Antibiotics in the coastal water of the South Yellow Sea in China: Occurrence, distribution and ecological risks

•Twenty-five antibiotics in the coastal water of Yancheng were measured.•Antibiotics were widely present with the highest level up to 1349.2 ng/L.•DOC, salinity and distance were important in the fate and residues of antibiotics.•The attenuation of antibiotics was faster in this region than in Bohai Sea.•Individual antibiotic could pose low risk, while the mixture might pose high risk.

The occurrence and distribution of 25 antibiotics from 5 categories in Yancheng coastal area of the South Yellow Sea were investigated using solid-phase extraction coupled with high-performance liquid chromatography tandem mass spectrometry. Results showed that these antibiotics were widely present in this region with the total concentration up to 1349.2 ng/L. Fluoroquinolones and sulfonamides were the most abundant categories contributing 46.5%, and 21.4% to the total antibiotics burden. Trimethoprim was the antibiotic detected in all the samples. The detection rates of erythromycin-H2O, sulfamethoxazole and florfenicol were 70.0%, 56.7% and 53.4%, respectively. The distribution of antibiotics demonstrated a seaward decreasing trend with the attenuation rate ranging from 0.07 to 0.19 km− 1 in this region. Log total antibiotic concentrations was significantly correlated with DOC (dissolved organic carbon) contents, salinity and distance from the coast (p < 0.05), which indicated the vital effect of these factors on the transport and fate of antibiotics. Risk assessment revealed that individual antibiotic could mainly pose a low to medium ecological risk, while the risk of antibiotic mixture on aquatic organisms needed further investigation.

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