Comparison of different chemical agents in the single extraction of some potentially toxic elements (PTEs) from contaminated soils

Single-extraction methods are one of the common ways to study the mobility of potentially toxic elements (PTEs) in artificially contaminated soils. The present study was aimed to evaluate the power of eight chemical agents to mobilize five PTEs including cadmium (Cd), cobalt (Co), copper (Cu), nickel (Ni), and zinc (Zn) in 25 soils spiked with two contamination levels (T1 and T2) and the effect of soil properties on PTEs extractable by different extractants using statistical analysis and multivariable regression. Regarding average values of the relative percentage of PTEs extracted of their total amounts in contaminated soils, EDTA was the strongest reagent except for Co, while NaNO3 was the weakest one. pH showed a negative correlation with CaCl2-extractable Cd, Co, Ni, and Zn, DTPA- and EDTA-extractable Ni, HNO3-extractable Cd, Co, Cu, and Zn, MgCl2-, NaNO3-, and NH4NO3-extractable Co, Ni, and Zn, and NH4OAc-extractable Cd, Co, and Zn. Cation exchange capacity (CEC) was negatively significantly correlated with HNO3-extractable Cd, while it had a positive significant correlation with MgCl2-extractable Cd. Organic matter (OM) showed a negative correlation with HNO3-extractable Cd and Zn, whereas it had a positive correlation with NH4NO3-extractable Cu. Equivalent calcium carbonate (ECC) was negatively significantly correlated with CaCl2-extractable Cd, Co, and Ni, EDTA-extractable Co, Cu, Ni, and Zn, HNO3-extractable Cd, Co, Cu, Ni, and Zn, MgCl2- and NaNO3-extractable Zn, NH4NO3-extractable Cd, Co, Ni, and Zn, and NH4OAc-extractable Cd and Co. According to the results, pH and ECC were the most effective parameters among soil properties in multivariable regression equations.