Sorption and retention of Mn, Fe, Zn, and Cu in some non-acidic and acidic soil

Sorption and desorption of heavy metals by soil solid phase are of crucial role on their behaviour. To assess sorption and desorption of Zn, Cu, Fe, and Mn, four non-acidic and four acidic soil samples were collected from Guilan and West Azerbaijan provinces, respectively. A linear regression procedure was utilized for fitting the linearized forms of the Langmuir and Freundlich isotherm equations to the sorption data. Results showed that for all the studied metals either in non-acidic or acidic soils, the Freundlich equation (R2>0.88) described the sorption data better than the Langmuir equation (R2=0.28-0.90). The amount of sorption parameters for all studied soils was higher in non-acidic soils in comparison with acidic ones. Sorption behaviour of metals differently varied among soils. The highest value for the adsorption maxima was achieved for Fe in both soil types. However, the lowest adsorption maxima were observed for Zn and Mn in acidic and non-acidic soils, respectively. Mean immobilization percent of metals in acidic soils for Mn, Fe, Zn and Cu were 13.2, 11.6, 11.7 and 6.6 percent respectively, and lower than that of non-acidic soils. The lowest and highest immobilization percent for Fe and Mn was observed in soil (5) and soils (3, 4), respectively. Soil (8) showed low Cu and Zn immobilization potential, however soil (4) and soil (1) highly immobilized Cu and Zn, respectively. It is concluded that from an ecological point of view higher sorption potential of studied soils in particular non-acidic soils can be considered in decreasing heavy metals toxicity risks processes.