抗生素和纳米银对大肠杆菌耐药性的联合效应

以大肠杆菌（E.coli）为模式生物,研究了磺胺类抗生素（SAs）和纳米银（AgNPs）在单一或联合作用下对RP4质粒接合转移效应及E.coli突变效应的影响,并对联合作用方式进行了判别,基于分子对接技术和线性回归分析,探讨了两种效应的机制及其与毒性效应的关系.结果表明,在较低浓度范围内,所测12种SAs以及AgNPs在单一或联合暴露下对接合转移和突变均有促进作用,12组SAs-AgNPs混合物对接合转移频率促进率峰值的最大值和最小值分别为105.32%和46.96%,对突变体促进率峰值的最大值和最小值分别为1410.25%和238.38%.此外,SAs和AgNPs联合暴露对RP4质粒接合转移效应主要表现为协同作用,对E.coli突变效应主要表现为拮抗作用,且接合转移效应、突变效应与毒性效应之间具有良好的相关性.     

改性活性炭对内分泌干扰物的吸附效能与机制

为提高活性炭对内分泌干扰物的吸附效率,分别采用混合酸溶液,氨水,KMnO₄溶液和表面活性剂溶液对活性炭进行改性.采用比表面积及孔隙度分析仪、扫描电子显微镜（SEM）、傅里叶红外光谱（FT-IR）和Boehm滴定法对改性后活性炭表面化学性质及孔隙特征的变化进行评价.通过静态吸附实验确定活性炭的最佳改性方法,并对改性后活性炭吸附机理进行探讨.实验结果表明,KMnO₄改性活性炭（AC-K）表现出最佳的污染物吸附性能,其对邻苯二甲酸二丁酯（DBP）、阿特拉津（Atrazine）和磺胺甲恶唑（SMZ）的去除率分别可达到94.5%、93.8%和95.5%,且吸附过程符合二级动力学方程和D-R模型.由模型计算结果可知,AC-K对目标污染物的吸附速率明显加快,其中对Atrazine的二级吸附速率常数是AC的1.75倍.AC-K对DBP、Atrazine和SMZ的理论饱和吸附量也分别比改性前分别提高了42.2%、629%和122%.经KMnO₄改性后,活性炭的吸附机制由物理吸附占主导,转化为离子交换吸附.     

Effect of water matrices on removal of veterinary pharmaceuticals by nanofiltration and reverse osmosis membranes

This study explored the removal of five veterinary pharmaceuticals (VPs) (sulfamethoxazole (SMETOX), trimethoprim (TMP), ciprofloxacin (CIPRO), dexamethasone (DEXA) and febantel (FEBA)) from different water matrices (Milli-Q water, model water, tap water and real pharmaceutical wastewater using four types of nanofiltration (NF) membranes (NF90, NF270, NF and HL) and two reverse osmosis (RO) membranes (LFC-1 and XLE). All VPs were added to different water matrices at a concentration of 10 mg/L. Rejections of VPs and water flux were measured. The rejection increased with increase of molecular weight. The highest rejections were obtained with RO membranes (LFC-1, XLE) and tight NF (NF90) membrane. In general, the rejection of VPs was higher in model water and tap water than in Milli-Q water, but the water flux was lower. This was mainly explained by ion adsorption inside the membranes pores. Narrower pore size counteracted the effect of presence of low concentration of natural organic matter (NOM) in tap water. The NOM was assumed to enhance the adsorption of VPs onto membrane surface, increased the size exclusion and electrostatic repulsion also appeared during the transport. Investigated water matrices had influence on water flux decline due to their complexity.     

Behavior toxicity to Caenorhabditis elegans transferred to the progeny after exposure to sulfamethoxazole at environmentally relevant concentrations

Sulfamethoxazole (SMX) is one of the most common detected antibiotics in the environment. In order to study whether SMX can a ect behavior and growth and whether these e ects could be transferred to the progeny, Caenorhabditis elegans was exposed at environmentally relevant concentrations for 24, 48, 72 and 96 hr, respectively. After exposure, the exposed parent generation (P0) was measured for behavior and growth indicators, which were presented as percentage of controls (POC). Then their corresponding unexposed progeny (F1) was separated and measured for the same indicators. The lowest POC for P0 after 96 hr-exposure at 100 mg/L were 37.8%, 12.7%, 45.8% and 70.1% for body bending frequency (BBF), reversal movement (RM), Omega turns (OT) and body length (BL), respectively. And F1 su ered defects with the lowest POC as 55.8%, 24.1%, 48.5% and 60.7% for BBF, RM, OT and BL, respectively. Defects in both P0 and F1 showed a time- and concentration-dependent fashion and behavior indicators showed better sensitivity than growth indicator. The observed e ects on F1 demonstrated the transferable properties of SMX. Defects of SMX at environmental concentrations suggested that it is necessary to perform further systematical studies on its ecological risk in actual conditions.     

环境浓度抗生素选择性压力改变活性污泥微生物群落结构

为探究环境浓度抗生素(5μg·L~(-1)和50μg·L~(-1))选择性压力下活性污泥微生物的性能变化,选择四环素及磺胺甲噁唑2种高频检出的抗生素作为研究对象,分别考察2种抗生素单一和复合作用下对序批式活性污泥反应器(SBR)中废水处理效能、微生物活性及群落结构的影响。结果表明,与不添加抗生素的空白对照组相比,2种抗生素在50μg·L~(-1)和5μg·L~(-1)暴露浓度下,经过60 d运行,COD和NH+4-N去除效果未受明显影响(P0.05),微生物的活菌比变化不显著(P0.05),ATP含量显著降低(P0.05)。在微生物群落结构方面,革兰氏阳性菌增加,革兰氏阴性菌减少,原生动物含量减少,香农-威尔生物多样性指数下降。添加抗生素的样品中微生物优势菌群由变形菌门变为放线菌门,放线菌含量(均高于45%),高于空白对照组(30.72%);放线菌门的Micropruina属所占比例最高(24%),且高于空白对照组(18.77%)。抗生素选择性压力可改变活性污泥微生物的活性及群落结构,但长期作用下对污水处理效能及抗生素抗性基因传播的影响还需要进一步研究。     

磺胺类药物在土壤中的形态转化及降解研究

采用批量平衡试验法研究了磺胺嘧啶和磺胺甲恶唑在添加模拟根系分泌物处理和对照中的形态转化及降解规律.结果表明,有机溶剂提取态、水溶态和结合态含量占总量的比例分别为86.5%~98.5%、0.6%~7.3%和0.1%~12.5%,有机溶剂提取态是2种药物在土壤中的主要存在形态.结合态所占比例随时间的增加而增高,添加模拟根系分泌物有利于土壤中磺胺嘧啶和磺胺甲恶唑结合态的形成,对水溶态和有机溶剂提取态形成的影响较小.土壤中磺胺嘧啶和磺胺甲恶唑的降解遵循一级反应动力学,可决系数为0.9273~0.9963.2种药物在添加模拟根系分泌物处理中的降解速率大于在对照的降解速率.     

天津水产业磺胺类耐药细菌及其分布

水产养殖中抗生素的滥用可能会诱导水产品和周围环境中的耐药菌.针对天津市北辰区、西青区、东丽区和津南区的6个水产养殖场的底泥和水样,采用抗性平板筛选耐药细菌,通过对磺胺甲恶唑的耐药率分析,发现底泥中的耐药率要大大高于水中的耐药率,并且与国外的某些研究相比,底泥的细菌耐药率呈现较高的趋势.另外,利用16S-rDNA鉴定出8...     

磺胺抗生素在河流沉积物中的吸附特性研究

地表水环境是抗生素污染物的重要汇。磺胺类抗生素是地表水环境中重要的抗生素类污染物,对生态系统及人类健康构成严重威胁。磺胺类抗生素在水-土界面的迁移、扩散研究对维护水环境及人类健康有重要意义。采用OECD Guideline批量平衡法,通过对磺胺嘧啶(SD)在河流沉积物中吸附过程、吸附机理及不同阳离子影响的研究,探讨了SD在水-土界面的环境行为。结果表明,SD在各断面沉积物中的吸附动力学过程均最适于用Elovich方程描述。SD在各断面沉积物中的吸附行为最适宜用Freundlich方程描述。SD在沉积物中的吸附量与沉积物的有机质质量比及阳离子交换量显著相关(p0.05)。不同价态阳离子的竞争吸附能力为价态越高,竞争能力越强,从小到大为M+(Na+、K+)、M~(2+)(Ca~(2+)、Mg~(2+))。     

紫外活化过硫酸盐工艺降解水中磺胺二甲氧嘧啶动力学特征与机理

采用紫外活化过硫酸盐(UV/PS)工艺降解典型磺胺类抗生素磺胺二甲氧嘧啶(SDM),比较单一紫外(UV)、单一过硫酸盐(PS)和UV/PS对SDM的去除效果,考察各因素对降解动力学的影响,并探究其降解机理,对SDM及其中间产物进行毒性测定和风险评价.结果显示,UV/PS可以加速SDM降解,反应速率常数分别是单一UV和单...     

中药渣生物炭对磺胺甲基嘧啶的吸附及机理研究

以传统中药-黄芪废渣为原料,分别在200℃、400℃、500℃、600℃和700℃的厌氧氛围下热解制备生物炭材料（BC200、BC400、BC500、BC600和BC700）,并利用BET比表面积分析、FTIR光谱分析、扫描电子显微镜等方法对其进行表征,同时考察不同投加量、吸附时间、初始浓度和pH值下生物炭对磺胺甲基嘧啶的吸附特征.结果表明,随制备温度的升高,生物炭的表面积及吸附性能也显著增加.相比原状黄芪渣（S_BET=0.42m²/g）,BC700的BET比表面积（S_BET=155.69m²/g）增大370倍,对磺胺甲基嘧啶的吸附容量增加185倍.BC700对磺胺甲基嘧啶的等温吸附过程符合Langmuir模型（R²=0.9977）,最大吸附容量为11.96mg/g,吸附反应过程满足准二级动力学方程（R²>0.994）,且为化学吸附.同时随着溶液初始pH值和投加量的升高,生物炭的吸附容量先增大后减小,最佳吸附pH值为4.