Evaluating of many chemical extractants for assessment of Zn and Pb uptake by bean in polluted soils

Assessment of bioavailability of trace elements, such as zinc (Zn), and lead (Pb), in polluted soils is needful to management and use of these soils. A greenhouse experiment was performed to investigate bioavailability of Zn and Pb for bean by various extractants (DTPA-TEA, AB-DTPA, Mehlich 2, Mehlich 3, 0.01 M CaCl2, and 0.1 M HCl) in 10 polluted soils. The results showed that extraction capacity was as follows: Mehlich 3>AB-DTPA>DTPA-TEA>Mehlich 2>CaCl2>HCl. The average of Zn extracted by Mehlich 3, AB-DTPA, and DTPA-TEA were 25.68, 9.73, and 7.30 mg kg(-1), respectively. In addition, the average of Zn extracted by Mehlich 2, CaCl2, and HCl were 6.53, 0.13, and 0.11 mg kg(-1), respectively. The average of Pb extracted by Mehlich 3, AB-DTPA, and DTPA-TEA were 12.56, 7.32, and 4.91 mg kg(-1), respectively. Also, the average of Pb extracted using Mehlich 2, CaCl2, and HCl were 0.93, 0.62, and 0.44 mg kg(-1), respectively. The results of correlation analysis revealed that the Zn extracted by DTPA-TEA, AB-DTPA, Mehlich 3, Mehlich 2, and HCl correlated significantly with Zn uptake. Moreover, significant correlation was found between DTPA-TEA, AB-DTPA, HCl, and CaCl2 with Zn concentration in bean. The concentration of Pb in bean and Pb extracted by DTPA-TEA, AB-DTPA, Mehlich 3, and Mehlich 2 correlated significantly. Therefore, application of extracting methods contains chelating agents would be recommended in the future research on the availability of Zn and Pb in polluted soils.