一种新型电化学体系降解苯酚的机理研究

通过使用自制的碳聚四氟乙烯(CPTFE)气体扩散电极作为阴极,TiIrO2RuO2材料为阳极,研究了隔膜电解槽中电化学降解苯酚的机理.结果表明,在阴极室,CPTFE气体扩散阴极通过外界曝气提供的O2在阴极还原产生H2O2,电解80min后H2O2的稳定浓度达到8.3mg·L-1.采用电子自旋共振法(ESR)在阴极室中检测到羟自由基(HO·)的存在.采用高效液相色谱(HPLC)在阴极室检测到羟基加合物对苯二酚,证明HO·参与了苯酚的降解过程.在该电化学体系中苯酚的降解是在阳极直接、间接氧化及阴极产生的H2O2、HO·的氧化共同作用下完成的.阴极室检测到了对苯二酚、苯醌等苯环化合物和顺丁烯二酸、反丁烯二酸、丙烯酸、丙二酸、草酸、乙酸、甲酸等短链羧酸,据此提出了苯酚降解的可能历程,并对阴、阳极室中苯酚降解途径之间的差异进行了初步比较.     

光合细菌乳酸代谢机制的初步研究

分离获得4株能利用乳酸作为唯一碳源分别进行好氧生长和厌氧生长的光合细菌菌株，对其无细胞抽提液进行透析和乳酸转化为丙酮酸能力的测定．结果表明，这4株光合细菌在好氧和厌氧条件下对乳酸的代谢机制是不同的．对筛选获得的高乳酸转化能力的S1菌株的进一步研究表明，黑暗好氧条件下，S1菌株的乳酸代谢能力与生长呈正相关关系；而光照厌氧条件下，乳酸代谢酶的合成滞后于生长．图5表1参10     

鼎湖山主要植被类型土壤微生物生物量研究

对鼎湖山国家级自然保护区3种主要植被类型：季风常绿阔叶林，针阔叶混交林和马尾松林土壤微生物生物量进行了研究。结果表明，土壤微生物生物量（mg.kg^-1）在季风常绿阔叶林、针阔叶混交林和马尾松林中分别为：822，588，530，季风常绿阔叶林显著高于针阔叶混交林和马尾松林（P〈0．01），而针阔叶混交林和马尾松林无显著差异（P〉0．05）；土壤中微生物量高的土壤中，有机碳含量也相应高，两者的比值可反应土壤碳的积累或损失，研究表明，鼎湖山3种主要植被类型土壤均处于碳积累过程；季风常绿阔叶林、针阔叶混交林和马尾松林土壤微生物碳周转量（t.hm^-2．a^-1）依次为：14．07，11．45，9，60，碳素的周转带动了其他营养元素的循环和能量的流动；土壤微生物代谢熵（mg.g^-1．h^-1）由低到高依次是季风常绿阔叶林（0．59）、针阔叶混交林（0．96）和马尾松林（1．33），表明土壤微生物对土壤碳的利用效率季风常绿阔叶林较高，马尾松林较低。     

A new approach to graphical and numerical analysis of links between plant chemotaxonomy and secondary metabolism from HPLC data smoothed by a simplex mixture design

Summary. HPLC analysis of secondary metabolites represents an efficient tool for the studying of plant chemical diversity under different aspects: chemotaxonomy, metabolomics, adaptative responses to ecological factors, etc. Statistical analyses of HPLC databases, e.g. correlation analysis between HPLC peaks, can reliably provide information on the similarity/dissimilarity degrees between the chemical compounds. The similarities, corresponding to positive correlations, can be interpreted in terms of analogies between chemical structures, synchronic metabolisms or co-evolution of two compounds under certain environment conditions, etc. . In terms of metabolism, positive correlations can translate precursor-product relationships between compounds; negative correlations can be indicative of competitive processes between two compounds for a common precursor(s), enzyme(s) or substrate(s). Furthermore, the correlation analysis under a metabolic aspect can help to understand the biochemical origins of an observed polymorphism in a plant species. With the aim of showing this, we present a new approach based on a simplex mixture design, Scheffé matrix, which provides a correlation network making it possible to graphically visualise and to numerically model the metabolic trends between HPLC peaks. The principle of the approach consisted in mixing individual HPLC profiles representative of different phenotypes, then from a complete mixture set, a series of average profiles were calculated to provide a new database with a small variability. Several iterations of the mixture design provided a smoothed final database from which the relationships between the secondary metabolites were graphically and numerically analysed. These relationships were scale-dependent, namely either deterministic or systematic: the first consisted of a monotonic global trend covering the whole variation field of each metabolites’ pair; the second consisted of repetitive monotonic variations which gradually attenuated or intensified along a global trend. This new metabolomic approach was illustrated from 404 individual plants of Astragalus caprinus (Leguminoseae), belonging to four chemical phenotypes (chemotypes) on the basis of flavonoids analysed in their leaves. After smoothing, the relationships between flavonoids were numerically fitted using linear or polynomial models; therefore the co-response coefficients were easily interpreted in terms of metabolic affinities or competitions between flavonoids which would be responsible of the observed chemical polymorphism (the four chemotypes). The statistical validation of the approach was carried out by comparing Pearson correlations to Spearman correlations calculated from the smoothed and the crude HPLC database, respectively. Moreover, the signs of the smoothed relationships were finely supported by analogies and differences between the chemical structures of flavonoids, leading to fluent interpretation in relation to the pathway architecture.     

矿业城市浅层地下水污染机制研究

分析了不同来源的污染物对矿业城市浅层地下水的污染机制，重点阐述淮南市区浅层地下水的主要污染源及其分布形状、主要污染物及其性状特征。     

生物过滤塔中微生物群落的代谢特性

了解微生物群落结构与代谢功能对于提高生物反应器运行性能具有重要意义.为此,本研究用Biolog方法在160d的运行过程中研究了处理甲苯气体的木屑生物过滤塔和活性炭生物过滤塔中微生物群落的代谢特性.研究发现,木屑过滤塔和活性炭过滤塔中微生物群落的平均代谢活性在长期运行时均有下降趋势.主成分分析结果表明,生物过滤塔中微生物群落代谢指纹在运行前期未发生显著变化,但103d后在过滤塔进气端出现显著变化,到160d时整个过滤塔内的微生物群落代谢指纹均发生改变.2套过滤塔中微生物群落代谢活性与代谢特征指纹未表现出较大差异,表明长期运行时填料对微生物代谢的影响较小.在Biolog平板内的95种碳源中,羧酸类物质和氨基酸类物质更容易被过滤塔中的微生物群落利用.     

Enhanced nitrogen removal and microbial analysis in partially saturated constructed wetland for treating anaerobically digested swine wastewater

Anaerobically digested swine wastewater was treated by a novel constructed wetland. Tidal operation was better for total nitrogen removal than intermittent flow. Mechanism of nitrogen removal by biozeolite-based constructed wetland was discussed. Simultaneous nitrification and denitrification were determined in zeolite layer. Nitrogen removal of wastewater containing high-strength ammonium by the constructed wetlands (CWs) has been paid much attention. In this study, the ability of a partially saturated CW to treat anaerobically-digested decentralized swine wastewater under varying operating parameters from summer to winter was investigated. The partially saturated CW achieved better NH₄⁺-N and TN removal by tidal flow than intermittent flow. With surface loading rates of 0.108, 0.027, and 0.029 kg/(m²·d) for COD, NH₄⁺-N, and TN, the partially saturated CW by tidal operation achieved corresponding removal efficiencies of 85.94%, 61.20%, and 57.41%, respectively, even at 10°C. When the rapid-adsorption of NH₄⁺-N and the bioregeneration of zeolites reached dynamically stable, the simultaneous nitrification and denitrification in the aerobic zeolite layer was observed and accounted for 58.82% of the total denitrification of CW. The results of Illumina high-throughput sequencing also indicated that nitrifiers (Nitrospira and Rhizomicrobium) and denitrifiers (Rhodanobacter and Thauera) simultaneously existed in the zeolite layer. The dominant existence of versatile organic degraders and nitrifiers/denitrifiers in the zeolite layer was related to the removal of most COD and nitrogen in this zone. The contribution of the possible nitrogen removal pathways in the CW was as follows: nitrification-denitrification (86.55%)>substrate adsorption (11.70%)>plant uptake (1.15%)>microbial assimilation (0.60%).     

细胞色素P450代谢污染物的化学模拟与优化

利用Fe2+EDTAH2O2联氨混合体系模拟了生物细胞色素P450的代谢功能,选择三氯乙烯作为典型污染物与模拟体系反应,产生的活性中间体与4(对硝基苄基)吡啶(NBP)反应生成紫红色物质,用分光光度法检测.根据产生活性中间体的多少对模拟体系的组成和反应条件进行了优化,对活化机理进行了初步探讨.结果发现联氨等还原剂的存在对模拟体系的代谢活化能力有重要影响,是体系区别于Fenton试剂的重要标志.在优化条件下,低至2×10-6mol·L-1的三氯乙烯在模拟体系中可以代谢产生活性中间体,表明该体系能够较好地模拟细胞色素P450的代谢功能.     

Ecological network and emergy analysis of urban metabolic systems: Model development,and a case study of four Chinese cities

Analysis of the structure and function of urban metabolic systems is an important goal of urban research. We used network pathways and network utility analysis to analyze the basic network structure of the urban metabolic system and the complex ecological relationships within the system, providing a new way to perform such research. Using four Chinese cities as examples, we developed an ecological network model of the urban metabolic system. By using network pathway analysis, we studied the changing relationships between metabolic length and the number of metabolic pathways, and between metabolic length and reachability. Based on the distribution of the number of metabolic pathways, we describe the basic structure and intercompartment relationships of the system. By using the sign distribution in the network utility matrix, we determined the ecological relationships and degree of mutualism between the compartments of the system. The basic components of the system consisted of the internal environment, the external environment, and the agricultural, industrial, and domestic sectors. With increasing metabolic length, the ecological relationships among the components of the system became more diverse, and the numbers of metabolic paths and their reachability improved. Although the basic network structure of the four cities was identical, the mutualism index differed. Beijing's mutualism index was superior to that of Shanghai, and much higher than those of Tianjin and Chongqing. By analyzing the structure and function of the urban metabolic system, we provide suggestions for optimizing the structure and adjusting the relationships, and propose methods for the application of ecological network analysis in future urban system research.