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391.
本文采用顶空-固相微萃取-毛细管气相色谱联用技术测定了洗涤制品中二噁烷量,使用50μmPEG/树脂萃取头。顶空平衡温度为80℃,萃取时间为40min。使用石英毛细管柱:30m×0.32mm×0.4μmi.d.内壁涂有5%二苯基(95%)二甲基硅氧烷固定液。外标法定量,二噁烷测定结果的相对标准偏差(RSD)为9.33%;在0.35μg/g~120μg/g范围,色谱峰面积与质量浓度之间呈良好线性关系,线性相关系数(R)为0.9998;回收率为98.7%~102%。 相似文献
392.
393.
研究了用气相色谱法分离测定工业废气中乙酸乙酯、异丙醇、甲苯含量,进行了各种色谱条件选择、精密度、样品回收率、方法检出限及样品稳定性实验. 相似文献
394.
Jung Y Han B Mostafid ME Chiu P Yazdani R Imhoff PT 《Waste management (New York, N.Y.)》2012,32(2):297-304
Gas tracer tests can be used to determine gas flow patterns within landfills, quantify volatile contaminant residence time, and measure water within refuse. While gas chromatography (GC) has been traditionally used to analyze gas tracers in refuse, photoacoustic spectroscopy (PAS) might allow real-time measurements with reduced personnel costs and greater mobility and ease of use. Laboratory and field experiments were conducted to evaluate the efficacy of PAS for conducting gas tracer tests in landfills. Two tracer gases, difluoromethane (DFM) and sulfur hexafluoride (SF6), were measured with a commercial PAS instrument. Relative measurement errors were invariant with tracer concentration but influenced by background gas: errors were 1-3% in landfill gas but 4-5% in air. Two partitioning gas tracer tests were conducted in an aerobic landfill, and limits of detection (LODs) were 3-4 times larger for DFM with PAS versus GC due to temporal changes in background signals. While higher LODs can be compensated by injecting larger tracer mass, changes in background signals increased the uncertainty in measured water saturations by up to 25% over comparable GC methods. PAS has distinct advantages over GC with respect to personnel costs and ease of use, although for field applications GC analyses of select samples are recommended to quantify instrument interferences. 相似文献
395.
Chunmei Gong Jiajia Wang Congxia Hu Junhui Wang Pengbo Ning Juan Bai 《环境科学学报(英文版)》2015,27(8):184-196
C4 plants possess better drought tolerance than C3 plants. However, Hedysarum scoparium, a C3 species, is dominant and widely distributed in the desert areas of northwestern China due to its strong drought tolerance. This study compared it with Haloxylon ammodendron, a C4 species, regarding the interactive effects of drought stress and different leaf–air vapor pressure deficits. Variables of interest included gas exchange, the activity levels of key C4 photosynthetic enzymes, and cellular anatomy. In both species, gas exchange parameters were more sensitive to high vapor pressure deficit than to strong water stress, and the net CO2 assimilation rate (An) was enhanced as vapor pressure deficits increased. A close relationship between An and stomatal conductance (gs) suggested that the species shared a similar response mechanism. In H. ammodendron, the activity levels of key C4 enzymes were higher, including those of phosphoenolpyruvate carboxylase (PEPC) and nicotinamide adenine dinucleotide phosphate-malate enzyme (NADP-ME), whereas in H. scoparium, the activity level of nicotinamide adenine dinucleotide-malate enzyme (NAD-ME) was higher. Meanwhile, H. scoparium utilized adaptive structural features, including a larger relative vessel area and a shorter distance from vein to stomata, which facilitated the movement of water. These findings implied that some C4 biochemical pathways were present in H. scoparium to respond to environmental challenges. 相似文献
396.
为强化潮汐流人工湿地(TFCW)中基于亚硝化的全程自养脱氮(CANON)作用,探究了不同排水速率(vd)下系统中氮素的迁移转化机制与微生物特征.结果表明,vd可显著影响TFCW中脱氮功能微生物的数量与活性,进而影响其氮素转化速率.当vd由1.00降至0.50L/min时,填料层中逐渐形成较为严格的限氧环境,有利于短程硝化的稳定和厌氧氨氧化菌的富集,进而有助于CANON反应体系在TFCW中形成.而当vd小于0.50L/min时,填料层中溶解氧相对不足,好氧氨氧化菌活性受到抑制,数量随之减少,CANON作用的强化效果有限,系统脱氮性能受到影响.当vd为0.50L/min时,TFCW中的CANON作用可得到最大限度的强化,系统脱氮性能达到最佳,其TN和NH4+-N的去除负荷分别为(116.79±13.16)和(102.75±4.35) mg/(L·d).对vd的合理设置可实现TFCW中CANON作用的强化,有利于CANON型人工湿地的构建. 相似文献
397.
398.
Hideki Okamoto Yasushiro Gomi 《Journal of Loss Prevention in the Process Industries》2011,24(5):531-540
Chemical plants and gas utilities own large underground pipelines to transport material such as combustible gas. For example, city gas utilities in Japan have about 230,000 km of pipelines, even if only the pipelines to deliver gas to their customers are considered. Any accidents involving such pipelines can lead to enormous human and physical damage, and their security is therefore a top-priority issue for utilities. For the safety management of underground pipelines, in addition to assessment of the long-term reliability of pipeline materials, it is extremely important to understand the diffusion behavior of gases in the ground, such as the diffusion range and time, in the case of leakage, and the impact on the surrounding area is a fundamental factor to be considered in the design and maintenance of safe facilities and for emergency response. Although many papers introduce the situations of gas diffusion in the atmosphere such as indoor and outdoor conditions, only fundamental surveys have been conducted on gas diffusion in the ground, and there have been few full-scale empirical studies. This study reports the results of the verification of the diffusion behavior with full-scale gas leakage experiments simulating real underground pipelines, as well as the outcomes of the applicability test of a numerical simulation model investigated and proposed based on the results. This technical knowledge regarding security will contribute to further improvement of safety in the industry. 相似文献
399.
C.-L. ChaiX. Liu W.J. ZhangZ. Baber 《Journal of Loss Prevention in the Process Industries》2011,24(5):688-694
As a typical process industry, the Oil & Gas industries play a key role within a networked critical infrastructure system in terms of their interconnection and interdependency. While the tight coupling of infrastructures increases the efficiency of infrastructure operations, interdependency between infrastructures may cause cascading failure of infrastructures. The interdependency between critical infrastructures gives rise to an infrastructure network. In this paper, we apply social network analysis, an analytical tool used by social scientists, to study human interactions and to analyze characteristics of the critical infrastructure network. We identify Oil & Gas, Information & Communication Technologies (ICT), and Electricity as three infrastructures that are most relied upon by other infrastructures, thus these may cause the greatest cascading failure of the infrastructures. Among the three, we further determine that Oil & Gas and Electricity are the more vulnerable infrastructures. As a result, priority toward critical infrastructure protection should be given to the Oil & Gas and Electricity infrastructures since they are most relied upon but at the same time depend more on other infrastructures. 相似文献
400.