Study On The Remediation Effect Of Biochar On Two Kinds Of Cadmium Polluted Soil

Biochar,because of its rich porous structure,stable carbon elements and nutrient elements required by crops,can be used as a good material for soil water fixation and fertilizer conservation,and its unique appearance structure will affect the remediation effect.Therefore,how to improve the effect of biochar on heavy metal contaminated soil to obtain a more friendly biochar as a"blade"in the future environmental and agricultural fields”In this study,corn straw biochar was used as raw material to obtain modified biochar treatment?SWT-H?by chemical method.The properties of biochar and modified biochar and their adsorption characteristics for heavy metal Cd²⁺were compared.The biochar before and after treatment was added to two undisturbed cadmium polluted soils of soil H and soil S according to a certain proportion,and its target pollution was discussed through soil culture test on this basis,the regulation effect of different biochar in pot experiment was discussed,and its remediation effect in two kinds of cadmium polluted soil was clarified.The main results are as follows:?1?The adsorption capacity of biochar and modified biochar for Cd²⁺increase d with the increase of the mass concentration of the solution,which was in ac cordance with the Langmuir isotherm and Freundlich isotherm adsorption curve s.The saturated adsorption capacity of biochar for Cd²⁺was17.96 mg/g?288.15k?,18.43 mg/g?298.15 K?,21.07 mg/g?308.15 K?,respectively.The saturated adsorption capacity of modified biochar for Cd²⁺was 18.63 mg/g?288.15 k?,19.93 mg/g?298.15 K?and 21.27 mg/g?308.15 K?;the results of electron micros copy p H owed that the adsorption rate of Cd²⁺by chemical treatment was also increased The results p H owed that the amount of oxygen-containing function al groups in the modified biochar was more,and more Cd²⁺could be adsorbed through the surface.When the p H was 2-8,the adsorption capacity of biochar increased first and then decreased with the increase of p H.?2?Soil culture experiment showed that:with the increase of the proportion of biochar,the p H of the two soils increased in different degrees,but in the whole culture process,the change of soil p H of soil h and s showed a trend of first increasing and then decreasing;the application of biochar can effectively reduce the content of available cadmium in soil H and S,but in the whole culture cycle,5%of the biochar addition proportion on the soil of soil H The effect of reducing available cadmium content is the best,while soil S soil is the best 2.5%In addition,biochar can change the distribution proportion of cadmium in soil,promote the exchangeable cadmium in soil to carbonate combined state The transformation of organic combined and residual cadmium.The conversion effect of 5%biochar is better than that of 5%biochar 2.5%The amount of biochar can promote the transformation from exchangeable to residual cadmium.In the whole culture process,with the addition of biochar,the activities of urease and sucrase in soil increased except for the decrease of acid phosphatase activity,and the promotion effect of 5%biochar on the two enzymes was significantly higher than that of the others 2.5%The content of catalase increased significantly in soil H soil,but decreased in soil S soil.?3?The results of pot experiment phowed that biochar and modified biochar promoted the growth of soybean,increased soil p H,and reduced the content of soil available Cd.The results p Howed that:the effect of soil S soil available Cd was better than soil H soil,and the content of soybean Cd treated with biochar and modified biochar was lower than that of blank treatment,Compared with biochar,the content of Cd in soybean seeds treated with modified biochar was lower.The content of Cd in soybean root was much higher than that in p Hoot and grain,which reduced the transport and enrichment coefficient of Cd in soybean.