Total Volatile Organic Compounds Emissions Research Articles

Air pollutant emissions from the asphalt industry in Beijing, China

Improving our understanding of air pollutant emissions from the asphalt industry is critical for the development and implementation of pollution control policies. In this study, the spatial distribution of potential maximum emissions of volatile organic compounds (VOCs) in the complete life cycle of asphalt mixtures, as well as the particulate matter (PM), asphalt fume, nonmethane hydrocarbons (NMHCs), VOCs, and benzoapyrene (BaP) emissions from typical processes (e.g., asphalt and concrete mixing stations, asphalt heating boilers, and asphalt storage tanks) in asphalt mixing plants, were determined in Beijing in 2017. The results indicated that the potential maximum emissions of VOCs in the complete life cycle of asphalt mixtures were 18,001 ton, with a large contribution from the districts of Daxing, Changping, and Tongzhou. The total emissions of PM, asphalt fume, NMHC, VOCs, and BaP from asphalt mixing plants were 3.1, 12.6, 3.1, 23.5, and 1.9 × 10−3 ton, respectively. The emissions of PM from asphalt and concrete mixing stations contributed the most to the total emissions. The asphalt storage tank was the dominant emission source of VOCs, accounting for 96.1% of the total VOCs emissions in asphalt mixing plants, followed by asphalt heating boilers. The districts of Daxing, Changping, and Shunyi were the dominant regions for the emissions of PM, asphalt fume, NMHC, and BaP, while the districts of Shunyi, Tongzhou, and Changping contributed the most emissions of VOCs.

VOCs Emission Inventory and Variation Characteristics of Artificial Sources in Hubei Province in the Yangtze River Economic Belt

In this study, a 2018 anthropogenic volatile organic compounds (VOCs) emission inventory in Hubei Province was conducted using the emission factor method based on activity levels of five sources. The emission characteristics and variation trends of process sources from 2009 to 2018 were further analyzed. Total anthropogenic VOCs emissions were 6.52×105 tons in Hubei Province, accounting for about 6.41% of the country's total omissions. The contributions of fossil combustion sources, process sources, solvent sources, mobile sources, and waste disposal sources were 3.26%, 76.39%, 4.54%, 14.72%, and 1.09%, respectively. Process sources involving 45 sub-categories of nine industries accounted for a significant proportion of VOCs emissions, with Wuhan and Yichang recording the highest VOCs emission levels. The VOCs emissions intensity of each city and state were analyzed based the level of economic activity and territorial area. Tianmen and Shennongjia had higher VOCs emissions per unit of GDP, while Wuhan, Ezhou, and Tianmen had higher VOCs emissions per unit area. Regarding process source contributions, VOCs emissions increased progressively to 2.45×105 tons in 2009 and then stabilized between 2015 and 2017 with maximum emissions of 7.01×105 tons. In 2018, VOCs emissions decreased to 4.98×105 tons. This trend was similar to national anthropogenic emissions. Two industrial sectors, namely chemical raw materials and rubber and plastics, were the main driving force with contributions of 33.85%-51.55% and 7.07%-38.13%, respectively. Among them, the production of chemicals and active pesticide and pharmaceutical ingredients played an important role in contributing to VOCs emissions, while emissions during foam plastics production varied greatly, increasing sharply to more than 2.00×104 tons in 2015-2017. Under the guidance of the relevant national and local policies, emissions from key industries were significantly reduced in Hubei Province.

Volatile organic compounds (VOCs) allow sensitive differentiation of biological soil quality

Understanding the change in function of the biological community under different soil conditions is key to effective soil quality monitoring and mitigation of soil degradation. Current measures of biological soil quality suffer from drawbacks with most techniques having high expense, low throughput or a narrow focus on one component of the community. The aim of this study was to assess the use of volatilomics as a method to profile the soil microbial community and compare the technique to phospholipid fatty acid (PLFA) profiling as a measure of biological soil quality. An agricultural grassland soil (Eutric Cambisol) was subjected to a range of stresses in replicate laboratory mesocosms. Treatments included the imposition of hypoxia/anoxia by flooding with freshwater or saltwater in the presence or absence of plant residues. The volatile organic compound (VOC) and PLFA profile of each treatment was then compared to unamended mesocosms. We hypothesized that the VOC fingerprint of soil would be highly responsive to changes in microbial metabolic status/functioning and thus provide a complementary approach to PLFAs for evaluating soil biological health. We also hypothesized that the VOC profile would have greater discriminatory power than PLFAs for determining differences between soil treatments. A headspace solid phase microextraction (HSSPME) method coupled with gas chromatography quadrupole-time of flight mass spectrometry (GC/Q-TOFMS) was used to analyse the broad spectrum of VOCs produced by each soil. Across all soil treatments 514 unique VOC peaks were detected. Overall, VOCs showed greater sensitivity than the PLFA analysis in separating soil quality treatments. Eighteen individual VOCs were identified which were primarily responsible for this separation (e.g. indole, α-ionone, isophorone, 3-octanone, p-cresol, 2-ethyl-phenol). Anaerobic soils amended with residues showed the greatest separation from other treatments, with most of this differentiation associated with ten individual VOCs. The anaerobic soils also showed a significant reduction in the number of VOCs emitted but an increase in total VOC emissions. In conclusion, our findings provide evidence that soil VOCs rapidly respond to changes in soil quality and therefore hold great potential as a novel functionally relevant diagnostic measure of biological soil quality.

VOC emissions of coal-fired power plants in China based on life cycle assessment method

During the coal-fired power generation process, both direct and indirect volatile organic compounds (VOCs) emissions are generated and emitted, releasing aerosols and particulate matter in the atmosphere. However, the indirect VOC emissions from coal-fired power plants (CFPPs) are often ignored, which causes considerable underestimation of total VOC emissions and their polluting effects on the atmosphere and human health. In this work, for the first time, the direct and indirect VOC emissions from coal-fired power generation processes are comprehensively assessed through life cycle assessment (LCA). Results show that the VOC emissions from coal mining, coal-fired power generation systems, flue gas cleaning systems, and waste disposal systems are estimated to be 2.31E−03 to 1.10E−02, 2.24E−03 to 1.46E−02, 2.38E−03 to 2.36E−03, 1.30E−05 to 1.33E−05 kg/MWh, respectively. The life cycle VOC emissions from the coal-fired power generation process as a whole are calculated as: 1.78E−02 to 9.85E−02 kg/MWh, without considering air pollution control devices' effects (APCDs). This value is reduced to 6.95E−03 to 2.80E−02 kg/MWh if the APCDs are implemented (61–72% reduction). Indirect emissions account for 48.46%–68.13% of life cycle VOC emissions, mainly from coal mining and flue treatment system. If considering all the CFPPs in China, the value of the total VOC emissions reaches at least 3.29E+04 t in 2017, while indirect emissions are up to 2.32E+04 t. The paper also analyzes the impact of the change of key input variables on the overall VOC emissions. Based on the results, proposing possible abating measures, which can be considered by authorities and decision-makers for promoting strategies to abate VOC emissions.

Evaluating the effects of olefin components in gasoline on GDI engine combustion and emissions

Olefins are part of the most important components in gasoline fuel. In this paper, olefin component diisobutylene (DIB), 1-pentene and 1-hexene are involved into research. Three quinary gasoline model fuels containing each of these three olefins are used to support this research. Results prove these three olefins exhibit comparable effects on engine combustion and regulated emissions. However, their differences in affecting VOC and particulate matter emissions are of great significance. DIB leads to higher ethane emission while 1-hexene results in remarkably lower acetylene emission. 1-pentene generally leads to lower formaldehyde and acetaldehyde emissions. Nevertheless, these three olefins lead to comparable total VOC emissions. Further analyses show that alkane, olefin and aromatics take the most part of VOCs while olefin in emission take the most responsibility of ozone formation potential. Although 1-pentene in gasoline does not lead to the lowest VOC emissions, it results in the lowest OFP value when compared with DIB and 1-hexene. Such a finding signifies that gasoline with more 1-pentene content help to alleviate emission photochemical effect when compared with olefin content DIB or 1-hexene, which hints that gasoline with C5 olefin might be favorable than C6 olefin content when OFP of engine VOC emission is considered.

Volatile organic compound emission in tundra shrubs – Dependence on species characteristics and the near-surface environment

Temperature is one of the key abiotic factors during the life of plants, especially in the Arctic region which is currently experiencing rapid climate change. We evaluated plant traits and environmental variables determining leaf temperature in tundra shrubs and volatile organic compound (VOC) emissions with field measurements on deciduous tundra shrubs, Salix myrsinites and Betula nana, and evergreen Cassiope tetragona and Rhododendron lapponicum. Higher leaf-to-air temperature difference was observed in evergreen, compared to deciduous shrubs. Evergreen shrubs also showed continuously increasing photosynthesis with increasing temperature, suggesting high thermal tolerance. For the deciduous species, the optimum temperature for net photosynthesis was between our measurement temperatures of 24 °C and 38 °C. Air temperature and vapor pressure deficit were the most important variables influencing leaf temperature and VOC emissions in all the studied plants, along with stomatal density and specific leaf area in the deciduous shrubs. Using climate data and emission factors from our measurements, we modelled total seasonal tundra shrub VOC emissions of 0.3–2.3 g m−2 over the main growing season. Our results showed higher-than-expected temperature optima for photosynthesis and VOC emission and demonstrated the relative importance of plant traits and local environments in determining leaf temperature and VOC emissions in a subarctic tundra.

Mobile Measurement System for the Rapid and Cost-Effective Surveillance of Methane and Volatile Organic Compound Emissions from Oil and Gas Production Sites.

In this study, a ground-based mobile measurement system was developed to provide rapid and cost-effective emission surveillance of both methane (CH4) and volatile organic compounds (VOCs) from oil and gas (O&G) production sites. After testing in several controlled release experiments, the system was deployed in a field campaign in the Eagle Ford basin, TX. We found fat-tail distributions for both methane and total VOC (C4-C12) emissions (e.g., the top 20% sites ranked according to methane and total VOC (C4-C12) emissions were responsible for ∼60 and ∼80% of total emissions, respectively) and a good correlation between them (Spearman's R = 0.74). This result suggests that emission controls targeting relatively large emitters may help significantly reduce both methane and VOCs in oil and wet gas basins, such as the Eagle Ford. A strong correlation (Spearman's R = 0.84) was found between total VOC (C4-C12) emissions estimated using SUMMA canisters and data reported from a local ambient air monitoring station. This finding suggests that this system has the potential for rapid emission surveillance targeting relatively large emitters, which can help achieve emission reductions for both greenhouse gas (GHG) and air toxics from O&G production well pads in a cost-effective way.

Analysis of Industrial VOCs Emission Inventory and Countermeasures in Xiamen

Based on data from industrial activities and environmental surveys in the six districts of Xiamen, the emission inventory of industrially sourced volatile organic compounds (VOCs) from eight industries in the six districts of Xiamen was calculated for 2019 by applying the emission factor analysis method. The spatial distribution pattern of VOC emission intensity in the six districts of Xiamen was analyzed. VOCs treatment technologies applied in the industries in the VOCs emission inventory were analyzed and countermeasures for improving VOC control were proposed based on the survey of the industries. The results showed that the total VOCs production and VOCs emission from industrial sources in Xiamen was 16027.88 t and 5514.58 t in 2019, respectively. Among them, the VOCs emission from Haicang, Tong'an, Xiang'an, and Jimei districts outside Xiamen Island were 1648.35, 2111.13, 667.52, and 750.48 t, respectively. Fewer VOC emissions from Xiamen Island were observed, which included 292.42 and 44.68 t from Huli and Siming districts, respectively. Except for the Huli District, the spatial distribution of emissions showed a spatial characteristic that the VOCs emission intensities outside Xiamen Island are higher than that of Xiamen Island. Among the eight industries in Xiamen, VOCs emissions were mainly from coating, printing, chemical, and rubber industries, which accounted for 51.21%, 20.18%, 13.63%, and 10.67%, respectively, of the total emissions. The analytic results of the VOCs waste gas disposal technique in Xiamen indicate that, from the perspective of source control, enterprises can effectively control the generation and emission of the VOCs at the source by using low (zero) raw materials. For the terminal disposal procedure, the actual disposal efficiency of UV photolysis/photocatalysis, low-temperature plasma, and biological methods are all lower than 80%, and that of the combined technique of adsorption and catalytic combustion, and the combustion method are both higher than 90%.

Emission Inventory and Emission Factors of Volatile Organic Compounds (VOCs) from Architectural Adhesives

Architectural decoration is an important anthropogenic emission source of VOCs in China, and there are few studies on the emission of VOCs from architectural adhesives. In this study, the VOCs content level and emission factors of various architectural adhesives were measured and then, a VOC emission inventory of architectural adhesives in China from 2013 to 2017 was established by a top-down emission factor method. Results showed that the comprehensive VOCs emission factor of architectural adhesives was 97.0 kg·t-1, of which 543 kg·t-1 was from solvent-based architectural adhesives, 45 kg·t-1 was from water-based architectural adhesives, and 63 kg·t-1 was from bulk architectural adhesives. The VOCs emissions from architectural adhesives were 165 kt, 181 kt, 188 kt, 201 kt, and 219 kt from 2013 to 2017 in China. The contribution of VOCs emission of various disparate architectural adhesives was 25.5%, 23.6%, and 50.9% for water-based, bulk, and solvent-based types, respectively. Shandong, Jiangsu, Zhejiang, Sichuan, Guangdong, Henan, Yunnan, and Fujian provinces contributed significant amounts, with a total emission of 120 kt in 2017, accounting for nearly 55% of the total VOCs emission for architectural adhesives.

Industrial Volatile Organic Compounds (VOCs) Emission Inventory in China

An industrial volatile organic compounds (VOCs) emission inventory was developed in China in 2018. It was based on the emission factors method, using a revised and updated source classification system and emission factors of key industrial sources. Results showed that the total industrial VOCs emission in China in 2018 reached as high as 12698 kt. Processes using products containing VOCs were the largest contributors, accounting for 59% of the total emission. The industrial coating industry, printing, the basic organic chemical industry, gasoline storage and transport, and the oil refinery industry were the five largest emitters, accounting for 54% of the total emission. Guangdong, Shandong, Zhejiang, and Jiangsu were the four largest emission contributors, contributing to 41% of the total emission. Hainan, Ningxia, Tibet, Heilongjiang, and Xinjiang showed the largest VOCs emission intensities, with more than 80 t·(100 million yuan)-1. Processes using products containing VOCs were the main emission contributors in most provinces. The uncertainty for the total industrial VOCs emission in 2018, based on a Monte Carlo simulation, was[-32%, 48%] at the 95% confidence interval.

Co-combustion, co-densification, and pollutant emission characteristics of charcoal-based briquettes prepared using bio-tar as a binder

In this study, charcoal-based briquettes prepared using bio-tar as a binder are proposed as a substitute for conventional coal in rural China; furthermore, the fuel properties of the blends of charcoal, semi-coke, and bio-tar and the co-densification and pollutant emission characteristics of charcoal-based briquettes are investigated. The addition of charcoal improved the heating value and combustion index; however, the addition of a small amount of bio-tar did not have any significant effect on the fuel properties of the charcoal and semi-coke blend. The blending of charcoal and semi-coke with a mass ratio of 1:1 increased the integrated combustion characteristics from 7.73 × 10−12 (only semi-coke) to 16.92 × 10−12 K−3min−2. Results of the co-densification experiments suggest that the bio-tar effectively improved the physical stability of charcoal-based briquette. By increasing the addition of bio-tar from 0 to 9 wt% at the densification temperature of 20 °C, the strength compaction and drop resistance increased by 8.6% and 13.9%, respectively. Increasing the densification temperature from 20 to 50 °C resulted in negative effects on mechanical strength. Pollutant emissions were observed during the ignition, stable combustion, and burnout phases of the stove. The bio-tar addition had distinct negative influences, increasing the total suspended particle and VOC emissions, which could be effectively weakened or eliminated by adding 3 wt% of hydrated lime. Herein, the applied chain and technical chain of charcoal-based briquettes are summarized. The study provides technical support for the industrial application of charcoal-based briquettes in rural China, with replication potential elsewhere.

Emission Inventory of VOCs Components in Zhengzhou and Their Ozone Formation Potential

In this study, according to the activity levels of volatile organic compounds (VOCs) sources and source profiles, a 2016-based inventory of the speciation emission of the VOCs was established and the ozone formation potential (OFP) were estimated in Zhengzhou. The results showed that the total VOCs emission in Zhengzhou in 2016 was 96215.3 t. The highest emission source was on-road mobile source (29.7%) followed by solvent use sources (28.1%). The species that contributed the highest emission was alkanes (29.8%) followed by aromatics (29.0%). The OFP in Zhengzhou in 2016 was 341291.0 t with the highest contributing source as on-road mobile (30.5%) followed by solvent use source (28.8%). Moreover, the light duty gasoline vehicle, use of interior wall coatings, vehicle surface coating, gas station loading and unloading, and manufacture of non-metallic mineral were the major secondary emission sources of OFP, which needed to be controlled for reducing ozone pollution in Zhengzhou. For VOCs species group, the higher contribution groups were aromatics (42.8%) and alkenes (38.9%). The sources that produced m/p-xylene, propylene, ethylene, and other species should be paid more attention.

An increasing role for solvent emissions and implications for future measurements of volatile organic compounds

Volatile organic compounds (VOCs) are a broad class of air pollutants which act as precursors to tropospheric ozone and secondary organic aerosols. Total UK emissions of anthropogenic VOCs peaked in 1990 at 2,840 kt yr−1 and then declined to approximately 810 kt yr−1 in 2017 with large reductions in road transport and fugitive fuel emissions. The atmospheric concentrations of many non-methane hydrocarbons (NMHC) in the UK have been observed to fall over this period in broadly similar proportions. The relative contribution to emissions from solvents and industrial processes is estimated to have increased from approximately 35% in 1990 to approximately 63% in 2017. In 1992, UK national monitoring quantified 19 of the 20 most abundant individual anthropogenic VOCs emitted (all were NMHCs), but by 2017 monitoring captured only 13 of the top 20 emitted VOCs. Ethanol is now estimated to be the most important VOC emitted by mass (in 2017 approx. 136 kt yr−1 and approx. 16.8% of total emissions) followed by n-butane (52.4 kt yr−1) and methanol (33.2 kt yr−1). Alcohols have grown in significance representing approximately 10% of emissions in 1990 rising to approximately 30% in 2017. The increased role of solvent emissions should now be reflected in European monitoring strategies to verify total VOC emission reduction obligations in the National Emissions Ceiling Directive. Adding ethanol, methanol, formaldehyde, acetone, 2-butanone and 2-propanol to the existing NMHC measurements would provide full coverage of the 20 most significant VOCs emitted on an annual mass basis.This article is part of a discussion meeting issue ‘Air quality, past present and future’.

Volatile Profiling of Fifteen Willow Species and Hybrids and Their Responses to Giant Willow Aphid Infestation

The giant willow aphid (Tuberolachnus salignus) is a large stem-feeding insect which forms dense colonies on infested plants. Since T. salignus is a new invasive species in New Zealand, we have a poor understanding of the plant chemical responses to aphid infestation. This study aimed to characterize the volatile organic compounds (VOCs) emissions of fifteen different willow species and hybrids growing in New Zealand, and to evaluate changes in response to T. salignus attack in a field trial. Volatiles were collected using a headspace sampling technique and analysed using gas chromatography-mass spectrometry (GC-MS). We found high variability in the volatile profiles of different species and hybrids, with (Z)-3-hexenyl acetate and (E)-β-ocimene being the only common components to all blends. Taxonomically related plants showed an overlapping pattern of VOC emission, and there seemed to be a clear separation between shrub and tree willows. Responses to aphid infestation were variable, with only four species/hybrids showing changes in their total VOC emission, or that of at least one class of VOCs. A weak positive correlation between aphid population estimates and VOC emissions suggests that responses are species-specific and not infestation-dependent. These results reveal useful information about the interaction between T. salignus and its potential host plants for biological control and pest management purposes.

Study on emissions of volatile organic compounds from a typical coking chemical plant in China

Coking chemical industry associated with high energy consumption and high pollution emits significant amount of volatile organic compounds (VOCs) to atmosphere, but is often ignored. This article reports a new study on emissions of VOCs from a typical coking chemical plant. Results show that about 70 species of VOCs including alkanes, alkenes, alkynes, aromatic hydrocarbons, halogenated hydrocarbons and oxygenates are detected, naphthalene and benzene could be used as the emission markers. Compared to coking stage, gas purifying stage is found to have 4 times more total concentrations of VOCs, in which condensing and blasting process is found to be the largest contributor with 77% ozone formation potential (OFP) contribution. Emission control measures currently used are insufficient and inefficient to reduce VOCs to meet regulatory emission standards. Further, by using a proposed integrated emission factor of 2.652 g/kg coke, the coking chemical industry in China was estimated to account for about 7.8–20% of total historical industrial VOCs emissions, and about 1241 Gg of VOCs were emitted in 2019. A large proportion is emitted from the northern China with a distinctive spatial distribution. Shanxi, Hebei, Shandong, and Shannxi provinces are the top four emitters. It is suggested that more stringent and efficient measures should be taken on the coking chemical industry, not just on the coking processes, but also on the gas purifying processes.

Comparative Assessment of Asphalt Volatile Organic Compounds Emission from field to laboratory

The quantifying evaluations of asphalt volatile organic compounds (VOCs) throughout the road construction process are growing concerned since VOCs are widely recognized for its adverse effects on both human health and environmental issues. This paper made a comparison on VOCs emission assessment between actual construction field and laboratory simulation, aiming to verify their research gap at similar applied conditions. Atmospheric sampling pump and adsorption tube were used to record the VOCs samples from practical construction site, involving in hot asphalt storage tank, mixture plant, and paving site. Correspondingly, a sealed simulator for experimental VOCs collection was set-up in laboratory to investigate the VOCs amount released in different temperatures. Moreover, thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) was applied to analyze the detailed chemical composition and released quantification of VOCs samples. The results indicated that substance varieties and content in asphalt VOCs had considerable dependence on heating temperature. Both oxygen and thermality will trigger the increasing generation of hydrocarbon derivatives (HYD) in asphalt VOCs. For construction site, the investigated scenarios behaved great difference due to the complexity from on-site factors, however, approximating 74% of aliphatic hydrocarbons (ALH) tested in laboratory were fitted with the main components detected in construction site. Therefore, experimental simulation in laboratory could obtain a workable effect in signalling practical VOCs amount and compositions released in construction sites. This study provided a significant reference in connecting construction sites and laboratory research toward asphalt VOCs quantification. It laid down a basis for further total VOCs emission amount estimation and environmental effect assessment in the life-cycle of asphalt pavement construction, which is little concerned in corresponding research field.

Synthesis and Characterization of Low-Cost Cresol-Based Benzoxazine Resins as Potential Binders in Abrasive Composites.

A series of cresol-based benzoxazines were synthesized for potential application as a polymer matrix in abrasive composites. The chemical structures of the obtained benzoxazine resins were investigated in detail using Fourier transform infrared spectroscopy (FTIR) and hydrogen-1 as well as carbon-13 nuclear magnetic resonance spectroscopy (1H NMR, 13C NMR) with an additional analysis using two-dimensional NMR techniques (2D NMR 1H-1H COSY, 1H-13C gHSQC and gHMBC). Structural analysis confirmed the presence of vibrations of -O-C-N- at ~950 cm−1 wavenumber, characteristic for an oxazine ring. The thermal properties of benzoxazine monomers were examined using differential scanning calorimetry (DSC) analysis. The polymerization enthalpy varied from 143.2 J/g to 287.8 J/g. Thermal stability of cresol-based benzoxazines was determined using thermogravimetry (TGA) analysis with additional analysis of the amount of volatile organic compounds (VOC) emitted from the synthesized benzoxazines during their crosslinking by static headspace coupled with gas chromatography technique (HS-GC). The amount of residual mass significantly differed between all synthesized polybenzoxazines in the range from 8.4% to 21.2%. The total VOC emission for benzoxazines decreased by 46–77% in reference to a conventional phenolic binder. The efficiency of abrasive composites with the benzoxazine matrix was evaluated based on abrasion tests. Performed analyses confirmed successful synthesis and proper chemical structure of cresol-based benzoxazines. All the experiments indicated that benzoxazines based on different cresol isomers significantly differ from each other. Good thermal performance and stability of the abrasive composites with the polybenzoxazine matrix and significantly lower VOC emission allow us to state that benzoxazines can be a promising and valuable alternative to the phenolics and a new path for the development of modern, eco-friendly abrasives.

Deriving emission fluxes of volatile organic compounds from tower observation in the Pearl River Delta, China

Accurate estimation of speciated emissions of volatile organic compounds (VOCs) is challenging due to the complexity of both species and sources. Evaluation of the bottom-up emission inventory (EI) by atmospheric observation is needed to better understand the VOC emissions and then to control air pollutions caused by VOCs. This study conducts vertical measurements of VOCs between November 3 and 11, 2018 at the Canton Tower in the urban core of Pearl River Delta (PRD), China. A mixed layer gradient (MLG) technique is applied to the tower observation data to derive emission fluxes for individual VOC. The results show that the measured VOCs concentrations at ground level were always higher than those at the heights of 118 m and 488 m. Obvious vertical gradients of concentrations were found for VOC species, such as benzene, toluene and isoprene. The emission flux was estimated to be largest for propane (3.29 mg m−2 h−1), followed by toluene (2.55 mg m−2 h−1), isoprene (2.24 mg m−2 h−1), n-butane (2.10 mg m−2 h−1) and iso-pentane (1.73 mg m−2 h−1). The total VOC emission fluxes were around 3 times larger than those in the EI, suggesting 1.5–2 times underestimations of ozone formation potential (OFP) and secondary organic aerosol potential (SOAP) by current EI. Substantial underestimations (3–20 times) were found for C2-C5 alkanes by current EI. Due to unmeasured input parameters, limited sample size and short sampling period, there are still large uncertainties (40%–117%) in the estimated emission fluxes for individual species. Whereas, this study shows that the tower observation and emission estimation using MLG method could provide useful information for better understanding vertical distributions and emission fluxes of VOCs, and pioneer in assessing the existing emission inventories at species-level and hour-level.

One decade of VOCs measurements in São Paulo megacity: Composition, variability, and emission evaluation in a biofuel usage context

In South America, the observations of atmospheric pollutants are deficient, and few cities have implemented air quality monitoring programs. In addition, Volatile Organic Compounds (VOCs) observations are still missing, and little is known about their contributions to the atmospheric composition and impacts in a large ethanol usage context like Brazil. Here, we present a wide range of VOCs that have been measured for ten years in São Paulo Megacity (SPM) in different campaigns at traffic, urban and background sites. When compared with other cities worldwide, the average VOCs ambient concentrations in SPM were higher by factors of 2 to 10. However, the ambient VOCs distribution among these cities is homogeneous even for ethanol, aldehydes and alkenes species. Emission ratios (ER) were established related to carbon monoxide and acetylene, which did not depict strong seasonal and interannual variability in SPM. When compared with previous studies, ERs showed an enrichment from road-tunnel to background, suggesting the presence of other sources than traffic. A good agreement in ER was found with Los Angeles and Paris; but limited consistencies with Middle East and Asia cities. Our ethanol measurements show that contrasted ER can be obtained depending on the emission process involved, with a strong impact of evaporation on ethanol concentrations. The multiyear acetaldehyde analysis displayed that ER could be a valuable metric to assess the long-term changes in emissions sources. Finally, VOCs emissions were calculated from ER and compared with those estimated by the global emission inventory (Edgar). The total VOC emissions estimated by the global inventory agree very well with those from our observations up to 75%. Nevertheless, the VOCs speciation is misrepresented in the inventory, mainly for oxygenated and heavier alkanes compounds. These inconsistencies will also have an impact on the quantification of secondary atmospheric pollutants formation associated to road transport emissions.

Definition of an Emission Factor for VOC Emitted from Italian and European Refineries

Refineries are a major source of atmospheric emissions, which typically include CO, SO2, NOX, particulates, and volatile organic compounds (VOCs). There has been an increasing level of attention toward the emissions of VOCs related to their environmental impact as well as their potential to cause adverse effects on human health and the discomfort associated with their unpleasant odor. In general, an emission factor (EF) represents a model for a first order estimate of emissions, which correlates the quantity of pollutant released into the atmosphere with a so-called “activity index” related to the release of that pollutant. Based on the study of the scientific and technical literature regarding the Italian and European refining scenarios, an attempt was made to verify the existence of a correlation between the size of a refinery and the related total VOC emissions. Once this correlation was evaluated, it was possible to develop an emission factor for VOC emissions considering the plant capacity as the related activity index. After collecting and analyzing data concerning operative capacity and total VOCs emitted from 15 refineries in 2018, the resulting emission factor turned out to be equal to 188 ± 166 g per ton of crude oil processed. This value is in agreement with the range of 50–1000 g/ton reported in the European Best Available Techniques Reference Document for the Refining of Mineral Oil and Gas.