Antibiotic Contamination in Groundwater Across Major Chinese Basins: Which Compounds Require Priority Control?

Antibiotic contamination of groundwater and the associated risks to human health and ecosystems have become global concerns. However, the antibiotics requiring priority control in groundwater at the national basin scale remain inadequately defined. This study compiled a dataset of groundwater antibiotic concentrations spanning the major river basins of China over the past two decades and proposed a groundwater health prioritization index (GHPI) by integrating prevalence (Pv), occurrence (O), persistence-migration (PM), bioaccumulation-toxicity (BT), and antibiotic resistance-related risk (RQARGs). At the national scale, 13 antibiotics were identified as high-priority groundwater contaminants, with quinolones accounting for the largest share (46.15%), while tetracyclines exhibited comparatively higher overall GHPI scores (mean: 0.62). Significant positive correlations were observed between Pv, O, PM, RQARGs, and GHPI (r = 0.49-0.77). The composition of priority antibiotics differed markedly among river basins, with the Yangtze River Basin containing the greatest number (10). Chlorotetracycline, enrofloxacin, roxithromycin, oxytetracycline, and ciprofloxacin were repeatedly identified as high-priority antibiotics in multiple basins (≥3). Moreover, the dominant contributors to elevated GHPI scores for the same priority antibiotic varied across basins, underscoring the need for region-specific control strategies. Six antibiotics requiring priority control were identified for the first time. Overall, this framework explicitly integrates antimicrobial resistance risks into groundwater antibiotic prioritization and provides a scientific basis for priority control, basin-specific management, and the protection of human health and ecological security.