Characteristics of antibiotic pollution and assessment of ecological risk of lake water in typical urban landscape in the context of a epidemic

As widely used drugs, antibiotics pose a serious threat to humans and the ecosystem. However, the outbreak of the COVID-19 pandemic significantly changed patterns of human activity and antibiotic use. The characteristics of antibiotic pollution in lakes in the urban landscape and their ecological risks due to the pandemic are still unclear. In this study, the levels, distributions, sources, and ecological risks of antibiotics in Xingqing Lake before and after the COVID-19 pandemic were investigated. The results revealed that macrolide antibiotics dominated in the environmental matrices. The synergistic effect of the pandemic outbreak and the lake renovation was the main factor driving the differences in the distribution of antibiotics. The positive matrix factorization model indicated that the potential sources of antibiotics in the water were domestic drainage, hospital discharge, and livestock drainage. The ecological risk assessment revealed that antibiotics posed a medium-high risk (RQ > 0.1) to algae. Notably, azithromycin, clarithromycin, and sulfadiazine presented higher risk values for crustaceans than for other aquatic organisms. A toxicity assessment of a single species may severely underestimate the actual ecological risks of antibiotics. This study provides a scientific basis identifying and controlling the sources of antibiotics in lakes in the urban landscape.