硅酸盐菌剂对污染土壤中砷、硅活性的影响效应研究

Effects of Exogenous Silicate Bacterial Inoculants on Availability of Silicon and Arsenic in As-contaminated Soil

采用摇床短期培养和梯度长期土壤培养方法，研究硅酸盐菌剂（含胶质芽孢杆菌）对砷污染土壤固相中砷、硅向液相释放或迁移的影响效应，并筛选调控土壤砷有效性的菌剂适宜添加量。采用自然土和砷污染土为研究对象的摇床短期培养结果表明，添加硅酸盐菌剂处理的自然土、砷污染土的土壤浸提液中As浓度较CK（灭菌培养基）分别降低了92．8％和65．5％；较硅酸盐菌剂的灭菌菌液处理分别降低了54．4％和37．0％，这说明硅酸盐菌剂对土壤中砷有钝化作用，降低了土壤中砷的活性；自然土、污染土的土壤浸提液中si浓度较CK（灭菌培养基）分别降低了40．6％和53．5％，较灭菌菌液分别降低了42．5％和54．3％，即硅酸盐菌剂也降低了土壤固相硅向液相的释放。另外，梯度长期土壤培养试验结果表明，添加菌剂量在10～100ml的范围内，土壤溶液中硅浓度并没有随着菌剂量的增加而增加，而添加10ml菌剂的处理土壤溶液中As浓度较添加菌剂50ml，100ml处理分别降低了29．3％和85．6％，因此钝化污染土中砷活性的硅酸盐菌剂适宜用量为10mI。

Short-term and long-term incubation experiments were carried out to study the effects of different amounts of exogenous silicate bacterial inoculants（only including Bacillus muciIaginosus） on the concentra- tions of silicon and arsenic in soil solution, and to screen the appropriate application rate of silicate bacterial inoculants able to control the availability of arsenic in contaminated soil. The results from short-term test showed that, in the treatment of silicate bacterial inoculants for natural and As-contaminated soil, the concentrations of As were 92.8% and 65. 5% lower than that in CK, respectively, and were 54.4% and 37.0% lower than that in the treatment of sterilized silicate bacterial inoculants, respectively. The results indicated that silicate bacterial inoculants led to inactivation of As in soil. For natural and As-contaminated soil, the concentrations of Si in the treatment of silicate bacterial inoculants were 40.6% and 53.5 % lower than that in CK, respectively, and were 42. 5% and 54. 3~/oo lower than that in the treatment of sterilized silicate bacterial inoculants, respectively. These indicated that application of silicate bacterial inoculants reduced arsenic and silicon release from soil solid phase to soil solution. In addition, the results from long- term test showed that application rate from 10 ml to 100 ml of silicate bacterial inoculants did not increase the Si concentration in soil solution, while application of 10 ml silicate bacterial inoculants decreased the As concentrations by 29. 3% or 85. 6% compared to 50 ml or 100 ml application rate of silicate bacterial inoculants, respectively. Therefore, the appropriate application rate of silicate bacterial inoculants could be 10 ml, which may reduce As availability in arsenic-contaminated soil.