Studying the impact of hollow mesoporous MnO2 on remediating heavy metal-contaminated soil: Implications for soil structure and microbial dynamics

Heavy metals in soil pose serious threat to the ecological environment and human health. The application of nanomaterials in the remediation process of heavy metal contaminated soil has made significant progress. This work investigated the impact of hollow mesoporous MnO₂ nanomaterials (HMN) on soil aggregates and microbial communities during soil remediation process. The study found that applying HMN promotes the formation of large aggregates, and the microbial communities that improve soil structural functions were more sensitive to HMN in the remediation process of Cd-contaminated soils, while microbial communities that responded to HMN in Pb contaminated soils were associated with heavy metal stress, plant growth, and nutrient cycling functions. Additionally, the addition of HMN to Pb and Cd contaminated soils affected amino acid-related metabolic pathways. The application of HMN regulated the microbial membrane transport functions in these contaminated soils, enhanced nucleotide metabolism in Cd contaminated soils, and improved carbohydrate metabolism in Pb contaminated soils. HMN drove soil microbial community assemblage to change the metabolic process, thereby improving soil quality. However, the formation of soil aggregates as well as the change of the porosity and fertility deserved further investigation.