Passivation Agent Screening And Its Effect On Passivation Of Cadmium Contaminated Soil In Vegetable Fields

The facility agriculture in the Beijing-Tianjin-Hebei region plays an important role in Chinese agricultural production.With the increase of intensification,agricultural waste such as tail vegetables has been increasing,resulting in the accumulation of organic and inorganic pollutants in the farmland,which has seriously hindered economic and social sustainable development and the coordinated development of Beijing,Tianjin and Hebei.Faced with the current situation that farmland heavy metal pollution and agricultural product accumulated in Beijing-Tianjin-Hebei area,the selection and optimization of heavy metal passivation agents and integrated facility farmland heavy metal pollution barrier and passivation technology models have become a solution to farmland heavy metal pollution in Beijing-Tianjin-Hebei facilities and the quality of agricultural products.This article takes the heavy metal cadmium(0.4-0.8mg?kg^-1)in the farmland of Jing-Jin-Ji facilities as the research object,and explores the passivation agents such as carbon-based,phosphorus-based,silicate-based and clay-minerals through the indoor cultivation and the experiment of vegetable plots.The effects of carbon-based,phosphorus-based,silicate-based,clay-based and other passivating agent concentrations and organic-inorganic inactivators on the stability of soil cadmium inactivation and the effects on plant growth were investigated.Effects of Application Concentration and Organic-inorganic Inactivation Additives on Stabilization of Soil Cadmium and Its Effects on Plant Growth.The main findings are as follows:?1?Soil culture experiments showed that 8 kinds of passivation materials such as hydroxyapatite could increase soil pH,decrease soil conductivity and available cadmium content,and have different degrees of passivation effect on Cd.Comprehensive analysis of its characteristics,hydroxyapatite,wheat biochar,rice biochar and passivation effect is the most obvious,followed by montmorillonite,fly ash,corn biochar and peanut shell biochar passivation effect is not ideal.?2?The application of the passivation agent to the field reduced the total salt content of the soil,indicating that the application of passivation material can relieve the salinization of the soil in the north to a certain extent.The effective Cd content of contaminated soil can be reduced,and Cd accumulation in rape can be reduced by3.9%-51.2%compared with the control.The combination application of hydroxyapatite and 0.6%biomass carbon significantly reduced the available cadmium content in the vegetable field,with a decrease of 66.52%to 78.11%.The passivator applied reduced the cadmium enrichment coefficient of rape and reduced the plant's Cd Absorption and transfer of roots to the edible parts of the ground significantly reduced the heavy metal content of the edible parts of the rapeseed.?3?The application of passivated materials can improve soil fertility,increase crop yield,and improve soil quality.In summary,the application of biochar and hydroxyapatite in combination not only can significantly reduce the soil available Cd content,but also improve soil fertility and increase crop yield.The effect of cadmium on the soil is continuously stable and can be used as a preferred passivation of Cd contaminated soil material.