Studies on the Zinc Adsorption-desorption Characteristics of Vegetable Garden Soils

This paper deals with Zinc (Zn) adsorption/desorption characteristics of three vegetable garden soils. After 24hr equilibration with interval shaking, Zn 2+ amounts adsorbed by soils increased with the initial concentrations of Zn 2+ added. The isothermal adsorption of Zn 2+ by the three soils fitted very well with both Langmuir equation and Freundlich equation as the coefficients are all 0.9. The soil maximum adsorbed Zn 2+ and soil maximum buffering capacity from Langmuir equation are in the order of Fluvio-marine yellow loamy soil ( Huang Song Tu ) Aquic silt loamy soil ( Fen Ni Tu ) Fluvio marine polder soil ( Jiang Tu Tu ). But soil maximum buffering capacity from Langmuir equation and the intensity of soil Zn 2+ adsorption shown in Freundlich equation is in the order of Fluvio-marine yellow loamy soil Aquic silt-loamy soil Fluvio marine yellow polder soil. It was also observed that both desorption amount and desorption ratio of Zn 2+ increased with the Zn 2+ amount adsorbed.