Occurrence of Antibiotics at a Typical Livestock Farm in Northwest China: Emergence Characteristics and Ecological Risk Assessment.

This study analyzed veterinary antibiotics (VAs) and resistance genes (ARGs) in manure and soil at a typcial livestock farm in Northwest China using LC-MS and metagenomics. Sulfonamides (SAs) were highest in chicken manure, while quinolones (QNs) dominated cattle manure and adjacent soil (172.784 ng g−1 total QNs). Transfer rates of QNs and tetracyclines from manure to soil exceeded 100%, indicating significant ecological risk via the food chain. Metagenomics revealed the tetracycline resistance gene tetA (58) dominated the soil ARG pool. Significant positive correlations (p < 0.05) existed between QN concentrations (including ciprofloxacin, lomefloxacin) and quinolone resistance genes (flu), and between soil tetracyclines and multidrug resistance genes (mul). Ecological risk modeling confirmed a high mixed contamination risk for QNs (RQ = 2.36 > 1).