Contribution of Soil Components to Adsorption of Heavy Metals in Alluvial Soils and Grey Degraded Soils from Hanoi, Vietnam

Abstract

Two surface soil samples were collected from each of alluvial soils and grey degraded soils in Hanoi City, Vietnam and subjected to examination of adsorption of three heavy metals (Cu, Pb and Zn) by three adsorbing components (organic matter, free iron oxides and clay minerals). The results showed that Pb was adsorbed by all three components with the largest adsorbed amount and that Zn was adsorbed selectively by organic matter and clay minerals while Cu was selectively by organic matter and free iron oxides. The amount of heavy metals adsorbed per unit mass of adsorbing components was reduced in the sequence of organic matter＞clay minerals＞free iron oxides for Pb and Zn and of organic matter＞free iron oxides＞clay minerals for Cu. The difference in the adsorption capacity of heavy metals per unit mass of each component between the alluvial soil and grey degraded soil was attributed to the difference in the type of organic matter, form of free iron oxides or composition of clay minerals between them.