Vertical migration of antibiotics, ARGs, and pathogens in industrial multi-pollutant soils: Implications for...

Urban soils accumulating multiple pollutants act as critical reservoirs for antibiotic resistance genes (ARGs) and pathogens, yet their vertical migration in industrial soils remains poorly understood. Here, we investigated antibiotics, ARGs, and pathogenic hosts in soil profiles (0-310 cm) from Shanghai's Taopu Industrial Park (China) using ultra-performance liquid chromatography tandem mass spectrometry and metagenomic sequencing. Nineteen antibiotics (0.7-113.6 ng g⁻¹) decreased exponentially with depth, influenced by polycyclic aromatic hydrocarbons (PAHs). Among 1183 ARG subtypes, 437 persisted across depths, with relative abundance increasing with soil depth, primarily driven by microbial community shifts, where metabolic pathways (e.g., carbohydrate and nitrogen metabolism as network hubs) contributed substantially to ARG dissemination. Random forest modelling identified clay (38 %) and fluoranthene (21 %) as primary drivers for bacterial communities, while pathogens responded divergently: antibiotics explained 48 % of Acinetobacter abundance variation, whereas clay governed 36 % of Pseudomonas abundance. The top 30 ARG-host genera included seven pathogens enriched in middle-deep layers (20-310 cm), indicating elevated groundwater contamination risks. Our findings reveal synergistic pollutant-microbial metabolic interactions promoting deep-soil resistance propagation, advocating urgent co-pollutant mitigation to safeguard urban soil systems.