Study On The Effect Of Biochar Remediating On Heavy Metals In Soil Of Nanshan Mine

It is quite important to study the effect of heavy metal pollution on soils and the effect of biochar on the remediation of heavy metals in soil under different conditions.The discover has very important significance to understand the characteristics of heavy metals in soils and to control the pollution of heavy metals.In this study,we take the soil of Nanshan mine as our research object.The physical and chemical properties of soil and the status of heavy metal pollution in soil were obtained by obtainning soil sampling and laboratory analysis.The risk of heavy metal pollution in the study area was evaluated by using the potential ecological risk assessment method,the accumulation index method and the risk assessment coding method.In order to discover whether the biochar has the ability to remediate heavy metals in the soil,preparing the biochar and determining the physical and chemical properties of biochar.On the basis of this,we select three levels in the pot experiment.Respectively,pollution degree,biochar dosing quantity and time.The changes of extracted and free contents of heavy metals Cu or Cd in soils were analyzed,and the changes of remediation time,different biochar dosage and different pollution degree were analyzed.Depth study of the application of biochar after the restoration of heavy metals in the soil for the restoration of heavy metals in the mining area to provide a reference.The main contents and results are as follows:(1)Through the laboratory test and routine statistical analysis,the soil status of the study area was obtained.Nanshan mineral soil are acidic and pH value are range from 2.62 to 6.86.Cation exchange capacity are between 1.98 and 4.24 cmol / kg(+).The activity of urease are between 7.00 and 12.71ugNH3-N/g and the activity of catalase are between 32.27 and 43.56 ml.These data indicate that the soil is fertility in the study area.(2)The heavy metal elements of As,Cd,Cr,Cu,Ni and Zn were selected to evaluate the soil heavy metal pollution in the study area.In terms of the total amount of heavy metals in soil,the contents of As,Cd,Cu and Zn were higher than those of the national soil secondary standard or Ma’anshan local environmental background value,among which Cu and Cd were the most serious.From the view of the chemical form of heavy metals,the toxicity of Cd is relatively large.The results showed that the pollution of Cu and Cd were medium pollution,and the other heavy metal pollution belonged to low pollution level.The ecological risk of heavy metals was evaluated by risk assessment method.The results showed that the ecological risk of Cu and Cd was mild-moderate pollution level,and the remaining elements were mild pollution level.In general,the pollution of heavy metals in the soil of Nanshan mining area is mild pollution level.Especially,Cu and Cd elements exceeded the pollution and the situation are most serious.(3)The biochar was prepared for the determination of physical and chemical properties,to test whether the biochar has the ability to remediate heavy metals in the soil.The results show that the biochar pH is 8.76,which is alkaline.Isoelectric point is high.The surface is loose,porous and have many basic functional groups such as hydroxyl,carboxyl and lactone groups.Therefore,the biochar is suitable as a material for soil of heavy metal remediation.(4)Using the method of polluting treatment,the Cu or Cd heavy metal contaminated soil samples with light,medium,heavy and serious pollution degree were obtained.The soil samples of Cu or Cd heavy metal contaminated with different pollution degree were reclamated by biochar,studing the remediation effect of Cu or Cd heavy metal contaminated soil samples with different pollution levels.The application of biochar can reduce the content of heavy metal Cu or Cd in contaminated soil to a certain extent.The effect of adding 10% of biochar dosage to remediate heavy metal is better than that of 0.5% dosage.After the addition of biochar,with the increasing of remediation time,different forms of Cu or Cd content has changed.The average reduction rate of Cd was 56.24%,while the average reduction rate of Cu was 12.52%.The effect of biochar remediation of Cd was stronger than that of Cu.After the application of biochar,with the increasing of remediation time,the soil of research pH are increased and urease and catalase activity are decreased.However,it had little effect on soil nature.The effect of ion exchange and complexation on the removal of Cu or Cd in the soil was studied by the addition of biochar to remediate the heavy metals in the soil.In principle to provide theoretical basis.