Abstract:

【Objective】The effects of magnetic field on microbial communities and enzyme activities in red soil by nanoscale Fe3O4 were investigated, and the degradation of herbicide 2,4-D in red soil after nanoscale Fe3O4 treatment was also studied. The research will provide a basis for soil remediation by magnetic nanoparticles treatment. 【Method】 The red soil was treated by different dosages of nanoscale Fe3O4, then the microbial communities and enzyme activities were analyzed by dilution plate method and chemical assay, and the concentration of 2,4-D in soil was determined by high performance liquid chromatography (HPLC). 【Result】 The results indicated that the nanoscale Fe3O4 treatment had a positive effect on bacteria and actinomycetes, however, the fungi number was decreased by the same treatment. The effects of magnetic field on microbial communities increased with the dosage of nanoscale Fe3O4, and the microbial number reached the maximum at the dosage of 80 g•kg-1. Similarly, the nanoscale Fe3O4 could also improve the activities of amylase, urease, neutral phosphatase and catalase, but the effects of magnetic field on enzyme activities were different. The degradation rate of 2,4-D in red soil treated with the nanoscale Fe3O4 was significantly higher than that without treatment, and the 84% of 2,4-D could be degraded in 7 days.【Conclusion】The nanoscale Fe3O4 can improve the microbial communities and enzyme activities as well as the degradation of 2,4-D in red soil.

Key words: nanoscale Fe3O4, microbes, enzyme activities, 4-D, degradation