This study focused on the occurrence and spatial distribution of 13 common antibiotics in agricultural soils of the Yangtze River Delta (YRD), China. Antibiotics were detected in all the 241 soil samples (i.e., 100% detection rate) with the total concentrations ranging from 4.55 to 2010 ng/g dry weight. The concentrations of three antibiotic classes decreased in the order: quinolones (mean 48.8 ng/g) > tetracyclines (mean 34.9 ng/g) > sulfonamides (mean 2.35 ng/g). Ciprofloxacin was the prevalent compound with a mean concentration of 27.7 ng/g, followed by oxytetracycline (mean of 18.9 ng/g). A distinct spatial distribution was observed, where high concentrations of antibiotics were detected in the sites adjacent to the livestock and poultry farms. The potential sources of antibiotics in agricultural soils were the application of manure and wastewater irrigation in this region. Risk assessment for single antibiotic compound indicated that tetracyclines and quinolones could pose a potential risk, in which doxycycline and ciprofloxacin had the most severe ecological effect in agricultural soils. Antibiotic resistance genes (ARGs), such as tetA, sulI, and qnrS, were detected in 15 analyzed soil samples, and sulI showed significant correlations with quinolones, tetracyclines, copper, and zinc. Further studies on the distribution of other ARGs in agricultural soil at region-scale are needed for the risk management of extensively used antibiotics and major ARGs.

中文翻译：

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长江三角洲农业土壤中的抗生素

这项研究的重点是长江三角洲（YRD）的农业土壤中13种常见抗生素的发生和空间分布。在所有241个土壤样品中都检测到了抗生素（即，总检出率为100％），总浓度范围为4.55至2010 ng / g干重。三种抗生素的浓度依次降低：喹诺酮类（平均48.8 ng / g）>四环素类（平均34.9 ng / g）>磺酰胺类（平均2.35 ng / g）。环丙沙星是最常见的化合物，平均浓度为27.7 ng / g，其次是土霉素（平均18.9 ng / g）。观察到了明显的空间分布，在与牲畜和家禽养殖场相邻的地点发现了高浓度的抗生素。农业土壤中抗生素的潜在来源是该地区粪便和废水灌溉的应用。对单一抗生素化合物的风险评估表明，四环素和喹诺酮类药物可能构成潜在风险，其中强力霉素和环丙沙星在农业土壤中具有最严重的生态影响。抗生素抗性基因（ARG），例如在15个分析过的土壤样品中检测到了tet A，sul I和qnr S，并且sul I与喹诺酮，四环素，铜和锌具有显着相关性。对于广泛使用的抗生素和主要ARG的风险管理，需要进一步研究其他ARG在区域农业土壤中的分布。