Arsenic biomethylation by photosynthetic organisms

Arsenic (As) is a ubiquitous element that is widespread in<br />the environment and causes numerous health problems.<br />Biomethylation of As has implications for its mobility and<br />toxicity. Photosynthetic organisms may play a significant<br />role in As geochemical cycling by methylating it to different<br />As species, but little is known about the mechanisms<br />of methylation. Methylated As species have been found in<br />many photosynthetic organisms, and several arsenite<br />S-adenosylmethionine (SAM) methyltransferases have<br />been characterized in cyanobacteria and algae. However,<br />higher plants may not have the ability to methylate As.<br />Instead, methylated arsenicals in plants probably originate<br />from microorganisms in soils and the rhizosphere.<br />Here, we propose possible approaches for developing<br />&lsquo;smart&rsquo; photosynthetic organisms with an enhanced<br />and sensitive biomethylation capacity for bioremediation<br />and safer food

A System Dynamics Approach for Local Settlement Morphology Planning Based on Household Consumption Carbon Footprint

<span style="line-height: 115%"><font size="3"><font face="Times New Roman">Energy consumption and greenhouse gas emission (GHG emission) from household consumption became increasingly important under the background of global urbanization. Taking Xiamen Island, a rapidly urbanizing area, as the case study area, this article categorized the settlement morphology of Xiamen Island into three types according to the key factors influencing the GHG emission of urban household consumption. The feedback loops intra- and inter-subsystems (settlement morphology, population, and carbon footprint) were induced by clarifying the causal relationship and feedback loops among variables. Then, the three subsystems were coupled based on feedback loops into the system dynamic model of carbon footprint of residential area in Xiamen Island and the validity of the model was verified. At last, the dynamic mechanism between the transition of settlement morphology and household consumption was characterized through the system dynamic simulation. The result proved that the model can dynamically characterized the effect of social and economic factors upon the household consumption carbon footprint, and is beneficial to the urban land planning of Xiamen Island and design and construction of residential settlement morphology.</font></font></span

城市污水厂污泥化学调理深度脱水机理

城市污水厂剩余污泥脱水是当前实际生产中亟待解决的问题。考察了厦门市集美污水厂剩余污泥经FeCl3和CaO,投加量分别为污泥质量分数的0.5%～0.7%和1.0%～1.5%化学调理前后污泥粒度、形态及胞外聚合物（extracellular polymeric substances,EPS）的变化。结果表明,调理后污泥比阻降低86%,污泥颗粒之间细碎紧密,细菌表面变得粗糙,经板框压滤后含水率低于60%。由三维荧光光谱（three-dimensional emission and excitation matrixs,EEM）光谱分析可知,LB-EPS（loosely bound-EPS）同TB-EPS（Tightly bound-EPS）的荧光峰整体发生红移,出现位于IV区域的色氨酸类蛋白质荧光峰Ex/Em=313/380 nm。FeCl3和CaO的加入一方面破坏了污泥颗粒的细胞结构,使EPS大量溶出,细胞结合水变成表面吸附水;另一方面Fe3＋和CaO水解,中和污泥负电荷,通过压缩双电层作用破坏污泥胶体颗粒的稳定,去除表面吸附水,大幅提高了污泥的脱水性能,利于进一步板框压滤脱水。The excess sludge dewaterbility of municipal wastewater treatment plant （WWTP） is a key issue in practice. The excess sludge of Jimei WWTP was chemical conditioning by FeC13 and lime. The dosage was 0.5% -0.7% and 1.0% -I. 5% of sludge mass fraction for FeC13 and lime, respectively. The size distribu- tion, SEM and extracellular polymeric substances （EPS） changes of excess sludge were investigated before and after conditioning. After chemical conditioning, the specific resistance to filtration of sludge declined by 86%. The sludge particles crushed and bacterial surface became rough. The sludge cake moisture decreased below 60%. According to three-dimensional emission and excitation matrixs （EEM） results, the fluoresce peaks of LB -EPS （loosely bound-EPS） and TB-EPS （tightly bound-EPS） showed red movement and new peak Ex/Em = 313/380 nm was found. The floc structure was destroyed by FeC13 and lime, which made EPS released. The re- leased EPS enhanced the floc＇ s compressibility, forcing the internal water out of floe. Fe3 ~ and lime hydrolysis made the negative sludge charge neutralization, and the stability of sludge colloidal particles was destroyed by the effect of electric double layer compression. The surface attached water was removed, therefore, the dehydration property of excess sludge was enhanced obviously, which was favor for further sludge dewaterability by plate and frame filter press

景观元素视觉特性对其感知优先度的影响分析

作为环境影响评价中景观资源影响评价研究的基础，采用照片测试法对景观元素感知优先度进行研究，分析了景观元素的客观视觉特性对其感知优先度的影响． 结果表明: ①不同景观元素的感知优先度得分不同． ②景观元素感知优先度受到景观元素视觉特性的影响． 元素的相对面积、形状以及在视域范围内所处的位置都会影响人们对景观元素的感知． 相对面积较大、形状较规则、边界整齐且位于视域中下部的景观元素更易被识别，感知优先度得分相应较高． ③元素视觉特性对于景观元素感知优先度的影响随元素类别不同而有明显差别

Biogenic silver nanoparticles (bio-Ag0) decrease biofouling of bio-Ag0/PES nanocomposite membranes

Biofouling is a major problem for the application of membrane technology in water and wastewater treatment. One of the practical strategies to decrease biofouling is the use of advanced anti-biofouling membrane material. In this study, different amounts of biogenic silver nanoparticles (bio-Ag^{<font size="1">0</font>}) were embedded in polyethersulfone (PES) membranes, using the phase-inversion method. The effects of the bio-Ag^{<font size="1">0</font>} content on the structure of the membrane and its filtration performance were systematically investigated. The results demonstrated that silver-containing nanostructures were uniformly distributed on membrane surface. Bio-Ag^{<font size="1">0</font>} incorporation slightly increased the hydrophilicity of the PES membrane and increased the permeate flux. The anti-bacterial and anti-biofouling properties of the bio-Ag^{<font size="1">0</font>}/PES nanocomposites membrane were tested with pure cultures (<em>Escherichia coli</em> and <em>Pseudomonas aeruginosa</em>) and a mixed culture (an activated sludge bioreactor), respectively. The bio-Ag^{<font size="1">0</font>}/PES composite membranes, even with the lowest content of biogenic silver (140&nbsp;mg&nbsp;bio-Ag^{<font size="1">0</font>}&nbsp;m^{<font size="1">&minus;2</font>}), not only exhibited excellent anti-bacterial activity, but also prevented bacterial attachment to the membrane surface and decreased the biofilm formation during a 9 weeks test

Environmental contextualisation of potential toxic elements and polycyclic aromatic hydrocarbons in biochar

Nine dissimilar biochars, produced from varying feedstock at different pyrolysis temperatures, are appraised with respect to concentrations of potentially toxic elements, specifically, metals, metalloids and polycyclic aromatic hydrocarbons (PAHs). Concentrations of the metals and metalloids varied with the following ranges (mg kg(-1)): 0.02-0.94, Cd; 0.12-6.48, Cr; 0.04-13.2, Cu; 0.1-1.37, Ni; 0.06-3.87, Pb; 0.94-207, Zn and 0.03-0.27, As. &Sigma;(16)PAH concentrations (16 Environmental Protection Agency (EPA) PAHs) range between 0.08 mg kg(-1) to 8.7 mg kg(-1). Subsequent comparison with background soil concentrations, concentration applied to the regulation of composted materials (Publicly Available Specification (PAS 100)) and European Union (EU) regulations relating to the application of sewage sludge to agricultural land suggest low risk associated with the concentrations of PTEs observed in biochar. Collectively, results suggest that environmental impacts attributable to metals, metalloids and PAHs associated with biochar following its application to soil are likely to be minimal

城市污水厂活性污泥胞外聚合物的三维荧光特性分析

<p>对厦门5个城市污水处理厂活性污泥溶解性有机物SMP,松散型胞外聚合物LB-EPS和紧密结合型胞外聚合物TB-EPS的三维荧光光谱分析表明,SMP,LB-EPS和TB-EPS都有3个明显的特征峰,其中Peak A(Ex/Em=225～230/335～350nm)和Peak B(Ex/Em=275～280/330～350nm)都为类蛋白荧光物质,Peak C(Ex/Em=320～350/420～445nm)为腐殖酸类荧光物质.LB-EPS和TB-EPS荧光峰强度同其对应的TOC浓度有一定相关性.荧光强度综合指数FRI分析表明,微生物副产物更多的存在于TB-EPS中,其FRI总和同TOC浓度呈一定相关性.</p

Determination of global DNA methylation in biological samples by liquid chromatography-tandem mass spectrometry

DNA methylation is one of the most common epigenetic modifications. Global genomic DNA hypomethylation is<br />considered to induce chromosome instability and high incidence of genetic mutation, which is closely related to the emergence and<br />development of cancer. In this study, a method based on liquid chromatography-electrospray ionization tandem mass spectrometry<br />(LC-ESI-MS/MS) was developed to determine global DNA methylation ratios in various biological samples. DNA was extracted from the samples and hydrolyzed by three specific enzymes into single nucleosides. Liquid chromatography coupled to tandem mass<br />spectrometry was used to measure the concentrations of 2&rsquo;-deoxycytidine and 2&rsquo;-deoxy-5-methylcytidine respectively, so as to<br />calculate the global DNA methylation ratios. The developed method was further used to explore the global DNA methylation ratios in<br />normal human liver cell L-02 exposed to perfluorooctane sulfonate (PFOS) and plasma samples of 10 hepatocellular carcinoma<br />patients and 10 healthy participants as controls. This approach has high sensitivity and stability, and is easy to be operated, enabling<br />us to analyze the global DNA methylation ratios in various biological samples, especially those valuable samples (such as serum,<br />plasma et al.) with extremely low concentration of DNA

废砖块作为人工湿地填料的除磷能力研究

<span>对废砖块的物理化学特性进行了分析,并对其进行了磷素吸附能力试验,结果表明,废砖块适于湿地微生物的富集和植物的生长且具有较高的磷素吸附能力. 通过构建以废砖块为填料的垂直流人工湿地系统考察并初步探索了其对生活污水中磷素的去除效果和去除机制.结果表明,当水力负荷为5 cm&middot;d^-1、运行时间为1 a时,湿地系统除磷效率在90%以上,且效果稳定; 废砖块的吸附沉淀作用是湿地系统除磷的主要途径,而植物和微生物直接吸收所起的作用不大; 被截留磷素在湿地填料层中具有明显的空间特征,对废砖块中的无机磷形态分析结果表明,废砖块中能与磷素发生沉淀反应的元素含量和其在废砖块中的化学形态是影响其吸附沉淀磷素作用途径的重要因素. 因此,废砖块是人工湿地污水处理系统构建过程中较为理想的填料.</span><span>Physico-chemical properties of broken bricks (BB) were determined, as well as its phosphorus adsorption ability. The results showed that BB was appropriate for enrichment of microorganisms and growth of plants as filter medium in CWs, in addition, BB had high phosphorus adsorption ability. A vertical subsurface flow constructed wetland (VSSF) filled with BB was constructed in order to investigate the phosphorus removal effect of domestic sewage, and the phosphorus removal mechanism of VSSF was also explored. The results showed that the phosphorus removal rate of VSSF was more than 90%, which remained stable when the hydraulic loading rate was 5 cm&middot;d^-1 and the running time was 1 a; adsorption and precipitation within BB played the greatest role in phosphorus removal; distribution characteristics of total phosphorus in the filter media were attributed to the vertical flow state of wastewater in the system, besides, the contents and chemical forms of elements which could precipitate with phosphorus should be principal factors for the phosphorus removal processes of BB. Therefore, BB might be an ideal filter medium used in CWs.</span