Effect Of Biochar Prepared By 4 Kinds Of Raw Material On Zn, Cd Forms And Enzyme Activities In Soils

Metal contamination could not only degenerate the soil fertility, reducing the yield and quality of agricultural products, but also could endanger human health through the food chain ultimately. Biochar was a highly carbonaceous particulate matter that generated by incomplete combustion or anaerobic low temperature pyrolysis using straw, animal manure and other agricultural or forestry waste. It had a huge surface area and superior adsorption capacity, so that it could be used in the repair of environmental pollution and other processes. Therefore, it was important to restore farmland soil health security of agricultural products safety and human health was of great significance that strengthening research biochar on soil heavy metal pollution.In this study, apple wood, peanut shells, corn straw and wheat straw were select as raw material preparation of biochar as experiment material to pot experiment. This topic mainly researched the effect of four different amounts of biochar and not carbonized material on the forms of Zn and Cd, absorption effect of Chinese cabbage and soil enzyme activity, to provide a theoretical basis for soil Zn, Cd contaminated soil remediation. The main conclusions were as follows:(1)The yield, ash content and pH were greatly influenced by the raw material. Yield: P-BC> A-BC> W-BC> C-BC;ash content:C-BC > W-BC >A-BC > P-BC. Four kinds of biochar were alkaline, and pH: C-BC > W-BC > P-BC>A-B. The etching of biochar sample surface was more obvious than the raw material with cell deformation occurred in tubular structure, gap, fracture and stripping. And the hole wall surface of biochar becomed smooth, emerging some porous structure.(2) Zn, Cd residual fraction of adding four kinds of biochar at 0.1%, 0.5%, 1% and 5% four levels of soil were higher than that of control group, showing varying degrees of increase, and with the increase of addition amount increase. The raw material could fixed the effect of heavy metals, but they were not more obvious than biochar. There were no differences of residual heavy metal content among four kinds of biochar in the same amount,and the passivation repair effect was not affected by the raw material.(3)Under the action of four addition level of four kinds of biochar, the Zn, Cd in the Chinese cabbage were lower than that of control. The more biochar added, the lower Zn, Cd in the Chinese cabbage increased. There were no significant differences of heavy metals in Chinese cabbage under the same amount of four kinds of biochar.(4)Under the action of four addition level of four kinds of biochar, the enzyme(urease, catalase, invertase) activity in the soil were higher than that of control. URS and CAT increased gradually with the increase of the amount of biochar. But with the increase of the amount of biochar, the increase of SEA content increased firstly and then decreased, and it reached to the highest when added amount of 1%. However, the enzyme activity of the biochar treatment group was lower than that of the raw material. Under the same additive amount, the activities of P-BC and A-BC on soil urease activity were significantly greater than that of C-BC and W-BC, and catalase activity and invertase activity were not affected by the raw material.