Influence of mineral and organic components on copper, lead, and zinc sorption by acid soils

Abstract

Sorption isotherms were constructed for the sorption of Cu, Pb and Zn by the surface horizons of three soils [a Humic Cambisol (G1), a Haplic Podzol (G2) and an Umbric Gleysol (G3)] and by fractions obtained by sequential removal of organic matter and oxides. All were of L-type except the H-type isotherms recorded for sorption of lead by whole G2, and all were fitted well by the Langmuir model, with determination coefficients > 0.91. Langmuir equation parameter β correlated well (r ² = 0.985) with experimentally maximum sorption capacity. For all soils, metal sorption capacities decreased in the order Zn > Cu > Pb. Sorption by organic matter was one of the main contributions to total sorption. Sorption by oxides was generally most substantial in G1, which had the largest total oxides content, while the sorption of lead by G3 was attributable to its high Mn oxides content. The clayey residue contributed significantly to sorption of zinc by G1, and G3 (due to their respective vermiculite and gibbsite contents) and to sorption of copper by G1 due to its vermiculite content.

Keywords:

• Soils
• sorption
• organic matter
• oxides
• clays
• copper
• lead
• zinc

Acknowledgments

This research was supported by the Spanish Ministry of Education and Science under Project CGL2006-01016/ BTE.