固体电解质SO_2（SO_3）传感器测定烟道气中的SO_2

本文论述了利用北京科技大学研制的固体电解质ＳＯ２（ＳＯ３）传感器对测定烟道气中的ＳＯ２进行的研究。利用该传感器测定烟道气中的ＳＯ２，其测量范围为：５０—１７０００ｍｇ／ｍ３，相对标准偏差小于４．０％。因而具有测量范围宽，精确度高以及稳定性好的特点。设计的试验样机的总体噪声和漂移小于１．０ｍｇ／ｍ３，同时具有体积小．重量轻和操作简单的特点。     

Development of a personal monitoring method for nitrogen dioxide and sulfur dioxide with Sep-Pak C18 cartridge sampling and ion chromatographic determination

Personal monitoring methods for the determination of hourly integrated concentrations of NO2 and SO2 in ambient air have been developed. Triethanolamine (TEA)-impregnated C18 Sep-Pak cartridges were used to collect NO2 and SO2 simultaneously. After sampling, NO2 and SO2 as their nitrite, nitrate, sulfite and sulfate analogues were stripped from the cartridges with a solution of 5% methanol in distilled, deionized water (DDW) and then determined by ion chromatography. Laboratory tests were conducted to evaluate the sampling rate, collection and recovery efficiencies, breakthrough volumes, absorption capacity, interference and sample stability on the cartridge during storage. NO2 and SO2 detection limits of 0.3 and 0.4 ppb respectively for 1 h samples were obtained. Recoveries for both NO2 and SO2 exceeded 85%.     

Chemical characteristics of aerosols and trace gas distribution over North and Central India

A field campaign on aerosol chemical properties and trace gases measurements was carried out along the Delhi-Hyderabad-Delhi road corridor (spanning about 3,200 km) in India, during February 1-29, 2004. Aerosol particles were collected on quartz and cellulose filters using high volume (PM(10)) sampler at various locations along the route (i.e., urban, semi-urban, rural, and forest areas) and have been characterized for major cations (Na(+), Ca(2+), Mg(2+), K(+), and NH (4) (+)), anions (Cl(-), NO (3)(-), and SO (4)(2-)), and heavy metals (Cu, Cd, Fe, Zn, Mn, and Pb). Simultaneously, we measured NO(2) and SO(2) gases. These species show large spatial and temporal variations. The ambient PM(10) concentration has been observed to be the highest (55 ± 4 μg m(-3)) near semi-urban areas followed by forest areas (48 ± 2 μg m(-3)) and in rural areas (44 ± 22 μg m(-3)). The concentrations of NO( x ) (NO(2)+NO) and SO(2) ranged from 16 to 69 μg m(-3) and 4 to 11 μg m(-3), respectively. Among anions, NO(3)(-) and SO(4) (2-) are the major constituents of PM(10). The urban and semi-urban sites showed enhanced concentrations of Fe, Zn, Mn, Cd, and Pb. This study provide information about atmospheric concentrations of various species in the northern to central India, which may be important for policy makers to better understand the air quality of the region.     

2017年厦门金砖会晤期间PM2.5的化学特征及来源

为了探讨厦门金砖会晤期间的排放控制措施以及天气形势对大气颗粒物污染特征的影响,于2017年8月10日至9月10日对厦门气态污染物、细颗粒物(PM2.5)中的水溶性离子以及有机碳(OC)、元素碳(EC)等主要化学成分开展了高时间分辨率的在线监测。根据空气质量管控措施和天气形势将研究期分为6个阶段。管控前、管控期Ⅰ(非台风)和管控期Ⅱ(非台风) PM2.5质量浓度分别为(33. 12±9. 48)、(30. 30±17. 00)、(16. 01±4. 71)μg/m^3。管控期Ⅰ(台风)和管控期Ⅱ(台风) PM2.5质量浓度分别为(12. 40±3. 73)、(12. 45±3. 28)μg/m^3。结果表明:管控期Ⅰ(非台风)阶段受静稳天气的影响,管控效果削弱,PM2.5质量浓度下降幅度小;台风对颗粒物质量浓度下降的影响比管控更显著。管控初期,PM2.5中二次无机离子的质量浓度下降明显;台风对碳质组分质量浓度的影响不如无机组分显著。PMF源解析结果表明,二次无机源是PM2.5主要来源,随着管控措施的实行,扬尘源的贡献从21%降低到6%,而机动车源的贡献降幅不明显。台风期间SO4^2-、NO3^-、SO2、NO2以及硫酸盐氧化比值(SOR)均明显低于非台风期间,氮氧化比值(NOR)反而升高。台风和非台风期间NOR的日变化特征一致,NOR与阳离子的相关性分析结果表明,台风或高风速海风期间NOR与Na^+呈现很强的正相关性,说明海盐粒子可促进NO2非均相反应生成NO3-。     

南通市PM2.5中水溶性离子季节分布特征

对南通市2016年12月-2018年10月大气污染季节分布特征进行了分析。结果表明,南通市ρ(PM2.5)和ρ(水溶性离子)为冬、春季高,夏、秋季低。春夏秋冬四季ρ(水溶性离子)占ρ(PM2.5)百分比分别为68.2%,70.6%,64.5%和74.5%,其中二次离子SNA(NO3-、SO42-和NH4+)占ρ(PM2.5)的百分比分别为63.1%,67.0%,59.3%和66.8%;ρ(NO3-)/ρ(SO42-)表明,移动源已成为南通市春、秋、冬季的主要污染源,四季均存在不同程度的二次转化,且SO2的转化率均大于NO2,NO2冬季转化率最大、夏季最小,SO2夏季转化率最大、秋季最小。南通市NO2转化为硝酸盐的主要形式是气相均相反应,非均相反应和均相反应对SO2转化为硫酸盐的贡献差异不大。     

Atmospheric aerosol concentration level and chemical characteristics of water-soluble ionic species in wintertime in Beijing,China

Total suspended particulate (TSP) samples were collected during wintertime from November 24, 1998 to February 12, 1999 in Beijing. Ionic species including Cl-, NO3(-), SO4(2-), Na+, NH4(+), K+, Mg2+ and Ca2+ were determined by Ion Chromatography (IC). The sum average concentration of all the determined ions accounted for 18.9% of the TSP concentration, and SO4(2-) appeared the dominant ion with an average concentration of 30.84 microg m(-3); the sum mass concentration of SO4(2-), NO3(-), Ca2+ and NH4(+) accounted for about 83.2% of all the eight ions measured. The study indicated that the chemical form of sulfate and ammonium varies with TSP concentration levels. During heavy pollution periods, the average TSP concentration was 0.66 mg m(-3), and the NH4(+)/SO4(2-) molar ratio was low (0.58). It indicated that sulfate may present as CaSO4 and (NH4)2SO4 x CaSO4 x 2H2O. When TSP concentration (average 0.186 mg m(-3)) was relatively low, the NH4(+)/SO4(2-) molar ratio was 1.94, close to the theoretical ratio of 2 of (NH4)2SO4. Under this condition (NH4)2SO4 is expected to exist as the major form of sulfate. When the TSP concentration level was medium (average 0.35 mg m(-3)), the NH4+/SO4(2-) molar ratio appeared an average value (1.27), (NH4)2SO4, (NH4)2SO4 x CaSO4 x 2H2O and CaSO4 are expected to be present in those aerosol particles. Meteorological conditions including wind speed and wind direction were related to the TSP concentration level.     

燃用蔗髓锅炉的硫平衡及二氧化硫排放分析

通过现场监测和调研数据,分析燃用蔗髓锅炉的硫平衡及SO 2排放情况。结果显示,烟气排放的SO 2主要来源于鲜蔗和回用洗布水中含有的硫。8个锅炉硫排放在线监测均值与手工监测均值相对偏差为3.76%~14.9%,表明结果一致性较好。蔗髓硫质量分数为0.01%~0.04%,蔗髓含硫折算后的SO 2值和在线监测SO 2值分别为22.1 mg/m 3~49.9 mg/m 3和43.9 mg/m 3~114.5 mg/m 3,说明鲜蔗和制糖工艺流程的共同影响使得燃用蔗髓锅炉排放烟气SO 2值偏高。     

A novel wet-scrubbing process using Fe(VI) for simultaneous removal of SO2 and NO

The objective of this work was to develop a novel wet-scrubbing process using Fe(VI) for the simultaneous removal of gaseous NO and SO(2). The oxidation of SO(2) and NO with Fe(VI) was studied in aqueous solution at alkaline pH (9.0-11.0). A stoichiometric molar ratio for NO and SO(2) oxidation with Fe(VI) was determined to be nearly 3.0. Sulfate and nitrate was identified as final products by ion chromatography from the reaction at pH 9.0-11.0. The feasibility of simultaneous removal of multiple gas pollutants with the continuous feeding of ferrate in lab-scale was investigated from the view of industrial application. It was found that the removal efficiency of NO and SO(2) was enhanced with the increase of Fe(VI) concentration, more than 90% NO removal efficiency and 100% SO(2) removal efficiency were achieved by wet-scrubbing process using Fe(VI) at room temperature and ambient atmosphere. The results demonstrate that Fe(VI) could be an effective wet-scrubbing agent for the simultaneous removal of NO and SO(2).     

Air Quality and Monitoring Strategy in the Helsinki Metropolitan Area, Finland

The Helsinki Metropolitan Area Council (YTV) is responsible for air quality monitoring in the Helsinki area. Air quality has been monitored periodically since the late 1950s. An automatic SO2 monitoring network was constructed in 1975 and TSP measurements were added in 1978. Since then the network has been expanded and currently five automatic multicomponent stations form the basis of the network monitoring SO2, NO, NO2, CO, PM10 and O3 concentrations. Manual TSP and PM10 measurements are also conducted. Mobile monitoring units are also being used as well as special measurement campaigns. The effects of air pollution on nature are studied in bioindicator monitoring. An air quality index is used in order to inform the public of the current air quality situation. Changes in air quality are reflected in monitoring strategy. SO2 concentrations have decreased in the past two decades. Annual averages in 1995 were at or below 5 µg/m3. Traffic is the major source for pollutants even though catalytic converters have lowered traffic emissions somewhat. The highest annual average NO2 concentration at an urban site was 49 µg/m3 in 1995, and there has been no clear change in NO2 levels. There has been a decreasing trend in CO concentrations. Maximum annual TSP and PM10 averages in 1995 were 92 and 32 µg/m3, respectively. The highest average lead concentration was 0.01 µg/m3. Elevated concentrations are experienced from time to time. During the spring daily TSP and PM10 concentrations can go up to around 300 and 150 µg/m3, respectively. This is caused by resuspension mainly due to street sanding. Also a major winter NO2 episode occurred in December 1995. The highest hourly NO2 concentrations reached 400 µg/m3.     

Estimation of the rate of increase in nitrogen dioxide concentrations from power plant stacks using an imaging-DOAS

The emission of nitrogen compounds from power plants accounts for a significant proportion of the total emissions of nitrogen to the atmosphere. This study seeks to understand the nature of chemical reactions in the atmosphere involving nitrogen, which is important in undertaking quantitative assessments of the contribution of such reactions to local and regional air pollution. The slant column density (SCD) of power-plant-generated NO(2) was derived using imaging differential optical absorption spectroscopy (I-DOAS) with scattered sunlight as a light source. The vertical structure of NO(2) SCD from power plant stacks was simultaneously probed using a pushbroom sensor. Measured SCDs were converted to mixing ratios in calculating the rate of NO(2) increase at the center of the plume. This study presents quantitative measurements of the rate of NO(2) increase in a rising plume. An understanding of the rate of NO(2) increase is important because SO(2) and NO(x) compete for the same oxidizing radicals, and the amount of NO(x) is related to the rates of SO(2) oxidation and sulfate formation. This study is the first to directly obtain the rate of NO(2) increase in power plant plumes using the I-DOAS technique. NO(2) increase rates of 60 and 70 ppb s(-1) were observed at distances of about 45 m from the two stacks of the Pyeongtaek Power Plant, northwest South Korea.     

烟道气中二氧化硫的干扰消除

烟道气中的二氧化硫干扰因素多，不容易测准．本文通过对比实验认为．影响采样精度和分析准确度的干扰因素有：（１）转子流量计的影响；（２）冷凝水对二氧化硫的吸附；（３）氮氧化物对测定的干扰。严格控制上述实验条件，即可得到准确的二氧化硫浓度值。     

Assessment of uncertainty of NO2 measurements by the chemiluminescence method and discussion of the quality objective of the NO2 European Directive

Hereafter, an assessment of the ability of the chemiluminescence method to measure ambient NO2 with an accuracy within 15%, as requested by the data quality objective of European directive 1999/30/CE, is presented. In general, uncertainty is evaluated using the response to reference materials or by means of inter-comparisons used to determine some statistics like repeatability, reproducibility and calibration bias. These are incomplete approaches and the method of the Guide to the Expression of Uncertainty in Measurement, advised by the Directive, should be preferred. In fact, even if it requires a large data set, it allows the relative influence of all possible sources of uncertainty to be studied. The extent of NO2 uncertainty is mainly dependent on the level of NO. It is decreased by NOx and the correlation between NOx and NO. Furthermore, the uncertainty budget reveals that the contribution of accuracy of calibration standard, linearity, converter efficiency and drift of the analyser between calibration checks to the overall uncertainty is less important than the contribution of interference, mainly humidity and PAN in rural areas. The relative expanded uncertainty of the NO2 hourly average exceeds 30% for NO2 concentrations lower than 40 microg m(-3). Nevertheless, the data quality objective of 15% is reached for 200 microg m(-3), the hourly limit value of the European directive. On the contrary, at the limit value on the annual average, 40 microg m(-3), the data quality objective is not met if NO is higher than 100 microg m(-3). However, the data quality objective could be reached by correcting the measurements with the bias due to interference.     

湿法脱硫后高湿烟气中SO3酸雾监测方法研究

利用三氧化硫(SO3)发生装置以及模拟烟气湿法脱硫系统,研究了烟气再热温度、恒温水浴温度、采样速率、冷凝管类型规格及吸收瓶个数等不同采样参数对SO3酸雾采集率的影响。结果表明,当烟气再热温度低于烟气酸露点时会导致SO3酸雾收集率下降,采用控制冷凝法采样时应使用大流量(10L/min)采样,冷凝管应选择外套长度为400 mm的蛇形螺旋冷凝管,并将冷凝管置于温度为65℃左右的恒温水浴中;用碱液吸收法采样时应串联3个吸收瓶后,使用小流量(1L/min)采样。烟气温湿度、二氧化硫(SO2)浓度以及烟气中共存组分等对碱性吸收法的采集影响较大,而对控制冷凝法几乎没有影响。因此确立了针对湿法脱硫后高湿烟气环境下SO3酸雾的监测方法为控制冷凝法更为适宜。     

Chemical trends in background air quality and the ionic composition of precipitation for the period 1980-2004 from samples collected at Valentia Observatory, Co. Kerry, Ireland

A major Irish study, based upon more than 8000 samples collected over the measurement period of 22 years, for sulfur dioxide (SO2-S), sulfate (SO4-S) and nitrogen dioxide (NO2-N) concentrations (microg m(-3)) within air, and the ionic composition of precipitation samples based on sodium (Na+), potassium (K+), magnesium (Mg2+), calcium (Ca2+), chloride (Cl-), sulfate (SO4-S), non-sea salt sulfate (nssSO4-S), ammonium (NH4-N), and nitrate (NO3-N) weighted mean concentrations (mg l(-1)), has been completed. For the air samples, the sulfur dioxide and sulfate concentrations decreased over the sampling period (1980-2004) by 75% and 45%, respectively, whereas no significant trend was observed for nitrogen dioxide. The highest concentrations for sulfur dioxide, sulfate and nitrogen dioxide were associated with wind originating from the easterly and northeasterly directions i.e. those influenced by Irish and European sources. The lowest concentrations were associated with the westerly directions i.e. for air masses originating in the North Atlantic region. This was further verified with the use of backward (back) trajectory analysis, which allowed tracing the movement of air parcels using the European Centre for Medium range Weather Forecasting (ECMWF) ERA-40 re-analysis data. High non-sea salt sulfate levels were being associated with air masses originating from Europe (easterlies) with lower levels from the Atlantic (westerlies). With the precipitation data, analysis of the non-sea salt sulfate concentrations showed a decrease by 47% since the measurements commenced.     

Combined Non-Catalytic Reduction of NOx and SO2 by Ammonia Liquor during Staged Fluidized-Bed Combustion

Emissions of NOx and SO2 were monitored in the presence of ammonia liquor in a 0.09 m2 and 2 m high stainless-steel fluidized-bed combustor. Experiments were carried out at 2 m/s fluidizing velocity, 40% excess air, and 870 °C bed temperature. Ammonia liquor with 7% ammonia by weight was injected into the freeboard of the combustor 52 cm above the distributor through a water-cooled injector. A 65 : 34 primary/secondary air ratio was maintained throughout the investigation. Approximately 70% of NO and 20% of SO2 was reduced at an NH3/NO molar ratio of 2 : 1, respectively. However, a higher reduction in SO2 emissions (62%) was achieved at a very high NH3/NO molar ratio of 7 : 1. These experiments showed that ammonia addition did have a significant effect in SO2 reduction if injected in an excess amount. The injection of ammonia liquor combined with staged combustion was found to be very effective in reducing NOx emissions. A reduction of about 50% was achieved at an NH3/NO molar ratio of 0.6 : 1 which is also coupled with a very low level of ammonia in the flue.     

南通市冬季PM2.5中水溶性离子污染特征

根据南通市2016和2017年冬季大气多参数站自动监测PM2.5数据和在线离子色谱分析仪Marga监测的PM2.5中水溶性离子数据,分析了南通市冬季PM2.5中水溶性离子污染特征。结果表明,南通市2016和2017年冬季,ρ(PM2.5)分别为58和54μg/m 3,均高出其年均值(14μg/m^3);ρ(水溶性离子)总占ρ(PM2.5)百分比分别为74.5%和74.3%;二次离子ρ(NO3^-、SO4^2-和NH4^+)占ρ(PM2.5)百分比分别为66.8%和66.6%;各水溶性离子占比大小依次为:NO3^-、SO4^2-、NH4^+、Cl^-、K^+、Na^+、Ca^2+、Mg^2+。对ρ(NO3^-)/ρ(SO 4^2-)分析表明,移动源已经成为南通市冬季的主要污染源,且呈逐年增强趋势。对氯氧化率和硫氧化率的分析表明,南通市冬季存在较明显的二次污染,SO2的转化程度大于NO2。除Na^+和Mg^2+外,其他离子与PM2.5均呈显著相关性,NO3^-、SO4^2-与NH4^+之间的相关系数最高,Cl^-与除Na^+外的所有阳离子均呈显著相关性。     

An analysis of spatial and temporal properties of daily sulfate, nitrate and chloride concentrations at UK urban and rural sites

Daily measurements of sulfate, nitrate and chloride in PM(10) have been made at three geographically separated UK sites over a three year period. Chloride shows a clear seasonal pattern with highest concentrations in winter, whilst sulfate and nitrate both show highest concentrations in the spring, apparently related to weather patterns. Spatial variability of both sulfate and nitrate is low in comparison to temporal variations, with high correlations of both species between all three sites, London (North Kensington), Harwell and Belfast, despite a geographic separation of 510 km. Both SO/SO(2) and NO/NO(x) ratios are considerably higher in summer than winter, reflecting a greater oxidising capacity of the atmosphere. SO(4)(2-)/NO(3)(-) ratios are higher in summer than winter, suggesting that aqueous phase oxidation of SO(2), expected to be most important in the winter months is not appreciably influencing production of sulfate aerosol, although greater dissociation of ammonium nitrate in summer may also play a role. Regression of concentrations at London, North Kensington with those from the proximate rural site of Harwell is interpreted as showing a similar effect of regional transport at the two sites and a small influence of local formation in the urban atmosphere or primary emissions, averaging 0.46 microg m(-3) of nitrate and 0.22 microg m(-3) of sulfate.     

Use of real-time sensors to characterise human exposures to combustion related pollutants

Concentrations of black carbon and nitrogen dioxide have been collected concurrently using a MicrAeth AE-51 and an Aeroqual GSS NO(2) sensor. Forty five sampling events with a duration spanning between 16 and 22 hours have collected 10,800 5 min data in Birmingham (UK) from July to October 2011. The high temporal resolution database allowed identification of peak exposures and which activities contributed the most to these peaks, such as cooking and commuting. Personal exposure concentrations for non-occupationally exposed subjects ranged between 0.01 and 50 μg m(-3) for BC with average values of 1.3 ± 2.2 μg m(-3) (AM ± SD). Nitrogen dioxide exposure concentrations were in the range 相似文献   

The evaluation of a low resolution fourier transform infrared (FTIR) gas analyser for monitoring of solvent emission rates under field conditions

The applicability of a low resolution (8 cm-1) Fourier transform infrared (FTIR) gas analyser with an absorption path length of 3 m was evaluated for the on-line monitoring of organic solvent mixture emissions in a flexographic ink manufacturing plant. The on-line monitoring revealed that the highest variations of solvent concentrations, up to three decades, occurred in the exhaust air. The FTIR analyser with a dynamic range of four decades covers well the concentration ranges typically found in the exhaust air and in the workroom air of ink manufacturing plants. The average emission rate of solvent mixture based on a sampling period of two days was 1.8 kg h-1 consisting of mainly ethanol (70%), ethyl acetate (15%) and propan-2-ol (11%). The detection limits of the analyser for the solvent compounds ranged from 0.3 to 4.3 mg m-3 and the measurement uncertainty was less than 10% in the concentration range of 8-15,000 mg m-3. These characteristics make the apparatus appropriate for most industrial hygiene applications. An FTIR spectrophotometer, equipped with an multipoint sampling unit, facilitates rapid identification of solvent components, real-time display of concentration data relevant to workroom air and environment monitoring as well as process control. Furthermore, the on-line concentration information enabled a rapid selection of representative sampling locations. The spectrophotometer is transportable, rugged and relatively simple to calibrate even in a hostile industrial environment.     

An indoor test campaign of the tomography long path differential optical absorption spectroscopy technique

In this study we validate the two-dimensional long path DOAS tomography measurement technique by means of an indoor experiment with well-known concentration distributions. The experiment was conducted over an area of 10 m x 15 m using one and two cylindrical polycarbonate containers of diameter 2 m, respectively, filled with NO2. The setup was realized with three of the multibeam instruments recently developed by Pundt and Mettendorf (Appl. Opt., 2005, in press), which allow the simultaneous measurement along at least four light paths each. The configuration consisted of twelve simultaneous light beams, 39 horizontal light paths in total, and 18 different cylinder positions inside the field. It was found that for the discretization and inversion technique shown here reconstructions of the concentration distributions from experimental data agree well with simulated reconstructions. In order to draw conclusions for atmospheric applications, numerical studies including instrumental errors were carried out. It was found that with the presented measurement setup it is possible to measure and reconstruct one or two NO2 plumes of 600 m diameter and average concentrations above 4.2 ppbv each, on a scale of 13.5 km2. Theoretical investigations show that it should be possible to localize and quantify 600 m diameter plumes of SO2 > 1.5 ppbv, H2CO > 6.3 ppbv, HONO > 3.2 ppbv, and ozone > 46.2 ppbv. Larger plumes can be measured with higher precision.