全世界生产的抗生素总量中约50%用于畜禽养殖场。未完全代谢的兽用抗生素以母体化合物或者代谢产物的形态排出动物体外并残留于养殖场粪污中。其中的抗生素随着畜禽粪便、尿液及污水土地利用等农业活动进入土壤和水体，并对生态系统产生影响。然而，有关规模化养殖场残留抗生素的环境行为和生态风险的研究较少，为此，有必要开展以下的研究：（1）不同类型畜禽排放的抗生素种类和总量；（2）兽药抗生素在水体中的残留浓度，分布规律及对土壤微生物生态的影响；（3）厌氧消化处理能否有效地去除粪污中残留的抗生素，降低其生态环境风险。 因此，本论文围绕着我国典型的兽用抗生素类别，首先分析了主要畜禽类型的56个规模化养殖场粪污中抗生素的残留特征，并初步估算了这些畜禽的抗生素排放量；在此基础上，以典型养殖地区为重点，系统研究了养殖区域地表水-沉积物中兽药抗生素的污染程度和空间分布规律，水体中粪大肠杆菌（E. coli）的耐药性特征与机理；通过室内微宇实验探究了典型兽药抗生素对农业土壤中共存雌激素降解的影响，土壤微生物群落对两类共存污染物的响应关系；最后，通过实际养猪场粪污厌氧消化系统中抗生素的残留浓度分析和室内厌氧消化模拟实验，研究了猪粪污厌氧消化反应过程中不同类别抗生素的降解与分配规律，以及厌氧消化产物的土地利用风险。取得了以下的主要结论：（1）56个养殖场的粪便，尿液和污水中均广泛检出多种兽药抗生素，最高检出浓度分别为32.22 mg/kg，71.70 μg/L和3345.00 μg/L。养殖排污中抗生素的残留种类和浓度与畜禽类型有关，四环素、土霉素、金霉素、磺胺嘧啶和磺胺间甲氧嘧啶在猪粪中平均残留浓度最高，而诺氟沙星和恩诺沙星分别在鸡粪和牛粪中平均残留浓度最高。抗生素的残留浓度与养殖数量没有明显的相关性。估算显示，我国主要畜禽15种典型兽药抗生素年排放总量约2561吨，猪，鸡和牛3种畜禽对抗生素排放总量的贡献率分别为76%，17%和7%。（2）典型养殖区域兽药抗生素使用和残留导致了区域地表水严重的抗生素和耐药性粪大肠杆菌污染。地表水和沉积物中抗生素的最高浓度分别为450.00 ng/L和237.00 ng/g，并分别以磺胺类和四环素类为主。从空间分布来看，河流中、下游及交汇点相对于上游有污染累积的过程。水体中88%的粪大肠杆菌（E. coli）对所测试的8种抗生素药物共显示出48种耐药模式。但是，耐某种药物的粪大肠杆菌数量比例与水体中相应药物的浓度之间并没有明显的相关性，表明暴露于水体抗生素并不是这些粪大肠杆菌产生耐药性的主导机制。（3）雌酮和17β-雌二醇在土壤中会被快速生物降解，浓度为10 mg/kg 和 100 mg/kg的共存磺胺甲恶唑不会对这两种雌激素的微生物降解产生明显的影响。然而，磺胺甲噁唑的共存会抵消两种雌激素对土壤脱氢酶的刺激作用，与空白相比明显抑制了土壤脱氢酶活性（p<0.05）。PCR-DGGE结果表明，单独雌激素刺激了某些细菌种类的生长，而共存磺胺甲恶唑抑制了雌激素的这种刺激效应，并且，雌激素和磺胺甲恶唑共存诱导了可能耐磺胺甲恶唑细菌的出现。（4）实际养猪场粪污处理系统和室内模拟实验均表明，厌氧消化能在一定程度上去除粪污中抗生素，去除效果受药物类别与初始浓度影响，喹诺酮类去除率最高（>90%），四环素类次之（41%-93%），磺胺二甲基嘧啶（大约40%）最低。由于四环素类化合物在粪污固体上强烈地吸附而累积在消化后沼渣中，导致较高的土地利用风险。添加3种药物明显抑制了厌氧微生物产甲烷的能力，50 mg/L浓度下的抑制程度远大于5 mg/L浓度的抑制程度，但高浓度的抗生素处理随着培养时间的延长反而促进了甲烷的产生，其中的机理还有待进一步研究。

Almost half of the antibiotics produced per year are used in animal production in the world. As they are poorly adsorbed by the animals, the majority of veterinary antibiotics (VAs) will be excreted as parent compounds or metabolized products through feces and/or urine, which may result in the huge amounts of VAs concentrated in animal wastes. Land application of animal manure as organic fertilizer is a common practice. Concentrated animal feeding operations (CAFOs) have been recognized as one of the major sources of antibiotics in the environment. However, few works concerning environmental behaviors and risks of VAs from CAFOs had been carried out. Hence, it is necessary to well understand (1) how many types and quantities of VAs are excreted in different types of animal wastes; (2) what do they behave in the environment and how do they influence soil ecosystem; (3) is the current anaerobic digestion system effective in reducing the VAs residues in animal wastes? Therefore, this study focused on the typical veterinary antibiotics (VAs), analyzed the concentrations of 15 VAs in fresh feces, urine and farm wastewater of the primary animal types including pig, dairy and chicken, and preliminarily estimated their excretion amounts of 15 VAs. Furthermore, the study investigated the antibiotics and antibiotic resistant E. coli pollution in a typical animal feeding region in Beijing, China and estimated the effect of antibiotics on degradation of coexistent estrogens in agriculture soil as well as the response of soil microbial community to these contaminants. Finally, it explored the potential of anaerobic digestion system in reducing and control of antibiotic pollution in animal farms through on-farm survey and laboratory simulation experiment. The primary results are as follows:(1) All of the 15 VAs were widely detected in the investigated fecal, urine and wastewater samples with the highest concentration of 32.22 mg/kg, 71.70 μg/L and 3345.00 μg/L, respectively. The residual VAs concentrations varied with animail types. The averaged concentrations of the three TCs, SDZ and SSH in pig feces were obviously higher than that in chicken and dairy feces. The averaged concentration of NFC was the highest in chicken feces. The averaged concentration of EFC was the highest in dairy feces. No obvious correlation was observed between the number of VAs detected or the total concentrations of 15 VAs and the animal number. According to the preliminary evaluation, approximately 2561 tons of 15 VAs will be excreted by pig, dairy and chicken per year. The contribution rate of pig, chicken and dairy was 76%, 17% and 7%, respectively.(2) VAs utilization had resulted in serious VAs and antibiotic resistant E. coli pollution in the rivers of a typical animal feeding region. The antibiotics were detected at maximum concentration of 450.00 ng/L in water and of 237.00 ng/g in sediment. SAs were the dominant antibiotics in water, and TCs were the dominant antibiotics in sediment. The mid- and downstream showed increasing VAs contamination relative to the upstream. Approximately 88% of the E. coli isolates in the rivers presented a total of 48 resistance patterns to the eight tested drugs. No obvious correlation was found between the rates of resistant E. coli isolates and the concentrations of according drugs, indicating that exposure to antibiotic probably was not the most primary mechnism for the resistance of E. coli in these rivers.(3) Due to biodegradation, 1 mg/kg estrone and 1 mg/kg 17β-estradiol in the soil can eliminate 70% and 90%, respectively, after incubation for 6 hours. The coexistence of 10 mg/kg or 100 mg/kg sulfamethoxazole（SMX）did not affect the biodegradation of the two estrogens. However, the coexistence of 10 mg/kg or 100 mg/kg SMX offset the stimulation of the two estrogens on soil DHA and obviously inhibited soil DHA in comparison with the control (p<0.05). PCR-DGGE analysis revealed that single estrogens spiking stimulated bacteria growth, while coexistence of SMX inhibited this stimulation. Meanwhile, some new bacteria which might be resistant to SMX appeared in the estrogens and SMX co-spiked soils.(4) Both on-farm investigation and laboratory simulation revealed that anaerobic treating is an effective way to elimilate VAs contamination in fecal wastewater to some extent. The efficiency was affected by VAs types in the order of FQs (>90%) > TCs (41%-93%) > SMZ (about 40%). Due to strong adsorption of OTC on solid phase in wastewater, OTC will accumulate in solid digestion products and will cause potential ecological risk if they are re-used on farmland. The degradation rates of the three drugs were higher at initial spiking concentration of 50mg/L than that at the spiking concentration of 5 mg/L. In the first week of digestion experiment, spiking of drugs at both levels of 5 mg/L and 50 mg/L suppressed the biogas production of anaerobic microbes. The suppression level at the spiking concentration of 50 mg/L was higher than the level at the spiking concentration of 50 mg/L. However, after the 15th day, spiking of drugs at 50 mg/L obviously increased biogas product, for which the mechanism needs further study.