Targeted Screening, Distribution and Sources of Antibiotics in Drinking Water Sources and its Risk Assessment in Sichuan Province, China.

The misuse of antibiotics has led to frequent detection of antibiotics in the environment and triggered a series of environmental pollution problems. As the upper reaches of the Yangtze and Yellow Rivers, Sichuan Province has a large population, and the safety of its drinking water is of great importance to the local and even downstream areas. In this study, ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was used for targeted screening 41 antibiotics from 4 categories including tetracyclines, sulfonamides, macrolides, and quinolones in 35 water sources in Sichuan Province, China. Results showed that 30 antibiotics existed in the water samples. The total concentration of antibiotics (∑30 antibiotics) was 0.03-33.09 ng·L-1, with sulfonamide antibiotics exhibiting the highest concentration. In terms of different types of water sources, the concentration of ∑30 antibiotics showed the trend of in the river type (8.15 ± 10.18 ng·L-1) > the lake and reservoir type (2.62 ± 1.60 ng·L-1) > the groundwater type (0.33 ± 0.31 ng·L-1). Veterinary antibiotics predominated in the groundwater and river type sources, while veterinary-agricultural antibiotics dominated in the lake and reservoir type sources. The order of ∑30 antibiotics concentration of in water sources from different economic zones showed that in the South Sichuan Economic Zone > Chengdu Plain Economic Zone > Northeast Sichuan Economic Zone > Panxi Economic Zone > Northwest Sichuan Ecological Demonstration Zone. Cluster analysis showed that antibiotics in water sources mainly originated from human medical treatment, breeding and agricultural use. The risk evaluation indicated that there were no high-risk points in the study area, and most of the points were at the no-risk to low-risk levels. The results supplied data and a scientific foundation for implementing a tiered and zoned water resource management strategy for controlling antibiotic pollution.