Effect of iron-modified biochars on soil nutrients and bioavailability of As and Pb
[Objective]To investigate the effects of raw and iron-modified biochar on the nutrient content and bioavailability of arsenic(As)and lead(Pb)in con-contaminated agricultural soil.[Method]An experiment using rice potted in soil mixed with 2％raw Ficus microcarpa biochar(FMB)and Polyferric Sulfate(iron)-modified biochar(Fe-FMB)was conducted,no biochar soil as control.Soil nutrient availability,soil enzyme activity,rice biomass and As and Pb concentrations in various plant organs at different growth stages were measured.The bioavailable As and Pb in the soil were determined using the NH4H2PO4 and DTPA extraction methods,respectively.[Result]The results indicated that,compared to the control,Fe-FMB significantly enhanced the availability of nutrients such as phosphorus(P)and silicon(Si)in the soil and significantly altered the distribution of Si forms in the soil(P＜0.05),primarily increasing the content of amorphous silicon(by 25.2％)and iron-manganese oxidized silicon(by 11.1％).Fe-FMB was more effective in immobilizing soil As(P＜0.05),reducing it by 37.9％compared to the control,while original biochar(FMB)was more effective for soil Pb immobilization,reducing it by 24.9％.Application of Fe-FMB led to a 67.2％reduction in As content in rice grains as compared to the control.Furthermore,Fe-FMB significantly increased the activities of leucine aminopeptidase,acid phosphatase,and catalase(P＜0.05),with maximum increases of 121.1％,99.1％,and 33.2％,respectively.Pearson correlation analysis showed that soil enzyme activity was significantly related to pH and As availability(P＜0.05),indicating that biochar application can regulate soil enzyme activity by influencing soil pH and As bioavailability.[Conclusion]While F.microcarpa biochar is effective in remediating soils contaminated with Pb only,it is not suitable for the treatment of soils co-contaminated with As and Pb.On the other hand,iron-modified biochar shows a better prospect for remediating soils co-contaminated with As and Pb.[Ch,8 fig.2 tab.36 ref.]
万方数据
维普
