Spatio-temporal dynamics, drivers and cross-media risks of antibiotic resistance in constructed wetland sediments

Constructed wetlands (CWs), commonly employed for secondary wastewater treatment, exhibited spatio-temporal dynamics that influenced the proliferation of antibiotic resistance genes (ARGs). ARGs, mobile genetic elements, and bacterial communities were quantified to assess their risks and driving mechanisms. Notably, aac(6')-Ib emerged as the dominant subtype, with an average abundance of 7.3 × 10⁸ copies/g. The elevated abundance, coefficient of variation (15.5 %), and ARG risks observed during the ice period were primarily driven by their interactions with integrase. By integrating spatio-temporal dynamics with co-occurrence network, intI-1 was identified as a key node connecting bacterial functions to ARGs. Structural equation model further revealed that spatial variation significantly influenced ARGs, mainly attributed to the denitrification process (NO to N₂). Take home message, this study innovatively elucidated the hierarchical drivers of ARG dynamics in CWs, laying a theoretical foundation for mitigating ARG risks via the integrated management of nitrate and antibiotic resistance in ecological wastewater treatment systems.