Microplastics (PET and PVC) disrupt palygorskite-mediated cadmium stabilization in paddy soil: Polymer-specific rhizosphere mechanisms and ecological consequences.

Microplastics (MPs) are emerging disruptors to soil heavy metal remediation, yet how different polymer types undermine mineral-mediated in-situ immobilization remains unclear. Using a multi-omics approach (16S rRNA gene sequencing, metagenomics, transcriptomics and metabolomics), we aimed to elucidate the polymer-specific mechanisms by which polyethylene terephthalate (PET) and polyvinyl chloride (PVC) residues destabilize palygorskite-immobilized cadmium (Cd) in paddy soil, at both the soil and microbial levels. PET and PVC differentially induced the remobilization of palygorskite-immobilized Cd (F1: +132.43% and 85.52%) via distinct rhizosphere pathways. At the soil/plant level, PET enriched PETase-carrying Acidobacteriota and suppressed the ammonium transporter gene OsNRT2.3, lowering rhizosphere pH from 7.05 to 6.30. This acidification was associated with the remobilization of mineral-bound Cd and increased brown rice Cd from 0.03 to 0.06 mg/kg. PVC, in contrast, did not acidify the rhizosphere but instead induced severe root oxidative stress (MDA +78%, POD +60%), likely impairing root-barrier integrity and enhancing Cd uptake. At the microbial level, PET enriched keystone taxon Gaiella via homogeneous selection (HoS), supporting stress adaptation through branched-chain amino acid metabolism, whereas PVC redirected microbial carbon flux toward the pentose phosphate pathway and increased the genetic potential for acetate-dependent methanogenesis (acs +22.67%). These findings demonstrate that MPs compromise the durability of Cd immobilization through polymer-specific rhizosphere processes, with distinct ecological trade-offs, providing critical insights for heavy metal remediation in microplastic-polluted paddy soils.