Occurrence, source, and ecological risk of antibiotics in Dongting Lake, China.

The pollution characteristics and ecological risk of 12 classified as sulfonamide, trimethoprim, quinolone, and tetracycline antibiotics in Dongting Lake, China, were studied. The total concentrations of the antibiotics ranged from 1.06 to 135.40 ng L-1 for all sampling sites. The highest average concentration was observed for sulfadiazine, followed by sulfamethoxazole. The detection frequencies (over 60%) of sulfonamides were higher than those of other antibiotics. The direct discharge of the aquaculture, livestock, and poultry wastewater might be the main pollution sources of antibiotics in the Dongting Lake. The pollution levels of antibiotics decreased in the order of East Dongting Lake > South Dongting Lake > West Dongting Lake, which may be related to the distribution and the scale of the aquaculture, livestock, and poultry sources. The seasonal changes of antibiotic concentration were relatively diversified, with the dry season generally having higher concentrations than the wet season. The results of the ecological risk assessment indicated that sulfamethoxazole, ciprofloxacin, and sarafloxacin might pose a significant risk to the aquatic organisms in Dongting Lake, especially in Potou and Nandu. This study enriches the research of emerging pollutants in freshwater lake. Graphical abstract.