Composted livestock manures, in both solid and liquid form, are used as fertilizers in cropland. However, excess solid and liquid manures in agricultural watersheds are considered as nonpoint pollution sources because of their high nutrient and heavy metal contents of, as well as their antibiotic contents, especially veterinary antibiotics (VAs). In this study, 21 VAs under nine classes (i.e., cephems, ionophores, lincosamides, penicillins, pleuromutilins, quinolones, streptogramins, sulfonamides, and tetracyclines) found in agricultural watersheds were simultaneously analyzed via UHPLC-q-orbitrap high-resolution mass spectrometry using an on-line solid-phase extraction system. The residues of VAs in the surface water of two intensive livestock rearing watersheds (Cheongmi and Gwangcheon streams) in Korea were successfully quantified, and the values were found to range from 1.84 ± 0.42 ng L^-1 to 835.6 ± 31.9 ng L^-1. Time lags of 2–3 months were observed between the periods of liquid manure application and the periods with the maximum concentrations of VAs. In both watersheds, samples from points close to areas with extensive application of liquid manure exhibited high concentrations of most of the 21 VAs. Between the watersheds, the one with heavier application of liquid manure showed higher concentrations of the target VAs. To the best of our knowledge, this study represents the first attempt at evaluating the correlation between liquid manure application and environmental occurrence of VAs in surface water. The findings reveal that liquid manure application plays an important role in introducing VAs into aquatic environments.

固体和液体形式的堆肥牲畜粪肥都被用作农田的肥料。但是，农业流域中过多的固体和液体粪肥被认为是非点源​​污染源，因为它们的高养分和重金属含量，以及它们的抗生素含量，尤其是兽用抗生素（VAs）。在这项研究中，通过UHPLC-q-orbitrap高分辨率质谱法同时分析了农业流域中发现的21种VA，共分9类（即头孢，离子载体，林可酰胺，青霉素，截短侧耳素，喹诺酮，链霉菌素，磺酰胺和四环素）。在线固相萃取系统。在韩国两个集约化畜牧集水区（清米溪和光川溪）的地表水中，VA的残留量得到了成功的定量，^-1至835.6±31.9 ng L ^-1。在施用液体肥料的时间与最大VA浓度的时间之间存在2-3个月的时间间隔。在这两个流域中，大量使用液态肥料的地区附近的点的样品在21种VA中大部分都表现出较高的浓度。在分水岭之间，施肥量较大的流域显示出较高的目标VA浓度。据我们所知，本研究代表了首次尝试评估液体肥料施用与地表水中VA的环境发生之间的相关性。研究结果表明，液体肥料的应用在将VA引入水生环境中起着重要作用。