Zn-Fe LDHs改性石英砂生物膜体系对BDE-47的去除效果与机理

文章以四溴联苯醚(BDE-47)为目标污染物, 利用共沉淀法制备Zn-Fe LDHs覆膜改性石英砂基质, 在好氧、厌氧及两者交替条件下, 研究腐败希瓦氏菌CN32(Shewanella putrefaciens CN32) 在LDHs改性基质上生物膜形成过程及其对培养液中BDE-47的去除效果; 通过监测反应体系中Fe2+和H₂O₂浓度变化探讨BDE-47的生物及非生物去除机制。结果表明, LDHs改性不影响石英砂基质表面生物膜的形成, 但在好氧条件下, Zn-Fe LDHs石英砂改性基质对CN32电子传递链活性存在一定抑制作用, 而在厌氧条件下, LDHs改性会影响基质生物膜胞外聚合物(EPS)组成特性, 使多糖占比升高。无论在好氧还是厌氧条件下, 基质生物膜反应体系中EPS总浓度均显著高于纯菌CN32体系; 且在好氧与交替条件下, 基质生物膜的形成均显著提高反应体系中BDE-47的去除效果(约25%)。在交替条件下, 前3次循环(72h内)BDE-47的去除以基质吸附为主; 72h后, 生物膜吸附与生物降解共同发挥作用, 且LDHs改性基质在后期上升潜力更大。研究报道了LDHs改性基质生物膜形成特性及其对水相中PBDEs去除的潜力, 为强化人工湿地中PBDEs生物降解提供新思路。     

实验室模拟高负荷SPAC厌氧反应器运行

采用模拟废水, 对新型高负荷螺旋式自循环(Spiral automatic circulation, SPAC)厌氧反应器的运行性能进行了实验室模拟研究。结果表明: 在30oC, 水力停留时间(HRT)为12 h, 进水COD浓度从8000 mg/L升至20 000 mg/L的条件下, 反应器的COD去除率为91.1%~95.7%, 平均去除率为93.6％。在进水浓度为20 000 mg/L, HRT由5.95 h缩短至1.57 h的工况下, COD去除率从96.0%降低至78.7%, 反应器达到最高容积负荷率306 g COD/(L·d), 最大容积COD去除率240 g/(L·d), 最高容积产气率131 L/(L·d)。该反应器对基质浓度的连续提升具有良好的适应能力。进水COD浓度由8000 mg/L提升至20 000 mg/L时, 出水COD浓度一直处在较低水平(平均为852?mg/L), 容积COD去除率和容积产气率分别提高162%和119%。该反应器对HRT的连续缩短也有良好的适应能力。HRT由5.95 h缩短至1.57 h时,反应器容积COD去除率和容积产气率分别升高191%和195%。     

对-氯代苯胺(PCA)在填充床生物反应器中的降解作用

以氯代苯胺(PCA)为选择基质,用驯化技术从降解对二氯苯(p-DCB)的富集培养物中得到了以同化PCA为唯一碳源和氮源的混合微生物。将这种固定在填充床反应器中的微生物用于PCA的降解作用研究中。在该反应器里,PCA的生物降解遵循Logistic方程q=q_max/(1+e^α-βU_v).由方程求出了主要的动力学常数,K_s(半速率常数)和q_max(最大比基质降解速率).于PCA降解的同时,释放氯离子到培养基中。在水力停留时间3h, 进水PCA浓度为360mg·L^-1情况下,基质的体积降解率达到125mg·L^-1·h^-1;基质的百分去除率为91%.     

缬沙坦治疗糖尿病肾病疗效观察

目的观察血管紧张素Ⅱ1型受体拮抗剂(AT1Ra)缬沙坦(Valsartan)对伴大量白蛋白尿的临床糖尿病肾病的治疗作用.方法 32例2型糖尿病患者,24h尿白蛋白排泄率(24hUAER)＞200μg/min,均伴高血压,维持原糖尿病治疗不变,分组比较应用缬沙坦(80 mg/d)或贝那普利(10 mg/d)治疗8周前后平均动脉压(MAP)、24h UAER、HbA1c、尿酸(UA)等指标的变化.结果缬沙坦治疗组和贝那普利治疗组24h UAER分别由(703.2±987.9)μg/min降至(664.2±970.6)μg/min(P＜0.01)和由(778.6±1005.0)μg/min降至(734.9±996.0)μg/min(P＜0.01).二者疗效相似,且均与血压变化不相关.结论AT1Ra缬沙坦可以降低临床糖尿病肾病的尿蛋白,其肾脏保护作用除了与降血压有关,还有不依赖降压效应的其他机制.     

优化联合降压治疗对高血压左室肥厚患者左室重量指数及血清瘦素水平的影响

目的:比较优化联合降压治疗及标准联合降压治疗对高血压左室肥厚患者左室重量指数及血清瘦素水平的影响,并探讨左室肥厚与血清瘦素水平的关系.方法:72例高血压左室肥厚患者随机分配到优化联合降压组(n=36)或标准联合降压组(n=36).优化降压组为:氨氯地平5 mg/d+替米沙坦80 mg/d.标准降压组为:氨氯地平5 mg/d+复方盐酸阿米洛利1片/d.治疗6个月后,检测并比较两组患者治疗前后左室重量指数及血清瘦素水平的变化.结果:标准联合降压组及优化联合降压组患者经过6个月药物干预后,(1)平均左室重量指数分别由183.3±44.6 g/m2,174.9±37.2 g/m2降至154.4±34.4 g/m2,138.0±33.9 g/m2(均P<0.01),优化降压组降低程度更为显著(P<0.05).(2)血清瘦素水平分别由(7.3±1.6)μg/L,(7.2±1.9)μg/L降至(4.8±1.3)μg/L,(3.4±1.3)μg/L,差异有统计学意义(P<0.01),且优化降压组降低程度更为明显(P<0.05).结论:优化联合降压组比标准联合降压组对高血压患者左室肥厚的逆转效果及降低血清瘦素水平的作用更佳.瘦素参与了左心室肥厚的发生、发展.     

人工湿地净化污水处理厂低浓度尾水的效果

文章构建一种以双向横流过滤单元为核心的人工湿地系统,以实际污水处理厂尾水为进水,研究了尾水湿地系统净化效果,发现采用该湿地模式的出水能稳定提升1个等级。为了进一步探究湿地系统除污机理,以污水处理厂实际低浓度尾水为进水,研究了该湿地系统不同植物单元污染物去除功效,讨论了植物、基质与微生物的协同作用机制。研究结果表明:(1)在不同植物的去污效果对比实验中,花叶芦竹植物单元对COD、TN、NH₄⁺-N和TP的平均去除率最高,分别为20.11%、17.17%、28.08%和18.12%;(2)不同运行阶段时基质进出水端主要微生物群落差异较小;(3)系统反向进水时,湿地系统TN去除率可提升50.00%。研究结果对于尾水湿地建设具有一定指导意义。     

一株十溴联苯醚高效好氧降解菌的筛选、鉴定及降解特性

【目的】从广东贵屿镇电子垃圾拆解地采集的沉积物样品中分离十溴联苯醚(BDE-209)高效好氧降解菌,并考察其对BDE-209的降解特性。【方法】通过生理生化实验和16S rRNA测序鉴定菌种,正交实验优化降解条件,并分析不同降解体系及影响因素对菌降解BDE-209的影响。【结果】鉴定结果显示,该BDE-209好氧降解菌为短短芽孢杆菌(Brevibacillus brevis)。B.brevis对1 mg/L BDE-209 5 d的降解率可达54.38%。正交实验结果表明,B.brevis降解BDE-209的最优条件为:pH 7,投菌量3 g/L,温度30°C。降解特性研究结果显示B.brevis对BDE-209降解的最佳菌龄为36 h,最佳氮源为(NH4)2SO4,B.brevis对Cu2+、Cd2+有较好的耐受性,但Cu2+和Cd2+的存在会影响其对BDE-209的降解。当Cu2+浓度在1 5 mg/L,Cd2+浓度在0.3 0.5 mg/L范围内时,B.brevis对BDE-209降解均可达50%以上。【结论】B.brevis对BDE-209有很好的降解效率,研究结果对BDE-209的好氧微生物降解及环境中BDE-209的生物修复具有较好的科学意义和应用价值。     

十溴联苯醚降解菌的分离鉴定、降解特性及降解机理

【背景】十溴联苯醚(decabromodiphenyl ether,BDE-209)是应用最广泛的溴代阻燃剂之一,其持久性毒性给生态环境和生物体带来了严重危害。【目的】分离出一株能有效降解BDE-209的好氧细菌并研究其降解特性及机理,以探究BDE-209的微生物降解规律。【方法】以BDE-209为唯一碳源,通过富集、分离和纯化,从活性污泥中筛选出BDE-209好氧降解细菌。采用高效液相色谱(high-performance liquid chromatography,HPLC)和液相色谱-质谱联用仪(liquid chromatography-mass spectrometry,LC-MS)分别检测BDE-209的浓度和中间产物。【结果】筛选得到一株BDE-209好氧降解细菌F,经鉴定初步判定为硝基还原假单胞菌(Pseudomonas nitroreducens)。在30℃、pH7.0、接种量为10%(体积分数)、葡萄糖浓度为250mg/L的优化降解条件下,对初始浓度为10mg/L的BDE-209的降解率可达76.2%。低浓度的Cd²⁺(≤5mg/L)未对BDE-209的微生物降解和菌体生长产生显著影响,而高浓度的Cd²⁺(≥15mg/L)对BDE-209的微生物降解和菌体生长则产生显著影响。BDE-209对细胞表面疏水性(cell surface hydrophobicity,CSH)具有一定的影响。BDE-209的微生物降解机理主要包括脱溴、羟基化、二苯醚键断裂和开环等过程。【结论】菌株F对BDE-209具有很好的降解能力,研究结果对BDE-209的好氧微生物降解及BDE-209污染环境的生物修复具有较好的科学意义。     

复合菌对十溴联苯醚的降解特性研究

【目的】利用6株十溴联苯醚(decabromodiphenyl ether, BDE-209)降解细菌，探究复合菌对BDE-209的降解特性和降解路径，为BDE-209污染环境的生物修复提供科学依据。【方法】利用高效液相色谱法测定BDE-209的浓度，通过液相色谱-质谱联用仪分析鉴定BDE-209降解产物。【结果】短芽孢杆菌属(Achromobacter sp.) M1和无色杆菌属(Achromobacter sp.) M2的组合对BDE-209的降解效果最好，在30 ℃、pH值7.0、接种量15%的条件下，120 h后10 mg/L BDE-209的降解效率可达87.7%。相比于单一菌株，复合菌M(1+2)可以更有效、更快地降解BDE-209。在0.5-10 mg/L范围内，复合菌M(1+2)对BDE-209的降解率随着BDE-209初始浓度的增大而增大。通过液相色谱-质谱联用仪(liquid chromatograph-mass spectrometer, LC-MS)检测到11种BDE-209微生物降解产物，复合菌M(1+2)通过脱溴、羟基化、去质子化、醚键断裂和开环等反应对BDE-209进行降解。【结论】复合菌M(1+2)对BDE-209具有良好的降解能力，研究结果为进一步提高微生物对BDE-209污染环境的生物修复能力提供了良好的微生物资源。     

人工湿地污水处理系统中的植物效应与基质酶活性

为了解植物在湿地污水净化系统中的作用与机理,构建了A-B-C三级串连垂直流人工湿地系统,并选择水葱(Scirpus validus)风车草(Cyperus alternifolius)、美人蕉(Canna indica)、和芦苇(Phragmites australis)作为测试植物,进行了生活污水处理试验.结果表明,系统中有植物单元单位面积污染物的去除量均高于无植物对照单元.与对照相比,在A、B、C三级系统中由植物效应产生的CODCr去除增量分别为43.52 g/(m2·d),20.38 g/(m2·d),30.94 g/(m2·d);TN去除增量为13.14 g/(m2·d),28.61 g/(m2·d),6.97 g/(m2·d);TP去除增量为1.2 g/(m2·d),0.66 g/(m2·d),0.06 g/(m2·d).从A到C级,污水中污质浓度递减,呈现根系活力显著增强,而植物生长量、过氧化物酶含量、生长量与氮磷积累量等显著下降趋势.基质酶活性在对照单元中较低,在有植物单元中,基质酶活性明显增大并与根系活力成正相关.     

Microbial Electricity Generation Enhances Decabromodiphenyl Ether (BDE-209) Degradation

Due to environmental persistence and biotoxicity of polybrominated diphenyl ethers (PBDEs), it is urgent to develop potential technologies to remediate PBDEs. Introducing electrodes for microbial electricity generation to stimulate the anaerobic degradation of organic pollutants is highly promising for bioremediation. However, it is still not clear whether the degradation of PBDEs could be promoted by this strategy. In this study, we hypothesized that the degradation of PBDEs (e.g., BDE-209) would be enhanced under microbial electricity generation condition. The functional compositions and structures of microbial communities in closed-circuit microbial fuel cell (c-MFC) and open-circuit microbial fuel cell (o-MFC) systems for BDE-209 degradation were detected by a comprehensive functional gene array, GeoChip 4.0, and linked with PBDE degradations. The results indicated that distinctly different microbial community structures were formed between c-MFCs and o-MFCs, and that lower concentrations of BDE-209 and the resulting lower brominated PBDE products were detected in c-MFCs after 70-day performance. The diversity and abundance of a variety of functional genes in c-MFCs were significantly higher than those in o-MFCs. Most genes involved in chlorinated solvent reductive dechlorination, hydroxylation, methoxylation and aromatic hydrocarbon degradation were highly enriched in c-MFCs and significantly positively correlated with the removal of PBDEs. Various other microbial functional genes for carbon, nitrogen, phosphorus and sulfur cycling, as well as energy transformation process, were also significantly increased in c-MFCs. Together, these results suggest that PBDE degradation could be enhanced by introducing the electrodes for microbial electricity generation and by specifically stimulating microbial functional genes.     

Identification and biodegradation efficiency of a newly isolated 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) aerobic degrading bacterial strain

Polybrominated diphenyl ethers (PBDEs) are bioaccumulative, toxic and persistent, globally distributed organic chemicals in environment. However, very little is known for their aerobic biodegradation. In this research, 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) was selected as a model congener of PBDEs to study its aerobic biodegradation. A new BDE-47 degrading strain BFR01 identified as Pseudomonas stutzeri was isolated from polluted soil in a former brominated flame retardant production corporation. Stain BFR01 could utilize BDE-47 as a sole source of carbon and energy, and transformed 97.94% of BDE-47 in two weeks; the biodegradation of BDE-47 fitted well with the first-order kinetics, with the first-order kinetics constant of 0.32 d⁻¹. The biodegradation efficiency of stain BFR01 was higher than other reported PBDEs aerobic degrading bacteria. The biodegradation efficiency achieved maximum at pH 7.0 and 40 °C. The presence of additional carbon sources could enhance the biodegradation efficiency of BDE-47 by 1–6%. Furthermore, no lower brominated diphenyl ethers or biphenyl were detected, suggesting that the pathway of BDE-47 biodegradation by strain BFR01 might not be debromination with lower brominated diphenyl ethers as products. This is the first report of aerobic degradation of BDE-47 by P. stutzeri.     

Effects of electron donors on anaerobic microbial debromination of polybrominated diphenyl ethers (PBDEs)

Polybrominated diphenyl ethers (PBDEs) are a class of widely used flame retardants that have been highly accumulated in sediments. It is reported that microorganisms play an important role in the reductive debromination of PBDEs in anaerobic sediments. However, little is known about the effects of electron donors on the microbial community structure and their debromination capacity in PBDE transformation. In this study, alternate carbon substrates were used as electron donors to enrich the PBDE-debrominating microbial consortia to evaluate the effects of electron donors on PBDE microbial debromination. Decabromodiphenyl ether (BDE-209) was found to be the dominant (more than 50%) PBDEs congener in all consortia, and the percentage of BDE-209 was deceased by 12% (methanol), 11% (ethanol), 8% (acetate), 9% (lactate), 5% (pyruvate), and 11% (no electron donors), while the relative abundances of most lesser-brominated PBDEs increased after 90-day incubation compared to the initial profile of PBDEs. Substantial shifts in the microbial community structure among different amendments were observed based on denaturing gradient gel electrophoresis results. Pseudomonas spp. were identified to be the predominant organisms and the abundances of Band R, which was associated with Pseudomonas sp. SCSWA09, was well correlated with the biodegradation rate of BDE-209. Finally, the microbial community structure was highly correlated with the concentration of deca-BDE, octa-BDE and total nitrogen. These results provide insights into in situ bioremediation of environments contaminated by PBDEs and our understanding of microbial ecology associated with PBDE-debromination.     

Distribution of biomarkers of human exposure to persistent organic pollutants from the group of organohalogen compounds as a result of the impact of the environment

Abstract

Organohalogen compounds constitute one of the important groups of persistent organic pollutants (POPs). Among them, due to their long-term health effects, one should pay attention on polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and perfluoroalkylated substances (PFASs). In case of that anthropogenic group of environmental pollution, the scientific world faces a problem of not only checking their toxic influences on the human organism at different age, from the natal period till late elderly years, but also monitoring the levels of such a numerous group of compounds in various environments, including human tissues and body fluids. This gave birth to a concept of checking the levels of selected biomarkers of exposure in the human organism, calculating body burden and assessing the hazard exposure to human beings. This article is an attempt to answer the question whether testing only biomarkers for different groups of pollutants is enough to determine the threat to different human populations. CB-153 levels represent a significant share in the sum of the six indicator NDL-PCBs (42.96%). In contrary to PCBs, in the case of PBDEs, not only BDE-47 is a biomarker of exposure to the entire PBDEs group, the congener BDE-153 cannot be omitted. Among the compounds belonging to PFASs, only four are detected in the biological material. The PFOS is the dominant representative of this group in the blood samples. It constitutes approximately 75% of the total PFASs.     

Photolysis of Low-Brominated Diphenyl Ethers and Their Reactive Oxygen Species-Related Reaction Mechanisms in an Aqueous System

To date, no report was concerned with participation of reactive oxygen species in waters during photolysis of low-brominated diphenyl ethers (LBDEs). Herein, we found that electron spin resonance (ESR) signals rapidly increased with increasing irradiation time in the solution of LBDEs and 4-oxo-TMP solutions. But this phenomenon did not occur in the presence of NaN₃ (¹O₂ quencher) demonstrating generation of ¹O₂ in process of LBDEs photolysis. The indirect photolytic contribution rate for BDE-47 and BDE-28 was 18.8% and 17.3% via ¹O₂, and 4.9% and 6.6% via ·OH, respectively. Both D₂O and NaN₃ experiments proved that the indirect photolysis of LBDEs was primarily attributable to ¹O₂. The bimolecular reaction rate constants of ¹O₂ with BDE-47 and BDE-28 were 3.12 and 3.64 × 10⁶ M^-1 s^-1, respectively. The rate constants for BDE-47 and BDE-28 (9.01 and 17.52 × 10⁻³ min^-1), added to isopropyl alcohol, were very close to those (9.65 and 18.42 × 10⁻³ min^-1) in water, proving the less indirect photolytic contribution of ·OH in water. This is the first comprehensive investigation examining the indirect photolysis of LBDEs in aqueous solution.     

Biomonitoring of polybrominated diphenyl ether (PBDE) pollution: a field study

Polybrominated diphenyl ethers (PBDEs) and cytochrome P450 enzyme activities were investigated in European eels (Anguilla anguilla) collected from seven sites in a coastal lagoon in the north-western Mediterranean Sea, Orbetello lagoon (Italy). Twelve PBDE congeners were measured in muscle and two CYP1A enzyme activities, 7-ethoxyresorufin-O-deethylase (EROD) and benzo(a)pyrene monooxygenase (BP(a)PMO), were investigated in liver microsomal fraction in order to obtain insights into the health of the lagoon environment. PBDE muscle levels were low and the most abundant congeners were 2,2',4,4'-tetrabromodiphenylether (BDE-47), 2,2',4,4',5,5'-hexaBDE (BDE-153) and 2,2',4,5'-tetraBDE (BDE-49). EROD and B(a)PMO activities were also low and no differences were observed between eels from different sites. Multivariate analysis (PCA) did not indicate correlations between PBDEs and either P450 activities.     

Pyridine biodegradation in a novel rotating rope bioreactor

A novel immobilised bioreactor has been developed especially for the treatment of pollutants characterized by high volatility along with high water solubility and low microbial yields. The new bioreactor referred to as the rotating rope bioreactor (RRB) provides higher interfacial area (per unit reactor liquid volume) along with high oxygen mass transfer rate, greater microbial culture stability; and consequently higher substrate loadings and removal rates in comparison to other conventional rectors for the treatment of volatile compounds. Pyridine was used as a model compound to demonstrate the enhanced performance with RRB, when compared to that reported with other conventional bioreactors. The experimental results indicate that the novel RRB system is able to degrade pyridine with removal efficiency of more than 85% at higher pyridine concentration (up to 1000 mg/l) and loading [up to 400 mg/m(2)/h (66.86 g/m(3)/h)], with a shorter hydraulic retention time (9-18 h). The reactor has been in operation for the past 15 months and no loss of activity has been observed.     

Pollutant Dehalogenation Capability May Depend on the Trophic Evolutionary History of the Organism: PBDEs in Freshwater Food Webs

Organohalogen compounds are some of the most notorious persistent pollutants disturbing the Earth biosphere. Although human-made, these chemicals are not completely alien to living systems. A large number of natural organohalogens, part of the secondary metabolism, are involved in chemical trophic interactions. Surprisingly, the relationship between organisms' trophic position and synthetic organohalogen biotransformation capability has not been investigated. We studied the case for polybromodiphenyl ethers (PBDE), a group of flame-retardants of widespread use in the recent years, in aquatic food webs from remote mountain lakes. These relatively simple ecosystems only receive pollution by atmospheric transport. A large predominance of the PBDE congener currently in use in Europe, BDE-209, largely dominated the PBDE composition of the basal resources of the food web. In contrast, primary consumers (herbivores and detritivores) showed a low proportion of BDE-209, and dominance of several less brominated congeners (e.g. BDE-100, BDE47). Secondary consumers (predators) showed large biomagnification of BDE-209 compare to other congeners. Finally, top predator fish characterized by low total PBDE concentrations. Examination of the bromine stable isotopic composition indicates that primary consumers showed higher PBDE biotransformation capability than secondary consumers. We suggest that the evolutionary response of primary consumers to feeding deterrents would have pre-adapted them for PBDE biotransformation. The observed few exceptions, some insect taxa, can be interpreted in the light of the trophic history of the evolutionary lineage of the organisms. Bromine isotopic composition in fish indicates that low PBDE values are due to not only biotransformation but also to some other process likely related to transport. Our finding illustrates that organohalogen compounds may strongly disturb ecosystems even at low concentrations, since the species lacking or having scarce biotransformation capability may be selectively more exposed to these halogenated hydrophobic semi-volatile organic pollutants due to their high bioaccumulation potential.