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Antibiotics have become a global public concern due to the widespread presence of antibiotic-resistant bacteria and genes. This study investigated the spatial and seasonal variation of conventional water quality parameters and 10 selected antibiotics in rivers inflowing into Taihu Lake. The results showed that total nitrogen, as a pollution driver factor, varied with the seasons, and higher concentrations of pollutants were generally found in the dry season compared with the wet season. For antibiotics, seven of them were detected in surface waters (n = 66) with detection frequencies (DFs) of 1.52–100% and eight antibiotics with DFs of 2.56–100% in sediments (n = 39). Sulfamethoxazole (SMZ, median: 1.47 ng/L), trimethoprim (TMP, median: 0.35 ng/L), and roxithromycin (ROX, median: 0.47 ng/L) with 100% DFs followed by erythromycin (ERY, median: 0.56 ng/L) with a DF of 90.91% accounted for a median percentage of 44.54%, 9.08%, 20.42%, and 13.16% of the ΣABs concentrations in surface waters. In contrast, enrofloxacin (ENR, median: 0.54 ng/g) and ROX (median: 0.29 ng/g) with 100% DFs accounted for a median percentage of 58.21% and 31.71% of the ΣABs concentrations in sediments. Antibiotics in surface waters were mainly related to T, DO, TN and NH 3 –N, but were mainly related to T, pH and TN for antibiotics in sediments. Furthermore, most of the detected antibiotics showed higher concentrations and more species of antibiotics in winter than in summer or autumn. Similarly, the ecological risk values of antibiotics showed higher in winter than in the other two seasons, whereas the overall risk levels were considered acceptable. [Display omitted] • High concentrations and ecological risk in the dry season than the wet season. • Total nitrogen was a pollution driver factor for conventional water quality parameters. • Strongly significant correlations were found among conventional water quality parameters and antibiotics. • The dominant antibiotic was SMX in surface water, ENR in sediments, whereas ROX for ecological risk. [ABSTRACT FROM AUTHOR]

With rapid improvements in industrialization and urbanization, antibiotics are now extensively used to prevent and treat human and animal diseases and husbandry and aquaculture. Some research has been conducted to assess the environmental distribution and risk level of antibiotics, but their distribution remains largely uncharacterized. Thus, this study investigated the distribution and abundance of 39 antibiotics belonging to five groups, and their associated risks in surface water around Luoma Lake in the north of Jiangsu province, China. Nineteen antibiotics were detected, at a detection frequency (DF) ranging from 2.27% to 100%. The total antibiotics (ΣABs) concentrations ranged from 34.91 to 825.93 ng/L, with a median concentration of 195.45 ng/L. Among these antibiotics, chlortetracycline (DF: 100%; median: 172.02 ng/L) was the dominant antibiotic, accounting for a median percentage of 91.0% of ΣABs concentrations. Spearman rank correlation method found a significant correlation between clindamycin (DF: 72.7%; median: 2.01 ng/L) and lincomycin (DF: 79.5%; median: 4.58 ng/L). The ecological risk quotient (RQ) values for two out of 44 sampling sites were higher than 1, indicating a high risk; 11.4% of the RQ values fell between 0.1 and 1, indicating a medium risk. Moreover, roxithromycin was found to be the dominant contributor to the ecological risk, accounting for a median of 79.7% of ΣABs. However, the total non-carcinogenic (<6.54 × 10−4) and carcinogenic risks (<1.64 × 10−7) of ΣABs were negligible at the detected concentrations. Image 1 • Concentrations and distributions of 39 antibiotics around Luoma Lake were revealed. • Chlortetracyclin was found to be the dominant antibiotic, with a median of 172.02 ng/L. • Ecological risks of antibiotics were at medium level (11.4%) or slightly high level (4.6%). • Non-carcinogenic and carcinogenic risks of antibiotics were low at the detected concentrations. [ABSTRACT FROM AUTHOR]