Simulation experiment of the geochemical behavior of Cd in soils—A case study of typical soils in Shanxi， China

Soil samples were taken from Datong, Taiyuan and Linfen. The experiment comprised three parts: adsorption-desorption, competitive adsorption and transport experiment. Soils for the adsorption experiment were sieved into the sand-sized fraction and silt- and clay-sized fraction. The main results indicate that: it is suitable to use the Langmuir model to fit the adsorption of Cd by the three types of soil at normal temperature and pressure. The adsorption capacity of the clay-sized fraction is higher than that of the sand-sized fraction. In the case of coexistence of Zn2＋ and Cd2＋, Cd adsorption is inhibited. At the concentration in this experiment, humic acid shows no pronounced effect on the inhibition of Cd adsorption. The desorption experiment shows that there was a negative correlation between Cd desorption capacity of soils and TOC and CEC. The penetration curve of Cd in soils was the integrated manifestation of adsorption, desorption, complexing and transport of Cd in soils. Cd was transported more rapidly in the Datong soil than in the other two kinds of soil. Consequently the authors conclude that Cd is transported most rapidly in loamy sand and most slowly in sandy loam.