Occurrence, distribution, and risk assessment of quinolone antibiotics in municipal sewage sludges throughout China

A nationwide study of the occurrence, distribution, potential drivers, and ecological risks of 24 quinolone an-tibiotics (QNs) in 74 Chinese sludge samples from 48 wastewater treatment plants (WWTPs) was conducted. In domestic sludge, the n-ary sumation QNs concentrations were 21,925.10 ug/kg (mean: 4808.67 ug/kg), and ofloxacin had the highest concentration (11,138.52 ug/kg), and detection frequency (98.48%). Of four generations QNs, the levels showed the following order: 2nd-generation QNs > 3rd-generation QNs > 4th-generation QNs > 1st-generation QNs. Meanwhile, abundant veterinary and human/veterinary quinolones (2606.96 and 12,643.47 ug/kg, respectively) were detected in municipal sludge. Interestingly, the relatively low levels of veterinary quinolones (299.21 ug/kg) were also found in industrial sludge (the relevant WWTPs receiving <= 10% domestic wastewater, without other direct entry of antibiotics). The corre-lation analysis demonstrated QNs contamination was negatively influenced by the air temperature of sampling days. The positive correlation between moxifloxacin contents and regional economy possibly suggested local regions with relatively high economic levels face a more difficult situation of QNs antibacterial activity. Envi-ronmental risk assessment indicated ofloxacin, ciprofloxacin, and moxifloxacin posed high ecological risks to the domestic sludge. This work delineates a valuable nationwide QNs contamination profile to support their safe use and control in China.