Investigation of the sorption of Zn(II) on surface soils using a radiotracer technique

Radiometric sorption experiments were carried out on surface soil samples collected from several sites around Sapporo city (Hokkaido, Japan) in order to evaluate their capacities for the sorption of Zn(II). The maximum sorption (Am) of Zn(II), obtained from the sorption isotherm, was only 2–5% of the cation exchange capacity (CEC). The Am values were correlated with the pH of the soil suspensions, which indicates that zinc sorption would occur competitively with protons in the suspension. The effect of organic matter on the Zn(II) uptake was estimated from the Am change of the individual samples before and after heat treatment. Coordinate uptake of the Zn(II) into the degrading organic matrices was believed not to be important for Zn(II) sorption in some of the present soil samples.