Remediation of antimony-contaminated soil by food waste organic fertilizer and rhizosphere microbial response mechanism

Shenglian Luo ¹ Yingxuan Ouyang ² Weimin Zeng ³ Xiaoyan Wu ^2*

• ¹ Nanchang Hangkong University, Nanchang, Jiangxi Province, China
• ² University of South China, Hengyang, Hunan Province, China
• ³ Central South University, Changsha, Hunan Province, China

Antimony pollution is a major issue in our country, endangering the ecological environment and health of residents in mining areas. The application of organic fertilizers is considered an efficient strategy for remediation of heavy metal pollution in soil. The purpose of this study was to investigate the remediation of antimony-contaminated soil by food waste organic fertilizer (FF) and rhizosphere microbial response mechanism. The analysis results of soil physicochemical properties showed that the application of FF had the most significant effect in reducing bulk density (from 1.57 to 1.08 g cm -3 ), improving salinization degree, increasing organic matter content, and available nitrogen, phosphorus, and potassium contents (P < 0.05). The plant height of Pteris vittate in the FF group increased by 82.12% compared to the control group. The analysis of antimony valence state transformation showed that after applying FF, the Sb(III) content in the rhizosphere and endosphere of Pteris vittate was significantly lower than other groups (P < 0.05), and the Sb(V) content in the endosphere was the highest. This indicated that FF could promote the oxidation and detoxification of Sb(III) in the soil to produce Sb(V), which is further enriched in the root of Pteris vittate. Microbial community analysis showed that the application of FF promoted the continuous enrichment of Proteobacteria, Actinobacteria, Firmicutes, and Bacteroidetes in the root of Pteris vittate, especially the specific microbial groups with Sb(III) oxidation, nitrogen fixation, and phosphorus and potassium solubilization functions such as Acinetobacter, Sphingomonas, Comamonas, Bradyrhizobium, Alphaproteobacteria, Acidovorax, and Paenibacillaceae, which can alleviate the stress of poor soil conditions and heavy metals on the growth of Pteris vittate in mines. This study provides a new approach for the resource utilization of food waste and the remediation of antimony-contaminated sites.