On-line analysis of urban particulate matter focusing on elevated wintertime aerosol concentrations

A 10-day winter sampling campaign was conducted in downtown Toronto for particulate matter (PM) air pollution in the fine (<2.5 microm) size range. An aerosol laser ablation mass spectrometer (LAMS), a tapered-element oscillating microbalance (TEOM), and an aerodynamic particle sizer (APS) were operated in parallel to characterize the PM on-line. In this study, the LAMS observed differences in the chemical composition between three separate episodes with higher PM2.5 mass and APS counts. LAMS results showed that in one instance of elevated PM, organic amines were present in the particulates. Temporal analyses of this episode revealed chemical transformations as the amines, characterized by m/z peaks 58(C3HeN)+, 86(C5H2N)+, and nitrates, increased in number concentration while Ca and hydrocarbon particle classes concurrently decreased. On another day, sulfates were found to have increased significantly. The third event was only 4 h in duration and exhibited an increase in the number of submicron-sized K/hydrocarbons and sulfate-containing particles. In this last event, the hydrocarbons and a K to Fe ratio enrichment indicated there was likely a contribution from a combustion source. This work offers some of the first insights into single particle size and chemistry in a cold winter climate.     

Concentrations and sources of VOCs in urban domestic and public microenvironments

Concentrations of 15 VOCs including 1,3-butadiene, benzene, and styrene were measured in a wide range of urban microenvironments, viz: homes, offices, restaurants, pubs, department stores, coach and train stations, cinemas, libraries, laboratories, perfume shops, heavily trafficked roadside locations, buses, trains, and automobiles. For most target VOCs-including 1,3-butadiene and benzene-mean concentrations at heavily trafficked roadside locations were exceeded by those in automobiles and were comparable to those in pubs and train stations. With regard to indoor-outdoor relationships in homes, this study revealed higher mean indoor concentrations, no correlation between simultaneously measured indoor and outdoor concentrations, and significantly different patterns of diurnal variation. Thus-in poorly ventilated buildings-indoor emission source strength is considered a more significant influence on VOC concentrations than infiltration of outdoor air. In the six smoking homes studied, environmental tobacco smoke (ETS) was found to make a substantial contribution to concentrations of 1,3-butadiene. This finding was based on the significantly higher concentrations detected in smoking compared to nonsmoking homes, the significant correlation between 1,3-butadiene concentrations and those of 3-ethenylpyridine (an ETS marker), factor analysis, and the results of a source apportionment exercise based on ratios of 1,3-butadiene to 3-ethenylpyridine.     

Comparing air dispersion model predictions with measured concentrations of VOCs in urban communities

Air concentrations of nine volatile organic compounds were measured over 48-h periods at 23 locations in three communities in the Minneapolis-St. Paul metropolitan area. Concentrations at the same times and locations were modeled using a standard regulatory air dispersion model (ISCST3). The goal of the study was to evaluate model performance by comparing predictions with measurements using linear regression and estimates of bias. The modeling, done with mobile and area source emissions resolved to the census tract level and characterized as model area sources, represents an improvement over large-scale airtoxics modeling analyses done to date. Despite the resolved spatial scale, the model did not fully capture the spatial resolution in concentrations in an area with a sharp gradient in emissions. In a census tract with a major highway at one end of the tract (i.e., uneven distribution of emissions within the tract), model predictions atthe opposite end of the tract overestimated measured concentrations. This shortcoming was seen for pollutants emitted mainly by mobile sources (benzene, ethylbenzene, toluene, and xylenes). We suggest that major highways would be better characterized as line sources. The model also failed to fully capture the temporal variability in concentrations, which was expected since the emissions inventory comprised annual average values. Based on our evaluation metrics, model performance was best for pollutants emitted mainly from mobile sources and poorest for pollutants emitted mainlyfrom area sources. Important sources of error appeared to be the source characterization (especially location) and emissions quantification. We expect that enhancements in the emissions inventory would give the greatest improvement in results. As anticipated for a Gaussian plume model, performance was dramatically better when compared to measurements that were not matched in space or time. Despite the limitations of our analysis, we found thatthe regulatory air dispersion model was generally able to predict space and time matched 48-h average ambient concentrations of VOC species within a factor of 2 on average, results that meet regulatory model acceptance criteria.     

On-line versus off-line NIRS analysis of intact olives

Visible/near-infrared calibrations were developed for the determination of the quality parameters (fat content, moisture and free acidity) of intact olive fruits. The reflectance spectra were acquired in two different instruments (diode-array versus grating monochromator based instruments). The grating monochromator based instrument was used at the laboratory (off-line analysis), whereas the portable diode-array based device was placed on top of a conveyor belt set to simulate measurements in an olive oil mill plant (on-line analysis). Partial least squares (PLS) regression and least squares support vector machine (LS-SVM) were used for the development of the calibration models. A total of 174 samples were prepared for the calibration (N = 122) and validation (N = 52) sets. The root mean square error of prediction (RMSEP) and the residual predictive deviation (RPD) values were better using the diode-array instrument and applying the PLS regression method for the fat content parameter while for the free acidity and moisture content, the LS-SVM algorithm gave the best results. The results obtained seems to suggest the viability of the on-line system, instead of the off-line analysis, for the determination of physicochemical composition in intact olives.     

氩气回路中杂质CO的在线分析方法

模拟正在建造的中国实验快中子反应堆的气体回路,建立了一个工程上可行的、有多条固定管线和阀门的50 m长快堆覆盖气体放射性氩气取样系统、计算机控制的阀门进样以及氩气中杂质CO的间断性在线分析方法.通过热导检测器出口气体可以排放入通风系统的办法,避免了使用氢火焰离子化检测器以后,放射性气体氩气扩散排放到气体分析实验室产生工作环境的放射性污染问题.其检测限、测量精度和准确度满足了中国实验快堆规定的氩气中杂质CO的分析要求,并达到了美国试验和材料协会(ASTM)在快堆覆盖气体杂质的标准中提出的分析氩气中杂质CO的标准要求.     

人为源VOC清单及重点工业贡献和治理分析

VOC的大量污染不仅不利于社会可持续发展,更为人们的生活和身体带来了严重的伤害,VOC治理问题迫在眉睫.基于此,本文以人为源VOC污染为研究对象,分析其污染特性,及人为源VOC清单排放特征,从整体排放、省份排放及地区排放特征对我国工业VOC排放的特征进行分析,结合当前所使用的人为源VOC治理的技术进行阐述.     

脱墨和造纸过程中可溶性物质的在线分析

该文介绍一种使用紫外吸收和电导率传感器的在线测量设备,测量造纸系统中无机和有机可溶性物质,并对其物质加以限制和控制,以减少生产障碍,提高产品质量.     

气体管路和手套箱氩气中微量水的在线分析

1:1地模拟金属钠冷反应堆的工程条件,建立了气体管路和手套箱氩气中微量水的分析方法.实验结果表明:当氩气中φ(H2O)≈3×10-4%时,测量的相对偏差<18%.在增压泵帮助下可以分析常压甚至微负压状况下手套箱内氩气中的微量水分.该方法完全满足了中国实验快中子反应堆CEFR对所使用氩气中微量水分的测量要求.     

VOCs fate and partitioning in vegetation: use of tree cores in groundwater analysis

Analysis of tree cores collected from contaminated sites has shown that concentrations of VOCs in cores are related to groundwater concentrations. However, initial research was highly qualitative. To better understand the relationship of groundwater VOC concentrations to measured VOCs in tree cores, detailed understanding of contaminant behavior in vegetation is required. Work presented here investigates the interaction, with focus on the chlorinated solvents trichloroethylene, 1,1,2,2-tetrachloroethane, and carbon tetrachloride. The sorption and desorption partitioning of these compounds between air and woody biomass were investigated. Partitioning coefficients were determined for cores of trunks of large trees and smaller stem cuttings. The internal partitioning of these compounds between the transpiration stream and the woody biomass within the tree was also determined for cores. The partitioning coefficients of the compounds between air, water, and biomass of tree cores and trunks were related to the physicochemical characteristics of contaminants, mainly the Henry's law constant and vapor pressure. These partitioning coefficients relate the contaminants' concentration in the bulk solution and analyzed headspace of vials and therefore can be utilized to quantify the fate of contaminants in natural settings and in phytoremediation systems. Tissue analysis and determination of partitioning coefficients may provide an effective way to estimate the concentration of compounds in the transpiration stream and in the soil or groundwater in a noninvasive, extremely rapid, and cost-effective manner.     

氩气中微量氧和水的在线分析

为了监测快堆正常运行工况下覆盖气体系统中氩气的质量状况，保证快堆安全运行，采用长距离固定管线取样、集中测量的方法实现对快堆氩气中微量氧和水的间断在线分析。实验结果表明：当氩气中水的体积比为6μL/L时，测量的相对偏差＜10％；当氩气中氧的体积比为10μL/L时，测量偏差为3％－9％；当氩气中氧的体积比为2μL/L时，测量偏差为24％－31％。不同测量时间的测量值扣除相应系统本底后其结果接近样气中水或氧的体积比，基本达到设计的技术指标要求。     

On-line detection of eggshell crack based on acoustic resonance analysis

An on-line system based on acoustic resonance was developed for eggshell crack detection. The system employed digital signal processing (DSP) as core processor to collect and analyze the response signal of shell eggs. The effects of excitation point, speed of the conveying system, impact intensity and egg mass on the frequencies response signals were investigated. Based on previous experiments, differences between the signals of intact eggs and cracked eggs were analyzed. Five excited resonance frequency characteristics expressing the differences between intact and cracked eggs were explored as input vectors. A simple and robust calibration model was built to discriminate intact and cracked eggs, while meeting speed requirement of on-line measurement. The identification rates for intact and cracked eggs were 100% and 96.1% respectively. It is concluded that the system has significant potential in the on-line detection of cracked eggs.     

活性染料色牢度的测试分析

棉织物用活性染料X型、KN型、K型染色,测试了这3类活性染料的色牢度,结论显示活性橙K-GN的耐洗色牢度、耐汗渍色牢度、耐摩擦色牢度、耐水浸色牢度、耐海水色牢度、耐斑滴色牢度和耐热水色牢度都是最好的。     

On-line1H-NMR to facilitate tube preparation in SNIF-NMR analysis

The detection of adulteration of wine by SNIF-NMR (site-specific natural isotopic fractionation-nuclear magnetic resonance) analysis of wine alcohol is a well established and widely used method. Quantitative deuterium ([²H]) NMR spectroscopy of defined distillate/tetramethylurea (TMU) mixtures enables the calculation of the site-specific deuterium/hydrogen ([²H]/H) ratios in the ethanol molecule. TMU with a known [²H]/H ratio serves as the internal standard. The comparison of the [²H]/H ratios of unknown samples with values obtained from authentic samples allows conclusions to be drawn, in terms of the origin of the sugar in the must before fermentation. Up to now, the calculation of [²H]/H ratios has required the exact weighing of both the distillate and the quantity of TMU for the tube preparation, as they affect²H-NMR measurements. The precise quantity of ethanol in the distillates must be determined by Karl-Fischer titration or densitometry. Volatile distillate components are quantified by gas chromatography to ensure a satisfactory purity of the ethanol under study. The quantitative¹H-NMR method described involves determining the TMU/ethanol mass ratios in the tubes prepared for SNIF-NMR measurements. This mass ratio is necessary for the calculation of the [²H]/H ratio. The mass ratios measured using conventional procedures and those determined by on-line¹H-NMR agree 100%. Using this method means that the exact weighing of distillates and TMU for tube preparation and the determination of ethanol content in the distillates are no longer required. At the same time, higher concentrations of volatile components in the distillates, e.g. methanol, can be easily detected.     

液体活性染料的水解性分析及水解控制

通过室温自然存放和升温强化观察体系pH值的变化，分析了液体活性染料水解的影响因素，探讨了控制液体染料水解的有效途经。pH调节剂和弱氧化剂可有效防止液体活性染料的水解。     

提高固定污染源VOCs废气治理效率的研究

随着国家工业化进程的不断发展,VOCs废气的排放问题也日渐凸显,给生态环境造成了极为不利的影响.为了给人们创造更加良好的环境条件,需要对VOCs废气实施治理.基于此,本文首先介绍了VOCs废气治理的关键性技术,研究了提高VOCs废气治理效果的相关措施,以期能够对VOCs废气治理工作的开展有所裨益.     

复合包装中VOCs的迁移模型

本文将复合包装材料的结构分为材料层、边界层、聚集层和材料分界层,分别讨论了VOCs在每层中的迁移过程,并依据VOCs在层到层间的迁移应遵循质量守恒的原理,获得了VOCs迁移的综合模型.进一步通过实验和模型拟合得到了VOCs的迁移规律,并发现VOCs的迁移量随着放置时间的增加而减少,并逐渐趋于平衡;VOCs的迁移率与温度有关,温度越高,VOCs的迁移率就越高.     

印刷材料VOCs含量测试简

挥发性有机化合物（VOCs）是主要的大气污染物,含有VOCs的印刷材料是印刷行业的污染源之一.本研究对印刷中使用的油墨、润版液、洗车水、胶黏剂、光油等主要原材料的VOCs含量进行测试比较,基于此,对各种印刷材料VOCs含量水平进行排序.测试结果表明,不同印刷方式所使用的油墨VOCs含量不同,凹印油墨的VOCs含量最多,溶剂型柔印油墨次之,单张纸胶印油墨相对较少;针对胶印印刷材料进行分析,润版液和洗车水是最主要的VOCs污染源,水性胶黏剂和光油的VOCs含量相对较小.因此,在制定相关的绿色印刷标准时应设立对印刷原材料VOCs含量的限值标准,以保证绿色印刷的准确评价和实施.     

环境烟草烟气中VOCs的GC分析

为研究环境烟草烟气(ETS)对室内空气的影响,建立了以Tenax TA、Carbosieve和Carbotrap三复合吸附剂作捕集剂,采用热脱附/气相色谱/火焰离子化检测法测定ETS中的1,3-丁二烯、异戊二烯、丙烯腈、苯、甲苯、苯乙烯、间二甲苯、乙苯、丙苯、1,3,5-三甲苯、柠檬烯的方法,并采用该方法测定了10种商品卷烟ETS中这11种VOCs的含量.结果显示:①Tenax TA、Carbosieve和Carbotrap三复合吸附荆适合ETS中这11种VOCs的捕集,适宜的采样流速200 mL/min、采样体积6 L、脱附温度300℃、脱附时间10 min;②方法的回收率为85.9%～98.3%,RSD 8.5%～16.8%,检测限0.28～1.58μg/m3,定量限为0.94～5.28μg/m3;③国产和进口卷烟之间、烤烟型卷烟和混合型卷烟之间ETS中这11种VOCs的含量差异不明显,且均是异戊二烯的含量最高.     

On-line, proximate analysis of ground beef directly at a meat grinder outlet

The fat, moisture and protein contents of ground beef were determined on-line by a diffuse reflectance near infrared (NIR) spectroscopy instrument at the outlet of a meat grinder. Beef samples in the range of 6.2–21.7% fat, 59.6–72.9% moisture and 18.1–20.7% protein were studied. Calibrations from samples ground with hole diameters of 4, 8, 13 or 19 mm in the grinder plate were validated. In addition, calibrations of combinations of these samples from the different hole diameters were validated. Prediction errors, expressed as root mean square error of cross validation of the beef samples, were 0.73–1.50% for fat, 0.75–1.33% for moisture and 0.23–0.32% for protein, depending on the hole diameter of the grinder plate. Calibrations from samples ground with the smallest hole diameters gave lowest prediction errors. The present prediction error results are only slightly higher compared to reported prediction error results using conventional at- and off-line NIR instruments.

It is concluded that the on-line NIR prediction results were acceptable for samples ground with grinder plates of 4, 8 or 13 mm hole diameter.