Distribution patterns of antibiotic residues in an urban river catchment

The residual patterns of 23 target antibiotics in five classes of compound in catchment sediments of a rapidly urbanizing city in east China were studied. A total of 14 antibiotics were detected in the catchment. The dominant classes were tetracyclines and fluoroquinolones and these occurred at substantial concentrations. High environmental risk at the sites sampled may be associated with antibiotics detected at high concentrations. For example, at one site chlortetracycline was found to occur at concentrations ≤ 4496 ng/g. Source traceability indicates that high intensity of urbanization (e.g. hospitals and livestock farms) had a high spatial relationship with sites of high antibiotic contaminations. Urban and suburban areas had some impacts on antibiotic residues in the catchment, especially on veterinary antibiotics such as chlortetracycline in suburban areas. Moreover, antibiotics detected at high concentrations in urban areas included fluoroquinolones associated with human medicine.