二十世纪，抗生素一经提出便迅速在世界范围内广泛应用，不仅能用于预防或治疗人类的细菌性疾病，还能在养殖业中用来促进动物的生长。但抗生素的大量使用也给生态安全和人类健康带来很大的威胁。作为抗生素最终归宿的流域环境，包含多种不同介质，在抗生素的迁移归趋中起到了重要作用。本研究以汾河流域中26种抗生素为研究对象，按照抗生素在多介质中“分布-来源-归趋-风险”的思路，通过实地调研、采样实验、模型模拟和风险评价等手段开展了以下研究：（1）分析了汾河流域水体、沉积物、悬浮物中抗生素的含量特征；（2）揭示了不同介质中抗生素污染的主要来源及其时空分布规律，提出了源分配比的概念，分析了不同来源抗生素在多介质中的分配；（3）构建了不同来源抗生素的流域环境多介质逸度模型，模拟了不同污染来源下抗生素在流域不同介质中的环境行为，定量描述了抗生素在不同介质中的分布、迁移转化及归趋；（4）评价了抗生素在不同环境介质中的生态风险和耐药性风险，识别出了汾河流域抗生素的关键风险源，在此基础上相应的提出了一些防控建议。结果见下：

（1）汾河流域水体、沉积物、悬浮物三个介质中共检出抗生素26种，枯水期检出25种，高于丰水期的21种。在三个介质中，水体中检出的抗生素种类最多，枯水期检出的抗生素种类高于丰水期，且抗生素浓度也是丰水期的1.32倍。其次是悬浮物中，丰水期检出抗生素种类低于枯水期，但其浓度为枯水期的2.62倍。而沉积物中，丰水期检出的抗生素种类只比枯水期少2种，但其浓度仅是枯水期的1/6。在空间上，汾河流域上游水体中抗生素含量低，中下游含量高，约为上游平均浓度的1.62-2.15倍。沉积物中抗生素的空间差异性较小，个别点位浓度较高。而悬浮物抗生素在丰水期空间差异小，枯水期上游浓度较高。

（2）抗生素源解析结果表明，汾河流域抗生素的主要来源有畜禽养殖源、水产养殖源、污水处理厂废水源、生活污水源和农田排水源。在水体中，丰水期的最主要来源是医药废水源，占比为40%，枯水期最主要来源为水产养殖源，占比为33%；农田排水对丰水期沉积物中抗生素贡献是最大的，占比为31%，而枯水期沉积物中抗生素的最主要来源是水产养殖源，占比为38%；污水处理厂废水源对丰水期悬浮物中抗生素贡献最大，占比达到37%，而在枯水期悬浮物最主要的来源是医药废水源，占比为36%。

（3）源分配比分析表明，水-沉积物体系中抗生素源分配比在枯水期普遍高于丰水期，是丰水期平均值的18倍。丰水期的源分配比高值主要集中在磺胺类、四环素类和氯霉素类抗生素，主要集中污染源为畜禽养殖、水产养殖、农田排水源。枯水期畜禽养殖和水产养殖源中的抗生素源分配比在也达到了较高的水平。水-悬浮物体系中源分配比高值主要集中在磺胺类抗生素，畜禽养殖源、农田排水源和污水处理厂废水源的源分配比高于其他来源。悬浮物-沉积物体系中源分配比高值主要集中于大环内酯类抗生素和污水处理厂废水源。

（4）基于来源解析的抗生素多介质模拟结果揭示了，由于受到赋存形态、排放量和逸度容量的影响，不同来源的抗生素在流域多介质中的浓度分配、迁移通量和动态归趋均有较大的差异。不同来源抗生素多介质预测浓度结果表明，在水相中的9种抗生素的预测浓度范围在23.08-724.80 ng/L，在沉积物相中9种抗生素的浓度范围为0-0.16ng/g。此外，水产养殖来源的ENO、CHL进入土壤和沉积物的浓度比例分别是其它来源的3倍和6-31倍，而畜禽养殖来源的NOR、ENRO、CTC和RTM进入土壤和沉积物的浓度比例仅是其他来源的1%。不同来源抗生素多介质迁移通量结果表明，大环内酯类抗生素的迁移通量受来源影响最大，生活污水来源的ETM从沉积物向水中再悬浮通量最高达到其他来源的11倍。不同来源的抗生素动态归趋模拟结果表明，喹诺酮类抗生素NOR的动态迁移受到不同来源影响最大，其达到相对稳定浓度的反应时间范围在4-40周，抗生素RTM在环境中稳定所需要的时间是最长，在50-90周左右，而ENRO、CTC、CHL和ETM在不同来源中的反应时间均在1周之内。

Over the past few decades, antibiotics have been widely used worldwide as an antibacterial drug to prevent or treat bacterial diseases, and as feed additives to promote animal growth in aquaculture. Although antibiotics play an important role in treating diseases and promoting livestock production, they also bring a series of potential environmental health and ecological security risks, which have become a major challenge faced by mankind in the 21st century. As the main destination of antibiotics after discharge, watersheds contain a variety of media and play an important role in the migration and fate of antibiotics. In this study, 26 antibiotics were studied in the Fen River basin, and based on the "source-migration-fate-risk" approach, the following studies were conducted through field research, sampling experiments, model simulations and risk assessment, including: (1) Analyzing the content characteristics of antibiotics in water, sediment and suspended matter in the Fenhe River Basin; (2) Revealing main sources of antibiotic pollution in different media and their spatial and temporal distribution patterns, proposing the concept of source distribution coefficient, and analyzing the distribution of antibiotics from different sources in multi-media; (3) Based on source analysis, constructing a multi-media fugacity model of antibiotic environment to simulate the behavior of antibiotics in the main environmental phases such as atmosphere, water, soil and sediment under different pollution sources.The quantitative characterization of their distribution, migration transformation and fate behaviour in the multi-media environment was achieved; (4) Evaluating its ecological risk and drug resistance risk in different environmental media, identifying the key risk sources of antibiotics in the Fen River Basin and putting forward recommendations  of prevention and control measures. The main conclusions are as follows:

(1) A total of 26 antibiotics were detected in the three media of the Fenhe River Basin: water, sediment and suspended matter, and 25 were detected in the dry season, which was higher than the 21 in the wet season. Among the three media, the most types of antibiotics were detected in the water body, the types of antibiotics detected in the dry period were higher than those in the wet period, and the antibiotic concentration was also 1.32 times that in the wet period. Followed by the suspended matter, the types of antibiotics detected in the wet period were lower than those in the dry period, but the concentration was 2.62 times that of the dry period. In the sediments, the types of antibiotics detected in the wet season were only 2 less than those in the dry season, but their concentration was only 1/6 of that in the dry season. Spatially, the content of antibiotics in the upper reaches of the Fenhe River Basin was low, and the content in the middle and lower reaches was high, which was about 1.62-2.15 times the average concentration in the upstream. The spatial differences of antibiotics in sediments were small, and the concentrations of individual sites were higher. However, the spatial difference of antibiotics in suspended solids was small in the wet season, and the upstream concentration was higher in the dry season.

 (2) The results of antibiotic source analysis showed that there were six main sources of antibiotics in the Fenhe River Basin: livestock and poultry breeding sources, aquaculture sources, wastewater treatment plant wastewater sources, domestic sewage sources and farmland drainage sources. In the water, the most important source in the wet season is the medical wastewater source, accounting for 40%, and the main source in the dry season is the aquaculture source, accounting for 33%. The farmland drainage contributes the most to the antibiotics in the sediment in the wet season, while the most important source of antibiotics in the sediments in the dry season is aquaculture, accounting for 38%. The wastewater source of the sewage treatment plant contributes the most to the antibiotics in the suspended matter in the wet season, accounting for 37%. In the dry season, the most important source of suspended matter is the medical wastewater source, accounting for 36%.

(3) The analysis of the source distribution coefficient showed that the antibiotic source distribution coefficient was 18 times that of the average in the wet period. The high value of the source distribution coefficient in the wet season is mainly concentrated in sulfonamides, tetracyclines and chloramphenicol antibiotics, and the main pollution sources are livestock and poultry breeding, aquaculture, and farmland drainage sources. The distribution coefficient of antibiotic sources in livestock and poultry breeding and aquaculture sources also reached a high level in dry season.

(4) The multi-media fate of antibiotics showed that in the aqueous phase, the predicted concentrations of 9 antibiotics were in the range of 23.08-724.80 ng/L, and the concentrations of the 9 antibiotics in the sediment phase ranged from 0 to 0.16 ng/g. There are also certain differences in the migration and transformation of antibiotics from different sources in the watershed. The aquaculture source has a great impact on the distribution and migration of the medium after the discharge of antibiotics ENO and CHL. The concentration ratio of ENO and CHL entering the soil and sediment from this source is 3 times and 6-31 times that of other sources, respectively. Livestock and poultry breeding sources have a great influence on the concentration ratio distribution of antibiotics NOR, ENRO, CTC and RTM. The concentration ratio of antibiotics entering soil and sediment from this source is only 1% of other sources. The distribution of medium concentration has a great influence. The simulation results of the multi-media migration of antibiotics from different sources show that the runoff from the water phase to the soil phase is the highest in the watershed. The multi-media dynamic fate simulation results of antibiotics from different sources show that the time required for macrolide antibiotic RTM to reach a stable concentration in the environment is the longest, and it takes about 50-90 weeks of reaction and migration; the response times of ENRO, CTC, CHL and ETM in different sources were all within 1 week, indicating that these four antibiotics could reach relatively stable concentration levels within one week after discharge.