[Application of Fe₃[KG-*2/5]O₄/Mulberry Stem Biochar Effects on Soil Arsenic Species and Rice Arsenic Content]

The passivation effect of Fe₃O₄/mulberry pole biochar (Fe-MBC) prepared at different carbonization temperatures on soil available arsenic content was studied through soil culture experiments, and Fe-MBC-800 (prepared by carbonization at 800℃) with good passivation effect was selected and characterized. The effects of 1%-7% (mass fraction of biochar to soil) Fe-MBC-800, MBC-800, and Fe₃O₄ on soil pH value, soil electrical conductivity, soil arsenic form, rice biomass, and total arsenic (As) content in rice were studied using a pot experiment. The results showed that:①Fe-MBC-800 successfully loaded Fe₃O₄, and its main functional groups were C=O double bond, O-H bond, C-O bond, and Fe-O bond. The specific surface areas of Fe-MBC-800, MBC-800, and Fe₃O₄ were 209.659 m²·g^-1, 517.714 m²·g^-1, and 68.025 m²·g^-1, respectively. ②The addition of Fe-MBC-800 could increase the soil pH value, decrease the soil EC value, increase the content of residual arsenic in soil, and reduce the content of water-soluble arsenic and available arsenic in the soil. Under the treatment using 7% Fe-MBC-800 (ω) amendments, the content of water-soluble arsenic and available arsenic in the soil decreased by 81.6% and 56.33%, respectively. ③When the addition ratio of Fe-MBC-800 in the soil was 5%-7%, it could promote the growth of rice plants, increase rice biomass, and reduce the bioaccumulation of arsenic by between 62.5% and 68.75%.