Comparison of different inorganic amendments on decreasing of Cd, Pb, Ni, Cu, and Zn sorption by wastewater-irrigated plants

Heavy metals fixation in-situ by using inorganic amendments is a method for immobilization of polluted soils. The goal of this research was to determine efficiency of five amendments for heavy metals fixation of waste-water-irrigated soils around Tabriz city. Cadmium, Pb, Cu, Ni, and Zn- containing solutions were added to 0.5 gram of five amendments including calcite, hematite, zeolite, illite, and bentonite. 10 soil samples from around of Tabriz city were taken. After shaking the samples, the concentrations of the five elements were determined in the 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 differences of heavy metals retention between amendments. Calcite had the highest retention of Cd (91%), Ni (78%), and Zn (94.7%); hematite had the highest Cu (90.5%) and Pb (94.3%); and illite showed the lowest retention of the 5 elements. Calcite, zeolite, bentonite, and hematite had significant higher retention capacities of Cd, Ni, and Zn in compared to 10 the soil samples. Among the studied amendments, retention capacities of calcite and hematite for the five elements were higher than the remaining ones for addition to the soil. These two amendments can cause low uptake and low accumulation of the elements in agricultural crops in polluted soils.