The role of five inorganic amendments on decreasing of some heavy metals adsorption by wastewater-irrigated plants

Heavy metals fixation in-situ by using inorganic amendments is a method for remediation of polluted soils. The goal of this research is to determine five kinds of amendments efficiency for heavy metals fixation of waste-water-irrigated soils of Tabriz city and to suggest the best amendment/amendments. For this purpose, solutions containing Cd, Pb, Cu, Ni, and Zn were added to 0.5 gram of five amendments including calcite, hematite, zeolite, illite, and bentonite; and 10 soil samples from around of Tabriz city. After shaking, these five element concentrations were determined in filtered solution by using atomic absorption instrument. Retention capacity percentages of these elements were calculated and the best amendments were determined by using Dunkan method. There were sharp differences of heavy metals retention between amendments. Calcite had the highest retention of Cd, Ni, and Zn; hematite the highest one of Cu and Pb; and the least one was for illite. Calcite, zeolite, bentonite, and hematite had significant (in 5 % level) higher retention capacities of Cd, Ni, and Zn in compared to 10 the soil samples. The highest retention capacities were done by calcite and hematite (without significant differences) for Pb. Calcite hematite, and zeolite had the highest retention of Cu. However, the highest retention was done by illite with significant difference with other two amendments. The retention capacities of calcite and hematite amendments for the five elements were higher than all 10 soil samples in 5% level and can cause low uptake and accumulation of these elements in agricultural crops of polluted soils of around Tabriz city.