The Remediation Of Heavy Metals Contaminated Soil Around Pb/Zn Mining Area By Biochar

China’s Pb and Zn mining reserves are large,in order to adapt to the economic development in the early days of China.History problems left over gradually prominent.Biochar has the characteristics of multi-pore structure and multiple functional groups,which can absorb heavy metals to alleviate its migration.There are some problems such as the selectivity of heavy metal pollution and limited adsorption capacity,so necessary modification is needed to enhance the adsorption and passivation capacity.With straw charcoal and fruit charcoal as objects,two kinds of biochar were modified by chemical(Mn Ox)modification method and biological(earthworm)modification method.The results showed that:1)The pH of the two biochar was enhanced 0.32,1.87 by chemical modification,and reduced 2.60,0.96 by biological modificationl;After modification by two methods,the modified EC of straw charcoal decreased,fruit charcoal increased(63%).The number of functional groups increased.The wall of the hole breaks or collapses,forming large granular holes with larger pore size and smaller specific surface area.2)Different types of biochar have different effects on plant height,root-cap ratio and root growth.Biochar modified by two methods promoted the growth of underground and aboveground parts of plants respectively.3)The nutrient composition and enzyme activity of soil were increased to different biochars.The former mainly promoted available potassium,cation exchange ability,catalase urease and sucrase,while the latter mainly promoted alkali-hydrolyzed nitrogen,organic matter and available phosphorus.4)Biochar can reduce the content of Pb and Zn,and the decrease is the largest(34.7%,33.0%)at Mn Ox-FCBC(7.5%)Pb and Zn exist in oxidizable state and weak acid extraction state respectively.Biochar can gradually transform them into inert residue state,so as to alleviate the migration and toxicity of heavy metals.Figure 22;Table 24;Reference 75...