亚硝酸盐对聚磷菌吸磷效果的影响

以厌氧/好氧生化反应器中的聚磷菌为实验对象,探讨了亚硝酸盐对聚磷菌吸磷效果的影响.结果表明:低浓度NO₂^--N可以作为聚磷菌的电子受体,实现NO₂^--N型反硝化除磷,但吸磷总量和吸磷速率明显低于NO₃^--N型反硝化除磷的效果;当NO₂^--N和NO₃^--N共存于缺氧环境时,NO₂^--N对NO₃^--N型反硝化除磷的除磷总量和速率没有影响,但会降低NO₃^--N的消耗量;NO₂^--N型反硝化除磷污泥的好氧吸磷量和速率均低于传统A/O厌氧放磷污泥的效果,但由于它经历了缺氧吸磷和好氧吸磷2个阶段,因此,从吸磷总量或出水水质看,二者相差不大.     

Fatty acids composition of Caenorhabditis elegans using accurate mass GCMS-QTOF

The free living nematode Caenorhabditis elegans is a proven model organism for lipid metabolism research. Total lipids of C. elegans were extracted using chloroform and methanol in 2:1 ratio (v/v). Fatty acids composition of the extracted total lipids was converted to their corresponding fatty acids methyl esters (FAMEs) and analyzed by gas chromatography/accurate mass quadrupole time of flight mass spectrometry using both electron ionization and chemical ionization techniques. Twenty-eight fatty acids consisting of 12 to 22 carbon atoms were identified, 65% of them were unsaturated. Fatty acids containing 12 to17 carbons were mostly saturated with stearic acid (18:0) as the major constituent. Several branched-chain fatty acids were identified. Methyl-14-methylhexadecanoate (iso- 17:0) was the major identified branched fatty acid. This is the first report to detect the intact molecular parent ions of the identified fatty acids in C. elegans using chemical ionization compared to electron ionization which produced fragmentations of the FAMEs.     

铜氰溶液的电子束辐照降解

研究了铜氰溶液中总氰初始浓度、pH、铜浓度等对总氰降解效率的影响,比较了KCN溶液和铜氰溶液的总氰降解率,初步推断了铜氰溶液在辐照过程中的降解机制.实验结果表明,在同样的辐照剂量下,随着总氰初始浓度的增加,总氰降解率降低,相应的总氰降解G值增大;铜浓度越低,总氰降解率越高;pH越小的铜氰溶液总氰降解率越高.电子束辐照KCN溶液和铜氰溶液的总氰降解反应属于表观一级反应.在相同的辐照剂量下,KCN溶液的总氰降解率比铜氰溶液要高得多.铜氰溶液的电子束辐照降解过程非常复杂,主要是铜氰络合离子逐步离解出的CN-与·OH的反应.     

乌鲁木齐冬季雾天可吸入颗粒物透射电子显微镜研究

利用透射电子显微镜(TEM)对乌鲁木齐冬季雾天采集的可吸入颗粒物(PM_2.5、PM_2.5~10)的形貌特征和集聚状态进行分析。将乌鲁木齐大气可吸入颗粒物分为烟尘集合体、飞灰、矿物颗粒、硫酸盐和有机颗粒等5种单颗粒类型,并讨论了其来源。TEM分析表明,PM_2.5中烟尘集合体占14%,飞灰占7.4%,矿物颗粒占24%,硫酸盐占16.7%,有机颗粒占20.4%;PM_2.5~10 中烟尘集合体没有观察到,飞灰占4.9%,矿物颗粒占26.8%,硫酸盐占12.2%,有机颗粒占58.5%。     

微生物-光-电化学耦合技术降解污染物和回收能源的研究进展

微生物电化学技术能同时实现污染物去除和能量回收,但存在污染物去除种类有限及产能效率低的局限,近几年将可再生的太阳能引入微生物电化学技术的微生物-光-电化学耦合技术应运而生。本文简要介绍了微生物-光-电化学耦合技术的发展背景和研究现状,对该技术现有的耦合形式进行分类,并对各种形式的耦合机理进行详细的阐释,最后对其未来的发展进行了展望。     

内源电子受体产生及其在抑制富磷剩余污泥释磷行为中的应用

根据生物脱氮除磷系统产生的富磷剩余污泥含有硝化细菌和生产废水含有高浓度氨氮的特点,将生产废水中的氨氮转化为硝酸盐(内源电子受体),并将获得的内源电子受体利用在富磷剩余污泥浓缩过程,同步实现内源电子受体反硝化及其抑制富磷剩余污泥释磷行为。结果表明,将富磷剩余污泥(excess activated sludge,EAS。EAS1是在好氧方式下添加,EAS2是在缺氧方式下添加)与生产废水(reject water)按4种比例(Ⅰ、生产废水∶EAS1∶EAS2=15%∶85%∶0%;Ⅱ、生产废水∶EAS1∶EAS2=15%∶80%∶5%;Ⅲ、生产废水∶EAS1∶EAS2=15%∶75%∶10%;Ⅳ、生产废水∶EAS1∶EAS2=15%∶65%∶20%)混合曝气用于产生内源电子受体时,最佳硝化时间均为12 h,可将液相中的氨氮分别由初始的(113.16±0.85)mg/L、(117.18±4.39)mg/L、(129.48±4.85)mg/L及(142.53±0)mg/L降至(0.74±0.41)mg/L、(0.45±0.15)mg/L、(0.41±0.15)mg/L及(0.38±0.08)mg/L;同时,硝酸盐氮分别由初始的(7.48±7.91)mg/L、(12.87±5.81)mg/L、(12.87±5.81)mg/L及(13.55±6.18)mg/L升为(128.37±11.03)mg/L、(141.43±12.71)mg/L、(148.01±14.84)mg/L及(146.22±7.53)mg/L。内源电子受体可将重力浓缩过程中释磷量分别削减85%、63%、64%及83%,同时使得由生产废水回流引起的氨氮积累量分别减少89.25%、69.93%、74.31%及85.40%。在整个内源电子受体产生及其应用于抑制污泥释磷阶段,TN去除率分别为39.59%、44.54%、51.86%及57.33%。上述内源电子受体胁迫条件下的浓缩过程中,不仅可以有效降低由重力浓缩释磷引起的磷积累量,且可同步实现减少由生产废水回流引起的氨氮积累量。     

Electrochemical oxidation of herbicide bifenox acid in aqueous medium using diamond thin film electrode

The electrochemical oxidation of bifenox acid was studied at a boron-doped diamond thin film by cyclic voltammetry and galvanostatic electrolysis. The course of the electrolysis was monitored by measurement of chemical oxygen demand (COD) and by gas chromatography/mass spectrometry (GC / MS) analysis. It was found that exhaustive electrolysis leads to degradation and, ultimately, to mineralization of the starting herbicide. The degradation intermediates were identified showing that the oxidation process begins with the fragmentation of the molecule followed by reactions involving the hydroxyl radical, which is generated by the discharge of water. The study of the effect of current density and concentration showed that the degradation efficiency increases with decreasing current densities and increasing concentrations. The whole results were interpreted in a mechanistic scheme involving two oxidation pathways, the first is a direct oxidation at the electrode and the second uses hydroxyl radical as mediator of the oxidation. Finally, a kinetic study based on spectrophotometric measurements showed that the degradation process is pseudo first order.     

高压实新疆阿尔泰膨润土微观结构随吸力变化特征

采用压汞法(MIP)和扫描电镜(SEM)法,在自由和侧限状态下,试验研究了高压实新疆阿尔泰膨润土在不同吸力条件下的微观结构变化特征。吸力的控制采用了气相法和渗析(液相)法。研究结果表明:(1)低吸力范围内,自由膨胀和侧限条件下的高压实膨润土土水特征存在明显差异;(2)膨润土在自由和侧限状态下的水化过程中呈现出了截然不同的微结构变化特征。自由膨胀条件下,土的吸水膨胀量主要来自土中大孔隙的逐渐膨胀。侧限状态下,随着控制吸力的降低,膨润土的大孔隙逐渐被压缩,较小孔隙的数量不断增加,土中孔隙分布变得更加均匀。     

Will photosynthetic capacity of aspen trees acclimate after long-term exposure to elevated CO2 and O3?

Photosynthetic acclimation under elevated carbon dioxide (CO₂) and/or ozone (O₃) has been the topic of discussion in many papers recently. We examined whether or not aspen plants grown under elevated CO₂ and/or O₃ will acclimate after 11 years of exposure at the Aspen Face site in Rhinelander, WI, USA. We studied diurnal patterns of instantaneous photosynthetic measurements as well as A/C_i measurements monthly during the 2004-2008 growing seasons. Our results suggest that the responses of two aspen clones differing in O₃ sensitivity showed no evidence of photosynthetic and stomatal acclimation under either elevated CO₂, O₃ or CO₂ + O₃. Both clones 42E and 271 did not show photosynthetic nor stomatal acclimation under elevated CO₂ and O₃ after a decade of exposure. We found that the degree of increase or decrease in the photosynthesis and stomatal conductance varied significantly from day to day and from one season to another.     

水体中常见无机阳离子对TiO2薄膜光催化还原Cr（Ⅵ）的影响

选择了6种水体中常见的阳离子（Na^＋、Mg^2＋、Ca^2＋、Al^3＋、Cu^2＋、Ni^2＋）,分别考查了其对TiO2薄膜光催化还原Cr（Ⅵ）的影响;从光吸收、无机离子本身的性质对光生电子的捕获及传递等讨论了上述离子影响TiO2薄膜光催化还原Cr（Ⅵ）的反应速率的原因。结果表明：由于其不能捕获光生电子,Na^＋、Mg^2＋、Ca^2＋本身对TiO2薄膜光催化还原Cr（Ⅵ）的反应速率影响不大;Al^3＋吸引电子能力较强,成为光生电子和Cr（Ⅵ）之间的桥梁,促进了Cr（Ⅵ）的还原;浓度为1 mmmol/L时,Cu^2＋显著地促进了Cr（Ⅵ）的光催化还原,其主要原因是Cu^2＋捕获光生电子的能力很强,起到了催化剂的作用,而浓度大于10 mmol/L时,Cu^2＋形成单质Cu以及对紫外光的吸收都使促进作用降低;Ni^2＋未充满的d轨道具有获得并传递光生电子的能力,也促进了Cr（Ⅵ）的还原;在浓度同为1mmol/L时,对Cr（Ⅵ）光催化还原的促进作用依次为：Cu^2＋〉Al^3＋〉Ni^2＋〉Na^＋、Ca^2＋、Mg^2＋。