Decrease of NH4+-N by bacterioplankton accelerated the removal of cyanobacterial blooms in aerated aquatic ecosystem

We used aerated systems to assess the influence of the bacterioplankton community on cyanobacterial blooms in algae/post-bloom of Lake Taihu, China. Bacterioplankton community diversity was evaluated by polymerase chain reaction-denaturing gradient gel electrophoresis(PCR-DGGE) fingerprinting. Chemical analysis and nitrogen dynamic changes illustrated that NH4+-N was nitrified to NO2-N and NO3-N by bacterioplankton. Finally, NH4+-N was exhausted and NO3-N was denitrified to NO2-N, while the accumulation of NO2-N indicated that bacterioplankton with completely aerobic denitrification ability were lacking in the water samples collected from Lake Taihu. We suggested that adding completely aerobic denitrification bacteria(to denitrify NO2-N to N2)would improve the water quality. PCR-DGGE and sequencing results showed that more than 1/3 of the bacterial species were associated with the removal of nitrogen, and Acidovorax temperans was the dominant one. PCR-DGGE, variation of nitrogen, removal efciencies of chlorophyll-a and canonical correspondence analysis indicated that the bacterioplankton significantly influenced the physiological and biochemical changes of cyanobacteria. Additionally, the unweighted pair-group method with arithmetic means revealed there was no obvious harm to the microecosystem from aeration. The present study demonstrated that bacterioplankton can play crucial roles in aerated ecosystems, which could control the impact of cyanobacterial blooms in eutrophicated fresh water systems.     

我国东部冲积平原区水成土壤元素背景值地域分异规律

从气候条件、母质物质组成的差异以及河流上下游物质之间的联系等角度，讨论了我国东部冲积平原区土壤中１３种元素的地理分布趋势及影响因素。研究表明，大多数元素具有明显的南北向地域分布趋势，这种趋势是地带性和非地带性因素共同决定的，而以非地带因素更重要。此外，东部平原土壤与相应主要河流上游侵蚀区土壤微量元素含量具有很好的共轭关系。     

磷酸铵镁沉淀法预处理垃圾渗滤液

探讨了用磷酸铵镁沉淀法预处理垃圾渗滤液时,沉淀剂种类、pH值、物质摩尔配比和反应时间等因素对氨氮去除效果的影响。得出了处理氨氮浓度为2 677.34 mg/L的垃圾渗滤液时,在兼顾所用镁盐量尽量低和处理出水氨氮或磷酸盐的残留量都比较低的较佳实验条件为:沉淀剂种类为:MgSO4.7H2O和Na2HPO4.12H2O,反应时间为20 min,pH=9.5,n(Mg)∶n(P)∶n(N)=1.3∶1.15∶1.0。在较佳实验条件下,垃圾渗滤液的NH3-N去除率为97.05%,处理出水PO34--P含量为8.35 mg/L,NH3-N含量为75.86 mg/L。对所得沉淀物进行了成分分析和X-衍射光谱、扫描电镜表征,表明大部分沉淀物为磷酸铵镁物质。     

吹扫捕集气质联用测定水中嗅味物质的研究

文章建立了一种用吹扫捕集—气相色谱质谱联用技术测定饮用水中土臭素(GSM)和二甲基异冰片(2-MIB)等嗅味物质的分析方法,确定了最佳的色谱条件、质谱条件和水样处理方法。当取样量为25mL时,回收率分别为96%和89%,RSD<10%,检出限为0.002mg/L。     

The role of doped-Mn on enhancing arsenic removal by MgAl-LDHs

To meet the challenges posed by global arsenic water contamination, the MgAlMn-LDHs with extraordinary efficiency of arsenate removal was developed. In order to clarify the enhancement effect of the doped-Mn on the arsenate removal performance of the LDHs, the cluster models of the MgAlMn-LDHs and MgAl-LDHs were established and calculated by using density functional theory (DFT). The results shown that the doped-Mn can significantly change the electronic structure of the LDHs and improve its chemical activity. Compared with the MgAl-LDHs that without the doped-Mn, the HOMO-LUMO gap was smaller after doping. In addition, the -OH and Al on the laminates were also activated to improve the adsorption property of the LDHs. Besides, the doped-Mn existed as a novel active site. On the other hand, the MgAlMn-LDHs with the doped-Mn, the increased of the binding energy, as well as the decreased of the ion exchange energy of interlayer Cl⁻, making the ability to arsenate removal had been considerably elevated than the MgAl-LDHs. Furthermore, there is an obvious coordination covalent bond between arsenate and the laminates of the MgAlMn-LDHs that with the doped-Mn.     

污泥静态好氧发酵中堆体板结与通风的研究

为研究污泥静态好氧发酵中板结对强制通风和发酵进程的影响,降低通风能耗,基于理论研究确定了压降为强制通风风量的决定性因素,并通过实验获取不同发酵阶段和强制通风条件下的堆体通风量和抗剪强度数据,分析堆体内板结的形成规律,通过计算验证板结的形成和消失对通风的影响,提出了需要改善通风的时间节点;然后基于风机的变频控制研究了风机功率变化对强制通风的影响。提出的通风解决方案采用阶段变频通风,实现了堆体温度和通风风量的有效控制。     

河流枯水流量特征研究

本文以泾、洛、渭三河流干流在陕西境内的主要控制断面为例,分析了１４个时段枯水流量的概率分布特征,选定了理论分布线型,揭示了各枯水序列的时段平均流量均值、变差系数和偏态系数的变化规律,建立了推求不同频率不同时段的枯水流量的经验公式。绘制了相应的关系曲线,应用十分方便。     

Seasonal variation and size distribution of biogenic secondary organic aerosols at urban and continental background sites of China

Size-resolved biogenic secondary organic aerosols(BSOA) derived from isoprene and monoterpene photooxidation in Qinghai Lake, Tibetan Plateau(a continental background site) and five cities of China were measured using gas chromatography/mass spectrometry(GC/MS). Concentrations of the determined BSOA are higher in the cities than in the background and are also higher in summer than in winter. Moreover, strong positive correlations(R2= 0.44–0.90) between BSOA and sulfate were found at the six sites,suggesting that anthropogenic pollution(i.e., sulfate) could enhance SOA formation,because sulfate provides a surface favorable for acid-catalyzed formation of BSOA. Size distribution measurements showed that most of the determined SOA tracers are enriched in the fine mode( 3.3 μm) except for cis-pinic and cis-pinonic acids, both presented a comparable mass in the fine and coarse( 3.3 μm) modes, respectively. Mass ratio of oxidation products derived from isoprene to those from monoterpene in the five urban regions during summer are much less than those in Qinghai Lake region. In addition, in the five urban regions relative abundances of monoterpene oxidation products to SOA are much higher than those of isoprene. Such phenomena suggest that BSOA derived from monoterpenes are more abundant than those from isoprene in Chinese urban areas.     

Mercury adsorption characteristics of HBr-modified fly ash in an entrained-flow reactor

In this study, the mercury adsorption characteristics of HBr-modified fly ash in an entrained-flow reactor were investigated through thermal decomposition methods. The results show that the mercury adsorption performance of the HBr-modified fly ash was enhanced significantly. The mercury species adsorbed by unmodified fly ash were HgCl₂, HgS and HgO. The mercury adsorbed by HBr-modified fly ash, in the entrained-flow reactor, existed in two forms, HgBr₂ and HgO, and the HBr was the dominant factor promoting oxidation of elemental mercury in the entrained-flow reactor. In the current study, the concentration of HgBr₂ and HgO in ash from the fine ash vessel was 4.6 times greater than for ash from the coarse ash vessel. The fine ash had better mercury adsorption performance than coarse ash, which is most likely due to the higher specific surface area and longer residence time.     

Geochemical characteristics of rare earth elements in Wuhan section of the Yangtze River

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