Divergent fates: Polystyrene microplastics alter trifloxystrobin degradation and microbial ecology differently in agricultural soil vs. river sediment

This study investigates the effects of polystyrene microplastics (PS-MPs) on trifloxystrobin (TRI) degradation behavior and microbial community structure in agricultural soil and river sediment. Degradation kinetics and machine learning modeling ( R 2 > 0.95) revealed that PS-MPs significantly inhibited TRI dissipation, with biological degradation identified as the primary driver. Specifically, the half-life of TRI was prolonged from 2.7 to 9.7 days to 4.0–18.1 days in soil, and from 3.1 to 8.3 days to 4.8–9.7 days in sediment. Trifloxystrobin acid remained the major transformation product overall, though a unique cyanide-containing compound appeared exclusively in sediment, suggesting distinctive metabolic routes. 16S rRNA sequencing showed that TRI and PS-MPs significantly altered the bacterial community structure. The PS-MPs treatment significantly reduced the relative abundance of potential TRI degrading bacteria, such as Sphingomonas and Pseudomonas , which is related to the observed delayed degradation. Microbial network analysis further revealed that TRI simplified the soil microbial network, reducing the number of nodes and connections by about 7%, while PS-MPs increased the complexity of the sediment network, increasing the number of nodes and connections by about 36%. These findings provide quantitative insights into the comprehensive ecological risks of microplastics and fungicides in different environmental matrices.