Distribution and potential risks of antibiotics in inland lakes in China

Antibiotics have been used extensively as important antimicrobials and growth promoters for decades. Owing to their incomplete absorption and metabolism by organisms, residual antibiotics are released into lakes and occur pseudopersistently in the environment. Systemically analyzing the environmental behavior of antibiotics in lakes at the national scale is crucial for regulating their production and consumption and governing them at the national level. In this study, antibiotic occurrence in the main inland lakes of China was investigated based on public data from in situ surveys in the last 14 years. Eighteen antibiotics in the categories of sulfonamides (SAs), fluoroquinolones (FQNs), tetracyclines (TCs), macrolides (MLs) and others (OTHs) were widely detected in lakes across the country. The total antibiotic concentrations in the water and sediments ranged from 1.3 ng/L to 625.31 ng/L and 2.08-214.85 ng/g dw, respectively. The Tibet-Qinghai region had the lowest residues, whereas the Yungui and Mengxin regions experienced more severe pollution. High anthropogenic activities promoted antibiotic concentrations in water but affected sediments less. Possible similarity in drug types and variation in dosage preferences were speculated between areas with different intensity anthropogenic activities. Antibiotic partitioning behaviors in lakes were investigated and the effects of factors shaping their spatial heterogeneity were analyzed. The potential ecological and human health risks of antibiotics were assessed and mapped based on their environmental exposure uncertainty. Approximately half of the lakes faced medium-to-high ecological risks; the predominant drivers were CTC and CIP for algae and CTC for fish. Antibiotics in 29.8 % of the lakes presented possible cumulative health risks to children and 23.4 % to adults under the high exposure scenario; FF presented a greater health risk to children than did other antibiotics. These results help elucidate the overall pollution situation and environmental behavior of antibiotics in lakes in China.