Microplastic pollution drives soil bacterial community shifts and alters phosphorus cycling across land use gradients

Microplastics (MPs) pollution is increasingly recognized as a pervasive threat to terrestrial ecosystems, yet its functional impacts on soil processes remain poorly understood under field conditions. Here, we conducted a landscape-scale study across four land-use types, urban, mining, agricultural, and rural, to quantify environmentally accumulated MP and assess their effects on phosphorus (P) cycling and microbial communities. High-resolution spectroscopy revealed that urban and mining soils contained the highest MP loads (600-1000 particles/kg), with distinct polymer types linked to anthropogenic activities. MP abundance was negatively correlated with P solubilization (R = -0.59, p < 0.01) and soil enzymatic activity, and positively with P immobilization (R = 0.53, p < 0.05), indicating impaired nutrient availability. Amplicon sequencing showed that MP-rich soils were enriched in certain taxa within Firmicutes and Actinobacteria often associated with stress tolerance, while low-MP soils supported functionally important groups, including specific Acidobacteria and nitrifying archaea (e.g., Candidatus Nitrososphaera). Co-occurrence network analysis revealed simplified and cooperative microbial structures in MP-polluted soils. Multivariate analyses confirmed that MP are independent drivers of microbial beta-diversity beyond land use. Overall, our findings provide in situ evidence that MP, even at moderate levels, alter microbial ecology and disrupt soil nutrient cycling, posing a potential risk to biogeochemical resilience in human-impacted landscapes.