Ozone Formation Potential Of Volatile Organic Compounds Research Articles

Characteristics of VOCs and Their Roles in Ozone Formation at a Regional Background Site in Beijing, China

As important precursors of near-surface ozone, secondary organic aerosols (SOAs), and volatile organic compounds (VOCs) play an important role in photochemical reactions and fine particle formation. In this study, real-time VOCs were measured continuously by Syntech Spectras GC955 analyzers at the regional background site of the North China Plain from September 1 to 27, 2017. The VOC concentration levels, compositions, spatiotemporal variations, and the ozone formation potential during the observation period were investigated. The potential sources of initial VOCs indicated from the diagnostic ratios were further studied. The averaged total mixing ratio of VOCs was 12.53×10-9. Among all measured VOC species, alkanes were the most abundant species, which accounted for 65.3% of the total concentrations, followed by alkenes (26.7%) and aromatics (6.5%). In addition, the total OH radical loss rate of VOCs (L·OH) was 5.2 s-1. In particular, the contribution of C4-C5 alkenes to L·OH was as high as 61%, followed by C2-C3 alkenes, with a 12.8% contribution of L·OH. The average ozone formation potential of VOCs was 36.5×10-9. Among all the measured VOC species, alkenes were the most abundant species, which accounted for 71.2%. Among alkenes, the contribution of C4-C5 alkenes was the most prominent. Although the concentration of alkanes in Shangdianzi was much higher than other VOC species, the ozone formation potential was lower. Diagnostic ratios and source implications suggested that Shangdianzi was affected mainly by biomass/biofuel/coal burning, with substantially elevated benzene levels during the observation period, whereas a slight influence of traffic-related emissions was observed.

Emission of volatile organic compounds from a small-scale municipal solid waste transfer station: Ozone-formation potential and health risk assessment

Volatile organic compounds (VOCs) are the main precursors of tropospheric ozone and secondary aerosol generation, posing a threat to human health and affecting the environmental climate. A large quantity of VOCs can be produced in the initial decomposition stage of municipal solid waste (MSW). In this study, the atmosphere in an MSW transfer station was monitored for one year. The emission characteristics of VOCs in different seasons and working hours were analyzed, and the ozone-formation potential of VOCs was calculated through the maximum incremental reaction method, and health risks posed by the VOCs in the MSW transfer station were assessed. The results showed that the highest concentration of VOCs appeared in spring and summer, accounting for 70.6% and 26.6% of total VOCs (TVOCs) in peak working periods, respectively. Oxygenated compounds and terpenes contributed most to ozone formation, accounting for 41.0% and 50.6% of total ozone formation, respectively. The carcinogenic risks were above the safe threshold, labeled “probable risks”. Tetrachloroethylene and 1,2-dichloroethane were the main contributors to carcinogenic risks. The mean non-carcinogenic risks were within the safe threshold in the MSW transfer station. From the perspective of protecting human health and ecological environmental safety, VOC control needs to be further strengthened in the transfer station.

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

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.

Emission Characteristics Analysis and Health Risk Assessment of Unorganized VOCs in the Carbon Industry, Zhengzhou

The three typical carbon enterprises in Zhengzhou were selected as research targets, and the emission characteristics of volatile organic compounds (VOCs) and their ozone formation potential (OFP) in different functional areas were studied. The US Environmental Protection Agency (EPA) health risk assessment model was used to evaluate the health risks of VOCs emitted by the carbon industry. The results showed that the concentration of VOCs in the production areas of the three research enterprises was between 89.77-964.60 μg·m-3, and the management area was between 51.46-121.59 μg·m-3. Naphthalene and carbon disulfide were at the highest concentrations in the carbon plants. The ozone formation potential of VOCs in the production area was between 75.42-1416.73 μg·m-3, and in the management area was between 65.32-202.42 μg·m-3, mainly from the contribution of aromatic hydrocarbons and olefins. The carcinogenic health risk (Risk) of VOCs in the production area was 3.5×10-5-2.8×10-3, and in the management area was 2.0×10-5-9.4×10-5, which was higher than the maximum acceptable level recommended by the EPA (10-6). The non-carcinogenic health risk index (HI) of the VOCs in the production area was 3.2-1.4×102, and in the management area was 4.3×10-1-3.8, except for the management area of the first enterprise, which was greater than 1, which may expose the workers. These health factors cause cancer and non-carcinogenic hazards.

Emission Characteristics and Ozone Formation Potential of VOCs in Printing Enterprises in Beijing-Tianjin-Hebei

In this study, 23 typical printing enterprises were selected in Beijing-Tianjin-Hebei. Through gas chromatography-mass spectrometry/flame ionization detection (GC-MS/FID), 46 sets of analysis results were obtained to quantitatively analyze the emissions characteristics of volatile organic compounds (VOCs) and the ozone generation potential of these printing enterprises. The results show that the emission concentrations of total VOCs (TVOCs) in exhaust funnels of the printing enterprises varied greatly, ranging from 3.3 mg·m-3 to 755.0 mg·m-3. In the printing stations of printing enterprises, the emission concentrations of VOCs were 129.7-958.4 mg·m-3 and 19.1-113.7 mg·m-3 in packaging and printing enterprises and publications printing enterprises, respectively. The concentration of VOCs emitted by packaging and printing enterprises was significantly higher than that of publications printing enterprises, which is related to the use of solvent-based inks. In terms of VOC composition, oxygen-containing VOCs were the primary type of those emitted by the printing station of packaging and printing enterprises and publications printing enterprises, which accounted for a ratio of 32.6%-99.4%, followed by alkanes. In terms of ozone generation potential, the average of ozone formation potential (OFP) of the printing enterprises was 505.5 mg·m-3, in which the packaging and printing enterprises was 564.1 mg·m-3, and the publication printing enterprises was 52.9 mg·m-3. The average VOC source reactivity (SR) emitted from the printing process was 1.24 g·g-1; that is, 1.24 g of O3 was formed owing to the unit mass of VOC emission, of which the packaging and printing enterprises was 1.70 g·g-1, and the publication printing enterprises was 0.89 g·g-1. According to the OFP and SR, the use of environmentally friendly ink can reduce the generation of O3 and promote air quality improvement.

Ozone Formation Potential and Priority Species of VOCs in an Industrial Park

Ground-level ozone (O3) pollution is a serious problem in major cities in China. The control of its precursors, volatile organic compounds (VOCs), is a key to limiting ozone production. The ozone formation potential of VOCs in an industrial park in Tianjin was studied by collecting gas samples at the factory boundaries of six representative enterprises. The PTR-TOF-MS was used to analyze VOCs quantitatively. The VOCs/NOx ratio was used to determine the control strategies. The priority VOCs were selected based on the entropy method. Our results indicated that, the ozone formation potential concentration of enterprise F was the highest with the concentration of 0.4233 mg·m-3 using the propylene-equivalent concentration (PEC) scale; the highest concentration was obtained at enterprise C with 1.5733 mg·m-3 using maximum incremental reactivity(MIR) scale. The result of PEC scale is closer to the O3 concentration, which is applicable to the study of ozone generation in this industrial park. Ozone production is sensitive to both VOCs and NOx in this industrial park, joint control should be considered. Alkanes contributed most to ozone formation, followed by alkenes & alkynes, alcohols, and aromatics. The prior VOC species that need to be controlled include n-heptane and its isomers, n-nonane, n-octane and its isomers, undecane, pentane, n-decane, and methanol.

Fuel Economy and Volatile Organic Compound Exhaust Emission for Motorcycles with Various Running Mileages

The implementation of control measures for motorcycles in urban areas depends on the establishment of baseline measures for fuel economy and emission characteristics. In this study, the fuel economy of motorcycles was determined to be 34.7 ± 1.4, 32.6 ± 1.8 and 29.5 ± 2.5 km L–1 for regulation phase V, IV, and III motorcycles, respectively. For regulation phase V motorcycles, the average emission factor was 84.3 ± 40.9 g L–1 for CO, 29.4 ± 13.1 g L–1 for HC, 8.0 ± 2.3 g L–1 for NOx, and 2098 ± 109 g L–1 for CO2. A comparison of the fuel economy of regulation phase III and IV motorcycles with that of regulation phase V motorcycle showed reductions of 15% and 6.2%, corresponding to increases of 156% and 48% in CO emission, increases of 84% and 9% in HC emission, and decreases of 30% and 17% in NOx emission, respectively. Based on fuel economy, the emission factors of a total of 67 volatile organic compounds(VOCs) were 25.2 ± 8.0 g L–1 for a running mileage of 5,231 ± 4,353 km, with emissions increasing to 47.1 ± 19.8 g L–1 for a running mileage of 47,617 ± 8,568 km. The exhaust of VOC groups profiled included paraffins (38–45%), olefins (9.7–15%), aromatics (38–48%), and carbonyls (1.8–3.0%) for various running mileages. Toluene, isopentane, m,p-xylene, o-xylene, 1-butene, 1,2,4-trimethylbenzene, ethylbenzene, n-pentane, and benzene were the main VOCs in motorcycle exhaust. Regarding the ozone formation potential of VOCs, 1-butene, xylene, isoprene, toluene, 1,2,4-trimethylbenzene, propene, and 1-hexene were the most abundant species in motorcycle exhaust.

Emission Characteristics and Ozone Formation Potential of VOCs from a Municipal Solid Waste Composting Plant

In Beijing, the chemical composition and component concentrations of volatile organic compounds (VOCs) were investigated during the municipal solid waste composting process using a portable gas chromatograph coupled with a mass spectrometer. The contributions of VOCs to the ozone formation potential were computed using the maximum incremental reactivity (MIR) scale and the propylene-equivalent concentration scale. The results showed that the concentrations of waste discharge in the sorting room, the first fermentation workshop, the second fermentation workshop, the compost product workshop, and the plant boundary were 10302.1, 15484.1, 929.9, 4693.6 and 370.4 μg·m-3, respectively. The main VOCs of the municipal solid waste composting plant were ethanol, limonene, and acetone. The propylene-equivalent concentrations of waste discharge in the sorting room, the first fermentation workshop, the second fermentation workshop, the compost product workshop, and the plant boundary were 25875.7, 4087.9, 378.0, 747.7 and 296.8 μg·m-3, whereas the O3 formation potentials computed using the MIR scale were 26979.3, 21168.3, 1469.3, 6439.6 and 455.8 μg·m-3. Reducing pollution by controlling the VOCs emission of waste discharge in the sorting room and the first fermentation workshop is important and can decrease the ozone formation potential. Given the accuracy and accessibility of the method, the MIR scale is more suitable for calculating the ozone formation potential of VOCs emitted from the municipal solid waste composting plant.

Characteristics and source apportionment of VOCs in the suburban area of Beijing, China

The measurement of volatile organic compounds (VOCs) was conducted during November 2014 in the suburban area of Beijing, China, covering the period of the Asia-Pacific Economic Cooperation (APEC) meeting period. The VOCs characteristics and source apportionment were analyzed. The average mass concentrations of VOCs were 27.6 ± 19.7 μg/m3 during the sampling period, and aromatics and alkanes were the most abundant VOCs species in atmospheric environment in Beijing which were 12.2 ± 10.3 μg/m3 and 11.3 ± 7.5 μg/m3, respectively. The hourly variation of VOCs was found, with the highest concentration occurring at 8:00 to 9:30 and lowest at 12:30 to 14:00. The sampling period was divided into two periods: period Ⅰ represent the period without emission-reduction measures, and period Ⅱ represent the period with reduction measures. The VOCs concentrations during the period Ⅱ was 31.0% lower than period Ⅰ. The Maximum Incremental Reactivity (MIR) method was applied to analysis the ozone formation potential (OFP). The OFP of VOCs from period Ⅰ was 1.6 times higher than period Ⅱ, and the majority of VOCs species were alkenes and aromatics. Positive matrix factorization was applied to estimate contributions of potential VOCs sources. The vehicle exhaust emission was the major source of VOCs during the two periods, and the contribution to VOCs was 5.7% lower during period Ⅱ than period Ⅰ due to the emission-reduction of vehicle operation.

Influence of Volatile Organic Compounds Emissions from Road Marking Paints on Ground-level Ozone Formation: Case Study of Kraków, Poland

Ground-level ozone, worldwide recognised amongst key pollutants responsible for smog and a significant pulmonary irritant is formed in troposphere via a photolytic process from nitrogen oxides (NOx). Volatile Organic Compounds (VOC) during their decomposition in the atmosphere interact with NOx and thus affect ozone formation. Their interactions are not equal and have been quantified in Maximum Incremental Reactivities (MIR). Using MIR, calculated was ozone formation potential of VOCs emitted from an aromatic solvent-containing paint that is used for marking of roads in Kraków, Poland. To simulate possible environmental benefits of using alternative materials, analysis was then extended to model paint without aromatic solvent and a waterborne paint.Ozone formation potential of the road marking paint currently used as standard in Kraków was calculated to be more than twice the amount of VOCs it emits: 240kg of solvents evaporating from one tonne of paint might cause formation of over 550kg of ozone – in Kraków that means up to 42 tonnes of tropospheric ozone annually. Elimination of the aromatic solvent would not lead to lesser VOC emissions, but decrease ozone production capability by about 50%. Further reductions could be realised with waterborne paint – VOC emissions lowered by 79% and potentially formed ozone reduced by up to 93%.A cradle-to-grave Life Cycle Assessment (LCA) performed on the three analysed paints demonstrated that durability is the main environmental impact factor. Assuming service life achieved at our test field, where modern waterborne paints applied at 600μm wet film and reflectorised with properly selected high-performance glass beads complied with the specification for two years, they definitely are more sustainable choices as compared to solventborne materials.Quantification of the effect of produced ozone on health was beyond the scope of this work, but based on literature reports a measureable effect is anticipated due to a well-documented correlation between increased tropospheric ozone level and increased mortality and morbidity.