[Occurrence Characteristics and Risk Assessment of Antibiotics in Source Water of the Nanjing Reach of the Yangtze River].

Occurrence characteristics of antibiotics in the source water of the Nanjing section of the Yangtze River were analyzed preliminarily by solid-phase extraction and high-performance liquid chromatography-tandem mass spectrometry (SPE-HPLC-MS/MS). The results showed that the cumulative concentration of 16 sampling points ranged from 13.37 ng·L-1 to 780.5 ng·L-1, with an average concentration of 92.95 ng·L-1. Four sulfonamides, three fluoroquinolones, one tetracycline, five macrolides, and one chloramphenicol antibiotic were detected with average concentration ranging from 0.14 ng·L-1 to 49.91 ng·L-1,including enrofloxacin (ERX) and clarithromycin (CLR) with the highest detection rate of 100%, and clindamycin (CLI) with the highest concentration of 739.44 ng·L-1. Overall, the concentration levels of antibiotics in the Nanjing section of the Yangtze River were low compared with other rivers and lakes in China. The risk assessment results showed that the largest cumulative risk of S2 was 0.31, and the environmental risk of sulfamethoxazole (SMX), doxycycline (DOX), and roxithromycin (ROX) had lower risk levels;the health risk indexes of nine antibiotics for different age groups were between 2.22×10-6and 4.86×10-3, while CLI and DOX are the main potential health risk factors for humans.