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色谱柱长期使用后 ,峰会变宽 ,分离效果变差 ,洗脱太快或无法洗脱 ,柱压上升等一些异常现象。原因是 :1离子交换剂破损引起柱压上升 ,薄壳上的微粒脱落从而使峰变宽 ,碱性流动相的作用会使其离子交换容量下降进而保留时间缩短。2流动相或样品溶液中存在尘埃和微生物 ,会使柱端筛孔堵塞 ,压力上升。3离子交换剂表面有附着物 ,它主要是在样品溶液中所含的待测离子之外的杂质 ,不可逆地附着于离子交换剂的表面 ,使正常的离子交换反应无法进行。出现上述现象就应该除去粒状尘埃和有机污染物 ,进行充分清洗。离子色谱柱的干扰问题@敖雪桔$齐齐哈… 相似文献
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用U1tra-2320μm色谱柱分离,可避免溶剂对测定甲基丙烯酸甲酯的干扰。选择二硫化碳及甲醇作为溶剂,保证了测定有足够的灵敏度及精确度。 相似文献
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将一根使用年限已达十年以上的 DionexAS4 A分离柱和一根使用年限达五年的国产HPIC- SA4分离柱进行串联 ,测定了酸雨、地面水中阴离子 F-、Cl-、NO-2 、NO-3 和 SO2 -4 。结果表明 ,两根本来已无法有效分离某些阴离子的分离柱经串级使用后能够较好地分离测定这些阴离子 ,并能获得重现性和稳定性较好的数据 ,增大了测定线性范围。该法对于经费紧张而又有许多工作需要通过离子色谱法进行的单位具有参考意义。串级分离柱法在离子色谱中的巧用@郭岩$汕头市环境监测站!广东汕头515041
@邝键$汕头市环境监测站!广东汕头515041… 相似文献
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采用不锈钢柱(Φ4 6mm×150mm)对生化降解过程的硝化甘油进行高效液相色谱测定,并对实验结果进行了分析,为进一步深入研究提供了一定的指导。 相似文献
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环境中三甲胺的气相色谱测定 总被引:4,自引:0,他引:4
采用PEG20M30m×530μm弹性石英毛细管色谱柱分离,FID检测器检测。环境空气用水吸收,水样直接或顶空进样测定环境中的三甲胺。方法有较高的灵敏度和良好的线性关系,简便快速。 相似文献
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离子色谱预处理是离子色谱分析测定过程中必不可少的重要环节,只有通过正确的预处理才可能使测定结果准确无误。在多次实验分析和总结的基础上,提出精确的确定预处理量、次数与实验分析准确性的关系。在预处理柱内通过3倍柱体积以上的样品后,可以保证实验数据的准确性和精密度。为离子色谱的精确测定提供了可靠的操作依据与指导。 相似文献
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An important research area in life sciences is devoted to modeling, prediction, and dynamics of gene-expression patterns.
As clearly understood in these days, this enterprise cannot become satisfactory without acknowledging the role of the environment.
To a representation of past, present, and most likely future states, we also encounter measurement errors and uncertainties.
This paper surveys and improves recent advances in understanding the foundations and interdisciplinary implications of the
newly introduced gene–environment networks, and it integrates the important theme of carbon dioxide emission reduction into
the networks and dynamics. We also introduce some operational and managerial issues of practical working and decision making,
expressed in terms of sliding windows, quadrants (modules) of parametric effects, and navigating (controlling) between such effects and directing them. Given data from DNA microarray experiments and environmental records, we extract
nonlinear ordinary differential equations that contain parameters that have to be determined. For this, we employ modern (Chebychevian)
approximation and (generalized semi-infinite) optimization. After this is provided, time- discretized dynamical systems are
studied. A combinatorial algorithm with polyhedra sequences allows to detect the region of parametric stability. Finally,
we analyze the topological landscape of gene–environment networks with its structural (in)stability. By embedding as a module
and investigating CO2 emission control and figuring out game theoretical aspects, we conclude. This pioneering work is theoretically elaborated,
practically devoted to health care, medicine, education, living conditions, and environmental protection, and it invites the
readers to future research.
相似文献
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Burger J 《Environmental monitoring and assessment》2003,83(2):145-162
Increasingly public and governmental agencies are concerned aboutrevitalizing coastal environments. Understanding how the publicuses these areas, and what they see as the most important improvements to these regions is critical to their assessment andmanagement. Uses of three estuaries, and perceptions of possiblemanagement and restoration options, were examined for people whowere interviewed in the New York/New Jersey Harbor, Manasquan Inlet, and Barnegat Bay, New Jersey. Nearly 90% of the people interviewed listed pollution as New Jersey's most important environmental problem. Most people (68%) used the habitat for outdoor sports, but rated communing with nature, walking, and the provision of open `green' space as the most valued uses. Pollution prevention was the most often mentioned habitat improvement desired, and people rated removing pollution, cleaning up garbage, and creating more fish breeding habitat the highest. There were significant locational differences inhow people used the estuaries, and in how they thought they should be improved. People from Barnegat Bay ranked most uses higher than did people from elsewhere, while the people from Manasquan Inlet rated the importance of most remediation and restoration actions higher. Many of the improvements fall withinenvironmental management, including (rank order from high to low)creating more fish breeding habitat, improving native vegetation,improving habitat for birds, increasing plant diversity,improving habitat for butterflies, and enlarging adjacentmarshes. The data provide clear support for the importance ofthese coastal habitats for communing with nature and having open`green space' spaces, and for providing recreationalopportunities. To enhance their value, people want to removepollution and improve both the habitat quality and the educational and recreational facilities. 相似文献
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污水处理厂出水中主要离子和重点元素的浓度特征及去除效果会影响受纳水体的盐度、碱度等指标,从而影响河湖的生态服务功能,但是这方面的研究长期以来未得到充分关注。在陕西省全境选择51家城镇污水处理厂,测定进水和出水中的钾、钙、钠、镁、氟、氯和硫酸根离子,以及铁、锰、硼、钼、锶等重点元素的浓度。测定结果显示:陕西省城镇污水处理厂进水和出水中的阳离子以钠离子为主,其次是钙、镁离子,钾离子浓度最低;阴离子中,氯离子浓度最大,其次为硫酸根离子。就总离子浓度而言,陕北和关中地区污水处理厂进水的离子浓度普遍高于陕南地区。相关性分析结果显示:在污水处理厂进水中,钠、氟、氯、镁及硫酸根离子相互之间均呈现显著正相关关系;铁、锰在进水中没有表现出明显的相关关系,而在出水中呈现显著的正相关关系。污水处理厂仅能够处理污水中少量的氟、钾和镁离子。铁元素和锰元素在经过污水处理厂的处理后,浓度有所升高。此研究的研究结果可为河湖水化学组成管理决策提供参考。 相似文献
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Carlson PR Yarbro LA Madley K Arnold H Merello M Vanderbloemen L McRae G Durako MJ 《Environmental monitoring and assessment》2003,81(1-3):393-408
We examined the response of demographic, morphological, and chemical parameters of turtle grass (Thalassia testudinum), to much-higher-than-normal rainfall associated with an El Niño event in the winter of 1997–1998. Up to 20 inches of added rain fell between December 1997 and March 1998, triggering widespread and persistent phytoplankton blooms along the west coast of Florida. Water-column chlorophyll concentrations estimated from serial SeaWiFS imagery were much higher during the El Niño event than in the previous or following years, although the timing and magnitude of phytoplankton blooms varied among sites. Seagrass samples collected in 1997, 1998, and 1999 provided an excellent opportunity to test the responsiveness of Thalassia to decline and subsequent improvement of water quality and clarity in four estuaries. Using a scoring technique based on temporal responsiveness, spatial consistency, and statistical strength of indicators, we found that several morphological parameters (Thalassia shoot density, blade width, blade number, and shoot-specific leaf area) were responsive and consistent measures of light stress. Some morphological parameters, such as rhizome apex density, responded to declines and subsequent improvement in water clarity, but lacked the statistical discriminating power necessary to be useful indicators. However, rhizome sugar, starch, and the total carbohydrate concentrations also exhibited spatially and temporally consistent variation as well as statistical strength. Because changes in shoot density, as well as water clarity, affect rhizome carbohydrate levels, a composite metric based on Thalassia shoot density and rhizome carbohydrate levels together is probably more useful than either parameter alone as an indicator of seagrass health. 相似文献
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Fate Modelling of DEHP in Roskilde Fjord, Denmark 总被引:1,自引:0,他引:1
Patrik Fauser Jørgen Vikelsøe Peter B. Sørensen Lars Carlsen 《Environmental Modeling and Assessment》2009,14(2):209-220
The fate of di(2-ethylhexyl)phthalate (DEHP) is modeled in Roskilde fjord, Denmark. The fjord is situated near Roskilde, which
comprises 80,000 PE, various industries, a central wastewater treatment plant, and adjacent agricultural fields. Roskilde
fjord is thus a suitable recipient for studying the transport and fate of DEHP, which is used in a variety of different industries
and consumer products. Wastewater from households and industries is led to the local wastewater treatment plant, which leads
the effluent to the fjord. The sludge is partly stored and partly amended on an adjacent field. The model applied in the present
study is a simple box model coupling water and sediment compartments of the fjord with wastewater treatment plant effluent,
streams leading to the fjord, and atmospheric deposition. The fjord model comprises first-order degradation, adsorption, sedimentation,
vertical diffusion in the sediment, dispersive mixing in the water, and water exchange with the surrounding sea. Experimental
measurements of DEHP were made in the fjord water and sediment, in the wastewater treatment plant inlet and effluent, and
in streams and atmospheric deposition. The experimental data are used to calibrate the model. The model results show that
freshwater from streams is the predominant DEHP source to the fjord, followed by atmospheric deposition and effluents from
wastewater treatment plants. Sedimentation is the predominant removal mechanism followed by water exchange with the sea and
degradation. 相似文献
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Criteria and Indicators of Sustainable Forest Management 总被引:2,自引:0,他引:2
Hall JP 《Environmental monitoring and assessment》2001,67(1-2):109-119
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A geophysical seismic survey was conducted in the summer of 2001 off the northeastern coast of Sakhalin Island, Russia. The
area of seismic exploration was immediately adjacent to the Piltun feeding grounds of the endangered western gray whale (Eschrichtius robustus). This study investigates relative abundance, behavior, and movement patterns of gray whales in relation to occurrence and
proximity to the seismic survey by employing scan sampling, focal follow, and theodolite tracking methodologies. These data
were analyzed in relation to temporal, environmental, and seismic related variables to evaluate potential disturbance reactions
of gray whales to the seismic survey. The relative numbers of whales and pods recorded from five shore-based stations were
not significantly different during periods when seismic surveys were occurring compared to periods when no seismic surveys
were occurring and to the post-seismic period. Univariate analyses indicated no significant statistical correlation between
seismic survey variables and any of the eleven movement and behavior variables. Multiple regression analyses indicated that,
after accounting for temporal and environmental variables, 6 of 11 movement and behavior variables (linearity, acceleration,
mean direction, blows per surfacing, and surface-dive blow rate) were not significantly associated with seismic survey variables,
and 5 of 11 variables (leg speed, reorientation rate, distance-from-shore, blow interval, and dive time) were significantly
associated with seismic survey variables. In summary, after accounting for environmental variables, no correlation was found
between seismic survey variables and the linearity of whale movements, changes in whale swimming speed between theodolite
fixes, mean direction of whale movement, mean number of whale exhalations per minute at the surface, mean time at the surface,
and mean number of exhalations per minute during a whales surface-to-dive cycle. In contrast, at higher received sound energy
exposure levels, whales traveled faster, changed directions of movement less, were recorded further from shore, and stayed
under water longer between respirations. 相似文献
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欧盟臭氧(O3)监测与评价起步相对较早。对比中国和欧盟O3例行评价,欧盟在O3标准限值、保护对象、评价指标、评价时间尺度、参评点位类型的设定和选取,以及O3浓度与前体物排放量的关联性分析等方面,均对中国O3评价具有一定的借鉴意义。以2017—2020年石家庄市8个国控站点O3观测数据为分析案例,采用欧盟常用的日最大8 h滑动平均浓度(MDA8)第4高值,以及O3暴露指标SOMO35和AOT40等3项评价指标,开展了尝试性评价应用和浓度对比。对照欧盟O3评价指标应用经验,未来可考虑从兼顾两类功能区、丰富评价指标、扩展参评点位类型、纳入暴露影响评估、关联前体物排放变化等方面,进一步完善中国环境空气O3评价方式,以更好地发挥其对空气质量精细化管理的数据支撑作用。 相似文献
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Hale SS Miglarese AH Bradley MP Belton TJ Cooper LD Frame MT Friel CA Harwell LM King RE Michener WK Nicolson DT Peterjohn BG 《Environmental monitoring and assessment》2003,81(1-3):133-148
Understanding the ecology, condition, and changes of coastal areas requires data from many sources. Broad-scale and long-term ecological questions, such as global climate change, biodiversity, and cumulative impacts of human activities, must be addressed with databases that integrate data from several different research and monitoring programs. Various barriers, including widely differing data formats, codes, directories, systems, and metadata used by individual programs, make such integration troublesome. Coastal data partnerships, by helping overcome technical, social, and organizational barriers, can lead to a better understanding of environmental issues, and may enable better management decisions. Characteristics of successful data partnerships include a common need for shared data, strong collaborative leadership, committed partners willing to invest in the partnership, and clear agreements on data standards and data policy. Emerging data and metadata standards that become widely accepted are crucial. New information technology is making it easier to exchange and integrate data. Data partnerships allow us to create broader databases than would be possible for any one organization to create by itself. 相似文献