Effects Of Different Materials On Heavy Metal Pollution In Saline - Alkaline Soils

The heavy metals pollution in soil became serious, with rapid development of industrialization and urbanization. There were two mainly ways to remedy soil polluted by heavy metals:1) immobilizing heavy metals from available form into stable form,2) leaching for removing heavy metals from soil. However, the remendiation heavy metals pollution to saline-alkali soil has received little attention. Therefore, the objective of the present work was to investigate the impact of immobilizing materials for biochar, Fe and super absorbent polymers on immobilizing heavy metals in saline-alkali soil, and leaching materials for citric acid, EDTA and straw powder on leaching heavy metals in saline-alkali soil. The results showed as follows:1) The application of Fe powder decreased available Cd concent, and increased stable Cd concent in saline-alkali soil. The decreament and increment for available Cd concent was 60.3% and 163.4% at 4% Fe powder rate, as compared to the unremedied soil. The application of biochar and super absorbent polymers showed no significant on available Cd concent in saline-alkali soil.2) The Cd concentration in maize decreased with increasing Fe powder rates. The decreament for Cd concentration in maize was 59.8% at 4% Fe powder rate, as compared to the unremedied soil. The application of biochar and super absorbent polymers showed no significant on Cd concentration in maize grown in saline-alkali soil.3) The Cd and Pb concentration in leachate decreased with increasing citric acid rates, and Cr concentration increased. The Cd, Pb and Cr concentration in leachate increased with increasing citric acid rates. With increasing application of straw powder rates, Cd and Pb concentration in leachate decreased, and Cr concentration in leachate increased.4) The application of EDTA decreased total Cd, Pb and Cr content in 0-25 cm soil layer, and decreased total Cd content in 25-50 cm soil layer, showed no significant on total Pb and Cr in 25-50 cm soil layer. The application of citric acid decreased total Cr content in 0-25 cm soil layer, showed no significant on heavy metal in other soil layers. The application of straw powder decreased total Cd and Pb content in 0-25 cm soil layer, showed no significant on heavy metal in other soil layers. The application of citric acid, EDTA and straw powder all increased the proportion of ORG+RES—Cd, Pb and Cr.