Contamination, distribution, and risk assessment of antibiotics in the urban surface water of the Pearl River in Guangzhou, South China

To assess the impact of antibiotic pollution to the ecosystem in urban water, the occurrence, seasonal, and spatial distributions, potential sources, and ecological risks of 18 targeted antibiotics in urban river, Pearl River located in Guangzhou city, were investigated. Surface water samples were sampled from 24 sites in Guangzhou center of Pearl River during dry and wet seasons. The results indicated that the concentrations of antibiotic residues were at the nanogram per liter level, except sulfamethazine (SMD) (μg/L). Sulfonamides (SAs) were the dominant antibiotics, contributing 60.4-65.0% to the total antibiotics. The concentrations of SAs, fluoroquinolones (QUs), macrolides (MLs), tetracyclines (TCs), and lincosamides (LCs) were higher in dry season than those in wet season at most sampling sites, which possibly resulted from the dilution effect of heavy rainfall. The concentrations of the antibiotic residues in Guangzhou were comparable or higher than other urban rivers. The calculation on risk quotients indicated that erythromycin-H₂O (ETM-H₂O) and tetracycline (TC) were of high risks. The source identification by the Pearson correlation analysis and principal component analysis-multiple linear regression (PCA-MLR) method suggested that municipal wastewater treatment plants were primary sources of antibiotics. These results would provide important information for the environmental protect.