is of particular
importance since the ability of Cl– ions to maintain relatively
high concentration of heavy metals in soil solution may
produce favourable condition for a faster leaching of metals
in the soil profile according to the soil texture or irrigation
condition. Avudainayagam et al., (1997) concluded that, the
amount of Cr desorbed varied with both the cationic charge
and with depth of soil sample. In the surface soils, the
desorbed Cr decreased with increasing cationic charge
(Water > Na+ > Ca++). While the reverse trend (Ca++ > Na+
> Water) was observed in the subsurface soils.There was a
strong effect of P (Na+ + 0.003 MP > Ca++ + 0.003 MP) in
surface soils and Ca++ +0.003M >Na+ + 0.003M> water in
sub surface soils. Highest Cr was released in the presence
of phosphate solutions and least when Cl– solution was
used as the leaching electrolyte