Study On The Passivation Of Cadmium In Polluted Soil By Modified Passivation Materials And The Effect Of Reducing Cadmium In Pepper

China's farmland soil is increasingly polluted by heavy metals,among which Cd is the most serious polluted element.The in-situ passivation repair technology is of low cost,high efficiency and convenient management process,but there are still certain limitations.Through the modification and optimization of passivation materials,its adsorption ability for heavy metals can be improved,so as to improve its repair potential for heavy metals.The repair effect of passivation in situ is not only related to the soil physicochemical nature,the type of heavy metal elements and their pollution degree,but also related to the type and dosage of passivation materials.This paper adopts Guizhou high-quality characteristic resources,Taking rosacea(carbon base)of Guizhou Maotai-flavor liquor industry,phosphate ore powder(including phosphate substance)produced by Guizhou phosphate ore industry,and abundant kaolin(clay mineral)in Guizhou as passivation materials,Prepare modified passivation materials,With raw alcoholic biocharcoal(BC),mercapto modified rosacea biocharcoal(SH-BC),iron modified alcoholic biocharcoal(Fe-BC),raw phosphate powder(PR),oxalic acid activated phosphate powder(OA-PR),citric acid activated phosphate powder(CA-PR),K,300 ? kaolin(300-K),500 ? kaolin(500-K),Carry out indoor training tests,Three modified passivation materials with good effect on Cd passivation are preferred,Use hot pepper as the test crop,Through a potted plant test,Three modified passivation materials in Cd contaminated soil,Repair effect on soil Cd passivation and cumulative Cd effect of pepper,Main research results are as follows:(1)The culture test results showed that the increase of raw biocarbon increased soil pH on day 90 by 0.08-0.11 units compared with controls.SH-BC,Fe-BC reduced soil pH,added PR,OA-PR and CA-PR increased the soil pH over time,and reached the maximum soil pH at 60 days.The addition of modified passivation materials has little impact on soil EC,and generally shows an upward trend with the increasing proportion of blunt addition.(2)The training test results showed that SH-BC treatment with 1% of carbon-based material had the best passivation effect on soil Cd.After 90 days of cultivation,the soil Cd effective state content was 60.00% lower than by comparison;adding PR,OA-PR,CA-PR had a significant effect on the passivation of soil effective Cd in short-term culture,and had the best passivation effect of soil Cd.After 90 d,the passivation materials can gradually transform the weak acid to the Cd,residue Cd and reduce the biological effectiveness of Cd in soil.(3)The potted test results showed that the reduction rate of soil effective Cd content was CA-PR> SH-BC> 500-K,citric acid activated phosphate powder on soil Cd,with 20.00%-25.50%.Each treatment reduces the content of weak acid extraction and reducible state Cd in the soil.The 500-K,of SH-BC,1% of 1% and CA-PR were better.(4)The potted test results showed that all modified materials can promote the growth of pepper fruit.CA-PR> 500-K> SH-BC,was 30.24%-47.51% and 28.35%-37.66%.After single SH-BC,500-K,CA-PR,the Cd content of pepper fruit decreased.SH-BC,500-K,CA-PR can effectively reduce the enrichment coefficient of pepper fruit,root,stem and leaves,and the reduction of the average enrichment coefficient of pepper root and fruit is the best reduction effect of CA-PR> 500-K>SH-BC,with CA-PR,SH-BC treatment.To sum up,mercapto modified rosacea biocarbon,500 ? thermal modified kaolin,and citric acid activated phosphate powder as passivation agent,can effectively reduce the content of effective Cd state in polluted soil,reduce the Cd concentration in pepper plants,has good passivation repair ability,as a new passivation material has great passivation value.