Dynamic responses of soil microbial communities to long-term co-contamination with PBAT and cadmium

The co-contamination of plastics and heavy metals poses novel challenges to agricultural soil ecosystems. However, research into the long-term effects of such co-contamination on soil microbial communities remains limited. This study, through a 540-day incubation experiment, investigated the impacts of poly(butylene adipate-co-terephthalate) (PBAT) and cadmium (Cd) co-contamination on the structure and function of soil microbial communities. The findings revealed that co-contamination significantly altered soil nitrate and ammonium nitrogen levels. Furthermore, the co-contamination continuously and significantly reduced bacterial diversity, producing a more pronounced negative impact compared to single pollution. Key microbial groups such as Proteobacteria, acting as core microorganisms, were significantly enriched under co-contamination conditions, with their relative abundance increasing significantly by 40.0 %. This indicates their potential role in plastic degradation and heavy metal resistance. In addition, the co-contamination also drove the shift of bacterial and fungal community assembly from deterministic processes to stochastic processes. These insights not only fill the research gap regarding the effects of long-term co-contamination on soil microorganisms but also provide a scientific foundation for the development of targeted soil management and remediation strategies, especially in regions where plastic and heavy metal pollution coexist.