Keywords: 
• antibiotic /
• source water /
• ecological risk /
• health risk /
• reservoir

Abstract: A large amount of environmental residues of antibiotics cause hazards and risks to the ecological environment and human health. In this paper, the ecological and health risk assessments were performed to evaluate the risk of 10 kinds of antibiotics, including lincomycin, erythromycin-H₂O, roxithromycin, sulfamethoxazole, sulfadimidine, cefuroxime, cefalexin, metronidazole, amoxicillin and chloromycetin, in a reservoir in a southern city, China. Results showed that 8 kinds of antibiotic were detected in 7 sampling points, with the concentrations ranged from 1.2 to 130 ng·L^-1. The detection frequency of erythromycin-H₂O, lincomycin, sulfamethoxazole reached 100% both in high flow period and low flow period, while sulfadimidine and cefuroxime could only be detected in low flow period. However, chloromycetin and amoxicillin could not be detected in the selected 7 sampling points. Further risk assessment results showed that the overall risk was not high except some points. The risk quotients exceeded 1 for the sulfamethoxazole in River A (both high flow and low flow periods). Among sampling points, the combined risk quotients of all 10 antibiotics in River A (both high flow and low flow periods), River B (high flow period) and point 3 in the reservoir (low flow period) were higher than 1. It indicated that the residuals of antibiotics had high ecological risk in these stations. The risk quotients of other stations ranged from 0.10 to 1.00, illustrating that the long-term observations for antibiotics residuals in water are necessary. The sum of non-carcinogenic risks for the 10 antibiotics was in range of 10^-15 to 10^-12, suggesting the acceptable health risks associated with antibiotics in the source water of the reservoir.