[Characteristics and Risk Assessment of Antibiotic Contamination in Chishui River Basin, Guizhou Province, China].

To preliminarily explore the antibiotic concentration distribution characteristics of Guizhou Chishui River basin surface water and potential ecological risks, we used solid phase extraction liquid chromatography tandem mass spectrometry (SPE-HPLC- MS) to analyze 21 types of antibiotics in surface water samples. Twelve types of antibiotics were detected in the Chishui River basin surface water, and the total concentrations of ofloxacin, sulfadiazine, and trimethoprim ranged from ND-1166.97 ng·L, with a detection rate of 100%. On average, the highest concentration of the three types of antibiotics detected were ofloxacin (221.59 ng·L), tetracycline (13.18 ng·L), and sulfadiazine (4.11 ng·L), and the antibiotic concentration distribution showed the following order of characteristics:downstream (359.41 ng·L) > midstream(224.59 ng·L) > upstream (179.72 ng·L). The ecological environment risk assessment results indicated the largest risk for downstream W21, tetracycline, doxycycline, enrofloxacin, norfloxacin, and erythromycin. The risk quotient revealed that lincomycin had a medium-risk level, and ofloxacin had a high-risk level. This shows that antibiotics in the waters of the Chishui River basin may cause certain ecological risks.