[Spatial Distribution, Source Apportionment, and Ecological Health Risk Assessment of Antibiotics in the Water Bodies...

To investigate antibiotic pollution in the Huangjia Lake Basin, 28 antibiotics from six classes were analyzed in water samples using solid-phase extraction coupled with high-performance liquid chromatography-tandem mass spectrometry (SPE-HPLC-MS/MS). The results revealed the detection of 10 antibiotics spanning five classes (sulfonamides, quinolones, macrolides, lincosamides, and tetracyclines) across 20 sampling sites. Cinoxacin and tilmicosin exhibited the highest detection rates (100%), followed by lincomycin, clindamycin, and chlortetracycline (all >90%). The top three antibiotics by mean concentration were clinafloxacin (33.12 ng·L^-1), chlortetracycline (14.84 ng·L^-1), and lincomycin (9.33 ng·L^-1). Spatial analysis indicated that antibiotic contamination was primarily point-source-dominated with significant heterogeneity. Ecological risk assessment identified elevated risk quotients (RQs) at sites S10, S11, S14, S15, and S16. Clinafloxacin posed high risk (RQ>1), while clindamycin and clarithromycin showed moderate risk (0.1 < RQ < 1). Principal component analysis (PCA) traced antibiotic sources to livestock/poultry farming effluents and aquaculture wastewater. Health risk assessment suggested negligible human health risks from drinking water exposure. Using the Toxicological Priority Index (ToxPi) framework, antibiotics were prioritized as follows: sulfamethoxazole (1.96)>clarithromycin (1.90)>sulfamerazine (1.80)>tilmicosin (1.52). These compounds warrant prioritized attention in future monitoring.