北京西北城区与清洁对照点夏季大气PM10的微观特征及粒度分布

应用高分辨率场发射扫描电镜(FESEM)和图像分析技术研究了北京西北城区和清洁对照点非取暖期(2001年夏季)大气单个颗粒物的形貌特征以及PM₁₀和PM_2.5的数量-粒度和体积-粒度分布.研究表明,烟尘集合体在2个采样点都普遍存在,具有区域性污染的特征;不规则状矿物颗粒物多见于市区PM₁₀样品中,而长条状石膏颗粒多出现在清洁对照点颗粒物样品中;在清洁对照点还观察到了生物质颗粒.PM₁₀的数量-粒度分布呈双峰分布,主峰为0.2～0.5μm,次峰为在1～2.5μm但PM₁₀的体积-粒度分布呈单峰分布,在1～2.5μm粒度范围内.综合分析得出,虽然粗颗粒,主要是矿物颗粒,在数量上对PM₁₀贡献很小,但是对总体积,因此对总质量的贡献可能很大但在PM_2.5中,烟尘集合体在数量和体积上均占优势.  

镉、铅在玉米幼苗中的积累和迁移--X射线显微分析

用扫描电镜-X射线能谱仪及原子吸收分光光度计,测定经不同浓度镉、铅处理的玉米根、叶中镉、铅的积累。结果表明,铅的积累为皮层>中柱;木质部薄壁组织>导管。镉则相反。铅主要以非共质体途径在根内横向迁移,镉主要以共质体途径在根内横向迁移。原于吸收分光光度计测定表明,镉、铅主要在玉米根内沉积,镉铅复合作用促进了玉米根叶对镉、铅的吸收,镉比铅更易为玉米吸收且更易从根向叶迁移。  

北京城区可吸入颗粒物(PM10)的矿物学研究

使用X射线衍射技术(XRD)和扫描电镜技术(SEM/EDX)对北京PM10中的矿物组分进行了分析.结果表明,北京PM10中的矿物组分存在明显的季节变化规律,春季PM10中的矿物组成种类最多;秋季PM10中的矿物种类最少;在夏季PM10中,矿物的种类有所减少,却有新的物种出现,如NH4Cl、K(NH4)Ca(SO4)2?H2O、As2O3?SO3等.粘土矿物是北京PM10中含量最高的矿物,石英的含量次之,其他依次为方解石、石膏、长石、白云石以及其他矿物颗粒;北京PM10中还存在一定数量的复合颗粒,颗粒表面常有S、Cl元素的存在.  

枣庄市大气颗粒物扫描电镜分析和来源识别

应用扫描电镜-X射线能谱对枣庄市大气颗粒物进行定性分析，得出如下结论：（1）枣庄市大气颗粒物中含有燃煤颗粒、土壤颗粒、水泥颗粒、汽车尾气颗粒、石膏颗粒、植物残体颗粒和未知颗粒；（2）依据颗粒粒数百分比统计结果。得出枣庄市大气颗粒物以水泥颗粒、土壤颗粒和燃煤颗粒为主，汽车尾气颗粒和其它颗粒含量很少；（3）对枣庄市大气颗粒物平均粒径进行统计，得出枣庄市大气颗粒物平均粒径集中分布在2．5μm～20岬范围内，其粒数百分比在80％以上。  

北京市沙尘天气中矿物单颗粒的物理化学特征

应用场发射扫描电子显微镜和X射线能谱仪,研究了2005年4月北京市区2次典型沙尘天气PM10样品中矿物单颗粒的形貌、数量-粒度分布和化学组成.研究表明:沙尘天气样品中的矿物颗粒呈边缘锋利的不规则状;数量-粒度分布在1.0～1.5 μm出现明显的峰值.根据X射线能谱的定量数据,将721个矿物单颗粒分为7类.沙尘天气样品中的矿物颗粒主要以硅铝酸盐和石英矿物为主,并且有富Ca颗粒出现.大部分颗粒是2种或更多种矿物的内部混合物.沙尘天气富Ca颗粒占矿物单颗粒总数的5.9%,主要以CaCO3以及硅铝酸盐或石英的混合物的形式存在;非沙尘天气样品中富Ca颗粒含量高达14.5%,其中约有一半来自人为源排放.单个矿物颗粒中Ca含量以及m(Ca)/m(Al)可以用来区分外来沙尘源与本地矿物颗粒.  

环境扫描电镜对废水生物样品形态结构的表征研究

 采用环境扫描电镜(ESEM)分析颗粒污泥和悬浮填料生物膜的微生物群落形态,并与扫描电镜(SEM)观察结果进行比较.结果表明,ESEM观察悬浮填料生物膜的适宜条件为样品台温度5℃,样品室汽压5.91×102Pa,相对湿度75%,加速电压15.00kV.观察颗粒污泥样品的适宜条件为样品台温度0℃,样品室汽压7.00×102Pa,相对湿度100%,加速电压10.00kV.表面存在的水滴凝聚和含水量高、结构脆弱的样品易因气压和入射电子束轰击收缩变形,是影响ESEM观察样品真实面貌的主要因素.悬浮填料生物膜的ESEM观察说明,相较于SEM,未经任何处理的载体生物膜样品在合适的ESEM条件下可得到的高放大倍数的清晰照片,能更真实的表征生物膜的微生物群落结构.含水量高、结构脆弱,承受能力差的颗粒污泥样品,则需要通过锇酸或者戊二醛等固定剂进行化学固定,降低ESEM的加速电压,并且尽量缩短观察时间,避免因气压和高速入射电子束的轰击而收缩变形,获得其原始形貌照片.  

常温ANAMMOX工艺运行性能及功能菌研究

 通过改变进水基质浓度,对以火山岩为填料的常温上向流厌氧氨氧化生物滤池在不同基质浓度下的脱氮性能进行了研究.借助显微镜、电镜(SEM)观察对滤池内的微生物形态进行了分析,利用变性凝胶电泳(DGGE)和克隆测序等微生物方法,对ANAMMOX种属进行了鉴定.试验结果表明,常温条件下,厌氧氨氧化滤池在高、低不同基质下都能够保持较高的脱氮效果,其中TN去除负荷最高能够达到2.99kgN/(m3×d),NH4+-N和NO2--N最高去除率分别能够达到99.4%和98.8%;显微镜、电镜观察显示:滤池下部的微生物种类更丰富,ANAMMOX菌在滤池的中部和上部的比例更高;16SrRNA克隆测序鉴定结果表明:滤池中的ANAMMOX菌为Candidatus Kuenenia stuttgartiensis,其对温度和基质浓度都有着较宽的适应性.  

Biofilm structure and its influence on clogging in drip irrigation emitters distributing reclaimed wastewater

Using reclaimed wastewater for crop irrigation is a practical alternative to discharge wastewater treatment plant effluents into surface waters.However,biofouling has been identified as a major contributor to emitter clogging in drip irrigation systems distributing reclaimed wastewater.Little is known about the biofilm structure and its influence on clogging in the drip emitter flow path.This study was first to investigate the microbial characteristics of mature biofilms present in the emitters and the effect of flow path structures on the biofilm microbial communities.The analysis of biofilm matrix structure using a scanning electron microscopy (SEM) revealed that particles in the matrix of the biofilm coupled extracellular polysaccharides (EPS) and formed sediment in the emitter flow path.Analysis of biofilm mass including protein,polysaccharide and phospholipid fatty acids (PLFAs) showed that emitter flow path style influenced biofilm community structure and diversity.The correlations of biofilm biomass and discharge reduction after 360 h irrigation were computed and suggest that PFLAs provide the best correlation coefficient.Comparatively,the emitter with the unsymmetrical dentate structure and shorter flow path (Emitter C) had the best anti-clogging capability.By optimizing the dentate structure,the internal flow pattern within the flow path could be enhanced as an important method to control the biofilm within emitter flow path.This study established electron microscope techniques and biochemical microbial analysis methods that may provide a framework for future emitter biofilm studies.  

城市雾天单个矿物颗粒物理和化学特征

应用场发射扫描电镜(FESEM)和带能谱的扫描电镜(SEM-EDX)对北京冬季雾天和正常天气下收集的4个样品进行研究.雾天中矿物颗粒的数量-粒度分布的峰值出现在0.1～0.3 μm和1～2.5 μm之间,并且发现雾天出现的二次矿物颗粒的数量百分含量(4.67%)高于正常天气条件(0.12%).单个矿物颗粒的EDX能谱显示,雾天和正常天气中单个矿物颗粒的主要化学成分有一定的差别,尤其是S元素.矿物颗粒分为9种不同类型:"富Si"、"富Ca"、"富S"、"富Fe""富Mg"、"富Al"、"富Ti"、"富K"和"富Cl",其中雾天"富Ca"中55%的颗粒含有Ca(50%±1.2%)和S(37%±1.6%),"富S"中72%的颗粒含有S(44%±1.5%)和Ca(33%±2%),说明了雾天中绝大部富集S的颗粒物中同时富集Ca,这在一定程度上说明了北京市大气中这些含Ca的碱性矿物对雾水酸性有一定的缓冲作用.雾天样品中S/Ca的平均比值为6.11,如果以冬季正常天气条件下S/Ca的均值0.73为背景值,雾天中S/Ca的比值是冬季正常天气的8倍,可见雾天中颗粒物表面的硫化现象相当严重,同时也显示出雾天SO2向硫酸盐的转化率比较高.  

Measurement of flow speed in the channels of novel threadlike structures on the surfaces of mammalian organs

There have been several reports on novel threadlike structures (NTSs) on the surfaces of the internal organs of rats and rabbits since their first observation by Bonghan Kim in 1963. To confirm this novel circulatory function, it is necessary to observe the flow of liquid through the NTS as well as the structurally corroborating channels in the NTS. In this article, we report on the measurement of the flow speed of Alcian blue solution in the NTSs on the organ surfaces of rabbits, and we present electron microscopic images depicting the cribrous cross-section with channels. The speed was measured as 0.3 ± 0.1 mm/s, and the flow distance was up to 12 cm. The flow was unidirectional, and the phase contrast microscopic images showed that the NTSs were strongly stained with Alcian blue. The ultrastructure of the NTSs revealed by cryo-scanning electron microscopy and high-voltage electron microscopy showed that (1) there were cell-like bodies and globular clumps of matter inside the sinus of the channel with thin strands of segregated zones which is a microscopic evidence of the liquid flow, (2) the sinuses have wall structures surrounded with extracellular matrices of collagenous fibers, and (3) there exists a cribriform structure of sinuses. To understand the mechanism for the circulation, a quantitative analysis of the flow speed has been undertaken applying a simplified windkessel model. In this analysis, it was shown that the liquid flow through the NTSs could be due to peristaltic motion of the NTS itself. Baeckkyoung Sung and Min Su Kim contributed equally to this work.