Comparison of passive and active sampling methods for the determination of nitrogen dioxide in urban air

Three different methods for sampling and determination of nitrogen dioxide in urban air are compared: an NO/NO_x-monitor and an active (pumped) and a passive sampling method. For the latter two methods, sodium iodide is used as absorbent. For weekly averages the results from the passive sampler are within 10–20% of the results for the two other methods in the concentration range 15–30 μg NO₂/m³. The detection limit for the passive sampler is 1 μg NO₂/m³ (7 days), the precision is 5% and the accuracy is estimated to 20%. The active iodide method agrees very well with the NO/NO_x-monitor. Compared on 24 h basis for a period of 3 months, covering a concentration range of 5–45 μg NO₂/m³, the deviation between the two methods is within 5%, and the absorption capacity of the iodide reagent is excellent as the breakthrough is below 1%. Received: 3 December 1996 / Revised: 11 March 1997 / Accepted: 15 March 1997     

Application of passive sampling technique in monitoring research on quality of atmospheric air in the area of Tczew,Poland

This paper presents the results of atmospheric air quality research in Tczew (adjacent to the Vistula River) on the content of BTEX compounds. procedure applied during the sampling of the analytes from the air used the passive sampling technique (diffusive passive sampler, Radiello^®). For determination of BTEX compounds in atmospheric air, two-stage thermal desorption technique combined with gas chromatography (TD-GC-FID) was applied.

Research was conducted from March to December 2011. The annual average concentration of benzene, toluene, ethylbenzene and total xylenes determined in atmospheric air for the monitoring period were: 0.87 μg m^–3, 2.9 μg m^–3, 1.3 μg m^–3 and 5.9 μg m^–3, respectively. In order to pre-identify potential sources of emissions of BTEX compounds, statistical analysis was carried out. This determined interactions between specified concentration levels of BTEX compounds in atmospheric air for the monitored area.     

A miniaturized active sampler for the assessment of personal exposure to nitrogen dioxide

A personalized, miniaturized air sampling system was evaluated to estimate the daily exposure of pediatric asthmatics to nitrogen dioxide (NO₂). The lightweight device (170 g) uses a sampling pump connected to a solid sorbent tube containing triethanolamine (TEA)-impregnated molecular sieve. The pump is powered by a 9 V battery and samples air over a 24 h period at a collection rate of 0.100 L/min. After exposure, the solid sorbent is removed from the tubes for spectrophotometric analysis (Griess Assay). The lower detection limit of the overall method for NO₂ is 11 μg/m³. The linearity, precision and accuracy of the sampler was evaluated. Different NO₂ concentrations generated in the laboratory (range: 50 to 340 μg/m³) were simultaneously measured by the TEA tube samplers and colocated continuous chemiluminescent NO_x analyzers (reference method). The coefficient of determination for the laboratory test derived from ordinary linear regression (OLR) was r ²=0.99 (y _OLR=0.94x−4.58) and the precision 3.6%. Further, ambient NO₂ concentrations in the field (range: 10–120 μg/m³) were verified with continuous chemiluminescent monitors next to the active samplers. Reweighted least squares analysis (RLS) based on the least median squares procedure (LMS) resulted in a correlation of r ²=0.68 for a field comparison in Riverside, CA (y _RLS=1.01x−0.94) and r ²=0.92 in Los Angeles, CA (y _RLS=1.31x−7.12). The precision of the TEA tube devices was 7.4% (at 20–60 μg/m³ NO₂) under outdoor conditions. Data show that the performance of this small active sampling system was satisfactory for measuring environmental concentrations of NO₂ under laboratory and field conditions. It is useful for personal monitoring of NO₂ in environmental epidemiology studies where daily measurements are desired.     

“Badge-type” passive sampler for monitoring ambient ammonia concentrations

A passive “badge-type” sampling device for the determination of gaseous ammonia was developed. The collection substrate is phosphoric acid. The sampler can be used for outdoor and indoor sampling of ammonia in the concentration range from 0.05 μg/m³ to 10 mg/m³. The performance was tested in the laboratory and in the field against an annualar denuder, a filter pack and an impinger technique. The intercalibration showed that the passive sampler compares very well with active samplers (r²=0.99; k=1.05). The average reproducibility of the sampler was 8%. Hence the badge sampler is well suited for the determination of ammonia in a wide range of concentrations and particularly for application under rural background conditions. The sampling rate of the device was calculated according to a simple multi-layer model.     

Laboratory and field measurements of a badge type passive sampler for the determination of ambient sulfur dioxide concentrations

The performance of a badge type passive sampler for the determination of sulfur dioxide is described. The trapping agent is triethanolamine. Analysis is performed by ion chromatography. Thus, the method allows the simultaneous detection of sulfur dioxide and nitrogen dioxide. The sampler was tested in the laboratory and in the field. The intercomparison with independent methods in the field showed very good agreement against two active sampling methods. Regression analyses (the results of the passive sampler always represent the y-axes) gave r² = 0.81 and k = 1.07 ± 0.01 for the intercomparison with an annular denuder technique and r² = 0.92 and k = 0.96 ± 0.01 for the intercomparison with a commercial fluorescence sulfur dioxide analyzer. The average reproducibility in the field was 7% (RSD). The detection limit was 0.18 μg SO₂/m³ for an exposure time of two weeks. Received: 9 February 1998 / Revised: 22 June 1998 / Accepted: 26 June 1998     

Laboratory and field measurements of a badge type passive sampler for the determination of ambient sulfur dioxide concentrations

The performance of a badge type passive sampler for the determination of sulfur dioxide is described. The trapping agent is triethanolamine. Analysis is performed by ion chromatography. Thus, the method allows the simultaneous detection of sulfur dioxide and nitrogen dioxide. The sampler was tested in the laboratory and in the field. The intercomparison with independent methods in the field showed very good agreement against two active sampling methods. Regression analyses (the results of the passive sampler always represent the y-axes) gave r² = 0.81 and k = 1.07 ± 0.01 for the intercomparison with an annular denuder technique and r² = 0.92 and k = 0.96 ± 0.01 for the intercomparison with a commercial fluorescence sulfur dioxide analyzer. The average reproducibility in the field was 7% (RSD). The detection limit was 0.18 μg SO₂/m³ for an exposure time of two weeks. Received: 9 February 1998 / Revised: 22 June 1998 / Accepted: 26 June 1998     

Design of air quality monitoring networks and its application to NO2 and O3 in Cordova, Spain

Air monitoring networks are necessary to assess air quality in order to reduce pollution to levels which minimise harmful effects on human health and the environment. This paper describes a method to design air quality monitoring networks for nitrogen dioxide and ozone and its application in Cordova, Andalusia, southern Spain. The city has a population of 325,453 inhabitants and traffic is its main source of air pollution. The first step of this method made it possible to determine from historical data that two control stations for NO₂ and one control stations for O₃ are necessary according to the legislation. Sampling campaigns with passive diffusion samplers at 81 sites were then carried out to obtain information on the pollution distribution in Cordova. The sampling campaigns in 2001–2002 revealed an average concentration of 19.5 μg/m³ for NO₂ with maximum values up to 28.6 μg/m³ in Cordova city centre. The average ozone concentrations were recorded downwind from the emission source, reaching 91.8 μg/m³; the average ozone value in Cordova was 65.3 μg/m³. After spatial interpolation of the obtained values with Geographical Information Systems, a selection of the best locations for the monitoring stations was made, in line with the macro- and microscale siting requirements of the European Directive 2008/50/EC on ambient air quality and cleaner air for Europe. A second sampling campaign with diffusive samplers was carried out in 2007 to control if the locations of the air quality assessment stations were still representative for their zone.     

Impact of rice crop residue burning on levels of SPM,SO2 and NO2 in the ambient air of Patiala (India)

Ground-based ambient air monitoring was conducted at five different locations in and around Patiala city (29°49′–30°47′N Latitude, 75°58′–76°54′E Longitude) in Northern India in order to determine the impact of open burning of rice (Oriza sativa) crop residues on concentration levels of suspended particulate matter (SPM), sulphur dioxide (SO₂) and nitrogen dioxide (NO₂). Covering sensitive, residential, agricultural, commercial and urban areas, sampling of these pollutants was organised during August 2006 to January 2007 and August 2007 to January 2008 casing two rice crop residue burning periods (October–November) using a high volume sampling technique combined with gaseous sampling systems. Gravimetric analysis was used in the estimation of total suspended particulate matter (TSPM) whereas SO₂ and NO₂ concentration was determined using spectrophotometer (Specord205, Analytikjena). Monthly average concentrations of SPM, SO₂ and NO₂ have shown significant up and down features at all the selected sampling sites during the study period. Monthly average concentrations (24 hour) of SPM, SO₂ and NO₂ varied from 100 ± 11 µg m^?3 to 547 ± 152 µg m^?3, 5 ± 4 µg m^?3 to 55 ± 34 µg m^?3 and 9 ± 5 µg m^?3 to 91 ± 39 µg m^?3. Substantially higher concentrations were recorded at the commercial area site as compared to the other sampling sites for all the targeted air pollutants. Levels of SPM, SO₂ and NO₂ showed clear increase during the burning months (October–November) incorporated with the effect of meteorological parameters especially wind direction, precipitation and atmospheric temperature.     

Comparative Analysis of Indoor Levels of Suspended Particulates and Nitrogen Dioxide a Few Hours later after an Asthmatic Attack

Suspended particulates （TSP） and nitrogen dioxide （NO2） are known respiratory irritants linked to asthma aggravation. This pilot study was designed to investigate the role of these pollutants on the frequency of asthmatic attack on two of the inhabitants of a household. The surveillance of TSP and NO2 in this household commenced a few hours later, after one of the occupants suffered an attack. The TSP load determination was done using a High Volume Gravimetric sampler and a light scattering method via a Haz-Dust 10 μm particulate monitor. Palmes Diffusion tubes for NO2 and a portable Crowcon Gasman toxic gas detector were utilized for NO2 screening. In the first day of monitoring in the living room, the in situ particulate sampler （Haz-Dust） recorded a mean TSP level of 26,000 μg·m^-3. A confirmatory test with the eight hour average Gravimetric sampler gave 25,833 μg·m^-3. With the use of the Gasman toxic gas detector for NO2, the NO2 concentration for the first few hours of sampling was lower than 188 μg·m^-3, the detection limit of this instrument. However, the exact NO2 concentrations for the 7 day monitoring after the attack were 27.50 μg·m^-3 （kitchen） and 12.03 μg·m^-3 （living room） as recorded by the Palmes diffusion tubes.     

Air quality monitoring network design to control nitrogen dioxide and ozone, applied in Malaga, Spain

Air monitoring networks are necessary to assess air quality in order to reduce pollution to levels which minimize harmful effects on human health and the environment. This paper describes a method to design or optimize air quality monitoring networks for nitrogen dioxide and ozone and its application in Malaga, a medium large city located in Andalusia, southern Spain, with traffic being the main source of air pollution. The completion of this method revealed that the old assessment network in Malaga was badly designed and made it possible to determine that one traffic-orientated and one background control station were necessary for NO₂ assessment in Malaga, as well as two control stations for O₃. First the number of stations necessary is obtained from historical data. Sampling campaigns with passive diffusion samplers at 74 sites were then carried out to obtain information on the pollution distribution in Malaga. The average concentrations found for NO₂ and O₃ were 22.8 μg/m³ and 64.3 μg/m³ respectively. Maximum values of up to 42.2 μg/m³ NO₂ were found in Malaga city centre and O₃ reached 91.5 μg/m³ downwind from the emission source. After spatial interpolation of the obtained values with Geographical Information Systems, a selection of the best locations for the monitoring stations was made, in line with the macro- and microscale siting requirements of the European Directive 2008/50/EC on ambient air quality and cleaner air for Europe.     

A smog chamber and modeling study of the gas phase NOx–air photooxidation of toluene and the cresols

An experimental and modeling study of irradiated toluene–NO_x–air, toluene–benzaldehyde–NO_x–air, and cresol–NO_x–air mixtures at part-per-million concentrations has been carried out. These mixtures were irradiated at 303 ± 1 K in a 5800-liter Teflon-lined, evacuable environmental chamber, with temperature, humidity, light intensity, spectral distribution, and the concentrations of O₃, NO, NO₂, toluene, PAN, formaldehyde, benzaldehyde, o-cresol, m-nitrotoluene, and methyl nitrate beingmonitored as a function of time. For the toluene and toluene–benzaldehyde–NO_x–air runs a variety of initial reactant concentrations were investigated. Cresol–NO_x–air runs were observed to be much less reactive in terms of O₃ formation and NO to NO₂ conversion rates than toluene–NO_x–air runs, with the relative reactivity of the cresol isomers being in the order meta » ortho > para. The addition of benzaldehyde to toluene–NO_x–air mixtures decreased the reactivity, in agreement with previous studies. Alternative mechanistic pathways for the NO_x photooxidations of aromaticsystems in general are discussed, and the effects of varying these mechanistic alternatives on the model predictions for the toluene and o-cresol–NO_x–air systems are examined. Fits of the calculations to most of the experimental concentration–time profiles could be obtained to within the experimental uncertainty for two of the mechanistic options considered. In both cases it is assumed that (1) O₂ adds to the OH–toluene adduct ～75% of the time forming, after a further addition of O₂, a C₇ bicyclic peroxy radical, and (2) this C₇ bicyclic peroxy radical reacts with NO ～75% of the time to ultimately form α-dicarbonyls and conjugated γ-dicarbonyls (e.g., methylglyoxal + 2-butene-1,4-dial) and ～25% of the time to form organic nitrates. The major uncertainties in the mechanisms concern (1) the structure of the bicyclicperoxy intermediate, and (2) the γ-dicarbonyl photooxidation mechanism. Good fits to the o-cresol concentration–time profiles in the toluene–NO_x runs are obtained if it is assumed that o7-cresol reacts rapidly with NO₃ radicals. However, it is observed that the model underpredicts nitrotoluene yields by a factor of ～10, but this is in any case a minor product. It is concluded that further experimental work will be required toadequately validate the assumptions incorporated in the aromatic photooxidation mechanisms presented here.     

The mechanism of reduction of NO with H<Subscript>2</Subscript> in strongly oxidizing conditions (H<Subscript>2</Subscript>-SCR) on a novel Pt/MgO-CeO<Subscript>2</Subscript> catalyst: Effects of reaction temperature

Steady State Isotopic Transient Kinetic Analysis (SSITKA) experiments using on-line Mass Spectrometry (MS) and in situ Diffuse Reflectance Infrared Fourier-Transform Spectroscopy (DRIFTS) have been performed to study essential mechanistic aspects of the Selective Catalytic Reduction of NO by H₂ under strongly oxidizing conditions (H₂-SCR) in the 120–300°C range over a novel 0.1 wt % Pt/MgO-CeO₂ catalyst. The N-path of reaction from NO to the N₂ gas product was probed by following the ¹⁴NO/H₂O₂ → ¹⁵NO/H₂/O₂ switch (SSITKA-MS and SSITKA-DRIFTS) at 1 bar total pressure. It was found that the N-pathway of reaction involves the formation of two active NO _x species different in structure, one present on MgO and the other one on the CeO₂ support surface. Inactive adsorbed NO _x species were also found on both the MgO-CeO₂ support and the Pt metal surfaces. The concentration (mol/g cat) of active NO _x leading to N₂ was found to change only slightly with reaction temperature in the 120–300°C range. This leads to the conclusion that other intrinsic kinetic reasons are responsible for the volcano-type conversion of NO versus the reaction temperature profile observed.     

A review of: “Potential Industrial Carcinogens and Mutagens,Studies in Environmental Science 4 by Lawrence Fishbein,Little Rock,Arkansas, 534 pages,many figures and tables,linen, format 250 × 175 mm,printed by Elsevier Scientific Publishing Company,Amsterdam, The Netherlands 1979, 73.25 US$ or 150.-Df1.”

Abstract

The design and calibration of a passive sampler operating according to the diffusion principle and its application to the analysis of indoor air are described. Taking aliphatic and aromatic hydrocarbons as representative pollutants, it is demonstrated that at constant concentration, the amount of substance trapped by the sampler is a linear function of the time of exposure. An equation is given relating this amount of substance to the mean pollutant concentration. The detection limit is of an order of 300μg/(m³.h). For test gas atmospheres variation coefficients of between 5 and 10%, were determined for a 24-hour exposure in an atmosphere with concentrations of the individual hydrocarbons between 150 and 600 μg/m³.     

NOx-Sorbing Metal Oxides, MnOx–CeO2. Oxidative NO Adsorption and NOx–H2 Reaction

(n)MnO_x–(1?n)CeO₂ binary oxides have been studied for the sorptive NO removal and subsequent reduction of NO_x sorbed to N₂ at low temperatures (≤150 °C). The solid solution with a fluorite-type structure was found to be effective for oxidative NO adsorption, which yielded nitrate (NO^? ₃) and/or nitrite (NO^? ₂) species on the surface depending on temperature, O₂ concentration in the gas feed, and composition of the binary oxide (n). A surface reaction model was derived on the basis of XPS, TPD, and DRIFTS analyses. Redox of Mn accompanied by simultaneous oxygen equilibration between the surface and the gas phase promoted the oxidative NO adsorption. The reactivity of the adsorbed NO_x toward H₂ was examined for MnO_x–CeO₂ impregnated with Pd, which is known as a nonselective catalyst toward NO–H₂ reaction in the presence of excess oxygen. The Pd/MnO_x–CeO₂ catalyst after saturated by the NO uptake could be regenerated by micropulse injections of H₂ at 150 °C. Evidence was presented to show that the role of Pd is to generate reactive hydrogen atoms, which spillover onto the MnO_x–CeO₂ surface and reduce nitrite/nitrate adsorbing thereon. Because of the lower reducibility of nitrate and the competitive H₂–O₂ combustion, H₂–NO reaction was suppressed to a certain extent in the presence of O₂. Nevertheless, Pd/MnO_x–CeO₂ attained 65% NO-conversion in a steady stream of 0.08% NO, 2% H₂, and 6% O₂ in He at as low as 150 °C, compared to ca. 30% conversion for Pd/γ–Al₂O₃ at the same temperature. The combination of NO_x-sorbing materials and H₂-activation catalysts is expected to pave the way to development of novel NO_x-sorbing catalysts for selective deNO_x at very low temperatures.     

Effectiveness of nitric oxide ozonation

Attempts to develop new technologies of NO _x (NO + NO₂) emission reduction are still carried out all around the world. One of the relatively new approaches is the application of ozone injection into the exhaust gas stream followed by the absorption process. Ozone is used to transform NO _x to higher nitrogen oxides which yield nitric acid with better effectiveness. The main objective of this paper was to study the influence of mole ratio (MR) O₃/NO used in the ozonation process of NO _x on the effectiveness of NO _x oxidation to higher oxides. The ozonation process was carried out in a flow reactor for concentrations of nitric oxide in the range of 1.5 × 10⁻⁵−7.7 × 10⁻⁵ mol dm⁻³ and varying O₃/NO mole ratios. Measurements were conducted with the use of a FTIR spectrometer. The results obtained prove that for MR higher than 1, the oxidation effectiveness of nitric oxides generally reaches 95 %, whereas for MR higher than 2, oxidation of NO _x to higher nitrogen oxides is completed.     

An outdoor smog chamber and modeling study of toluene–NOx photooxidation

An experimental investigation of the gas-phase photooxidation of toluene–NO_x–air mixtures at part-per-million concentrations has been carried out in a 65-m³, outdoor smog chamber to assess our understanding of the atmospheric chemistry of toluene. In addition, six CO? NO_x–air irradiations were conducted to characterize the chamber with regard to any wall radical sources. Measured parameters in the toluene–NO_x experiments included O₃, NO, NO₂, HNO₃, peroxyacetyl nitrate (PAN), CO, toluene, benzaldehyde, o-cresol, m-nitrotoluene, peroxybenzoyl nitrate (PBZN), temperature, relative humidity, aerosol size distributions, and particulate organic carbon. Predictions of the reaction mechanism of Leone and Seinfeld [7] are found to be in good agreement with the data under a variety of initial conditions. Additional simulations are used to investigate various mechanistic pathways in areas where our understanding of toluene chemistry is still incomplete.     

Optimization of the design of air quality monitoring networks and its application to NO2 and O3 in Jaen,Spain

The assessment of air quality is necessary in order to control and reduce pollution to levels which minimise harmful effects on human health and the environment. This paper describes a method to design air quality monitoring networks for nitrogen dioxide and ozone and its application in Jaen (southern Spain). A fibre-glass filter impregnated with triethanolamine was used in diffusive sampling badges for NO₂ determination. For O₃ analysis, sodium nitrite was selected and nitrate, a product of the reaction of ozone and nitrite, was used to assess the ozone concentrations. Sampling campaigns with passive diffusion samplers at 62 sites were then carried out to obtain information on the pollution emissions in Jaen. The sampling campaigns in 2001–2002 revealed an average concentration of 10.4 μg/m³ NO₂ with maximum values up to 22.5 μg/m³ in Jaen City centre. The average ozone concentrations were recorded downwind from the emission source, reaching 96.2 μg/m³; the average ozone value in Jaen was 72.0 μg/m³. After spatial interpolation of the obtained values with Geographical Information Systems, a selection of the best locations for the monitoring stations was made, in line with the macro- and microscale siting requirements of the European Directive 2008/50/EC on ambient air quality and cleaner air for Europe. A second sampling campaign with diffusive samplers was carried out in 2005–2006 to control if the locations of the air quality assessment stations were still representative for their zone.     

臭氧氧化结合湿法喷淋对玻璃窑炉烟气同时脱硫脱硝实验研究

采用臭氧氧化结合湿法喷淋对模拟玻璃窑炉烟气开展了同时脱硫脱硝实验研究.采用不同溶液(NaOH、Na₂S)进行了喷淋实验.结果表明,保证溶液pH值在10以上,NaOH浓度对NO_x脱除效率无影响,SO₂的存在促进了NO_x吸收.当O₃/NO物质的量比为1.6、溶液NaOH浓度为0.5%时,NO_x脱除效率可达70%,SO₂脱除效率在99%以上.往喷淋液中添加Na₂S,NO_x脱除效率随Na₂S浓度增加而提高,SO₂的存在对NO_x脱除效率无影响.当O₃/NO物质的量比为1.2、溶液中NaOH浓度为0.5%、添加剂Na₂S浓度为0.6%时,NO_x脱除效率可达70%,SO₂脱除效率在95%以上.60 min长时间运行实验证明,模拟烟气中的NO_x经碱液和添加剂吸收后主要以NO^-₂的形式存在于喷淋液中,且NO_x脱除效率不随溶液pH值的变化而变化.     

Smog chamber study of H2O2 formation in ethene?NOx and propene?NOx mixtures

Hydrogen peroxide formation in the photooxidation of CO? NO_x, ethene? NO_x, and propene? NO_x mixtures has been determined in the TVA 31 cubic meter smog chamber under the following conditions: [NO_x] ca. 22–46 ppb; ethene = 0.22–1.1 ppm, [propene] = 0.12–0.97 ppm; [H₂O] ca. 8 × 10^?3 ppm. Ethene, propene, NO, NO_x, PAN, HCHO, and CH₃CHO were also monitored. Computer modeling was performed using the gas phase ethene and propene mechanism of the Regional Acid Deposition Model. There is good agreement between the model predicted and observed H₂O₂ concentrations. However, to successfully model all the propene? NO_x experimental results, organic nitrate formation from the reaction of peroxy radicals with NO must be included in the mechanism.