Spatial and temporal distribution characteristics and host identification of sediment ARGs in Qiantang River Basin

River networks on land serve as significant pathways for the intake of antibiotics and the dissemination of antimicrobial resistance (AMR). Estuaries, as critical transition zones connecting land and sea, often experience highly dynamic sedimentary environments due to tidal, wave, and riverine actions. This study focuses on the spatial and temporal distribution characteristics of AMR in the estuarine sediments of the Qiantang River, with an emphasis on major antibiotic resistance genes (ARGs) such as multidrug, aminoglycoside, tetracycline, bacitracin, and macrolide-lincosamide-streptogramin (MLS) resistance classes. Among these, nine subtypes of Rank I risk ARGs are enriched.