Contrastive cognition into the occurrence, source identification and risk assessment of antibiotics in various drinking water sources.

Antibiotics are prevalent in aquatic ecosystems, particularly in critical drinking water sources, posing serious threats to human health and ecosystems. Focusing on rivers, lakes, reservoirs and groundwaters in Anhui Province (China), this study systematically investigated the occurrence, influencing factors and source apportionment of antibiotics and assessed their ecological and health risks. The results indicated that the total antibiotic concentrations ranged from 0.04 to 215.13 ng/L, and lincosamides and sulfonamides were the primary antibiotic groups, with concentrations of nd-167.00 ng/L and nd-47.38 ng/L, respectively. Specifically, lincomycin (nd-159.38 ng/L) and clindamycin (nd-100.45 ng/L) were the concentration of the two highest antibiotics, while sulfamethoxazole had the highest detection frequency (86.16 %). The total concentration of antibiotics in rivers was significantly higher than in lakes, reservoirs, and groundwaters, and the structural composition of antibiotics in groundwaters differed distinctly from that in other water sources. Nitrogen levels showed significant spatial correlation with antibiotic distribution, and anthropogenic activities may exacerbate antibiotic contamination. The study identified farmland drainage and aquaculture as the main sources of antibiotics in rivers and reservoirs, respectively, while livestock was the main source in lakes and groundwaters. The maximum ecological and human health risk quotient (8.83 and 0.32) of rivers was higher than that of other water sources. Antibiotics posing ecological risks included sulfamethoxazole, lincomycin, clindamycin, and clarithromycin, while tylosin and lincomycin exhibited potential threats to human health. Although the risks posed by individual antibiotics and their combined effects were within acceptable limits, the long-term exposure to low-dose antibiotics in drinking-water sources warrants close attention and further investigation.