香溪河库湾浮游细菌和病毒计数方法比较研究

液氮速冻后转入-80℃保存是流式细胞仪计数浮游细菌及病毒的样品保存之标准条件.以荧光显微镜计数法为参照,利用流式细胞仪对温和冷冻保存(-20℃冷冻2周后转入-80℃保存)的香溪河库湾水样分别计数了浮游细菌和浮游病毒丰度.结果显示,利用流式细胞仪计数香溪河库湾水样中的浮游细菌丰度与荧光显微镜计数法等效(P>0.05);流...     

X射线荧光光谱分析法及其应用

由于X射线荧光光谱具有选择性高、干扰较小、分析样品不被破坏的特性,应用光谱分析是一种特效性、准确度和灵敏度都很好的一种定量分析方法,因此X射线荧光光谱被广泛应用于各大领域。主要介绍X射线荧光光谱的产生、基本原理和方法,以及在筛选电子电气设备中限制使用物质铅、汞、铬、镉和溴的应用,并对X射线荧光光谱发展进行展望。     

水中隐孢子虫的检测技术

本文着重评述了水中隐孢子虫卵囊的检测技术,具体介绍了EPA1622法和1623法、流式细胞计、荧光原位杂交、SPR生物传感器以及PCR等方法,并对其操作技术、检测周期、回收率、检测限、可靠性、敏感性、稳定性以及能否种类鉴别等方面进行了比较。笔者认为我国应致力于开展快速检测卵囊活性与传染性的研究;随着IMS、细胞分类法等纯化手段不断完善,PCR技术对研究水中隐孢子虫的检测将会有更广阔的发展空间。     

PXRF法测定土壤中铅的应用研究

当前测定土壤中铅的国标方法为石墨炉原子吸收分光光度法（GFAAS法）,准确度高但时效性差,如何快速测定是目前支撑土壤应急监测亟须解决的问题。采用GFAAS法与便携式X射线荧光光谱法（PXRF法）测定土壤中的铅,比对2种方法的差异,分析土壤应急监测应用PXRF法测定土壤中铅的可行性。实验结果表明,检出限、精密度和正确度均满足规范要求,且PXRF法测定标准样品和实际样品的精密度均优于GFAAS法,因此在土壤应急监测及初步监测中应用PXRF法测定土壤中的铅可行。     

放射性化学去污废水中铀浓度分析方法研究

介绍了一种用于测定放射性化学去污废水中铀浓度的方法:样品加水稀释后加热至近干以去除低沸点杂质,然后用硝酸溶液提取残渣中的铀,形成硝酸铀酰清溶液,硝酸铀酰离子在铀荧光增强剂的作用下能够产生单一的、具有很高荧光效率的络合物,此络合物在紫外光照射下产生荧光,荧光强度与样品溶液中的铀浓度成正比,采用标准加入法直接用微量铀分析仪测定样品溶液中的铀浓度,从而计算出化学去污废水中铀含量。本方法检出限为8.42×10-4mg/L,检测范围为1.5×10~(-3)~4.0mg/L,回收率在96%~106%之间;相对标准偏差优于5%。该方法用于放射性化学去污废水中铀含量分析,取得了满意的结果。     

各类固体表面处理及改性进展

表面改性,即对固体的表面进行处理,改变其表面性质,以达到我们需要的理想结果。研究表面性质的方法就是引入某种“探针”考察它与表面的相互作用,通过这种方法对改性前后的样品进行表征。现以催化剂载体表面、电极材料表面及塑料表面为例对表面改性的最新研究进展进行概述。     

开展课外科技活动的体会

一个合格的中专毕业生，除应有一定的理论知识外，在实验操作、动手能力及独立工作能力方面亦应具有相当水平。1997年秋，我们结合专业理论课的教学，组织毕业班部分同学成立了课外科技活动小组，对校区空气微生物进行了一次初步监测。我们将校区划分为七个不同的环境功能区（即学生宿舍、教室、实验室、食堂、足球场。厨房及厕所）；15个采样小区；44个采样点，每点每天采样两次，每个样4个平。（细菌、霉菌、高渗霉菌及对照W），培养48小时后，分别对细菌、霉菌进行菌落识另11和计数，对优势种进一步进行革兰氏染色和个体形态观察，最后…     

~(209)Po示踪法测定生物样品中~(210)Po的方法

经过同位素示踪实验,对生物样品中~(210)Po的分析方法进行了实验研究,主要关注了酸的种类和浓度对生物样品中~(210)Po消解效果,以及Po自沉积的实验条件。依据实验结果给出了推荐分析流程,并通过实际样品的测量对该方法进行了验证。该方法的全程放化回收率范围为79.6%~87.9%,平均值为(83.3±3.5)%。测量时间为48h时,该方法探测限为0.04Bq/kg。     

UPLC-DAD-FLD测定土壤中多环芳烃

本文建立了以加速溶剂萃取（ASE）和固相萃取为提取和净化手段,采用超速液相色谱-二极管阵列-荧光检测器（UPLC-DAD-FLD）串联捡测土壤中16种多环芳烃的方法。通过色谱柱的比较,选择更小粒径和内径的分析柱（Supelco SILTMLC．PAH,100×3．0mm,3μm）,缩短了分析时间,也节省了溶剂（乙腈）,满足大量样品的快速灵敏分析的需要。在保留时间定性的基础上,利用PDA获取的紫外扫描光谱图与目标化合物的特征吸收标准谱图比较,提高了定性分析的准确性。在优化的实验条件下,该方法显示出良好的线性关系（r〉0．999）和精密度（RSD〈10％）,16种多环芳烃的检出限在0．005—1．33μg／kg之间,并成功应用于样品分析,样品加标回收率为71．4％～120％。实验中为了确保整个分析过程的可靠性,替代物的加标回收率控制在50％-150％之间;土壤标准参考物的测定结果都在预测值范围内,验证了该方法的准确性。     

土壤中~(90)Sr快速分析方法初步研究

针对土壤中90Sr的快速分析方法进行了初步研究。借鉴总β的测量方式,将某核素迁移试验土壤样品直接铺至样品盘中进行β计数,结合样品的本底及探测效率,计算得到90Sr的活度浓度。与标准分析方法相比,两种方法所得测量结果间的相对标准偏差均控制在±15%以内,符合性较好,表明实验流程可以应用于此类样品90Sr的快速分析,满足应急情况下土壤中90Sr快速分析的要求。指出了该方法后续的研究方向,方法完善后可以应用于各类土壤样品中90Sr的快速分析。     

Microbial populations identified by fluorescence in situ hybridization in a constructed wetland treating acid coal mine drainage

Microorganisms are an integral part of the biogeochemical processes in wetlands, yet microbial communities in sediments within constructed wetlands receiving acid mine drainage (AMD) are only poorly understood. The purpose of this study was to characterize the microbial diversity and abundance in a wetland receiving AMD using fluorescence in situ hybridization (FISH) analysis. Seasonal samples of oxic surface sediments, comprised of Fe(III) precipitates, were collected from two treatment cells of the constructed wetland system. The pH of the bulk samples ranged between pH 2.1 and 3.9. Viable counts of acidophilic Fe and S oxidizers and heterotrophs were determined with a most probable number (MPN) method. The MPN counts were only a fraction of the corresponding FISH counts. The sediment samples contained microorganisms in the Bacteria (including the subgroups of acidophilic Fe- and S-oxidizing bacteria and Acidiphilium spp.) and Eukarya domains. Archaea were present in the sediment surface samples at < 0.01% of the total microbial community. The most numerous bacterial species in this wetland system was Acidithiobacillus ferrooxidans, comprising up to 37% of the bacterial population. Acidithiobacillus thiooxidans was also abundant. Heterotrophs in the Acidiphilium genus totaled 20% of the bacterial population. Leptospirillum ferrooxidans was below the level of detection in the bacterial community. The results from the FISH technique from this field study are consistent with results from other experiments involving enumeration by most probable number, dot-blot hybridization, and denaturing gradient gel electrophoresis analyses and with the geochemistry of the site.     

Sorption of phenol and 4-chlorophenol onto pumice treated with cationic surfactant

The anaerobic digestion rate for flocculated sludge has been considered to be lower than that of original sludge, particularly in the later stages of digestion; attributed this relatively slower rate to the increased mass transfer resistance for reactants through the large flocs after flocculation. This study confirmed that methane production was retarded by flocculation. The structure of the floc was identified with fluorescence in situ hybridization (FISH) and a confocal laser scanning microscope (CLSM) technique. To verify the mass transfer resistance induced by flocculation, microsensors were applied to assess the response of oxygen concentration distribution inside the flocs that are subjected to sudden changes in ambient oxygen levels. Response time for the electrode at a floc's center was five times greater than the response time in original sludge flocs. Although the effective diffusivity of oxygen in the floc increased by 2.3 times after flocculation, the increased size of the flocculated floc was the major contributor to the total mass transfer resistance to oxygen.     

Combining Flow Cytometry and Real-Time PCR Methodology to Demonstrate Consumption by Prymnesium parvum1

Bowers, Holly A., Andreas Brutemark, Wanderson F. Carvalho, and Edna Granéli, 2010. Combining Flow Cytometry and Real-Time PCR Methodology to Demonstrate Consumption by Prymnesium parvum. Journal of the American Water Resources Association (JAWRA) 46(1):133-143. DOI: 10.1111/j.1752-1688.2009.00397.x Abstract: Harmful algal bloom species can persist in the environment, impacting aquatic life and human health. One of the mechanisms by which some harmful algal bloom species are able to persist is by consumption of organic particles. Methods to demonstrate and measure consumption can yield insight into how populations thrive. Here, we combine flow cytometry and real-time PCR to demonstrate consumption of a cryptophyte species (Rhodomonas sp.) by a toxic mixotrophic haptophyte (Prymnesium parvum). Using flow cytometry, the feeding frequency of a population of P. parvum cells was calculated using the phycoerythrin (PE) fluorescence signal from Rhodomonas sp. and the fluorescence of an acidotropic probe labeling the food vacuoles. Feeding frequency increased in the beginning of the experiment and then began to decline, reaching a maximum of 47.5% of the whole P. parvum population after 212 min. The maximum number of consumed Rhodomonas sp. cells was 0.8 per P. parvum cell, and occurred after 114 min corresponding to an ingestion rate of 0.4 Rhodomonas sp. cells/P. parvum/h. Cells from the feeding P. parvum population were sorted, washed, and subjected to a real-time PCR assay targeting the cryptophyte 18S locus. There was a correlation between cycle threshold (Ct) values and number of consumed prey cells calculated by fluorescence. Overall, this study shows that flow cytometric analysis, of the acidotropic probe and prey pigments, is an efficient and rapid tool in enumerating food vacuoles and the number of prey cells consumed. Furthermore, we suggest that real-time PCR can be applied to cells sorted by flow cytometry, thus allowing for the detection and potential quantification of the targeted prey cells.     

Identification and quantitative evaluation of nitrogen-converting organisms in a full-scale leachate treatment plant

The presence of ammonia nitrogen in landfill leachates poses a significant problem for treatment plant operators. The nitrification-denitrification process mostly carries out the nitrogen conversion in biological treatment systems. However, recent research shows that other processes by anaerobic ammonia-oxidizing bacteria (Anammox) and ammonia-oxidizing archaea (AOA) were also responsible for the removal of nitrogen in biological systems. In this study, the nitrogen-converting microorganisms in the Bursa Hamitler Leachate Treatment Plant were identified and monitored by using molecular tools. Fluorescent in situ hybridization (FISH) and slot-blot hybridization results showed that the Nitrosomonas and Nitrospira species were the dominant ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB), respectively. Quantitative real-time PCR results indicated that AOB, NOB, AOA and Anammox bacteria exist in the leachate treatment plant. However, the removal of ammonia can be ascribed mainly to nitrification because AOB (1.5%) and NOB (11.3%) were predominant among all nitrogen-converting bacteria. The results of the phylogenetic analysis based on amoA and 16S rDNA gene revealed that the uncultured bacterium clone 4-24, Kuenenia stuttgartiensis genome fragment KUST_E and the uncultured Crenarchaeota clone NJYPZT-C1 belong to AOB, Anammox and AOA populations, respectively, and were the dominant species in their cluster.     

Electrochemical control of bacterial cell accumulation on submerged glass surfaces

 Accumulation of bacterial cells on a transparent electrode was controlled by applying an alternating potential. Live and dead cells on a transparent electrode can be distinguished as blue and red cells, by staining with two fluorescent dyes, propidium iodide (PI) and 4′, 6-diamidino-   2-phenylindole dihydrochloride (DAPI) and propidium iodide (PI), respectively. Cells of the gram-negative marine bacterium, Vibrio alginolyticus attached to an indium/tin oxide (ITO) electrode were killed by applying a potential of 1.1 V versus saturated calomel electrode in seawater. By applying –0.4 V, 73% of the cells on the ITO electrode were desorbed in 10 min. Changes in pH and generation of chlorine were not observed after applying potentials in the range of –0.4∼1.2 V. After 21 h of immersion in V. alginolyticus cell suspension with the application of an alternating potential of 1.1 and –0.4 V, cells on the electrode were completely killed and the cell number decreased to 20% of that of no potential. Elution of indium and tin was not observed after 10 days application of alternating potential. Received: 11 August 1998 / Accepted: 30 September 1998     

Monitoring of the microbial community composition in saline aquifers during CO2 storage by fluorescence in situ hybridisation

This study reveals the first analyses of the composition and activity of the microbial community of a saline CO₂ storage aquifer. Microbial monitoring during CO₂ injection has been reported. By using fluorescence in situ hybridisation (FISH), we have shown that the microbial community was strongly influenced by the CO₂ injection. Before CO₂ arrival, up to 6 × 10⁶ cells ml⁻¹ were detected by DAPI staining at a depth of 647 m below the surface. The microbial community was dominated by the domain Bacteria that represented approximately 60% to 90% of the total cell number, with Proteobacteria and Firmicutes as the most abundant phyla comprising up to 47% and 45% of the entire population, respectively. Both the total cell counts as well as the counts of the specific physiological groups revealed quantitative and qualitative changes after CO₂ arrival. Our study revealed temporal outcompetition of sulphate-reducing bacteria by methanogenic archaea. In addition, an enhanced activity of the microbial population after five months CO₂ storage indicated that the bacterial community was able to adapt to the extreme conditions of the deep biosphere and to the extreme changes of these atypical conditions.     

Analysis of the nitrifying bacterial community in BioCube sponge media using fluorescent in situ hybridization (FISH) and microelectrodes

There is growing interest in the development of more cost-effective and retrofit technologies for the upgrade and expansion of existing wastewater treatment plants with extreme space constraints. A free-floating sponge media (BioCube) process, using a 24L lab scale reactor, was operated to study the nitrification profiles and microbial community. The COD removal efficiencies were maintained, at an average of 95%, with the mixed liquor suspended solids (MLSS) inside the BioCube sponge media maintained at 12,688mg/L. The nitrification removal efficiencies were between 92% and 100%, with an average value of 99%. From the results of microelectrode measurements, the ammonium ion concentration was found to rapidly decrease from the surface of the BioCube sponge media to a depth of 2mm due to chemical reactions carried out by ammonia oxidizing bacteria (AOB) species. Multi-fluorescence in situ hybridization (FISH) has been used to investigate the spatial distributions of various microbial activities within reactors. Microbial communities were targeted using different oligonucleotide probes specific to AOB and nitrite oxidizing bacteria (NOB). There were a large number of AOB populations, but these were not uniformly distributed in the biofilm compared to the NOB populations.     

Sources, sinks, and exposure pathways of lead in urban garden soil

The chemistry of Pb in urban soil must be understood in order to limit human exposure to Pb in soil and produce and to implement remediation schemes. In inner-city gardens where Pb contamination is prevalent and financial resources are limited, it is critical to identify the variables that control Pb bioavailability. Field-portable X-ray fluorescence was used to measure Pb in 103 urban gardens in Roxbury and Dorchester, MA, and 88% were found to contain Pb above the USEPA reportable limit of 400 mug g(-1). Phosphorus, iron, loss on ignition, and pH data were collected, Pb-bearing phases were identified by X-ray diffraction, and Pb isotopes were measured using inductively coupled plasma mass spectrometry. Four test crops were grown both in situ and in Roxbury soil in a greenhouse, and plant tissue was analyzed for Pb uptake by polarized energy-dispersive X-ray fluorescence. Variation at the neighborhood scale in soil mineralogical and chemical characteristics suggests that the bioavailable fraction of Pb in gardens is site specific. Based on Pb isotope analysis, two historical Pb sources appear to dominate the inventory of Pb in Roxbury gardens: leaded gasoline ((207) Pb/(206) Pb = 0.827) and Pb-based paint ((207)Pb/(206) Pb = 0.867). Nearly 70% of the samples analyzed can be isotopically described by mixing these two end members, with Pb-based paint contributing 40 to 80% of the mass balance. A simplified urban human exposure model suggests that the consumption of produce from urban gardens is equivalent to approximately 10 to 25% of children's daily exposure from tap water. Furthermore, analysis of over 60 samples of plant tissue from the four test species suggests that in these urban gardens unamended phytoremediation is an inadequate tool for decreasing soil Pb.     

Applications of time-resolved laser fluorescence spectroscopy to the environmental biogeochemistry of actinides

Time-resolved laser fluorescence spectroscopy (TRLFS) is a useful means of identifying certain actinide species resulting from various biogeochemical processes. In general, TRLFS differentiates chemical species of a fluorescent metal ion through analysis of different excitation and emission spectra and decay lifetimes. Although this spectroscopic technique has largely been applied to the analysis of actinide and lanthanide ions having fluorescence decay lifetimes on the order of microseconds, such as UO , Cm, and Eu, continuing development of ultra-fast and cryogenic TRLFS systems offers the possibility to obtain speciation information on metal ions having room-temperature fluorescence decay lifetimes on the order of nanoseconds to picoseconds. The main advantage of TRLFS over other advanced spectroscopic techniques is the ability to determine in situ metal speciation at environmentally relevant micromolar to picomolar concentrations. In the context of environmental biogeochemistry, TRLFS has principally been applied to studies of (i) metal speciation in aqueous and solid phases and (ii) the coordination environment of metal ions sorbed to mineral and bacterial surfaces. In this review, the principles of TRLFS are described, and the literature reporting the application of this methodology to the speciation of actinides in systems of biogeochemical interest is assessed. Significant developments in TRLFS methodology and advanced data analysis are highlighted, and we outline how these developments have the potential to further our mechanistic understanding of actinide biogeochemistry.