Distribution Characteristics and Ecological Risk Assessment of Tetracyclines Pollution in the Weihe River, China

To examine the residual and distributions of tetracycline antibiotics in the Weihe River, SPE-UPLC (solid phase extraction-ultra performance liquid chromatography with UV-Vis detection) was employed to analyze the oxytetracycline (OTC), chlortetracycline (CTC), and minocycline (MC) of 41 surface water and 35 sediment samples collected from main streams, tributaries, and main sewage outlets. The results showed that: (1) The order of residual levels of tetracycline antibiotics in water and sediment from high to low was the following: OTC > CTC > MC., considering the water solubilities are 313 mg/L, 630 mg/L, and 50200mg/L and octanol water partition coefficients (K_ow) are 7.94, 4.16, and 1.12 for OTC, CTC, and MC, respectively. Thus, the distribution of antibiotics was not only related to the basic properties of antibiotics, but also some environmental factors. The concentrations of OTC in water and sediment were in the range of 1.56⁻87.89 ng/L and 6.13⁻45.38 ng/g (mean value of 16.13 ng/L and 20.60 ng/g), respectively; while CTC was 1.07⁻26.78 ng/L and 6.17⁻32.29 ng/g (mean value of 4.96 ng/L and 14.48 ng/g), respectively; and MC was 0.28⁻12.35 ng/L and 4.80⁻29.74 ng/g (mean value of 1.70 ng/L and 12.96 ng/g), respectively. There were maximum concentrations in all sewage outlets. Compared with other areas in China, tetracyclines residual in the Weihe river were at a medium level; (2) in spatial distribution, the levels of tetracyclines in water and sediment from the middle and upper reaches were higher than the lower reaches. Meanwhile, the sewage outfalls and livestock farm waste water discharge appeared to be the main sources of tetracycline antibiotics in the Weihe River; (3) ecological risk assessment revealed that in main streams and tributaries, OTC and CTC may be at a low ecological risk level; while in sewage outfalls, they may represent a medium ecological risk level.