Application of Passivation Restoration in Heavy Metal Polluted Farmland
In the passivation restoration project of a heavy metal polluted farmland in Henan,the effects of different kinds of compound passivation agents were compared and analyzed through the design of the plot.In the first year,two passivating agent combinations of"silicoaluminate+organic matter"and"phosphate+organic matter",which have obvious inhibition effect on the activated state of heavy metals in soil,were screened out,and their passivating stability needs to be further verified.In the second year,it was verified that the optimal curing and aging time of"silicoaluminate+phosphate+organic matter"formula combination was 3-7 days,and the aging time was more than 7 days,which would cause the loss of silicoaluminate and organic matter components.There is little difference in passivation effect among different organic matter varieties,and there is no obvious synergistic effect in combination application.In the third year,under the same passivating agent formulation and curing time,the increase of the amount of foliar barrier agent did not have a positive effect on the heavy metal absorption of plants.By expanding the demonstration area,compared with the background survey results before wheat planting in 2019,the total soil Cd concentration during wheat harvesting in 2020 was reduced by an average of 11.43%;The total concentration of soil Cd continued to decrease from 2020 to 2021,and the average concentration decreased by 12.14%at the time of wheat harvest in 2021.The total concentration of cadmium in 2021-2022 has risen,and compared with 2019,the average reduction rate has risen to 5.19%,and the average concentration is about 1.88mg/kg.The implementation of this experiment can provide reference for passivation restoration projects in other heavy metal polluted farmland.
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