Thermodynamic assessment in heavy metal migration at El-Akader landfill site, North Jordan

Thermodynamic analysis of subsoil pore water indicates that Fe, Cu, Zn, and Pb exist as a metal hydroxy complex of the forms [Me OH]+ and [Me(OH2)]o, although a complex of [PbCl]+ is also significant, but not predominant. The analysis also demonstrates that the dissolved transition metal concentration of the subsoil pore waters are controlled at carbonate minerals saturation levels, whereas Fe concentration in leachate solutions associated with waters are controlled at FeS2 saturation levels. Thermodynamic calculations and Eh–pH diagrams suggest that Fe(OH)2, Zn(OH)2 and Pb(OH)2 are not stable phases in the solids of the subsoil.