[Distribution and Risk Assessment of Antibiotics in Surface Waters of the Yellow River Basin]

Antibiotic concentrations in surface waters of the Yellow River Basin were obtained to determine the concentration levels and distribution characteristics of the antibiotics， explore the impact of socioeconomic factors， and assess ecological risks. The results show that the concentration of antibiotics in the Yellow River Basin ranges from 0 to 233 700.0 ng·L^-1. The concentrations of quinolones are higher than others（223.51 ng·L^-1）， with enoxacin having the highest average concentration of 962.48 ng·L^-1. Each province along the river is affected by varying degrees of pollution， and there is an overall trend of gradually increasing concentration from upstream to downstream. The average concentration reaches its highest value in Shandong. The major socioeconomic factors influencing the distribution of antibiotics were identified through principal component analysis and Mantel analysis. The results revealed that the concentration of antibiotics in the surface waters of the Yellow River Basin is linked to fisheries， livestock， rural residents' consumption， rural medical care， and wastewater discharge. The results of a multi-level risk assessment suggest that antibiotics such as norfloxacin， ciprofloxacin， azithromycin， tetracycline， doxycycline， ofloxacin， and erythromycin present high aquatic ecological risks and should be monitored closely.