Occurrence and risk assessment of antibiotics in multifunctional reservoirs in Dongguan, China

It is necessary to study the contamination of antibiotics in natural water bodies and assess its impact on ecological and human risks because of the large-scale use in the world. The occurrence and distribution characteristics of 45 antibiotics in reservoirs in Dongguan were investigated. Approximately, 77.8% of the detectable concentration of 35 antibiotics were found in the evaluation samples with concentration ranged from not detected (ND) to 729.59 ng/L, and dehydrated erythromycin was the highest one that appeared in Tongsha Reservoir. Fluoroquinolones and tetracyclines were the most abundant antibiotics with the detection frequency of 100% at sum concentration of 7.23–212.43 ng/L and 13.46–72.66 ng/L, respectively. Macrolides had a lower detected frequency but with highest concentration level at five kinds of antibiotics. Sulfamethoxazole, lincomycin, dehydrated erythromycin, pefloxacin, and panofloxacin were selected as important evaluation indicators. Sulfaguanidine, sulfamethoxazole, sulfisoxazole, dehydrated erythromycin, and clarithromycin that showed a significant correlation with Cl⁻ and SO₄²⁻ indicated that the pollution source of these antibiotics may be related to wastewater treatment plants. Among detected antibiotics, trimethoprim, norfloxacin, sarafloxacin, lincomycin, oxytetracycline, novobiocin, dehydrated erythromycin, and clarithromycin presented high risk to aquatic ecosystem in the reservoirs. There was no risk to humans at different ages of detected antibiotics, but it should attract attention because of the cumulative effects of antibiotics, which may cause potential risks to the human body.