Characteristics of pharmaceutically active compounds in surface water in Beijing, China: Occurrence, spatial distribution and biennial variation from 2013 to 2017.

Pharmaceutically active compounds (PhACs) are widely found in the environment due to vast human consumption. Lots of work has been devoted to investigating the occurrence and seasonal variations globally. To fully understand characteristics and cross-year variation of PhACs in Beijing, 35 PhACs were analyzed in 46 sites across Beijing from both urban and suburban areas. Concentrations of target PhACs were ranged from levels of ng L to μg L. Metoprolol (524 ng L), caffeine (390 ng L) and acetaminophen (156 ng L) were the three most abundant non-antibiotics with the highest median concentration, and nalidixic acid (135 ng L), erythromycin (64 ng L) and sulfamethoxazole (77 ng L) were the most abundant antibiotics. Urban and suburban areas are distinguished by PhAC composition in cluster analysis due to different wastewater collection rate. The ratio of easily removable compound group and hardly removable group was then proposed to reflect the wastewater collection rate. The compositional comparison of PhACs in WWTPs' effluents and their receiving rivers further illustrates the impact of WWTPs in urban area. Higher proportion of antibiotics (>30%) in suburban area reflected the impact of presence of livestock farms, which should be concerned. Further statistical analyses show an improving trend of wastewater collection rate, and excluding metoprolol, an anti-hypertension medicine, the total concentration of 13 target PhACs was reduced by 72% during 2013-2017.