The Effect of Soil Passivator on Heavy Metal Cadmium in Alkaline Farmland Soil and Its Accumulation in Wheat

Field experiments were performed to investigate the effect of passivator on heavy metal cadmium in alkaline farmland soil and its accumulation in different growing period of wheat. The results show that the addition of passivator could decrease the available Cd in alkaline farmland soil. In Cd contaminated soil collected from Xinxiang (DTPA-Cd 1.24 mg·kg^-1), compared with the control experiment. By adding 0.20% (mass fraction) of the passivator, the available Cd content of the soil reduced by 28.09%-53.15% after 60-240 days; the Cd contents of the wheat root, stem and leaf were reduced by 43.20%, 53.00% and 53.00% after 140 days, respectively; the Cd contents of the wheat root, stem and leaf were reduced by 48.92%, 53.82% and 39.20% after 200 days, respectively; and the Cd contents of the wheat root, stem, leaf, and grain were reduced by 47.92%, 29.46% and 21.41% after 240 days, respectively. The results show that the passivator could decrease the available Cd content of soil and wheat, thus the Cd accumulation in different parts and different growing periods of wheat could be reduced. The contents of cadmium in wheat grain decreased from 0.22 to 0.09 mg·kg^-1, which meets with the national standard (GB 2762-2017). It indicates that the passivator is a potential material for the remediation of heavy metal contaminated alkaline farmland soil.