Detection, distribution and ecological risk assessment of typical antibiotics in water around Poyang Lake, Southeast of China

Antibiotics are synthetic broad-spectrum antibiotics that are widely used in human medicine, animal husbandry and aquaculture. China is a major producer of antibiotics. Poyang Lake is the largest freshwater lake in China. At present, there are still few research methods and applications for the simultaneous detection of multiple antibiotics in environmental water bodies. In this research, automatic solid phase extraction-ultra high performance liquid chromatography-mass spectrometry technology was used to simultaneously detect 27 antibiotics in 5 categories of macrolides, tetracyclines, quinolones, nitroimidazoles and sulfonamides in water. Based on this method, the concentration and distribution of 27 antibiotics in surface water, groundwater and wastewater of Poyang Lake Basin were analyzed. The ecological risk quotient method was used to evaluate the ecological risk of Poyang Lake Basin, in order to provide data support for ecological environment protection and antibiotic pollution prevention and control in Poyang Lake Basin. The results show that:

(1) Automatic solid phase extraction was used as the pretreatment method for antibiotic detection in water, and the process steps of the technology were optimized. Most of the recovery of ultrapure water was between 51.07% and 112.58%, and the recovery of matrix was between 56.16% and 137.57%. The limits of detection were 0.01-0.44 ng·L^-1, and the limits of quantitation were 0.03-1.36 ng·L^-1.

(2) The water around Poyang Lake was sampled, and its species characteristics and concentration levels were preliminarily analyzed. There are antibiotic pollutions around Poyang Lake and the tributaries of Ganjiang River, such as Jinjiang River and Yuanhe River. The overall detection of species: Poyang Lake surrounding surface water 24, groundwater 23, Jinjiang 24, Yuanhe at least 20. Overall concentration comparison: surface water around Poyang (26.81~503.06 ng·L^-1)> groundwater around Poyang Lake (12.66 ~ 286.85 ng·L^-1). Jin River (69.51~ 567.90 ng·L^-1) > Yuan River (47.33~ 873.52 ng·L^-1).

(3) Compared with other river basins, the surface water around Poyang Lake was polluted by two antibiotics, and the average concentrations of doxycycline and chlortetracycline were 6.93 ng·L^-1and 14.54 ng·L^-1. The groundwater around Poyang Lake had a high degree of roxithromycin pollution, with an average concentration of 31.86 ng·L^-1. The contamination levels of the two antibiotics in Jinjiang were relatively high, and the average concentrations of roxithromycin and sulfamethoxazole were 22.52 ng·L^-1 and 188.55 ng·L^-1. The contamination levels of the three antibiotics in Yuan River were relatively high, and the average concentrations of roxithromycin, doxycycline and sulfamethoxazole were 33.92 ng·L^-1, 7.49 ng·L^-1 and 138.07 ng·L^-1. On the whole, roxithromycin and sulfamethoxazole in all regions of the Poyang Lake Basin are at high levels, which should be paid full attention.

(4) The risk quotient method was used to evaluate the ecological risk of single antibiotics at each sampling point. The results showed that the antibiotics with medium risk to aquatic organisms in surface water of Poyang Lake Basin were SMX, and the low risk were DOC, CTC, RTM, SMZ and DMZ. Ecological risk: Poyang Lake surface water > Jinjiang > Poyang Lake groundwater > Yuan River.