Sources Of Volatile Organic Compounds Research Articles

How Does Personal Hygiene Influence Indoor Air Quality?

Humans are known to be a continuous and potent indoor source of volatile organic compounds (VOCs). However, little is known about how personal hygiene, in terms of showering frequency, can influence these emissions and their impact on indoor air chemistry involving ozone. In this study, we characterized the VOC composition of the air in a controlled climate chamber (22.5 m3 with an air change rate at 3.2 h-1) occupied by four male volunteers on successive days under ozone-free (∼0 ppb) and ozone-present (37-40 ppb) conditions. The volunteers either showered the evening prior to the experiments or skipped showering for 24 and 48 h. Reduced shower frequency increased human emissions of gas-phase carboxylic acids, possibly originating from skin bacteria. With ozone present, increasing the number of no-shower days enhanced ozone-skin surface reactions, yielding higher levels of oxidation products. Wearing the same clothing over several days reduced the level of compounds generated from clothing-ozone reactions. When skin lotion was applied, the yield of the skin ozonolysis products decreased, while other compounds increased due to ozone reactions with lotion ingredients. These findings help determine the degree to which personal hygiene choices affect the indoor air composition and indoor air exposures.

Stereoscopic imaging of volatile organic compounds distribution in the region and tracing emission sources of volatile organic compounds using a novel movable single-photon ionization time-of-flight mass spectrometer.

This paper presents a newly developed high-performance mobile single-photon ionization time-of-flight mass spectrometry (M-SPI-TOFMS) system for on-line analysis and stereoscopic monitoring of complex gas mixtures. The system is designed for stereoscopic imaging to map the distribution of volatile organic compounds (VOCs) and trace their emission sources in urban areas and industrial parks. It mainly consists of a SPI-TOFMS instrument, a customized commercial vehicle, a meteorological five-parameter monitor with GPS, a high-power generator, and an uninterruptible power supply. The SPI technique, using a 118 nm VUV lamp, can ionize compounds with an ionization potential below 10.78 eV. Mass spectra obtained using this technique show the profiles of various VOCs and some inorganic compounds. The VOCs composition information and mobile location data are simultaneously sent to the GIS software. In GIS software, this data is used for real-time stereoscopic imaging of VOC distribution and precise tracking of VOC movement. The system can achieve a spatial data resolution of 0.69 mm at 25 km/h due to the microsecond detection speed of the M-SPI-TOFMS instrument. The laboratory test provides a rapid overview characterization of benzene, toluene, and xylene. The M-SPI-TOFMS has limits of detection and mass resolution of 33.7 pptv and 1060, respectively. Several field applications were carried out using M-SPI-TOFMS at various locations to identify VOC sources near different factories. The M-SPI-TOFMS system has a navigation monitoring speed of 25 km/h with a time resolution of 1 s. The widespread use of this system will provide accurate data to support environmental management departments in formulating VOCs pollution control policies and improving control efficiency.

Do bromine and surface-active substances influence the coastal atmospheric particle growth?

New particle formation (NPF) is considered a major source of aerosol particles and cloud condensation nuclei (CCN); however, our understanding of NPF and the subsequent particle growth mechanisms in coastal areas remains limited. This study provides evidence of frequent NPF events followed by particle growth in the middle Adriatic Sea during the summer months at the coastal station of Rogoznica in Croatia. To our knowledge, this is the first study to report such events in this region. Our research aims to improve the understanding of NPF by investigating particle growth through detailed physicochemical characterization and event classification. We used a combination of online measurements and offline particle collection, followed by a thorough chemical analysis. Our results suggest the role of bromine in the particle growth process and provide evidence for its involvement in combination with organic compounds. In addition, we demonstrated the significant influence of surface-active substances (SAS) on particle growth. NPF and particle growth events have been observed in air masses originating from the Adriatic Sea, which can serve as an important source of volatile organic compounds (VOC). Our study shows an intricate interplay between bromine, organic carbon (OC), and SAS in atmospheric particle growth, contributing to a better understanding of coastal NPF processes. In this context, we also introduced a new approach using the semi-empirical 1st derivative method to determine the growth rate for each time point that is not sensitive to the nonlinear behavior of the particle growth over time. We observed that during NPF and particle growth event days, the OC concentration measured in the ultrafine mode particle fraction was higher compared to non-event days. Moreover, in contrast to non-event days, bromine compounds were detected in the ultrafine mode atmospheric particle fraction on nearly all NPF and particle growth event days. Regarding sulfuric acid, the measured sulfate concentration in the ultrafine mode atmospheric particle fraction on both NPF event and non-event days showed no significant differences. This suggests that sulfuric acid may not be the primary factor influencing the appearance of NPF and the particle growth process in the coastal region of Rogoznica.

Characteristics, sources, and health risks of volatile organic compounds in different functional regions of Shenyang

The concentration of 56 volatile organic compounds (VOCs) in the ambient air of Shenyang was continuously monitored at four sites in 2021. The characteristics, sources, secondary pollution potential and health risks of VOCs in different functional regions of Shenyang were discussed. The results indicate that the concentration of VOCs in industrial regions was significantly higher than that in non-industrial regions, with a mean of 41.09 ± 69.82 parts per billion volumes (ppbv) compared to 19.99 ± 17.86 ppbv (commercial & residential region in urban fringe), 27.51 ± 28.81 ppbv (educational & scenic region) and 29.71 ± 23.97 ppbv (commercial & residential region in urban center). The positive matrix factorization (PMF) model was utilized to assign the sources of VOCs in Shenyang, and six factors were recognized: gasoline vehicles (34.8 %), diesel vehicles (28.3 %), combustion (11.4 %), biogenic emissions (9.7 %), industrial processes (8.2 %), and fuel evaporation (7.7 %). The results of the reactivity evaluation indicated that the ozone (O3) formation potential (OFP) was primarily influenced by industrial processes (29.2 %), diesel vehicles (25.7 %), biogenic emissions (17.0 %). These three factors were also the top three contributors to secondary organic aerosol formation potential (SOAP), accounting for 44.2 %, 9.4 % and 30.3 %, respectively. At the all four sites, the non-carcinogenic and carcinogenic risks of VOCs ranged from 1.6 × 10−2 to 3.8 × 10−2 and from 2.3 × 10−6 to 3.3 × 10−6, respectively. And the main risks can be attributed to emissions from industrial processes and gasoline vehicles. These findings suggested to strengthen the control of vehicle emissions throughout all regions in Shenyang and industrial processes emissions in industrial regions.

Molecular Characterization of Gaseous Organic Acids and Nitrogen‐Containing Compounds From Crop Straw and Wood Burning

AbstractBiomass burning serves as important sources of volatile organic compounds (VOCs), yet our understanding of the molecular characteristics of oxygenated volatile organic compounds (OVOCs) from fresh emissions remains limited. In this study, gaseous organic compounds in fresh smokes from burning typical Chinese crop straws and woods are measured using an iodide time‐of‐flight chemical ionization mass spectrometer. Approximately 750 molecular formulas are identified, with CHO compounds containing carbon, hydrogen and oxygen atoms accounting for 77%–95% of the total. C1–C3 organic acids and dicarboxylic acids dominate the total CHO signal intensities by 27%–48%, while well‐known molecular markers of biomass burning, such as monosaccharide, guaiacol and syringol derivatives, contribute 7%–17%. Notably, crop straw and wood burning emit a higher abundance of guaiacol than syringol derivatives by a factor of 5. Additionally, a variety of nitrogen‐containing compounds (mainly in the CHON group) is identified, including isocyanate, amide, amino acids, and pyridine. The mass spectral profiles of organic compounds are largely similar between crop straw and wood burning fuels, although wood burning produces higher contributions of compounds with carbon atoms numbers >10. The saturation concentrations of organic compounds are estimated using molecular formula‐based volatility parameterization, revealing that semi‐volatile and intermediate VOCs (S/intermediate volatility organic compounds (IVOCs)) predominate smoke releases by 35%–60% and 20%–43%, respectively, with only a small fraction of low‐volatility compounds. Given the widespread nature of biomass burning in winter China, our results may have significant implications for interpreting secondary organic aerosol formation through gas‐particle partitioning or aqueous‐phase reactions.

Dual isotopic evidence of δ15N and δ18O for priority control of vehicle emissions in a megacity of East China: Insight from measurements in summer and winter

The source apportionment and main formation pathway of nitrate aerosols in China are not yet fully understood. In this study, PM2.5 samples were collected in Shanghai in the summer and winter of 2019. Water-soluble inorganic ions and isotopic signatures of stable nitrogen (δ15N-NO3−) and stable oxygen (δ18O-NO3−) in PM2.5 were determined. The results showed that NO3− was less important in summer (NO3−/SO42− = 0.4 ± 0.8), while it became the dominant species in winter (52.1 %). The average values of δ15N-NO3− and δ18O-NO3− in summer were + 2.0 ± 6.1 ‰ and 63.3 ± 9.4 ‰ respectively, which were significantly lower than those in winter (+7.2 ± 3.4 ‰ and 88.3 ± 12.1 ‰), indicating discrepancies between NOx sources and nitrate formation pathways. Both δ15N-NO3− and δ18O-NO3− were elevated at night, demonstrating that N2O5 hydrolysis contributed to the nocturnal nitrate increase even in summer. The contribution of the OH oxidation pathway to nitrate aerosols averaged at 70.5 ± 17.0 % in summer and N2O5 hydrolysis dominated the nitrate production in winter (approximately 80 %). On average, vehicle exhaust, coal combustion, natural gas burning, and soil emission contributed 50.7 %, 21.5 %, 15.9 %, and 11.9 %, respectively, to nitrate aerosols in summer, and contributed 56.8 %, 23.9 %, 13.6 %, and 5.7 %, respectively, to nitrate production in winter. Notably, natural gas burning is a non-negligible source of nitrate aerosols in Shanghai. In contrast to an inverse correlation between δ15N-NO3− and PM2.5, the value of δ18O-NO3− was positively correlated with nitrate concentration and aerosol liquid water content (ALWC) in winter, suggesting that explosive growth of nitrate was driven by continuous accumulation of N-depleted NOx and rapid N2O5 hydrolysis under calm and humid conditions. To continuously improve air quality, priority control should be given to vehicle emissions as the dominant source of NOx and volatile organic compounds (VOCs) in Shanghai.

Evaluating Health Risks of Volatile Organic Compounds in Various UK Environments: Insights from Health Indices

The health risks of twelve volatile organic compounds (VOCs) across three sites in the UK were analysed across an 11-year period (2013–2023) using US EPA proposed health indices; Inhalation Unit Risk (IUR) and Reference Concentration (RfC) for carcinogenic and non-carcinogenic risk, respectively. Significant decreases in carcinogenic risk were observed over the study period for 1, 3-butadiene, with reductions of 63%, 36%, and 45% at urban traffic, suburban background and rural background sites, respectively. Similar decreases in the carcinogenic risk associated with benzene (52%, 28% and 27%) and toluene (50%, 38% and 51%) are found for the three site types, respectively. However, the carcinogenic risk of these three pollutants still exceeds the acceptable threshold of 1 × 10-6 at the urban traffic and suburban background sites, necessitating further emission control strategies. Conversely, the carcinogenic risk associated with isoprene has increased at the urban traffic site over the study period. The study revealed a decrease of 51%, 39% and 37% of the total non-carcinogenic risk at all three sites over the study period. The seasonal variations in carcinogenic and non-carcinogenic health risks of pollutants with anthropogenic origin exhibit winter maxima and summer minima. Moreover, diurnal variations of pollutants with anthropogenic origin demonstrate a bimodal distribution reflecting that of traffic flow, e.g., peaks around 08:00 LT and 18:00 LT, corresponding with rush hours. This trend demonstrates the influence of traffic sources supported by the characteristic species ratio whereby Toluene/Benzene (T/B) ratios were less than two (0.72, and 0.42 at suburban and rural background sites, respectively), illustrating the influence of vehicular emissions. Despite following the same bimodal trend suggesting the dominance of vehicular emission sources, mean T/B ratios at urban traffic sites were consistently above 2 for all years considered (average 2.76) suggesting other VOC sources are becoming more dominant at this site.

Bedroom Concentrations and Emissions of Volatile Organic Compounds during Sleep.

Because humans spend about one-third of their time asleep in their bedrooms and are themselves emission sources of volatile organic compounds (VOCs), it is important to specifically characterize the composition of the bedroom air that they experience during sleep. This work uses real-time indoor and outdoor measurements of volatile organic compounds (VOCs) to examine concentration enhancements in bedroom air during sleep and to calculate VOC emission rates associated with sleeping occupants. Gaseous VOCs were measured with proton-transfer reaction time-of-flight mass spectrometry during a multiweek residential monitoring campaign under normal occupancy conditions. Results indicate high emissions of nearly 100 VOCs and other species in the bedroom during sleeping periods as compared to the levels in other rooms of the same residence. Air change rates for the bedroom and, correspondingly, emission rates of sleeping-associated VOCs were determined for two bounding conditions: (1) air exchange between the bedroom and outdoors only and (2) air exchange between the bedroom and other indoor spaces only (as represented by measurements in the kitchen). VOCs from skin oil oxidation and personal care products were present, revealing that many emission pathways can be important occupant-associated emission factors affecting bedroom air composition in addition to direct emissions from building materials and furnishings.

Characteristic, source apportionment and effect of photochemical loss of ambient VOCs in an emerging megacity of Central China

During the transportation from emission sources to sampling site, volatile organic compounds (VOCs) undergo photochemical losses which have significant effects for tropospheric ozone (O3) formation and VOCs source apportionment. In this study, based on hourly speciated VOC data from May 23, to July 8, 2019 with high O3 concentrations, the concentration level, chemical composition, and diurnal variation of observed VOCs were studied, and the initial concentration of VOCs was obtained by combining the local emission inventory in Zhengzhou, Central China. The impact of photochemical loss on source apportionment was evaluated using the Positive Matrix Factorization/Multilinear Engine 2-Species Ratio (PMF/ME2-SR) model based on observed and initial VOCs concentration (OC-PMF and IC-PMF). Results suggest that during the observed period, the average concentration of total VOCs (TVOCs) was 23.74 ± 9.20 ppbv, and alkanes (3.92 ± 2.40 ppbv) were the predominant component. The photochemical losses of TVOCs were approximately 10.15 ± 7.13 ppbv, with an average loss rate of 29.9%. The ozone formation potential (OFP) based on the initial VOCs concentration was 2.2 times higher than that observed VOCs concentration. Alkenes contributed the most to OFP and were also the largest contributors to photochemical losses. TVOC concentrations increased by 5.0% during O3 pollution compared to non-O3 pollution. Seven sources of VOCs were determined, including biomass burning, liquefied petroleum gas (LPG), vehicle emission, industrial emission, solvent usage, gasoline evaporation, and biogenic emission. Compared to the results of IC-PMF, the contributions of these sources in OC-PMF were underestimated by 15.4%, 14.4%, 13.0%, 11.7%, 31.5%, 7.6%, and 4.7%, respectively. This study still exhibits certain limitations in calculation method, and further exploration can be conducted in the future.

Contribution of cooking emissions to the urban volatile organic compounds in Las Vegas, NV

Abstract. Cooking is a source of volatile organic compounds (VOCs), which degrade air quality. Cooking VOCs have been investigated in laboratory and indoor studies, but the contribution of cooking to the spatial and temporal variability in urban VOCs is uncertain. In this study, a proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) is used to identify and quantify cooking emission in Las Vegas, NV, with supplemental data from Los Angeles, CA, and Boulder, CO. Mobile laboratory data show that long-chain aldehydes, such as octanal and nonanal, are significantly enhanced in restaurant plumes and regionally enhanced in areas of Las Vegas with high restaurant densities. Correlation analyses show that long-chain fatty acids are also associated with cooking emissions and that the relative VOC enhancements observed in regions with dense restaurant activity are very similar to the distribution of VOCs observed in laboratory cooking studies. Positive matrix factorization (PMF) is used to quantify cooking emissions from ground site measurements and to compare the magnitude of cooking with other important urban sources, such as volatile chemical products and fossil fuel emissions. PMF shows that cooking may account for as much as 20 % of the total anthropogenic VOC emissions observed by PTR-ToF-MS. In contrast, emissions estimated from county-level inventories report that cooking accounts for less than 1 % of urban VOCs. Current emissions inventories do not fully account for the emission rates of long-chain aldehydes reported here; thus, further work is likely needed to improve model representations of important aldehyde sources, such as commercial and residential cooking.

Emission factors and source profiles of volatile organic compounds from the automobile manufacturing industry

Controlling volatile organic compounds (VOCs) emitted from the automobile manufacturing industry requires establishing VOCs emission factors (EFs) and source profiles refinedly. In this study, 41 samples involved 32 VOCs discharge links were collected from three factories. The EFs and VOCs source profiles were estimated by the material balance method and weighted average method, respectively. The ozone formation potential (OFP) of the 110 VOCs species were calculated by the maximum incremental reactivity (MIR). According to estimations, the ranges of EFs were 0.23–1.66 kg VOCs/SUV car and 2.14–14.86 g VOCs/m2 painted area. EFs of six materials were firstly estimated, which are electrophoretic primer (152.31 ± 97.39 g VOCs/SUV car, 0.97 ± 0.38 g VOCs/m2 painted area), sealant (48.39 ± 26.20 g VOCs/SUV car, 0.46 ± 0.25 g VOCs/m2 painted area), floating coat (87.40 ± 75.63 g VOCs/SUV car, 0.86 ± 0.74 g VOCs/m2 painted area), colored paint (127.24 ± 168.24 g VOCs/SUV car, 1.25 ± 1.66 g VOCs/m2 painted area), varnish (205.46 ± 218.14 g VOCs/SUV car, 2.01 ± 2.15 g VOCs/m2 painted area), and cleaning solvent (328.54 ± 404.94 g VOCs/SUV car, 3.23 ± 3.98 g VOCs/m2 painted area). OVOCs (37.40–51.60 %) and aromatics (36.40–37.00 %) were the dominant components. n-Butyl acetate, 1,2,4-trimethylbenzene, undecane, n-hexanal, acetone, 1,2,3-trimethylbenzene, 1,3,5 -trimethylbenzene, m/p/o-xylene, 3-ethylbenzene, and 4-ethylbenzene were the major VOCs species, accounting for 68 % of total VOCs in the automobile manufacturing industry. Considering the OFP values of species, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, 1,2,3-trimethylbenzene, m/p-xylene, acetaldehyde, methyl ethyl ketone are the key active species that should be prioritized for control.

Ground-based MAX-DOAS observations of formaldehyde and glyoxal in Xishuangbanna, China

Multi-axial differential optical absorption spectroscopy (MAX-DOAS) measurements were conducted in Xishuangbanna, Yunnan, China, between November 1, 2021 and June 30, 2022 to obtain vertical distributions of formaldehyde (HCHO) and glyoxal (CHOCHO). The observations show an increase in vertical column densities (VCDs) and volume mixing ratios (VMRs) for both HCHO and CHOCHO concentrations during periods of biomass combustion. The VCDs of HCHO and CHOCHO from TROPOMI are in good agreement with the MAX-DOAS observations. (R2HCHO = 0.71; R2CHOCHO = 0.70). Regarding seasonal variations, HCHO predominantly occupies the upper layer (400-800 m) during the biomass burning, possibly attributed to the formation of secondary HCHO as the plume ascends during combustion. CHOCHO is primarily found in the lower layer (0-200 m), suggesting a longer lifespan for HCHO compared to CHOCHO, preventing the latter from diffusing to higher altitudes. Concerning the daily variation patterns, both HCHO and CHOCHO VMRs exhibited peaks at 9:00 and 13:00, which were attributed to the nighttime accumulation and midday oxidation. Furthermore, we also investigated the sources of volatile organic compounds (VOCs) using the CHOCHO to HCHO ratio (RGF). During the period of biomass burning, there are minimal differences in the daily RGF across layers, indicating that biomass burning is the predominant source. During the non-biomass burning period, the daily RGF shows significant differences among layers, indicating that emissions from biological and anthropogenic sources primarily contribute during the period.

Novel approach for identifying VOC emission characteristics based on mobile monitoring platform data and deep learning: Application of source apportionment in a chemical industrial park

Refined volatile organic compound (VOC) emission characteristics are crucial for accurate source apportionment in chemical industrial parks. The data from mobile monitoring platforms in chemical industrial parks contain pollution information that is not intuitively displayed, requiring further excavation. A novel approach was proposed to identify VOC emission characteristics using the class activation map (CAM) technology of convolutional neural network (CNN), which was applied on the mobile monitoring platform data (MD) derived from a typical fine chemical industrial park. It converts a large amount of monitoring data with high spatiotemporal complexity into simple and interpretable characteristic maps, effectively improving the identification effect of VOC emission characteristics, supporting more accurate source apportionment of VOC pollution around the park. Using this method, the VOC emission characteristics of eight key factories were identified. VOC source apportionment in the park was conducted for one day using a positive matrix factorization (PMF) model and seven combined factor profiles (CFPs) were calculated. Based on the identified VOC emission characteristics, the main pollution sources and their contributions to surrounding schools and residential areas were determined, revealing that one pesticide factory (named LKA) had the highest contribution ratio. The source apportionment results indicated that the impact of the chemical industrial park on the surrounding areas varied from morning to afternoon, which to some extent reflected the intermittent production methods employed for fine chemicals.

Probing Into Ozone Production Through Photochemistry of Organic Peroxyl Radicals: Implications for Source Control

AbstractOzone (O3) pollution is a focus of the international community due to its health and environmental impacts. Organic peroxyl (RO2) radicals play a significant role in O3 initiation processes, which has implications for O3 mitigation. RO2 generated from volatile organic compounds (VOCs) sources contribute substantially to O3 formation. However, quantifying the RO2 from diverse sources is a great challenge. For the first time, we proposed a new hybrid Receptor‐Kinetic model to quantify sources contributions to RO2 from the perspective of molecular level and functional groups of VOCs. We revealed that 3‐Hydroxy‐2‐butylperoxy (BUT2OLO2), 4‐Hydroxy‐3‐methyl‐1‐butene‐3‐ylperoxy (ISOPBO2) and 1‐Hydroxypropane‐2‐ylperoxy (HYPROPO2) radicals were the dominant RO2, which were driven by reactions of cis/trans‐2‐butene (from Biogenic Emissions and Solvent Usage), isoprene (from Biogenic Emissions), and propylene (from Liquid Petroleum Gas Evaporation), respectively. The three dominant RO2 radicals contributed significantly to O3 production (28%, 10% and 14%), comparing with other 16 RO2. Sensitivity studies indicated that O3 production can be decreased effectively by reducing the dominant RO2 species for each source. Quantitative evidence suggested that targeting dominant RO2 sources can be a novel direction for O3 control.

Seasonal estimates of ozone and secondary organic aerosol formation from volatile organic compounds in a rural atmosphere of India

Volatile Organic Compounds (VOCs) serve as precursors for tropospheric ozone (O3) and Secondary Organic Aerosol (SOA) formation. The formation of O3 and SOA are the indicators of the oxidative capacity specific to a given chemical environment. The current study investigates the oxidative capacity of the relatively less explored tropical rural atmosphere. This study is accomplished by measuring the concentrations of various VOCs and combining them with OH loss rates to estimate the potentials for O3 and SOA formation (OFP and SOAP, respectively). Continuous diel VOC measurement data from Gadanki (13.5°N, 79.2°E), Peninsular India, encompassing four distinct seasons and comprising over 4000 samples, have been utilized to estimate OFP and SOAP and their variations across different seasons. Additionally, efforts have been made to comprehend the contribution of different VOC sources to O3 and SOA formation. The results indicate that, 1, 3, 6-trimethyl benzene (20.09 %) among the VOCs and aromatics (44.37%) among the VOC groups exhibit the highest OFP at the observational site. Among seasons, the post-monsoon period exhibits the highest OFP (31.94%). The increased presence of biogenic VOCs, such as ethylene, propylene, and 1-butene during monsoon, likely due to the increased vegetation cover can be attributed for the elevated OFP. Similarly, n-dodecane (43.22%) and the VOC group of alkanes (50.79%) show the highest SOAP. The summer season has the highest SOAP (29.7%), owing to the enhanced concentrations and photochemistry initiated by OH radicals. Within the PMF-modelled sources, biomass-burning VOCs make a substantial contribution to both OFP and SOAP, distinguishing the rural atmosphere from its urban counterpart, where traffic emissions predominantly influence OFP and SOAP.

Production of oxygenated volatile organic compounds from the ozonolysis of coastal seawater

Abstract. Dry deposition of ozone (O3) to the ocean surface and the ozonolysis of organics in the sea surface microlayer (SSML) are potential sources of volatile organic compounds (VOCs) to the marine atmosphere. We use a gas chromatography system coupled to a Vocus proton-transfer-reaction time-of-flight mass spectrometer to determine the chemical composition and product yield of select VOCs formed from ozonolysis of coastal seawater collected from Scripps Pier in La Jolla, California. Laboratory-derived results are interpreted in the context of direct VOC vertical flux measurements made at Scripps Pier. The dominant products of laboratory ozonolysis experiments and the largest non-sulfur emission fluxes measured in the field correspond to Vocus CxHy+ and CxHyOz+ ions. Gas chromatography (GC) analysis suggests that C5–C11 oxygenated VOCs, primarily aldehydes, are the largest contributors to these ion signals. In the laboratory, using a flow reactor experiment, we determine a VOC yield of 0.43–0.62. In the field at Scripps Pier, we determine a maximum VOC yield of 0.04–0.06. Scaling the field and lab VOC yields for an average O3 deposition flux and an average VOC structure results in an emission source of 10.7 to 167 Tg C yr−1, competitive with the DMS source of approximately 20.3 Tg C yr−1. This study reveals that O3 reactivity to dissolved organic carbon can be a significant carbon source to the marine atmosphere and warrants further investigation into the speciated VOC composition from different seawater samples and the reactivities and secondary organic aerosol (SOA) yields of these molecules in marine-relevant, low NOx conditions.

Contribution of individual sources of volatile organic compounds to their cancer and non-cancer risks in the multi-industrial city of Ulsan, South Korea

Contribution of individual sources of volatile organic compounds to their cancer and non-cancer risks in the multi-industrial city of Ulsan, South Korea

Experimental research and estimation model of gasoline evaporative emissions from vehicles in China

Evaporative emission is an important source of vehicle pollutant emission and volatile organic compounds (VOCs), causing serious environmental pollution. Carbon canisters are used to store fuel vapor in evaporative emission control (EVAP) system, but canisters are prone to saturation, leading to the direct release of fuel vapor into the atmosphere. Therefore, accurate estimation of fuel vapor generation is crucial for EVAP system. Gasoline evaporation rate is mainly influenced by vapor-liquid interface area, gasoline saturated vapor pressure, filling level and temperature. The quantitative relation between different parameters and gasoline evaporation rate has rarely been reported, and a gasoline evaporative emission estimation model suitable for China needs to be proposed urgently. In this study, gasoline evaporative emission tests have been carried out in VT-SHED, and the effects of vapor-liquid interface area, filling level and temperature on gasoline evaporative emissions have been analyzed under the premise of consistent gasoline temperature and ambient temperature. Some valuable conclusions are obtained. The results show that different from expectation, gasoline evaporative emissions are not positively correlated with the vapor-liquid interface area. There is an approximately exponential relationship between the headspace volume and gasoline evaporative emissions. The widely used Reddy equation and Hata equation underestimate the gasoline vapor generation in China. Based on China VI test program and gasoline, accurate estimation of mass transfer coefficient has been conducted, and a new semi-empirical estimation model for vapor generation has been proposed. The model can accurately estimate the fuel evaporation of vehicles in China, providing guidance for the matching and optimization of EVAP system.

Characterization and sources of volatile organic compounds (VOCs) during 2022 summer ozone pollution control in Shanghai, China

An experimental study was conducted to evaluate the effectiveness of the measures for controlling ozone (O3) pollution in Jinshan District, Shanghai, China during the summer months of June 2022–August 2022. The study period was divided into a control period (CP) when measures were enforced and a non-control period (NCP) without interventions. The concentrations of volatile organic compounds (VOCs) were compared between the two periods, with the ranking of various types of identical VOCs, in which alkanes exhibited the highest (39.48%) concentrations, followed by aromatics (24.35%), halohydrocarbons (19.94%) and alkenes (16.23%). Compared to NCP, the mean levels of VOCs were 32.67% lower in CP, indicating the control measures significantly reduced the concentrations of VOCs during the months when control measures were in effect. The typical bimodal O3 pattern was eliminated during CP along with the absence of peak VOC levels between 10:00 Hrs and 16:00 Hrs, which surpassed the level of 40 μg/m3 during NCP. The analyses of O3 formation potential (OFP) and rate of loss of OH radicals (LOH) indicated that alkenes and aromatics were the most chemically active VOCs driving the production of O3. Following six types of sources were determined for VOCs using positive matrix factorization (PMF): (1) solvent use (8.2%); (2) fuel evaporation (25.1%); (3) petrochemical plant (17.3%); (4) LPG (20.1%); (5) industrial process (16.1%); (6) vehicular emissions (13.2%). Emissions from vehicles and solvent use declined by 19.21% and 15.43%, respectively, underscoring their importance as controllable VOC sources in Shanghai, China. Overall, the study demonstrated the effectiveness of regional control measures in improving air quality by reducing the production of O3 and related VOCs.

Enhanced VOC emission with increased temperature contributes to the shift of O3-precursors relationship and optimal control strategy

Assessing the impact of anthropogenic volatile organic compounds (VOCs) on ozone (O3) formation is vital for the management of emission reduction and pollution control. Continuous measurement of O3 and the major precursors was conducted in a typical light industrial city in the YRD region from 1 May to 25 July in 2021. Alkanes were the most abundant VOC group, contributing to 55.0% of TVOCs concentration (56.43 ± 21.10 ppb). OVOCs, aromatics, halides, alkenes, and alkynes contributed 18.7%, 9.6%, 9.3%, 5.2% and 1.9%, respectively. The observational site shifted from a typical VOC control regime to a mixed regime from May to July, which can be explained by the significant increase of ROx production, resulting in the transition of environment from NOx saturation to radical saturation with respect to O3 production. The optimal O3 control strategy should be dynamically changed depending on the transition of control regime. Under NOx saturation condition, minimizing the proportion of NOx in reduction could lead to better achievement of O3 alleviation. Under mixed control regime, the cut percentage gets the top priority for the effectiveness of O3 control. Five VOCs sources were identified: temperature dependent source (28.1%), vehicular exhausts (19.9%), petrochemical industries (7.2%), solvent & gasoline usage (32.3%) and manufacturing industries (12.6%). The increase of temperature and radiation would enhance the evaporation related VOC emissions, resulting in the increase of VOC concentration and the change of ROx circulation. Our results highlight determination of the optimal control strategies for O3 pollution in a typical YRD industrial city.