Environmental microbial community stabilization and plant growth enhancement by combined carbon nanomaterials and nitrification inhibitor in soil contaminated with polyvinyl chloride.

Microplastics are widely distributed in soil ecosystems, posing significant threats to soil health and plant growth. This study investigated the role of environmental microbial communities in mitigating the toxic effects of microplastics on soil-plant systems. Carbon nanomaterials and nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) can regulate soil microbial communities and nitrogen transformation enzyme activities. Microplastics polyvinyl chloride (PVC) significantly reduced the plant biomass and soluble sugar by 32.4% and 39.2%, respectively. However, combined multi-walled carbon nanotubes (MWCNTs), nanodiamonds, and DMPP alleviated those toxic effects. PVC significantly declined the soil bacterial community stabilization, and extra nanomaterials recovered soil bacterial community stabilization to blank control level. Moreover, extra nanomaterials exhibited double-edged sword effects on the endophytic microbes, which significantly inhibited the α-diversities and stabilizations of the endophytic bacterial community but promoted the α-diversities and stabilizations of the endophytic fungal community. Plant biomass was significantly correlated with the soil pH, plant soluble sugar and nitrate content, and α-diversities and stabilizations of the endophytic bacterial and fungal communities. These findings highlight the pivotal role of environmental microbial communities in mediating the response of plants to microplastic contamination and offer valuable insights for alleviating the toxic effects of microplastic contamination.IMPORTANCECarbon nanomaterials and nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) can serve as plant growth regulators and regulate soil health. Combined multi-walled carbon nanotubes, nanodiamonds, and DMPP could relieve the toxic impacts of polyvinyl chloride (PVC) on soil bacterial community stabilization, plant biomass, and quality. The extra nanomaterials exhibited double-edged sword effects in that they significantly inhibited the endophytic bacterial community α-diversities and stabilizations but promoted the endophytic fungal community α-diversities and stabilizations. This study would provide theoretical and practical foundations to relieve the toxic impacts of microplastics on the soil-plant system.