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1
HEICKLEN, JULIAN. "The Formation and Inhibition of Photochemical Smog." Annals of the New York Academy of Sciences 502, no. 1 Environmental (1987): 145–59. http://dx.doi.org/10.1111/j.1749-6632.1987.tb37649.x.
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Lu, Haoxian, Xiaopu Lyu, Hairong Cheng, Zhenhao Ling, and Hai Guo. "Overview on the spatial–temporal characteristics of the ozone formation regime in China." Environmental Science: Processes & Impacts 21, no. 6 (2019): 916–29. http://dx.doi.org/10.1039/c9em00098d.
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Ozone (O<sub>3</sub>), a main component in photochemical smog, is a secondary pollutant formed through complex photochemical reactions involving nitrogen oxides (NO<sub>x</sub>) and volatile organic compounds (VOCs).
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Muilwijk, C., P. J. C. Schrijvers, S. Wuerz, and S. Kenjereš. "Simulations of photochemical smog formation in complex urban areas." Atmospheric Environment 147 (December 2016): 470–84. http://dx.doi.org/10.1016/j.atmosenv.2016.10.022.
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Madronich, S., M. Shao, S. R. Wilson, K. R. Solomon, J. D. Longstreth, and X. Y. Tang. "Changes in air quality and tropospheric composition due to depletion of stratospheric ozone and interactions with changing climate: implications for human and environmental health." Photochemical & Photobiological Sciences 14, no. 1 (2015): 149–69. http://dx.doi.org/10.1039/c4pp90037e.
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Sakamaki, Fumio, and Hajime Akimoto. "HONO formation as unknown radical source in photochemical smog chamber." International Journal of Chemical Kinetics 20, no. 2 (1988): 111–16. http://dx.doi.org/10.1002/kin.550200204.
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Grenfell, John Lee, Barbara Stracke, Beate Patzer, Ruth Titz, and Heike Rauer. "Potential of ozone formation by the smog mechanism to shield the surface of the early Earth from UV radiation." International Journal of Astrobiology 5, no. 4 (2006): 295–306. http://dx.doi.org/10.1017/s1473550406003478.
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We propose that the photochemical smog mechanism produced substantial ozone (O3) in the troposphere during the Proterozoic period, which contributed to ultraviolet (UV) radiation shielding, and hence favoured the establishment of life. The smog mechanism is well established and is associated with pollution hazes that sometimes cover modern cities. The mechanism proceeds via the oxidation of volatile organic compounds such as methane (CH4) in the presence of UV radiation and nitrogen oxides (NOx). It would have been particularly favoured during the Proterozoic period given the high levels of CH4 (up to 1000 ppm) recently suggested. Proterozoic UV levels on the surface of the Earth were generally higher compared with today, which would also have favoured the mechanism. On the other hand, Proterozoic O2 required in the final step of the smog mechanism to form O3 was less abundant compared with present times. Furthermore, results are sensitive to Proterozoic NOx concentrations, which are challenging to predict, since they depend on uncertain quantities such as NOx source emissions and OH concentrations. We review NOx sources during the Proterozoic period and apply a photochemical box model having methane oxidation with NOx, HOx and Ox chemistry to estimate the O3 production from the smog mechanism. Runs suggest the smog mechanism during the Proterozoic period can produce approximately double the present-day ozone columns for NOx levels of 1.53×10−9 by volume mixing ratio, which was attainable according to our NOx source analysis, with 1% of the present atmospheric levels of O2. Clearly, forming ozone in the troposphere is a trade-off for survivability – on the one hand, harmful UV radiation is blocked, but on the other hand ozone is a respiratory irratant, which becomes fatal at concentrations exceeding about 1 ppmv.
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Wakamatsu, Shinji, Itsushi Uno, and Makoto Suzuki. "A field study of photochemical smog formation under stagnant meteorological conditions." Atmospheric Environment. Part A. General Topics 24, no. 5 (1990): 1037–50. http://dx.doi.org/10.1016/0960-1686(90)90072-u.
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Sipakov, Rostyslav, Olena Voloshkina, Julia Bereznitska, and Volodimir Trofimovich. "Assessment and forecast for the creation of photochemical smog over transport overpasses in Kyiv." DSpace at USEFUL.academy, no. 2018 (February 23, 2018): 44–51. http://dx.doi.org/10.32557/dsua/20.500.12334/24.
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This article deals with the analysis of existing models of smog situation formation over automobile overpasses and in places of substantial congestion of transport in large cities, for example, in Kyiv. A mathematical model consisting of two blocks – dynamic and kinetic, which allows determining the formation of the thermal dome of pollution and the concentration of hydrocarbon emissions in the air, depending on the number of working engines, is proposed. The kinetic block of the model allows determining the level of formaldehyde, as an indicator of the appearance of photochemical smog in conditions of atmospheric constancy. The concentration of emissions from motor vehicles in the air is calculated over the main transport overpasses of the city of Kyiv at their full load (peak hours).
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Lim, Yong Bin, Hwajin Kim, Jin Young Kim, and Barbara J. Turpin. "Photochemical organonitrate formation in wet aerosols." Atmospheric Chemistry and Physics 16, no. 19 (2016): 12631–47. http://dx.doi.org/10.5194/acp-16-12631-2016.
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Abstract. Water is the most abundant component of atmospheric fine aerosol. However, despite rapid progress, multiphase chemistry involving wet aerosols is still poorly understood. In this work, we report results from smog chamber photooxidation of glyoxal- and OH-containing ammonium sulfate or sulfuric acid particles in the presence of NOx and O3 at high and low relative humidity. Particles were analyzed using ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). During the 3 h irradiation, OH oxidation products of glyoxal that are also produced in dilute aqueous solutions (e.g., oxalic acids and tartaric acids) were formed in both ammonium sulfate (AS) aerosols and sulfuric acid (SA) aerosols. However, the major products were organonitrogens (CHNO), organosulfates (CHOS), and organonitrogen sulfates (CHNOS). These were also the dominant products formed in the dark chamber, indicating non-radical formation. In the humid chamber (> 70 % relative humidity, RH), two main products for both AS and SA aerosols were organonitrates, which appeared at m ∕ z− 147 and 226. They were formed in the aqueous phase via non-radical reactions of glyoxal and nitric acid, and their formation was enhanced by photochemistry because of the photochemical formation of nitric acid via reactions of peroxy radicals, NOx and OH during the irradiation.
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Wei, Xiaolin, Ka-se Lam, Chunyan Cao, Hui Li, and Jiajia He. "Dynamics of the Typhoon Haitang Related High Ozone Episode over Hong Kong." Advances in Meteorology 2016 (2016): 1–12. http://dx.doi.org/10.1155/2016/6089154.
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It has been previously established that photochemical smog occurring in the Pearl River Delta Region (PRD) was associated with stagnant meteorological conditions. However, the photochemical smog (17 July to 20 July 2005) induced by typhoon Haitang was associated with moderate wind speed and nonstagnant meteorological conditions. The dynamic process of this ozone episode was studied using an integrated numerical model, that is, a mesoscale meteorological model and Community Multiscale Air Quality (CMAQ) model. Model performance has been evaluated using both ground-based meteorological and air quality observations. Analysis of simulated wind fields and ozone budget has been performed. This dynamic process is summarized into three physical factors. First, the westerly wind placed Hong Kong directly downwind of the PRD emissions. Second, the convergence of wind flow stimulated a vertical local circulation near the surface layer. This recirculation allowed primary and secondary pollutants to accumulate. Third, the conditions of high air temperature and low humidity resulted in active photochemical reactions. These combined effects resulted in the formation of high ozone in this episode.
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Kashif, Saif-ur-Rehman, Sadia Ismail Shah, and Fariha Arooj. "Outdoor Air Quality as Influenced by Vehicular Exhaust in Metropolitan City of Lahore, Pakistan." Pakistan Journal of Scientific & Industrial Research Series A: Physical Sciences 62, no. 3 (2019): 190–96. http://dx.doi.org/10.52763/pjsir.phys.sci.62.3.2019.190.196.
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This study was conducted to estimate the contribution of vehicular exhaust gases towards ambient air quality in Lahore, Pakistan during 2017. LANDCOM-III flue gas analyzer was used for determination of vehicular exhaust pollutants (CO, SO2, NO2, NO, H2S, HC) for five vehicles groups (motor bikes, Qingqi rickshaw, local cars, imported cars and public transport vans) from April to September, 2017. Major pollutants were compared with their National Environmental Quality Standards (NEQS) for the country. Ambient air quality was monitored using Haz scanner HIM-6000 during smog formation in the city in October and November, 2017. From the study, it was concluded that except local and imported cars, all vehicles groups emit high concentration of pollutants as compared to the standard values. It is also observed that public transport vehicles i.e. Qingqi rickshaw and vans contribute more towards atmospheric pollution as compared to other vehicle groups in the city. During smog formation in the city, PM2.5 and PM10, NO, NO2 (NOx) concentration was decreased whereas concentration of O3, H2S and VOCs increased in November than October. Ozone concentration during the smog was below NEQS indicating that smog was not totally photochemical smog but mainly originated from vehicular and industrial exhaust gases.
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Moussiopoulos, N., P. Sahm, and Ch Kessler. "Numerical simulation of photochemical smog formation in Athens, Greece—A case study." Atmospheric Environment 29, no. 24 (1995): 3619–32. http://dx.doi.org/10.1016/1352-2310(95)00199-9.
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Sumaryati, Sumaryati, Asri Indrawati, and Dyah Aries Tanti. "Kondisi Gradien Temperatur terhadap Proses Pengenceran Smog Fotokimia di Cekungan Bandung." Jurnal Teknologi Lingkungan 21, no. 2 (2020): 219–26. http://dx.doi.org/10.29122/jtl.v21i2.3977.
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ABSTRACTBig cities with valley or basin topography such as Bandung, generally have problems with air pollution due to the inversion layer and photochemical smog formations. The inversion conditions cause photochemical smog settling so that the air looks dark on the surface. This study was conducted to analyze the character of inversion events in Bandung due to vertical temperature changes. The inversion layer is obtained from the TAPM (The Air Pollution Model) model and in situ measurement of vertical temperatures by flying a temperature sensor to get the temperature profile. The TAPM running model is carried out in July and December following the dry and rainy seasons. In situ temperature observations are carried out in September 2018 using a drone according to the dry season and data corresponding to the rainy season using data from previous research with a radiosonde balloon. The running model results show that the inversion layer in the rainy season is stronger and more persistent than in the dry season. The inversion layer at night until morning occurs at the surface level, then the inversion layer rises, and finally, the inversion layer breaks up around 10:00 in July and around 12:00 in December. Validation with in situ measurements shows similarity in the pattern. The inversion event correlates with the subsidence and dilution of smog and photochemical smog pollutants from the edge of the Bandung Basin area.Keywords: basin, urban, photochemical smog, inversionABSTRAKKota besar dengan topografi berbentuk lembah atau cekungan seperti Bandung, umumnya memiliki masalah dengan polusi udara karena adanya pembentukkan lapisan inversi dan smog fotokimia. Kondisi inversi menyebabkan terjadinya pengendapan smog fotokimia, sehingga udara terlihat gelap pada permukaan. Penelitian ini dilakukan untuk menganalisis karakter kejadian inversi di Cekungan Bandung akibat dari perubahan temperatur vertikal. Lapisan inversi diperoleh dari model TAPM (Model Polusi Udara) dan pengukuran in situ temperatur vertikal dengan menerbangkan sensor suhu untuk mendapatkan profil suhu. Running model TAPM dilakukan pada bulan Juli dan bulan Desember berkesesuaian dengan musim kemarau dan hujan, sedangkan pengamatan temperatur in situ dilakukan pada bulan September 2018 dengan menggunakan wahana drone yang berkesesuaian dengan musim kemarau, serta untuk data yang berkesesuaian dengan musim hujan menggunakan data hasil penelitian sebelumnya dengan wahana balon radiosonde. Hasil running model menunjukkan, lapisan inversi pada musim hujan lebih kuat dan lebih persisten dari pada musim kemarau. Lapisan inversi pada malam sampai pagi hari terjadi pada level permukaan, kemudian lapisan inversi ini naik dan akhirnya lapisan inversi pecah sekitar pukul 10:00 pada bulan Juli dan sekitar pukul 12:00 pada bulan Desember. Validasi dengan pengukuran in situ menunjukkan kemiripan pola. Kejadian inversi berkorelasi dengan pengendapan dan pengenceran polutan smog dan smog fotokimia dari pinggir Cekungan Bandung. Kata kunci: cekungan, urban, smog fotokimia, inversi
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Girotto, Sandy Bernardi Falcadi Tedesco, Flávio José Simioni, Yara de Souza Tadano, Valdeci José Costa, and Rodrigo Augusto Freitas de Alvarenga. "Evaluation of characterization models for the photochemical smog impact category focused on the Brazilian reality." LALCA: Revista Latino-Americana em Avaliação do Ciclo de Vida 3 (December 31, 2019): e34263. http://dx.doi.org/10.18225/lalca.v3i0.4263.
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The Life Cycle Impact Assessment (LCIA) is composed of characterization models, and in Brazil, the methodological and scientific LCIA framework is still under development. The research’s aim was to evaluate the literature available characterization models to photochemical smog category. Thus, the contribution of work is recommending one of these models to be used in Brazilian LCA studies, standardizing the studies in Brazil. The methodology consisted of searching the literature and selecting, describing and analyzing the characterization models as well as elaborating a table of criteria for better comparison. Aiming to visualize the differences in the results of each selected model, a case study was applied to analyze the photochemical smog formation potential to the transport of one ton of sugar using two transportation modes (road and railroad). Five characterization models related to smog category were selected, described and compared. Herewith, it was observed that the models present significant differences, that is, each model presents Characterization Factors (CF) for different categories within the environmental impact chain of the photochemical smog (midpoint and/or endpoint), differences in modeling, scale of the model (regional, continental or global), quantity and quality of elementary flows, etc. Those factors have influence in the CF’s calculation and, consequently, the LCA’s results, in the same case study. The criteria table’s results suggested that the model of Van Zelm et al. (2016) – World (midpoint and endpoint), is the best interim option to be used in studies of LCA in Brazil, because it was the model that resulted in the highest grade referring to the established criteria and it presents results on a Global scale. However, the results do not rule out the need for regionalization studies, which would develop a model that presents results and studies directed to the Brazilian reality or adjust the model of Van Zelm et al. (2016) - Brazil
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Miracolo, M. A., C. J. Hennigan, M. Ranjan, et al. "Secondary aerosol formation from photochemical aging of aircraft exhaust in a smog chamber." Atmospheric Chemistry and Physics Discussions 10, no. 11 (2010): 27893–924. http://dx.doi.org/10.5194/acpd-10-27893-2010.
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Abstract. Field experiments were performed to investigate the effects of photo-oxidation on fine particle emissions from an in-use CFM56-2B gas turbine engine mounted on a KC-135 Stratotanker airframe. Emissions were sampled into a portable smog chamber from a rake inlet installed one-meter downstream of the engine exit plane of a parked and chocked aircraft. The chamber was then exposed to sunlight and/or UV lights to initiate photo-oxidation. Separate tests were performed at different engine loads (4, 7, 30, 85%). Photo-oxidation created substantial secondary particulate matter (PM), greatly exceeding the direct PM emissions at each engine load after an hour or less of aging at typical summertime conditions. After several hours of photo-oxidation, the ratio of secondary-to-primary PM mass was on average 35 ± 4.1, 17 ± 2.5, 60 ± 2.2, and 2.7 ± 1.1 times the primary PM for the 4, 7, 30, and 85% load experiments, respectively. The composition of secondary PM formed strongly depended on load. At 4% load, secondary PM was dominated by secondary organic aerosol (SOA). At higher loads, the secondary PM was mainly secondary sulfate. Predictions of an SOA model are compared to the measured SOA formation. The SOA model predicts ~40% of the SOA produced during the 4% load experiment and ~60% for the 85% load experiment. Significant emissions of low-volatility compounds present in both the vapor- and particle-phase were measured in the exhaust and represent a significant pool of SOA precursors that appear to form SOA efficiently when oxidized. These results underscore the importance of accounting for atmospheric processing when assessing the influence of aircraft emissions on ambient PM levels.
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Weitkamp, Emily A., Amy M. Sage, Jeffrey R. Pierce, Neil M. Donahue, and Allen L. Robinson. "Organic Aerosol Formation from Photochemical Oxidation of Diesel Exhaust in a Smog Chamber." Environmental Science & Technology 41, no. 20 (2007): 6969–75. http://dx.doi.org/10.1021/es070193r.
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Leon-Rodriguez, Frida Ma, Armando Aguilar-Marquez, Vladimir Tchijov, and Arturo Aguirre-Gomez. "Reactivity of n-butane in the formation of photochemical smog in Mexico City." International Journal of Environment and Pollution 26, no. 1/2/3 (2006): 5. http://dx.doi.org/10.1504/ijep.2006.009096.
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Miracolo, M. A., C. J. Hennigan, M. Ranjan, et al. "Secondary aerosol formation from photochemical aging of aircraft exhaust in a smog chamber." Atmospheric Chemistry and Physics 11, no. 9 (2011): 4135–47. http://dx.doi.org/10.5194/acp-11-4135-2011.
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Abstract. Field experiments were performed to investigate the effects of photo-oxidation on fine particle emissions from an in-use CFM56-2B gas turbine engine mounted on a KC-135 Stratotanker airframe. Emissions were sampled into a portable smog chamber from a rake inlet installed one-meter downstream of the engine exit plane of a parked and chocked aircraft. The chamber was then exposed to sunlight and/or UV lights to initiate photo-oxidation. Separate tests were performed at different engine loads (4, 7, 30, 85 %). Photo-oxidation created substantial secondary particulate matter (PM), greatly exceeding the direct PM emissions at each engine load after an hour or less of aging at typical summertime conditions. After several hours of photo-oxidation, the ratio of secondary-to-primary PM mass was on average 35 ± 4.1, 17 ± 2.5, 60 ± 2.2, and 2.7 ± 1.1 for the 4, 7, 30, and 85 % load experiments, respectively. The composition of secondary PM formed strongly depended on load. At 4 % load, secondary PM was dominated by secondary organic aerosol (SOA). At higher loads, the secondary PM was mainly secondary sulfate. A traditional SOA model that accounts for SOA formation from single-ring aromatics and other volatile organic compounds underpredicts the measured SOA formation by ~60 % at 4 % load and ~40 % at 85 % load. Large amounts of lower-volatiliy organic vapors were measured in the exhaust; they represent a significant pool of SOA precursors that are not included in traditional SOA models. These results underscore the importance of accounting for atmospheric processing when assessing the influence of aircraft emissions on ambient PM levels. Models that do not account for this processing will likely underpredict the contribution of aircraft emissions to local and regional air pollution.
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Olcese, L. E., J. E. Penner, and S. Sillman. "Development of a secondary organic aerosol formation mechanism: comparison with smog chamber experiments and atmospheric measurements." Atmospheric Chemistry and Physics Discussions 7, no. 3 (2007): 8361–93. http://dx.doi.org/10.5194/acpd-7-8361-2007.
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Abstract. A new mechanism to simulate the formation of secondary organic aerosols (SOA) from reactive primary hydrocarbons is presented, together with comparisons with experimental smog chamber results and ambient measurements found in the literature. The SOA formation mechanism is based on an approach using calculated vapor pressures and a selection of species that can partition to the aerosol phase from a gas phase photochemical mechanism. The mechanism has been validated against smog chamber measurements using α-pinene, xylene and toluene as SOA precursors, and has an average error of 17%. Qualitative comparisons with smog chamber measurements using isoprene were also performed. A comparison against SOA production in the TORCH 2003 experiment (atmospheric measurements) had an average error of only 12%. This contrasts with previous efforts, in which it was necessary to increase partition coefficients by a factor of 500 in order to match the observed values. Calculations for rural and urban-influenced regions in the eastern U.S. suggest that most of the SOA is biogenic in origin, mainly originated from isoprene. A 0-dimensional calculation based on the New England Air Quality Study also showed good agreement with measured SOA, with about 40% of the total SOA from anthropogenic precursors. This mechanism can be implemented in a general circulation model (GCM) to estimate global SOA formation under ambient NOx and HOx levels.
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Xu, Z., J. Zhang, G. Yang, and M. Hu. "Acyl peroxy nitrate measurements during the photochemical smog season in Beijing, China." Atmospheric Chemistry and Physics Discussions 11, no. 3 (2011): 10265–303. http://dx.doi.org/10.5194/acpd-11-10265-2011.
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Abstract. In situ measurements of acyl peroxy nitrates (PANs), including peroxyacetyl nitrate (PAN), peroxypropionyl nitrate (PPN), and peroxymethacryloyl nitrate (MPAN), were conducted using a gas chromatography-electron capture detector (GC-ECD) system during the photochemical smog season in Beijing, China. The maximum mixing ratios were 17.81, 2.48, and 0.27 ppbv for PAN, PPN, and MPAN, respectively. During the measurement period, PAN levels twice exceeded the maximum recommended mixing ratio established by the World Health Organization (WHO). Average ratios of PAN/PPN, PAN/MPAN, and PPN/MPAN were 7.41, 47.65, and 6.91, respectively. The average ratio of PAN/O3 (0.15) in Beijing was significantly higher than those in other areas studied. The frequencies of PANs showed both Gaussian and Weibull modes of distribution. Wind direction was closely related to PAN variation. Anthropogenic sources played an important role in PAN formation, as estimated from PPN and MPAN levels. Relative humidity (RH) and total particle surface area were related with the heterogeneous reactions of PANs with surface concentrations of particulate matter ≤10 μm in diameter.
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Sipakov, Rostyslav, Olena Voloshkina, Volodimir Trofimovich, and Julia Bereznitska. "IMPACT OF WEATHER FACTORS ON THE SPEED OF THE REACTION OF FORMALDEHYDE FORMATION ABOVE MOTORWAY OVERPASSES." DSpace at USEFUL.academy, no. 2018 (July 2018): 97–102. http://dx.doi.org/10.32557/issn.2640-9631/2018-3.
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The analysis of the actual air condition in the city of Kyiv in the areas of big overpasses and crossroads shows that the average annual concentration of formaldehyde more than 3 times exceeds the maximum permissible concentration (MPC) of this toxic substance. One of the most powerful sources of formaldehyde formation in the air of the city is motor vehicles. The role of weather factors in formaldehyde formation rate (K) depending on capacity of emissions of internal combustion engines has been analyzed in this article. The equation for determining rate constant has been obtained, which depends on the temperature in the city of Kyiv and on the value of effective energy activation of the mentioned process. The comparison of the calculated and measured values of the rate reaction constant in Observation Point (OP) No. 9 in the area of Leningradska square has been given. The conducted research gives the opportunity to assess and obtain forecasting data on atmospheric pollution and probability of smog situations emergence in Kyiv. The suggested methodology can be used for other cities in Ukraine where motor vehicles are the main indicator of photochemical smog emergence.
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Lee, Seung-Bok, Gwi-Nam Bae, Young-Mee Lee, Kil-Choo Moon, and Mansoo Choi. "Correlation between Light Intensity and Ozone Formation for Photochemical Smog in Urban Air of Seoul." Aerosol and Air Quality Research 10, no. 6 (2010): 540–49. http://dx.doi.org/10.4209/aaqr.2010.05.0036.
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He, Zhuoran, Xuemei Wang, Zhenhao Ling, et al. "Contributions of different anthropogenic volatile organic compound sources to ozone formation at a receptor site in the Pearl River Delta region and its policy implications." Atmospheric Chemistry and Physics 19, no. 13 (2019): 8801–16. http://dx.doi.org/10.5194/acp-19-8801-2019.
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Abstract. Volatile organic compounds (VOCs) are key precursors of photochemical smog. Quantitatively evaluating the contributions of VOC sources to ozone (O3) formation could provide valuable information for emissions control and photochemical pollution abatement. This study analyzed continuous measurements of VOCs during the photochemical season in 2014 at a receptor site (Heshan site, HS) in the Pearl River Delta (PRD) region, where photochemical pollution has been a long-standing issue. The averaged mixing ratio of measured VOCs was 34±3 ppbv, with the largest contribution from alkanes (17±2 ppbv, 49 %), followed by aromatics, alkenes and acetylene. The positive matrix factorization (PMF) model was applied to resolve the anthropogenic sources of VOCs, coupled with a photochemical-age-based parameterization that better considers the photochemical processing effects. Four anthropogenic emission sources were identified and quantified, with gasoline vehicular emission as the most significant contributor to the observed VOCs, followed by diesel vehicular emissions, biomass burning and solvent usage. The O3 photochemical formation regime at the HS was identified as VOC-limited by a photochemical box model with the master chemical mechanism (PBM-MCM). The PBM-MCM model results also suggested that vehicular emission was the most important source to the O3 formation, followed by biomass burning and solvent usage. Sensitivity analysis indicated that combined VOC and NOx emission controls would effectively reduce incremental O3 formation when the ratios of VOC-to-NOx emission reductions were > 3.8 for diesel vehicular emission, > 4.6 for solvent usage, > 4.6 for biomass burning and 3.3 for gasoline vehicular emission. Based on the above results, a brief review of the policies regarding the control of vehicular emissions and biomass burning in the PRD region from a regional perspective were also provided in this study. It reveals that different policies have been, and continue to be, implemented and formulated and could help to alleviate the photochemical pollution in the PRD region. Nevertheless, evaluation of the cost-benefit of each policy is still needed to improve air quality.
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Xue, Likun, Rongrong Gu, Tao Wang, et al. "Oxidative capacity and radical chemistry in the polluted atmosphere of Hong Kong and Pearl River Delta region: analysis of a severe photochemical smog episode." Atmospheric Chemistry and Physics 16, no. 15 (2016): 9891–903. http://dx.doi.org/10.5194/acp-16-9891-2016.
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Abstract. We analyze a photochemical smog episode to understand the oxidative capacity and radical chemistry of the polluted atmosphere in Hong Kong and the Pearl River Delta (PRD) region. A photochemical box model based on the Master Chemical Mechanism (MCM v3.2) is constrained by an intensive set of field observations to elucidate the budgets of ROx (ROx = OH+HO2+RO2) and NO3 radicals. Highly abundant radical precursors (i.e. O3, HONO and carbonyls), nitrogen oxides (NOx) and volatile organic compounds (VOCs) facilitate strong production and efficient recycling of ROx radicals. The OH reactivity is dominated by oxygenated VOCs (OVOCs), followed by aromatics, alkenes and alkanes. Photolysis of OVOCs (except for formaldehyde) is the dominant primary source of ROx with average daytime contributions of 34–47 %. HONO photolysis is the largest contributor to OH and the second-most significant source (19–22 %) of ROx. Other considerable ROx sources include O3 photolysis (11–20 %), formaldehyde photolysis (10–16 %), and ozonolysis reactions of unsaturated VOCs (3.9–6.2 %). In one case when solar irradiation was attenuated, possibly by the high aerosol loadings, NO3 became an important oxidant and the NO3-initiated VOC oxidation presented another significant ROx source (6.2 %) even during daytime. This study suggests the possible impacts of daytime NO3 chemistry in the polluted atmospheres under conditions with the co-existence of abundant O3, NO2, VOCs and aerosols, and also provides new insights into the radical chemistry that essentially drives the formation of photochemical smog in the high-NOx environment of Hong Kong and the PRD region.
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Aidaoui, Lakhdar, Athanasios G. Triantafyllou, Abbes Azzi, Stylianos K. Garas, and Vasileios N. Matthaios. "Elevated stacks’ pollutants’ dispersion and its contributions to photochemical smog formation in a heavily industrialized area." Air Quality, Atmosphere & Health 8, no. 2 (2014): 213–27. http://dx.doi.org/10.1007/s11869-014-0300-9.
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Zhen, Wen Long, Rui Tang Guo, Wei Guo Pan, Yan Wu Gao, and Chao Lin Shi. "The Preparation and Current Situation of Ce and Mn Catalyst." Advanced Materials Research 864-867 (December 2013): 1612–15. http://dx.doi.org/10.4028/www.scientific.net/amr.864-867.1612.
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NOx is the main air pollutant of coal-fired power plants, which is one of the important reasons to cause pollution such as acid rain, photochemical smog and so on. Selective catalytic reduction process is the major technology for reducing NOx emissions from coal-fired power plants. However, the commercial vanaidia-based catalyst is active within a narrow temperature window of 300-400°C, easily to be deacticed by SO2 in the flue gas. And the formation of N2O and toxicity of vanaidia cause secondary pollution. Therefore, it is of more importance to develop a new environmental-friendly catalyst for low temperature SCR with high activity.
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Liu, T., X. Wang, W. Deng, et al. "Secondary organic aerosol formation from photochemical aging of light-duty gasoline vehicle exhausts in a smog chamber." Atmospheric Chemistry and Physics Discussions 15, no. 7 (2015): 10553–92. http://dx.doi.org/10.5194/acpd-15-10553-2015.
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Abstract. In China, fast increase in passenger vehicles has procured the growing concern about vehicle exhausts as an important source of anthropogenic secondary organic aerosols (SOA) in megacities hard-hit by haze. However, there are still no chamber simulation studies in China on SOA formation from vehicle exhausts. In this study, the SOA formation of emissions from two idling light-duty gasoline vehicles (LDGVs) (Euro 1 and Euro 4) in China was investigated in a 30 m3 smog chamber. Five photo-oxidation experiments were carried out at 25 °C with the relative humidity around 50%. After aging at an OH exposure of 5 × 106 molecules cm−3 h, the formed SOA was 12–259 times as high as primary OA (POA). The SOA production factors (PF) were 0.001–0.044 g kg−1 fuel, comparable with those from the previous studies at the quite similar OH exposure. This quite lower OH exposure than that in typical atmospheric condition might however lead to the underestimation of the SOA formation potential from LDGVs. Effective SOA yield data in this study were well fit by a one-product gas-particle partitioning model and quite lower than those of a previous study investigating SOA formation form three idling passenger vehicles (Euro 2–Euro 4). Traditional single-ring aromatic precursors and naphthalene could explain 51–90% of the formed SOA. Unspeciated species such as branched and cyclic alkanes might be the possible precursors for the unexplained SOA. A high-resolution time-of-flight aerosol mass spectrometer was used to characterize the chemical composition of SOA. The relationship between f43 (ratio of m/z 43, mostly C2H3O+, to the total signal in mass spectrum) and f44 (mostly CO2+) of the gasoline vehicle exhaust SOA is similar to the ambient semi-volatile oxygenated organic aerosol (SV-OOA). We plot the O : C and H : C molar ratios of SOA in a Van Krevelen diagram. The slopes of ΔH : C/ΔO : C ranged from −0.59 to −0.36, suggesting that the oxidation chemistry in these experiments was a combination of carboxylic acid and alcohol/peroxide formation.
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Liu, T., X. Wang, W. Deng, et al. "Secondary organic aerosol formation from photochemical aging of light-duty gasoline vehicle exhausts in a smog chamber." Atmospheric Chemistry and Physics 15, no. 15 (2015): 9049–62. http://dx.doi.org/10.5194/acp-15-9049-2015.
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Abstract. In China, a rapid increase in passenger vehicles has led to the growing concern of vehicle exhaust as an important source of anthropogenic secondary organic aerosol (SOA) in megacities hard hit by haze. In this study, the SOA formation of emissions from two idling light-duty gasoline vehicles (LDGVs) (Euro 1 and Euro 4) operated in China was investigated in a 30 m3 smog chamber. Five photo-oxidation experiments were carried out at 25 °C with relative humidity at around 50 %. After aging at an OH exposure of 5 × 106 molecules cm−3 h, the formed SOA was 12–259 times as high as primary organic aerosol (POA). The SOA production factors (PF) were 0.001–0.044 g kg−1 fuel, comparable with those from the previous studies at comparable OH exposure. This quite lower OH exposure than that in typical atmospheric conditions might however lead to the underestimation of the SOA formation potential from LDGVs. Effective SOA yields in this study were well fit by a one-product gas-particle partitioning model but quite lower than those of a previous study investigating SOA formation from three idling passenger vehicles (Euro 2–4). Traditional single-ring aromatic precursors and naphthalene could explain 51–90 % of the formed SOA. Unspeciated species such as branched and cyclic alkanes might be the possible precursors for the unexplained SOA. A high-resolution time-of-flight aerosol mass spectrometer was used to characterize the chemical composition of SOA. The relationship between f43 (ratio of m/z 43, mostly C2H3O+, to the total signal in mass spectrum) and f44 (mostly CO2+) of the gasoline vehicle exhaust SOA is similar to the ambient semi-volatile oxygenated organic aerosol (SV-OOA). We plot the O : C and H : C molar ratios of SOA in a Van Krevelen diagram. The slopes of ΔH : C / ΔO : C ranged from −0.59 to −0.36, suggesting that the oxidation chemistry in these experiments was a combination of carboxylic acid and alcohol/peroxide formation.
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Salvador, Christian Mark Garcia, Rongzhi Tang, Michael Priestley, et al. "Ambient nitro-aromatic compounds – biomass burning versus secondary formation in rural China." Atmospheric Chemistry and Physics 21, no. 3 (2021): 1389–406. http://dx.doi.org/10.5194/acp-21-1389-2021.
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Abstract. Nitro-aromatic compounds (NACs) were measured hourly at a rural site in China during wintertime to monitor the changes due to local and regional impacts of biomass burning (BB). Concurrent and continuous measurements of the concentrations of 16 NACs in the gas and particle phases were performed with a time-of-flight chemical ionization mass spectrometer (CIMS) equipped with a Filter Inlet for Gases and AEROsols (FIGAERO) unit using iodide as the reagent ion. NACs accounted for <2 % of the mass concentration of organic matter (OM) and total particulate matter (PM), but the total particle mass concentrations of these compounds can reach as high as 1000 ng m−3 (299 ng m−3 avg), suggesting that they may contribute significantly to the radiative forcing effects of atmospheric particles. Levels of gas-phase NACs were highest during the daytime (15:00–16:00 local time, LT), with a smaller night-time peak around 20:00 LT. Box-model simulations showed that this occurred because the rate of NAC production from gas-phase sources exceeded the rate of loss, which occurred mainly via the OH reaction and to a lesser degree via photolysis. Data gathered during extended periods with high contributions from primary BB sources (resulting in 40 %–60 % increases in NAC concentrations) were used to characterize individual NACs with respect to gas–particle partitioning and the contributions of regional secondary processes (i.e. photochemical smog). On days without extensive BB, secondary formation was the dominant source of NACs, and NAC levels correlated strongly with the ambient ozone concentration. Analyses of individual NACs in the regionally aged plumes sampled on these days allowed precursors such as phenol and catechol to be linked to their NAC derivatives (i.e. nitrophenol and nitrocatechol). Correlation analysis using the high time resolution data and box-model simulation results constrained the relationships between these compounds and demonstrated the contribution of secondary formation processes. Furthermore, 13 of 16 NACS were classified according to primary or secondary formation process. Primary emission was the dominant source (accounting for 60 %–70 % of the measured concentrations) of 5 of the 16 studied NACs, but secondary formation was also a significant source. Photochemical smog thus has important effects on brown carbon levels even during wintertime periods dominated by primary air pollution in rural China.
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Tomatis, Marco, Hong-Hui Xu, Jun He, and Xiao-Dong Zhang. "Recent Development of Catalysts for Removal of Volatile Organic Compounds in Flue Gas by Combustion: A Review." Journal of Chemistry 2016 (2016): 1–15. http://dx.doi.org/10.1155/2016/8324826.
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Volatile organic compounds (VOCs) emitted from anthropogenic sources pose direct and indirect hazards to both atmospheric environment and human health due to their contribution to the formation of photochemical smog and potential toxicity including carcinogenicity. Therefore, to abate VOCs emission, the catalytic oxidation process has been extensively studied in laboratories and widely applied in various industries. This report is mainly focused on the benzene, toluene, ethylbenzene, and xylene (BTEX) with additional discussion about chlorinated VOCs. This review covers the recent developments in catalytic combustion of VOCs over noble metal catalysts, nonnoble metal catalysts, perovskite catalysts, spinel catalysts, and dual functional adsorbent-catalysts. In addition, the effects of supports, coke formation, and water effects have also been discussed. To develop efficient and cost-effective catalysts for VOCs removal, further research in catalytic oxidation might need to be carried out to strengthen the understanding of catalytic mechanisms involved.
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Ceulemans, K., S. Compernolle та J. F. Müller. "Parameterising secondary organic aerosol from α-pinene using a detailed oxidation and aerosol formation model". Atmospheric Chemistry and Physics 12, № 12 (2012): 5343–66. http://dx.doi.org/10.5194/acp-12-5343-2012.
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Abstract. A new parameter model for α-pinene secondary organic aerosol (SOA) is presented, based on simulations with the detailed model BOREAM (Biogenic hydrocarbon Oxidation and Related Aerosol formation Model). The parameterisation takes into account the influence of temperature, type of oxidant, NOx-regime, photochemical ageing and water uptake, and is suitable for use in global chemistry transport models. BOREAM is validated against recent photooxidation smog chamber experiments, for which it reproduces SOA yields to within a factor of 2 in most cases. In the simple chemical mechanism of the parameter model, oxidation of α-pinene generates peroxy radicals, which, upon reaction with NO or HO2, yield products corresponding to high or low-NOx conditions, respectively. The model parameters – i.e. the temperature-dependent stoichiometric coefficients and partitioning coefficients of 10 semi-volatile products – are obtained from simulations with BOREAM, including a prescribed diurnal cycle for the radiation, oxidant and emission levels, as well as a deposition sink for the particulate and gaseous products. The effects of photooxidative ageing are implicitly included in the parameterisation, since it is based on near-equilibrium SOA concentrations, obtained through simulations of a two-week period. In order to mimic the full BOREAM model results both during SOA build-up and when SOA has reached an equilibrium concentration, the revolatilisation of condensable products due to photochemical processes is taken into account through a fitted pseudo-photolysis reaction of the lumped semi-volatile products. Modelled SOA mass yields are about ten times higher in low-NOx than in high-NOx conditions, with yields of more than 50% in the low-NOx OH-initiated oxidation of α-pinene, considerably more than in previous parameterisations based on smog chamber experiments. Sensitivity calculations indicate that discrepancies between the full model and the parameterisation due to variations in assumed oxidant levels are limited, but that changes in the radiation levels can lead to larger deviations. Photolysis of species in the particulate phase is found to strongly reduce SOA yields in the full model. Simulations of ambient conditions at 17 different sites (using oxidant, radiation and meteorological data from a global chemistry-transport model) show that overall, the parameterisation displays only little bias (2%) compared with the full model, whereas averaged relative deviations amount to about 11%. Water uptake is parameterised using fitted activity coefficients, resulting in a good agreement with the full model.
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Zhao, Qiuyue, Jun Bi, Qian Liu, et al. "Sources of volatile organic compounds and policy implications for regional ozone pollution control in an urban location of Nanjing, East China." Atmospheric Chemistry and Physics 20, no. 6 (2020): 3905–19. http://dx.doi.org/10.5194/acp-20-3905-2020.
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Abstract. Understanding the composition, temporal variability and source apportionment of volatile organic compounds (VOCs) is necessary for determining effective control measures to minimize VOCs and their related photochemical pollution. To provide a comprehensive analysis of VOC sources and their contributions to ozone (O3) formation in the Yangtze River Delta (YRD) – a region experiencing the highest rates of industrial and economic development in China – we conducted a 1-year sampling exercise using a thermal desorption GC (gas chromatography) system for the first time at an urban site in Nanjing (JAES site). Alkanes were the dominant group at the JAES site, contributing ∼53 % to the observed total VOCs, followed by aromatics (∼17 %), acetylene (∼17 %) and alkenes (∼13 %). We identified seasonal variability in total VOCs (TVOCs) with maximum and minimum concentrations in winter and summer, respectively. Morning and evening peaks and a daytime trough were identified in the diurnal VOC patterns. We identified VOC sources using positive matrix factorization (PMF) and assessed their contributions to photochemical O3 formation by calculating the O3 formation potential (OFP) based on the mass concentrations and maximum incremental reactivities of VOCs. The PMF model identified five dominant VOC sources, with highest contributions from diesel vehicular exhaust (34±5 %), followed by gasoline vehicular exhaust (27±3 %), industrial emissions (19±2 %), fuel evaporation (15±2 %) and biogenic emissions (4±1 %). The results of the OFP calculation inferred that VOCs from industrial and vehicular emissions were found to be the dominant precursors for OFP, particularly the VOC species of xylenes, toluene and propene, and top priority should be given to these for the alleviation of photochemical smog. Our results therefore highlight that priority should be given to limited VOC sources and species for effective control of O3 formation in Nanjing.
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Ge, Shuangshuang, Yongfu Xu, and Long Jia. "Secondary organic aerosol formation from ethyne in the presence of NaCl in a smog chamber." Environmental Chemistry 13, no. 4 (2016): 699. http://dx.doi.org/10.1071/en15155.
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Environmental context Ethyne is the lightest of the non-methane hydrocarbons, whose oxidation product, glyoxal, is an important precursor of secondary organic aerosol. This study explores the effects of relative humidity on the formation of secondary organic aerosol under irradiation in the presence of nitrogen oxides and sodium chloride. Results show that relative humidity can enhance aerosol formation, which provides evidence of the contribution of ethyne to organic particles. Abstract The heterogeneous photochemical oxidation of ethyne was investigated under different relative humidity (RH) conditions in the presence of nitrogen oxides and sodium chloride in a self-made indoor smog chamber. The purpose was to study the influence of RH on the formation of secondary organic aerosol (SOA) from C2H2. Through the experiments, we found that SOA was rarely formed at <22% RH in the presence of NaCl seed particles, and that SOA began to be formed at ≥29% RH in the presence of NaCl, which shows the importance of RH in the formation of SOA. The yield of SOA (YSOA) from C2H2 was 0.2% at 51% RH, and increased by a factor of 17.5 as RH reached 83%. The SOA yield increased with increasing RH. The geometric mean diameter of the particles increased by a factor of 1.17, 1.22, 1.28 and 1.51 at a RH of 51, 63, 74 and 83% respectively at the end of the experiment, indicating that the growth of the particle size also increased with increasing RH. Analysis of the SOA with Fourier-transform infrared (FTIR) spectrometry indicated that the particles generated from C2H2 contained the functional groups –OH, C=O, C–O–C and C–C–OH, for whose absorption peaks increase with increasing RH.
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Ceulemans, K., S. Compernolle та J. F. Müller. "Parameterising secondary organic aerosol from α-pinene using a detailed oxidation and aerosol formation model". Atmospheric Chemistry and Physics Discussions 11, № 8 (2011): 23421–68. http://dx.doi.org/10.5194/acpd-11-23421-2011.
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Abstract. A new 10-product parameter model for α-pinene secondary organic aerosol (SOA) is presented, based on simulations with the detailed model BOREAM (Biogenic hydrocarbon Oxidation and Related Aerosol formation Model). The parameterisation takes into account the influence of temperature, type of oxidant, NOx-regime, photochemical ageing and water uptake, and is suitable for use in global chemistry transport models. BOREAM is validated against recent photooxidation smog chamber experiments, for which it reproduces SOA yields to within a factor of 2 in most cases. In the simple chemical mechanism of the parameter model, oxidation of α-pinene generates peroxy radicals, which, upon reaction with NO or HO2, yield products corresponding to high or low-NOx conditions, respectively. The model parameters – i.e. the temperature-dependent stoichiometric coefficients and partitioning coefficients of the 10 semi-volatile products – are obtained from simulations with BOREAM, including a prescribed diurnal cycle for the radiation, oxidant and emission levels, as well as a deposition sink for the particulate and gaseous products. The effects of photooxidative ageing are implicitly included in the parameterisation, since it is based on near-equilibrium SOA concentrations, obtained through simulations of a two-week period. Modelled SOA mass yields are about ten times higher in low-NOx than in high-NOx conditions, with yields of about 50 % in the low-NOx OH-initiated oxidation of α-pinene, considerably more than in previous parameterisations based on smog chamber experiments. The parameterisation is only moderately sensitive to the assumed oxidant levels. However, photolysis of species in the particulate phase is found to strongly reduce SOA yields. Water uptake is parameterised using fitted activity coefficients, resulting in a good agreement with the full model.
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Kristensen, K., K. L. Enggrob, S. M. King, et al. "Formation and occurrence of dimer esters of pinene oxidation products in atmospheric aerosols." Atmospheric Chemistry and Physics Discussions 12, no. 8 (2012): 22103–37. http://dx.doi.org/10.5194/acpd-12-22103-2012.
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Abstract. Formation of carboxylic acids and dimer esters from α-pinene oxidation were investigated in a smog chamber and in ambient aerosol samples collected during the Biosphere Effects on Aerosols and Photochemistry Experiment (BEARPEX). Chamber experiments of α-pinene ozonolysis in dry air and at low NOx concentrations demonstrated formation of two dimer esters, pinyl-diaterpenyl (MW 358) and pinonyl-pinyl dimer ester (MW 368), under both low and high temperature conditions. Concentration levels of the pinyl-diaterpenyl dimer ester were lower than the assumed first-generation oxidation products cis-pinic and terpenylic acids, but similar to the second-generation oxidation products 3-methyl-1,2,3-butane tricarboxylic acid (MBTCA) and diaterpenylic acid acetate (DTAA). Dimer esters were observed within the first 30 min, indicating rapid production simultaneous to their structural precursors. However, the sampling time resolution precluded conclusive evidence regarding formation from gas- or particle-phase processes. CCN activities of the particles formed in the smog chamber displayed a modest variation during the course of experiments with κ values in the range 0.06–0.09 (derived at a supersaturation of 0.19%). The pinyl-diaterpenyl dimer ester was also observed in ambient aerosol samples collected above a ponderosa pine forest in the Sierra Nevada Mountains of California during two seasonally distinct field campaigns in September 2007 and July 2009. The pinonyl-pinyl ester was observed for the first time in ambient air during the 2009 campaign, and although present at much lower concentrations, it was correlated with the abundance of the pinyl-diaterpenyl ester suggesting similarities in their formation. The maximum concentration of the pinyl-diaterpenyl ester was almost 10 times higher during the warmer 2009 campaign relative to 2007, while the concentration of cis-pinic acid was approximately the same during both periods, and lack of correlation with levels of of cis-pinic and terpenylic acids for both campaigns indicate that the formation of the pinyl-diaterpenyl ester was not controlled by their ambient abundance. In 2009, the concentration of the pinyl-diaterpenyl ester was well correlated with the concentration of DTAA, a supposed precursor of diaterpenylic acid, suggesting that the formation of pinyl-diaterpenyl dimer was closely related to DTAA. Generally, the pinyl-diaterpenyl ester was found at higher concentrations under higher temperature conditions both in the smog-chamber study and in ambient air aerosol samples, and exhibited much higher concentrations at night relative to day-time in line with previous results. We conclude that analysis of pinyl dimer esters provides valuable information on pinene oxidation processes and should be included in studies of formation and photochemical aging of biogenic secondary organic aerosols, especially at high temperatures.
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Kristensen, K., K. L. Enggrob, S. M. King, et al. "Formation and occurrence of dimer esters of pinene oxidation products in atmospheric aerosols." Atmospheric Chemistry and Physics 13, no. 7 (2013): 3763–76. http://dx.doi.org/10.5194/acp-13-3763-2013.
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Abstract. The formation of carboxylic acids and dimer esters from α-pinene oxidation was investigated in a smog chamber and in ambient aerosol samples collected during the Biosphere Effects on Aerosols and Photochemistry Experiment (BEARPEX). Chamber experiments of α-pinene ozonolysis in dry air and at low NOx concentrations demonstrated formation of two dimer esters, pinyl-diaterpenyl (MW 358) and pinonyl-pinyl dimer ester (MW 368), under both low- and high-temperature conditions. Concentration levels of the pinyl-diaterpenyl dimer ester were lower than the assumed first-generation oxidation products cis-pinic and terpenylic acids, but similar to the second-generation oxidation products 3-methyl-1,2,3-butane tricarboxylic acid (MBTCA) and diaterpenylic acid acetate (DTAA). Dimer esters were observed within the first 30 min, indicating rapid production simultaneous to their structural precursors. However, the sampling time resolution precluded conclusive evidence regarding formation from gas- or particle-phase processes. CCN activities of the particles formed in the smog chamber displayed a modest variation during the course of experiments, with κ values in the range 0.06–0.09 (derived at a supersaturation of 0.19%). The pinyl-diaterpenyl dimer ester was also observed in ambient aerosol samples collected above a ponderosa pine forest in the Sierra Nevada Mountains of California during two seasonally distinct field campaigns in September 2007 and July 2009. The pinonyl-pinyl ester was observed for the first time in ambient air during the 2009 campaign, and although present at much lower concentrations, it was correlated with the abundance of the pinyl-diaterpenyl ester, suggesting similarities in their formation. The maximum concentration of the pinyl-diaterpenyl ester was almost 10 times higher during the warmer 2009 campaign relative to 2007, while the concentration of cis-pinic acid was approximately the same during both periods, and lack of correlation with levels of cis-pinic and terpenylic acids for both campaigns indicate that the formation of the pinyl-diaterpenyl ester was not controlled by their ambient abundance. In 2009 the concentration of the pinyl-diaterpenyl ester was well correlated with the concentration of DTAA, a supposed precursor of diaterpenylic acid, suggesting that the formation of pinyl-diaterpenyl dimer was closely related to DTAA. Generally, the pinyl-diaterpenyl ester was found at higher concentrations under higher temperature conditions, both in the smog-chamber study and in ambient air aerosol samples, and exhibited much higher concentrations at night relative to daytime in line with previous results. We conclude that analysis of pinyl dimer esters provides valuable information on pinene oxidation processes and should be included in studies of formation and photochemical aging of biogenic secondary organic aerosols, especially at high temperatures.
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Gordon, T. D., A. A. Presto, A. A. May, et al. "Secondary organic aerosol formation exceeds primary particulate matter emissions for light-duty gasoline vehicles." Atmospheric Chemistry and Physics Discussions 13, no. 9 (2013): 23173–216. http://dx.doi.org/10.5194/acpd-13-23173-2013.
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Abstract. The effects of photochemical aging on emissions from 15 light-duty gasoline vehicles were investigated using a smog chamber to probe the critical link between the tailpipe and ambient atmosphere. The vehicles were recruited from the California in-use fleet; they represent a wide range of model years (1987 to 2011), vehicle types and emission control technologies. Each vehicle was tested on a chassis dynamometer using the unified cycle. Dilute emissions were sampled into a portable smog chamber and then photochemically aged under urban-like conditions. For every vehicle, substantial secondary organic aerosol (SOA) formation occurred during cold-start tests, with the emissions from some vehicles generating as much as 6 times the amount of SOA as primary particulate matter after three hours of oxidation inside the chamber at typical atmospheric oxidant levels. Therefore, the contribution of light duty gasoline vehicle exhaust to ambient PM levels is likely dominated by secondary PM production (SOA and nitrate). Emissions from hot-start tests formed about a factor of 3–7 less SOA than cold-start tests. Therefore, catalyst warm-up appears to be an important factor in controlling SOA precursor emissions. The mass of SOA generated by photo-oxidizing exhaust from newer (LEV1 and LEV2) vehicles was only modestly lower (38%) than that formed from exhaust emitted by older (pre-LEV) vehicles, despite much larger reductions in non-methane organic gas emissions. These data suggest that a complex and non-linear relationship exists between organic gas emissions and SOA formation, which is not surprising since SOA precursors are only one component of the exhaust. Except for the oldest (pre-LEV) vehicles, the SOA production could not be fully explained by the measured oxidation of speciated (traditional) SOA precursors. Over the time scale of these experiments, the mixture of organic vapors emitted by newer vehicles appear to be more efficient (higher yielding) in producing SOA than the emissions from older vehicles. About 30% of the non-methane organic gas emissions from the newer (LEV1 and LEV2) vehicles could not be speciated, and the majority of the SOA formed from these vehicles appears to be associated with these unspeciated organics. These results for light-duty gasoline vehicles contrast with the results from a companion study of on-road heavy-duty diesel trucks; in that study late model (2007 and later) diesel trucks equipped with catalyzed diesel particulate filters emitted very little primary PM, and the photo-oxidized emissions produced negligible amounts of SOA.
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Gordon, T. D., A. A. Presto, A. A. May, et al. "Secondary organic aerosol formation exceeds primary particulate matter emissions for light-duty gasoline vehicles." Atmospheric Chemistry and Physics 14, no. 9 (2014): 4661–78. http://dx.doi.org/10.5194/acp-14-4661-2014.
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Abstract. The effects of photochemical aging on emissions from 15 light-duty gasoline vehicles were investigated using a smog chamber to probe the critical link between the tailpipe and ambient atmosphere. The vehicles were recruited from the California in-use fleet; they represent a wide range of model years (1987 to 2011), vehicle types and emission control technologies. Each vehicle was tested on a chassis dynamometer using the unified cycle. Dilute emissions were sampled into a portable smog chamber and then photochemically aged under urban-like conditions. For every vehicle, substantial secondary organic aerosol (SOA) formation occurred during cold-start tests, with the emissions from some vehicles generating as much as 6 times the amount of SOA as primary particulate matter (PM) after 3 h of oxidation inside the chamber at typical atmospheric oxidant levels (and 5 times the amount of SOA as primary PM after 5 × 106 molecules cm−3 h of OH exposure). Therefore, the contribution of light-duty gasoline vehicle exhaust to ambient PM levels is likely dominated by secondary PM production (SOA and nitrate). Emissions from hot-start tests formed about a factor of 3–7 less SOA than cold-start tests. Therefore, catalyst warm-up appears to be an important factor in controlling SOA precursor emissions. The mass of SOA generated by photooxidizing exhaust from newer (LEV2) vehicles was a factor of 3 lower than that formed from exhaust emitted by older (pre-LEV) vehicles, despite much larger reductions (a factor of 11–15) in nonmethane organic gas emissions. These data suggest that a complex and nonlinear relationship exists between organic gas emissions and SOA formation, which is not surprising since SOA precursors are only one component of the exhaust. Except for the oldest (pre-LEV) vehicles, the SOA production could not be fully explained by the measured oxidation of speciated (traditional) SOA precursors. Over the timescale of these experiments, the mixture of organic vapors emitted by newer vehicles appears to be more efficient (higher yielding) in producing SOA than the emissions from older vehicles. About 30% of the nonmethane organic gas emissions from the newer (LEV1 and LEV2) vehicles could not be speciated, and the majority of the SOA formed from these vehicles appears to be associated with these unspeciated organics. By comparing this study with a companion study of diesel trucks, we conclude that both primary PM emissions and SOA production for light-duty gasoline vehicles are much greater than for late-model (2007 and later) on-road heavy-duty diesel trucks.
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Lelieveld, J., P. Hoor, P. Jöckel, et al. "Severe ozone air pollution in the Persian Gulf region." Atmospheric Chemistry and Physics 9, no. 4 (2009): 1393–406. http://dx.doi.org/10.5194/acp-9-1393-2009.
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Abstract. Recently it was discovered that over the Middle East during summer ozone mixing ratios can reach a pronounced maximum in the middle troposphere. Here we extend the analysis to the surface and show that especially in the Persian Gulf region conditions are highly favorable for ozone air pollution. We apply the EMAC atmospheric chemistry-climate model to investigate long-distance transport and the regional formation of ozone. Further, we make use of available in situ and satellite measurements and compare these with model output. The results indicate that the region is a hot spot of photochemical smog where European Union air quality standards are violated throughout the year. Long-distance transports of air pollution from Europe and the Middle East, natural emissions and stratospheric ozone conspire to bring about relatively high background ozone mixing ratios. This provides a hotbed to strong and growing indigenous air pollution in the dry local climate, and these conditions are likely to get worse in the future.
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Shevchenko, O., S. Snizhko, and N. Danilova. "Air pollution by nitrogen dioxide in Kiev city." Ukrainian hydrometeorological journal, no. 16 (October 29, 2017): 6–16. http://dx.doi.org/10.31481/uhmj.16.2015.01.
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In the article main nitrogen dioxide emissions sources in a big cities was analysed. Shown the temporal dynamics of average annual concentrations of nitrogen dioxide in Kiev city for time period 1985 - 2012, analyzed concentration of this pollutant in different part of the city and frequency of cases of maximum allowable concentration (MAC) exceeding. The highest concentrations of nitrogen dioxide observed in the central part of the city in some months the warm season. The frequency of cases exceeding of MAC in the air usually exceeds 50% and in the warm season 2012 average concentration of NO2 in the air has been very high and frequency of exceeding of MAC reached 100% in almost all monitoring stations. Studies show that in the warm season in the air of Kyiv regularly observed abnormally high concentrations of nitrogen dioxide, which is a precursor of photochemical smog, and under favorable meteorological conditions will result in the formation of this negative phenomenon in the atmosphere of the city.
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Huang, C., H. L. Wang, L. Li, et al. "VOC species and emission inventory from vehicles and their SOA formation potentials estimation in Shanghai, China." Atmospheric Chemistry and Physics Discussions 15, no. 6 (2015): 7977–8015. http://dx.doi.org/10.5194/acpd-15-7977-2015.
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Abstract. VOC species from vehicle exhaust and gas evaporation were investigated by chassis dynamometer and on-road measurements of 9 gasoline vehicles, 7 diesel vehicles, 5 motorcycles, and 4 gas evaporation samples. The SOA mass yields of gasoline, diesel, motorcycle exhausts, and gas evaporation were calculated based on the mixing ratio of individual VOC species. The SOA mass yields of gasoline and motorcycle exhaust were similar to the results of the published smog chamber study with the exception of that of diesel exhaust was 20% lower than experimental data (Gordon et al., 2013, 2014a, b). This suggests the requirement for further research on SVOC or LVOC emissions. A vehicular emission inventory was compiled based on a local survey of vehicle mileage traveled and real-world measurements of vehicle emission factors. The inventory-based vehicular initial emission ratio of OA to CO was 15.6 μg m−3 ppmv−1. The OA production rate reached 22.3 and 42.7 μg m−3 ppmv−1 under high-NOx and low-NOx conditions, respectively. To determine the vehicular contribution to OA pollution, the inventory-based OA formation ratios for vehicles were calculated with a photochemical-age-based parameterization method and compared with the observation-based OA formation ratios in the urban atmosphere of Shanghai. The results indicated that VOC emissions from vehicle exhaust and gas evaporation only explained 15 and 22% of the total organic aerosols observed in summer and winter, respectively. SOA production only accounted for 25 and 18% of the total vehicular OA formation in summer and winter. VOC emissions from gasoline vehicles contribute 21–38% of vehicular OA formation after 6–24 h of photochemical aging. The results suggest that vehicle emissions are an important contributor to OA pollution in the urban atmosphere of Shanghai. However, a large number of OA mass in the atmosphere still cannot be explained in this study. SOA formation contributions from other sources (e.g. coal burning, biomass burning, cooking, dust, etc.) as well as IVOCs and SVOCs from the combustion sources need to be considered in future studies.
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Zyrkowski, Maciej, Monika Motak, Bogdan Samojeden, and Krzysztof Szczepanek. "Deactivation of V2O5−WO3/TiO2 DeNOx Catalyst under Commercial Conditions in Power Production Plant." Energies 13, no. 23 (2020): 6200. http://dx.doi.org/10.3390/en13236200.
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Nitrogen dioxide is one of the most dangerous air pollutants, because its high concentration in air can be directly harmful to human health. It is also responsible for photochemical smog and acid rains. One of the most commonly used techniques to tackle this problem in large combustion plants is selective catalytic reduction (SCR). Commercial SCR installations are often equipped with a V2O5−WO3/TiO2 catalyst. In power plants which utilize a solid fuel boiler, catalysts are exposed to unfavorable conditions. In the paper, factors responsible for deactivation of such a catalyst are comprehensively reviewed where different types of deactivation mechanism, like mechanical, chemical or thermal mechanisms, are separately described. The paper presents the impact of sulfur trioxide and ammonia slip on the catalyst deactivation as well as the problem of ammonium bisulfate formation. The latter is one of the crucial factors influencing the loss of catalytic activity. The majority of issues with fast catalyst deactivation occur when the catalyst work in off-design conditions, in particular in too high or too low temperatures.
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Spicer, C. W., M. W. Holdren, R. M. Riggin, and T. F. Lyon. "Chemical composition and photochemical reactivity of exhaust from aircraft turbine engines." Annales Geophysicae 12, no. 10/11 (1994): 944–55. http://dx.doi.org/10.1007/s00585-994-0944-0.
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Abstract. Assessment of the environmental impact of aircraft emissions is required by planners and policy makers. Seveal areas of concern are: 1. exposure of airport workers and urban residents to toxic chemicals emitted when the engines operate at low power (idle and taxi) on the ground; 2. contributions to urban photochemical air pollution of aircraft volatile organic and nitrogen oxides emissions from operations around airports; and 3. emissions of nitrogen oxides and particles during high-altitude operation. The environmental impact of chemicals emitted from jet aircraft turbine engines has not been firmly established due to lack of data regarding emission rates and identities of the compounds emitted. This paper describes an experimental study of two different aircraft turbine engines designed to determine detailed organic emissions, as well as emissions of inorganic gases. Emissions were measured at several engine power settings. Measurements were made of detailed organic composition from C1 through C17, CO, CO2, NO, NOx, and polycyclic aromatic hydrocarbons. Measurements were made using a multi-port sampling pro be positioned directly behind the engine in the exhaust exit plane. The emission measurements have been used to determine the organic distribution by carbon number and the distribution by compound class at each engine power level. The sum of the organic species was compared with an independent measurement of total organic carbon to assess the carbon mass balance. A portion of the exhaust was captured and irradiated in outdoor smog chambers to assess the photochemical reactivity of the emissions with respect to ozone formation. The reactivity of emissions from the two engines was apportioned by chemical compound class.
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Nguyen Duc, Hiep, Lisa Chang, Toan Trieu, David Salter, and Yvonne Scorgie. "Source Contributions to Ozone Formation in the New South Wales Greater Metropolitan Region, Australia." Atmosphere 9, no. 11 (2018): 443. http://dx.doi.org/10.3390/atmos9110443.
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Ozone and fine particles (PM2.5) are the two main air pollutants of concern in the New South Wales Greater Metropolitan Region (NSW GMR) due to their contribution to poor air quality days in the region. This paper focuses on source contributions to ambient ozone concentrations for different parts of the NSW GMR, based on source emissions across the greater Sydney region. The observation-based Integrated Empirical Rate model (IER) was applied to delineate the different regions within the GMR based on the photochemical smog profile of each region. Ozone source contribution was then modelled using the CCAM-CTM (Cubic Conformal Atmospheric model-Chemical Transport model) modelling system and the latest air emission inventory for the greater Sydney region. Source contributions to ozone varied between regions, and also varied depending on the air quality metric applied (e.g., average or maximum ozone). Biogenic volatile organic compound (VOC) emissions were found to contribute significantly to median and maximum ozone concentration in North West Sydney during summer. After commercial and domestic sources, power generation was found to be the next largest anthropogenic source of maximum ozone concentrations in North West Sydney. However, in South West Sydney, beside commercial and domestic sources, on-road vehicles were predicted to be the most significant contributor to maximum ozone levels, followed by biogenic sources and power stations. The results provide information that policy makers can use to devise various options to control ozone levels in different parts of the NSW Greater Metropolitan Region.
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Ortega, A. M., D. A. Day, M. J. Cubison, et al. "Secondary organic aerosol formation and primary organic aerosol oxidation from biomass-burning smoke in a flow reactor during FLAME-3." Atmospheric Chemistry and Physics 13, no. 22 (2013): 11551–71. http://dx.doi.org/10.5194/acp-13-11551-2013.
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Abstract. We report the physical and chemical effects of photochemically aging dilute biomass-burning smoke. A "potential aerosol mass" (PAM) flow reactor was used with analysis by a high-resolution aerosol mass spectrometer and a proton-transfer-reaction ion-trap mass spectrometer during the FLAME-3 campaign. Hydroxyl (OH) radical concentrations in the reactor reached up to ~1000 times average tropospheric levels, producing effective OH exposures equivalent to up to 5 days of aging in the atmosphere, and allowing for us to extend the investigation of smoke aging beyond the oxidation levels achieved in traditional smog chambers. Volatile organic compound (VOC) observations show aromatics and terpenes decrease with aging, while formic acid and other unidentified oxidation products increase. Unidentified gas-phase oxidation products, previously observed in atmospheric and laboratory measurements, were observed here, including evidence of multiple generations of photochemistry. Substantial new organic aerosol (OA) mass ("net SOA"; secondary OA) was observed from aging biomass-burning smoke, resulting in total OA average of 1.42 ± 0.36 times the initial primary OA (POA) after oxidation. This study confirms that the net-SOA-to-POA ratio of biomass-burning smoke is far lower on average than that observed for urban emissions. Although most fuels were very reproducible, significant differences were observed among the biomasses, with some fuels resulting in a doubling of the OA mass, while for others a very small increase or even a decrease was observed. Net SOA formation in the photochemical reactor increased with OH exposure (OHexp), typically peaking around three days of equivalent atmospheric photochemical age (OHexp~3.9 × 1011 molecules cm−3 s), then leveling off at higher exposures. The amount of additional OA mass added from aging is positively correlated with initial POA concentration, but not with the total VOC concentration or the concentration of known SOA precursors. The mass of SOA formed often exceeded the mass of the known VOC precursors, indicating the likely importance of primary semivolatile/intermediate volatility species, and possibly of unidentified VOCs as SOA precursors in biomass burning smoke. Chemical transformations continued even after mass concentration stabilized. Changes in the biomass-burning tracer f60 ranged from substantially decreasing to remaining constant with increased aging. With increased OHexp, oxidation was always detected (as indicated by f44 and O/C). POA O/C ranged from 0.15 to 0.5, while aged OA O/C reached up to 0.87. The rate of oxidation and maximum O/C achieved differs for each biomass, and appears to increase with the initial O/C of the POA.
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Mousavi, M., M. Soltanieh, and A. Badakhshan. "Influence of turbulence and atmospheric chemistry on grid size with respect to location in modeling and simulation of photochemical smog formation and transport." Environmental Modelling & Software 14, no. 6 (1999): 657–63. http://dx.doi.org/10.1016/s1364-8152(99)00010-9.
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Wittbom, C., J. H. Pagels, J. Rissler, et al. "Cloud droplet activity changes of soot aerosol upon smog chamber ageing." Atmospheric Chemistry and Physics Discussions 14, no. 7 (2014): 8851–914. http://dx.doi.org/10.5194/acpd-14-8851-2014.
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Abstract. Particles containing soot, or black carbon, are generally considered to contribute to global warming. However, large uncertainties remain in the net climate forcing resulting from anthropogenic emissions of black carbon (BC), to a large extent due to the fact that BC is co-emitted with gases and primary particles, both organic and inorganic, and subject to atmospheric ageing processes. In this study, diesel exhaust particles and particles from a flame soot generator spiked with light aromatic secondary organic aerosol (SOA) precursors were processed by UV-radiation in a 6 m3 Teflon chamber in the presence of NOx. The time-dependent changes of the soot nanoparticle properties were characterised using a Cloud Condensation Nuclei Counter, an Aerosol Particle Mass Analyzer and a Soot Particle Aerosol Mass Spectrometer. The results show that freshly emitted soot particles do not activate into cloud droplets at supersaturations ≤ 2%, i.e. the black carbon core coated with primary organic aerosol (POA) from the exhaust is limited in hygroscopicity. Before the onset of UV radiation it is unlikely that any substantial SOA formation is taking place. An immediate change in cloud-activation properties occurs at the onset of UV exposure. This change in hygroscopicity is likely attributed to SOA formed from intermediate volatile organic compounds (IVOC) in the diesel engine exhaust. The change of cloud condensation nuclei (CCN) properties at the onset of UV radiation implies that the lifetime of soot particles in the atmosphere is affected by the access to sunlight, which differs between latitudes. The ageing of soot particles progressively enhances their ability to act as cloud condensation nuclei, due to changes in: (I) organic fraction of the particle, (II) chemical properties of this fraction (POA or SOA), (III) particle size, and (IV) particle morphology. Applying κ-Köhler theory, using a κSOA value of 0.13 (derived from independent input parameters describing the organic material), showed good agreement with cloud droplet activation measurements for particles with a SOA mass fraction (mfSOA(APM)) ≥ 0.12 (slightly aged particles). The activation properties are enhanced with only a slight increase in organic material coating the soot particles (mfSOA(APM) < 0.12), however not as much as predicted with Köhler theory. The discrepancy between theory and experiments might be due to solubility limitations, unevenly distributed organic material or hindering particle morphology. The change in properties of soot nanoparticles upon photochemical processing clearly increases their hygroscopicity, which affects their behaviour both in the atmosphere and in the human respiratory system.
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Wittbom, C., A. C. Eriksson, J. Rissler, et al. "Cloud droplet activity changes of soot aerosol upon smog chamber ageing." Atmospheric Chemistry and Physics 14, no. 18 (2014): 9831–54. http://dx.doi.org/10.5194/acp-14-9831-2014.
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Abstract. Particles containing soot, or black carbon, are generally considered to contribute to global warming. However, large uncertainties remain in the net climate forcing resulting from anthropogenic emissions of black carbon (BC), to a large extent due to the fact that BC is co-emitted with gases and primary particles, both organic and inorganic, and subject to atmospheric ageing processes. In this study, diesel exhaust particles and particles from a flame soot generator spiked with light aromatic secondary organic aerosol (SOA) precursors were processed by UV radiation in a 6 m3 Teflon chamber in the presence of NOx. The time-dependent changes of the soot nanoparticle properties were characterised using a Cloud Condensation Nuclei Counter, an Aerosol Particle Mass Analyzer and a Soot Particle Aerosol Mass Spectrometer. The results show that freshly emitted soot particles do not activate into cloud droplets at supersaturations ≤2%, i.e. the BC core coated with primary organic aerosol (POA) from the exhaust is limited in hygroscopicity. Before the onset of UV radiation it is unlikely that any substantial SOA formation is taking place. An immediate change in cloud-activation properties occurs at the onset of UV exposure. This change in hygroscopicity is likely attributed to SOA formed from intermediate volatility organic compounds (IVOCs) in the diesel engine exhaust. The change of cloud condensation nuclei (CCN) properties at the onset of UV radiation implies that the lifetime of soot particles in the atmosphere is affected by the access to sunlight, which differs between latitudes. The ageing of soot particles progressively enhances their ability to act as cloud condensation nuclei, due to changes in: (I) organic fraction of the particle, (II) chemical properties of this fraction (e.g. primary or secondary organic aerosol), (III) particle size, and (IV) particle morphology. Applying κ-Köhler theory, using a κSOA value of 0.13 (derived from independent input parameters describing the organic material), showed good agreement with cloud droplet activation measurements for particles with a SOA mass fraction ≥0.12 (slightly aged particles). The activation properties are enhanced with only a slight increase in organic material coating the soot particles (SOA mass fraction < 0.12), however not as much as predicted by Köhler theory. The discrepancy between theory and experiments during the early stages of ageing might be due to solubility limitations, unevenly distributed organic material or hindering particle morphology. The change in properties of soot nanoparticles upon photochemical processing clearly increases their hygroscopicity, which affects their behaviour both in the atmosphere and in the human respiratory system.
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Li, Chen, Su Ping Cui, Xian Zheng Gong, Xian Ce Meng, Bo Xue Sun, and Yu Liu. "Life Cycle Assessment of Heavy-Duty Truck for Highway Transport in China." Materials Science Forum 787 (April 2014): 117–22. http://dx.doi.org/10.4028/www.scientific.net/msf.787.117.
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The detailed life cycle assessment of heavy-duty truck for highway transport in China is conducted by Centre of National Material Life Cycle Assessment (CNMLCA). The input of energy and output of pollutants emissions are documented as the life cycle inventory (LCI). The life cycle impact assessment (LCIA) results calculated with the CML method show that the hotspot of environmental impacts from transport in China. The environmental benefits from implementations of European emissions standards in China for transport are also analyzed. The analysis shows that the acidification potential (AP) makes the most huge contribution to total environmental impact, up to 33.7%. As the second hotsopt, global warming potential (GWP) takes up 26.83% of total environmental impact. Photochemical oxidant formation potential (POCP) takes up 23.42% of total environmental impact, which is more or less the same comparing with the result of GWP. Eutrophication potential (EP) takes up 15.05% of total environmental impact. The last but not the least environmental impact category - human toxicity potential (HTP), only takes up 0.95% of total environmental impact. If the heavy metal and dioxin emissions are also considered, maybe the results will be changed and the HTP will take more in the whole environmental impact. It can be concluded that if we pay more attention on SO2emissions especially NOx emissions reduction, the acidification and photochemical smog would be relieved a lot and the total environmental impact can be decreased a lot. More punishment on overload may be a good choice to reduce environmental load of heavy truck of highway transport in China.
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Laohalertdecha, Dararat, Kampanart Theinnoi, and Sak Sittichompoo. "The Prototype of Non-thermal Plasma After treatment System for Simultaneous Reduction of Nitrogen Oxide Emission in Flue Gas." E3S Web of Conferences 302 (2021): 01010. http://dx.doi.org/10.1051/e3sconf/202130201010.
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Nowadays, global warming is the main environmental problems all over the world. The air pollutants mainly from the burning of fossil fuels and coal in power plants, transportation, and automobiles. There are release major point emission of the atmosphere. The nitrogen oxides are the most relevant for air pollution that contribute to the formation of photochemical smog and acid rain. Numerous methods have been studied to eliminate the nitrogen oxides such as the use low-nitrogen fuels technology, the selective catalytic reduction (SCR), wet scrubbing. The aim of this research is investigated non-thermal plasma (NTP) techniques offer an innovation to eliminate both nitrogen oxide (NOx) and soot emissions from combustion. This study is used to selectively transfer input electrical energy to electrons without expending this in heating the entire gas flow which creates free radicals in the flue gases. The simulated flue gas from combustion process is applied to the system. The results showed that the prototype of nonthermal plasma system is shown the highly efficient of NOx removal was achieved. However, the optimised of NTP operating conditions are required to enhance the NOx reduction activities.