scholarly journals Seasonal Variations of Carbonyls and Their Contributions to the Ozone Formation in Urban Atmosphere of Taiyuan, China

Atmosphere ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 510
Author(s):  
Zeqian Liu ◽  
Yang Cui ◽  
Qiusheng He ◽  
Lili Guo ◽  
Xueying Gao ◽  
...  
Keyword(s):  
Total Concentration ◽  
Urban Atmosphere ◽  
Urban Site ◽  
Ozone Formation ◽  
Ozone Pollution ◽  
Four Seasons ◽  
Ozone Formation Potential ◽  
Higher Temperature ◽  
Taiyuan Basin ◽  
Sunlight Intensity

Ambient carbonyls are critical precursors of ozone (O3) and secondary organic aerosols (SOA). To better understand the pollution characteristics of carbonyls in Taiyuan, field samplings were conducted, and 13 carbonyls were detected in an urban site of Taiyuan for the four seasons. The total concentration of carbonyls in the atmosphere was 19.67 ± 8.56 μg/m3. Formaldehyde (7.70 ± 4.78 μg/m3), acetaldehyde (2.95 ± 1.20 μg/m3) and acetone (5.57 ± 2.41 μg/m3) were the dominant carbonyl compounds, accounting for more than 85% of the total carbonyls. The highest values for formaldehyde and acetone occurred in summer and autumn, respectively, and the lowest occurred in winter. The variations for acetaldehyde were not distinct in the four seasons. Formaldehyde and acetone levels increased obviously in the daytime and decreased at night, while acetaldehyde did not show significant diurnal variations. Higher temperature and stronger sunlight intensity could facilitate the photochemical reaction of volatile organic compounds (VOCs) and enhance the O3 levels in summer. Formaldehyde and acetaldehyde contributed 70–95% of carbonyls’ ozone formation potential (OFP) caused by carbonyls with the highest totals of 268.62 μg/m3 and 38.14 μg/m3, respectively. The highest concentrations of carbonyls from south and southwest winds in summer suggest that the coke industries in the southern Taiyuan Basin should be, firstly, controlled for the alleviation of ozone pollution.

scholarly journals Measurements of ozone and its precursors in Beijing during summertime: impact of urban plumes on ozone pollution in downwind rural areas

2011 ◽  
Vol 11 (23) ◽  
pp. 12241-12252 ◽  
Author(s):  
J. Xu ◽  
J. Z. Ma ◽  
X. L. Zhang ◽  
X. B. Xu ◽  
X. F. Xu ◽  
...  
Keyword(s):  
Rural Areas ◽  
Rural Site ◽  
Ozone Formation ◽  
Prevailing Wind ◽  
Ozone Pollution ◽  
Ozone Formation Potential ◽  
Rural Sites ◽  
Urban And Rural Areas ◽  
Urban Plumes ◽  
Urban Sites

Abstract. Sea-land and mount-valley circulations are the dominant mesoscale synoptic systems affecting the Beijing area during summertime. Under the influence of these two circulations, the prevailing wind is southwesterly from afternoon to midnight, and then changes to northeasterly till forenoon. In this study, surface ozone (O3), carbon monoxide (CO), nitric oxide (NO), nitrogen dioxide (NO2), nitrogen oxide (NOx) and non-methane hydrocarbons (NMHCs) were measured at four sites located along the route of prevailing wind, including two upwind urban sites (Fengtai "FT" and Baolian "BL"), an upwind suburban site (Shunyi "SY") and a downwind rural site (Shangdianzi "SDZ") during 20 June–16 September 2007. The purpose is to improve our understanding of ozone photochemistry in urban and rural areas of Beijing and the influence of urban plumes on ozone pollution in downwind rural areas. It is found that ozone pollution was synchronism in the urban and rural areas of Beijing, coinciding with the regional-scale synoptic processes. Due to the high traffic density and local emissions, the average levels of reactive gases NOx and NMHCs at the non-rural sites were much higher than those at SDZ. The level of long-lived gas CO at SDZ was comparable to, though slightly lower than, at the urban sites. We estimate the photochemical reactivity (LOH and the ozone formation potential (OFP) in the urban (BL) and rural (SDZ) areas using measured CO and NMHCs. The OH loss rate coefficient (LOH by total NMHCs at the BL and SDZ sites are estimated to be 50.7 s-1 and 15.8 s-1, respectively. While alkenes make a major contribution to the LOH, aromatics dominate OFP at both urban and rural sites. With respect to the individual species, CO has the largest ozone formation potential at the rural site, and at the urban site aromatic species are the leading contributors. While the O3 diurnal variations at the four sites are typical for polluted areas, the ozone peak values are found to lag behind one site after another along the route of prevailing wind from SW to NE. Intersection analyses of trace gases reveal that polluted air masses arriving at SDZ were more aged with both higher O3 and Ox concentrations than those at BL. The results indicate that urban plume can transport not only O3 but its precursors, the latter leading more photochemical O3 production when being mixed with background atmosphere in the downwind rural area.

scholarly journals Measurement Report: important contributions of oxygenated compounds to emissions and chemistry of VOCs in urban air

2020 ◽  
Author(s):  
Caihong Wu ◽  
Chaomin Wang ◽  
Sihang Wang ◽  
Wenjie Wang ◽  
Bin Yuan ◽  
...  
Keyword(s):  
Mass Spectrometer ◽  
Mass Spectra ◽  
Total Concentration ◽  
Proton Transfer Reaction ◽  
Urban Atmosphere ◽  
Urban Site ◽  
Oh Radicals ◽  
Secondary Formation ◽  
Primary Emissions ◽  
Tof Ms

Abstract. Volatile organic compounds (VOCs) play important roles in the tropospheric atmosphere. In this study, VOCs were measured at an urban site in Guangzhou, one of the mega-cities in Pearl River Delta (PRD) using a gas chromatograph mass spectrometer/flame ionization detection (GC-MS/FID) and a proton transfer reaction time-of-flight mass spectrometer (PTR-ToF-MS). Diurnal profile analyses show that stronger chemical removal by OH radicals for more reactive hydrocarbons during the daytime. Diurnal profiles of OVOCs indicate evidence of contributions from secondary formation. Detailed source analyses of OVOCs using a photochemical age-based parameterization method suggest important contributions from both primary emissions and secondary formation for measured OVOCs. During the campaign, around 1700 ions were detected in PTR-ToF-MS mass spectra, among of which 462 ions with noticeable concentrations. VOCs signals from these ions without calibration in PTR-TOF-MS are quantified based on sensitivities of available VOCs species. OVOC-related ions dominated PTR-ToF-MS mass spectra with an average contribution of 77.2 %. Combining measurements from PTR-ToF-MS and GC-MS/FID, OVOCs contribute 57.4 % to the total concentration of VOCs. Using concurrent measurement of OH reactivity, OVOCs measured by PTR-ToF-MS contribute greatly to the OH reactivity (19.3 %). In comparison, hydrocarbons account for 20.0 % of OH reactivity. Adding up the contributions from inorganic gases (47.9 %), ∼ 12 % of the OH reactivity remains as missing. Our results demonstrate the important roles of OVOCs in the emission and evolution budget of VOCs in urban atmosphere.

scholarly journals Distribution Characteristics of Volatile Organic Compounds and Contribution to Ozone Formation in a Coking Wastewater Treatment Plant

2020 ◽  
Vol 17 (2) ◽  
pp. 553
Author(s):  
Yuxiu Zhang ◽  
Tingting Zang ◽  
Bo Yan ◽  
Chaohai Wei
Keyword(s):  
Wastewater Treatment ◽  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Total Concentration ◽  
Treatment Plant ◽  
Photochemical Reactions ◽  
Ozone Formation ◽  
Water Tank ◽  
Ozone Pollution ◽  
Volatile Organic

Ozone pollution, which can be caused by photochemical reactions, has become a serious problem. The ozone formation potential (OFP) is used to describe the photochemical reactivity. Volatile organic compounds (VOCs) are main precursors of ozone formation, and wastewater treatment plants (WWTPs) are important sources of VOCs. Therefore, it is necessary to study the concentration level and OFP of VOCs from WWTPs. In this work, a coking WWTP with anaerobic-oxic-oxic (A/O/O) processes in Shaoguan city, Guangdong province, China, was selected to investigate the characteristics of VOCs at wastewater treatment areas and office areas. The OFP of VOCs was estimated by the maximum incremental reactivity (MIR) coefficient method. Results showed that 17 VOCs were detected, and the total concentration of VOCs was the highest at the raw water tank (857.86 μg m−3). The benzene series accounted for 69.0%–86.9% and was the main component of VOCs in the WWTP. Based on OFP data, the top six VOCs contributing most to the OFP were m-xylene, toluene, p-xylene, o-xylene, styrene, and benzene. This study provides field data and information on the environmental risk of VOCs for coking companies and environmental departments. We found that the priority control sources of VOCs were wastewater treatment units because of their larger OFP contributions.

Direct Measurements of the Ozone Formation Potential from Livestock and Poultry Waste Emissions

2010 ◽  
Vol 44 (7) ◽  
pp. 2292-2298 ◽  
Author(s):  
Cody J. Howard ◽  
Anuj Kumar ◽  
Frank Mitloehner ◽  
Kimberly Stackhouse ◽  
Peter G. Green ◽  
...  
Keyword(s):  
Ozone Formation ◽  
Poultry Waste ◽  
Formation Potential ◽  
Direct Measurements ◽  
Ozone Formation Potential

scholarly journals Emission factor, relative ozone formation potential and relative carcinogenic risk assessment of VOCs emitted from manufacturing industries

2020 ◽  
Vol 30 (1) ◽  
Author(s):  
Hsi-Hsien Yang ◽  
Sunil Kumar Gupta ◽  
Narayan Babu Dhital
Keyword(s):  
Acrylic Resin ◽  
Carcinogenic Risk ◽  
Manufacturing Industries ◽  
Emission Sources ◽  
Ozone Formation ◽  
Stencil Printing ◽  
Voc Emission ◽  
Formation Potential ◽  
Ozone Formation Potential ◽  
Level I

AbstractManufacturing industries are one of the important emission sectors of anthropogenic volatile organic compounds (VOCs). In this study, VOC emission factors, relative ozone formation potential (ROFP) and relative carcinogenic risk (RCR) were estimated for manufacturing industries (n = 13) located in central Taiwan. Emission samples were collected in stainless steel canisters and were analyzed with a system of gas chromatography-mass spectroscopy. Higher emission factors of total VOCs (∑VOCs) were observed for stencil printing (423 mg-VOC kg− 1) compared to other emission industries. Alkanes constituted the most prominent group of VOCs for steel foundry (42%), aluminum foundry (25%) and synthetic resin industries (25%). Oxygenated VOCs were the most abundant group in the organic solvent (80%), polyester resin (80%) and polyurethane (75%) industries. Moreover, emissions from acrylic resin manufacturing had a major contribution from aromatic compounds (> 95%). Toluene was the topmost compound in terms of its contribution to ∑VOCs in plastic tape manufacturing (44%), aluminum foundry (40%), steel foundry (12%), plastic coating (64%) and stencil printing (35%). Analysis of ozone formation potentials showed that the metal product and machinery acrylic resin manufacturing and stencil printing had a higher normalized relative ozone formation potential (ROFP) index and belonged to Level-I emission sources. However, in terms of the relative carcinogenic risk (RCR), integrated iron and steel manufacturing had the highest normalized RCR index that belonged to level-I emission sources. Level-I represents the most important VOC emission sources. This study provides a reactivity- and carcinogenicity-based approach to identify high-priority VOC emission sources. The results of this study would help formulate emission reduction policies and strategies for manufacturing industries.

scholarly journals The formation of nitro-aromatic compounds under high NO<sub><i>x</i></sub> and anthropogenic VOC conditions in urban Beijing, China

2019 ◽  
Vol 19 (11) ◽  
pp. 7649-7665 ◽  
Author(s):  
Yujue Wang ◽  
Min Hu ◽  
Yuchen Wang ◽  
Jing Zheng ◽  
Dongjie Shang ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Aromatic Compounds ◽  
Total Concentration ◽  
Fine Particulate Matter ◽  
Oxidation Products ◽  
Urban Atmosphere ◽  
Formation Pathway ◽  
Relative Contribution ◽  
Phase Oxidation ◽  
Nitro Aromatic

Abstract. Nitro-aromatic compounds (NACs), as important contributors to the light absorption by brown carbon, have been widely observed in various ambient atmospheres; however, their formation in the urban atmosphere was little studied. In this work, we report an intensive field study of NACs in summer 2016 at an urban Beijing site, characterized by both high-NOx and anthropogenic VOC dominated conditions. We investigated the factors that influence NAC formation (e.g., NO2, VOC precursors, RH and photolysis) through quantification of eight NACs, along with major components in fine particulate matter, selected volatile organic compounds, and gases. The average total concentration of the quantified NACs was 6.63 ng m−3, higher than those reported in other summertime studies (0.14–6.44 ng m−3). 4-Nitrophenol (4NP, 32.4 %) and 4-nitrocatechol (4NC, 28.5 %) were the top two most abundant NACs, followed by methyl-nitrocatechol (MNC), methyl-nitrophenol (MNP), and dimethyl-nitrophenol (DMNP). The oxidation of toluene and benzene in the presence of NOx was found to be a more dominant source of NACs than primary biomass burning emissions. The NO2 concentration level was found to be an important factor influencing the secondary formation of NACs. A transition from low- to high-NOx regimes coincided with a shift from organic- to inorganic-dominated oxidation products. The transition thresholds were NO2 ∼ 20 ppb for daytime and NO2∼25 ppb for nighttime conditions. Under low-NOx conditions, NACs increased with NO2, while the NO3- concentrations and (NO3-)/NACs ratios were lower, implying organic-dominated products. Under high-NOx conditions, NAC concentrations did not further increase with NO2, while the NO3- concentrations and (NO3-)/NACs ratios showed increasing trends, signaling a shift from organic- to inorganic-dominated products. Nighttime enhancements were observed for 3M4NC and 4M5NC, while daytime enhancements were noted for 4NP, 2M4NP, and DMNP, indicating different formation pathways for these two groups of NACs. Our analysis suggested that the aqueous-phase oxidation was likely the major formation pathway of 4M5NC and 3M5NC, while photo-oxidation of toluene and benzene in the presence of NO2 could be more important for the formation of nitrophenol and its derivatives. Using the (3M4NC+4M5NC) ∕ 4NP ratios as an indicator of the relative contribution of aqueous-phase and gas-phase oxidation pathways to NAC formation, we observed that the relative contribution of aqueous-phase pathways increased at elevated ambient RH and remained constant at RH > 30 %. We also found that the concentrations of VOC precursors (e.g., toluene and benzene) and aerosol surface area acted as important factors in promoting NAC formation, and photolysis as an important loss pathway for nitrophenols.

scholarly journals Ambient Non-Methane Hydrocarbons (NMHCs) Measurements in Baoding, China: Sources and Roles in Ozone Formation

Atmosphere ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1205
Author(s):  
Ming Wang ◽  
Kun Hu ◽  
Wentai Chen ◽  
Xueyong Shen ◽  
Wenjing Li ◽  
...  
Keyword(s):  
Urban Site ◽  
Ozone Formation ◽  
Traffic Emission ◽  
Automobile Manufacturing ◽  
Pmf Model ◽  
Relative Contribution ◽  
Scenario Analyses ◽  
Receptor Sites ◽  
Reduction Of Nox ◽  
Relationship Of

Ambient non-methane hydrocarbons (NMHCs) are important precursors of ozone (O3) and secondary organic aerosol (SOA). Online and offline measurements of NMHCs were conducted during September 2015 in Baoding, Hebei province of China, in order to investigate their sources and roles in ozone formation. Average levels of total NMHCs online measured at the urban site were 44.5 ± 26.7 ppb. Aromatics was the largest contributor to NMHCs levels and OH reactivity, with fraction of 27.1% and 35.9%, respectively. Based on offline measurements at eight sites, we found that toluene, ethylbenzene, and m,p-xylene displayed the highest level at the site close to automobile manufacturing factories, followed by downwind receptor sites and other sites. Positive matrix factorization (PMF) model was then used to analyze NMHCs sources. Four factors were identified, including traffic-related emission, automobile manufacturing coating, biogenic emission, and NG/LPG usage and background. Average relative contribution of automobile manufacturing coating to NMHCs levels during the entire online measurement period was 33.4%, and this value increased to 42% during two O3 pollution days. Sensitivity of O3 formation to NMHCs and NOX during an O3 pollution episode were analyzed using a box model based on observations. Relative incremental reactivity (RIR) results suggested that O3 formation was in NOx-titration regime (i.e., highly NMHCs-limited regime). Further scenario analyses on relationship of O3 formation with reduction of NOx and anthropogenic NMHCs (AHC) indicated that AHC and NOx should be reduced by a ratio greater than two and three to achieve 5% and 10% O3 control objectives, respectively. The largest RIR value for anthropogenic NMHC species was from xylenes, which were also an important contributor to SOA formation and dominantly from sources related to automobile manufacturing coating and traffic emission. This means reducing NMHCs emission from automobile manufacturing coating and traffic emission should be given priority for synergetic control of O3 and PM2.5.

scholarly journals Characterization of nighttime formation of particulate organic nitrates based on high-resolution aerosol mass spectrometry in an urban atmosphere in China

2018 ◽  
Author(s):  
Kuangyou Yu ◽  
Qiao Zhu ◽  
Ke Du ◽  
Xiao-Feng Huang
Keyword(s):  
High Resolution ◽  
Factorization Method ◽  
Urban Atmosphere ◽  
Ozone Production ◽  
Urban Site ◽  
High Time Resolution ◽  
Organic Nitrates ◽  
Aerosol Mass ◽  
Polluted Atmosphere

Abstract. Organic nitrates are important atmospheric species that significantly affect the cycling of NOx and ozone production. However, characterization of particulate organic nitrates and their sources in inorganic nitrate-abundant particles in polluted atmosphere is a big challenge, and has been little performed in the literature. In this study, an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) was deployed at an urban site in South China from 2015 to 2016 to characterize particulate organic nitrates with high time resolution. Based on two different data processing methods, 13–21 % of the total measured nitrates was identified to be organic nitrates in spring, 41–64 % in summer and 16%–25 % in autumn; however, in winter, most measured nitrates were inorganic. The good correlation between organic nitrates and fresh secondary organic aerosol identified by the positive matrix factorization method at night rather than in the daytime indicated a potentially important role of nighttime secondary formation. Therefore, we theoretically estimated nighttime NO3 radical concentrations and SOA formation using the various VOCs measured simultaneously. Consequently, the calculated products of monoterpene reacting with NO3 agreed well with the organic nitrates in terms of both concentration and variation, suggesting that the biogenic VOC reactions with NO3 at night are the dominant formation pathway for particulate organic nitrates in polluted atmosphere, despite of much higher abundance of anthropogenic VOCs.

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