Zinc Adsorption and Desorption Characteristics of Soils in Semi-Arid Region, Turkey

Abstract

The purpose of this study was to determine the zinc adsorption and desorption characteristics and their relationships with some soil properties in semi-arid regions of Tokat, Turkey. Zinc adsorption data of the studied soils fitted into the linear form of Langmuir, Freundlich and Temkin isotherms, but the fit to Freundlich and linear Langmuir model were statistically better than the Temkin model. The mean distribution coefficients (K_d) of the soils ranged from 414 to 1001 and the higher K_d values were calculated at soils having higher clay and CaCO₃. Similarly, the Zn adsorption maximum exceeds cation exchange capacity values of the soils high in clay and CaCO₃. This could be attributed to adsorption on the internal surface of clay and precipitation of the applied Zn to the soils. Besides, recovery values (%) by DTPA of the retained Zn on the soils having higher clay and CaCO₃ contents were lower than those of the other soils. According to the observed findings, clay and CaCO₃ contents at the soils are the most important soil properties affecting adsorption and desorption of Zn.