Aerosol Formation Potential Research Articles

Spatial heterogeneity of volatile organic compound pollution in a typical industrial park based on multi-point online monitoring: Pollution characteristics, health risks, and priority-controlled species

Emissions from industrial parks are crucial sources of ambient volatile organic compound (VOC) pollution, characterized by high concentrations, complex compositions, dispersed emission sources, and uneven spatial distribution. To better understand and address this issue, it is crucial to analyze the spatial differences in VOC pollution and associated health risks through multi-point monitoring. In this study, we established four online monitoring sites in a typical industrial park in Kaifeng, China. We monitored 115 VOC species and found significant differences in the concentration and chemical composition of total VOCs (TVOCs) among the four sites. Two sites were primarily composed of halohydrocarbons (49.80% and 41.21%), while the other two sites had a higher proportion of aromatics (54.78% and 39.03%). Acetaldehyde was the main contributor to ozone formation potential (OFP) at one site, while toluene was associated with the other three sites. The site with the highest VOC concentration and OFP also showed the highest secondary organic aerosol formation potential (SOAP). In terms of health risk assessment, acrolein posed a non-carcinogenic risk at all sites, but there were disparities in the carcinogenic risk among the four sites. 1,2-Dichloroethane at one site exceeded the definite risk limit, while 1,2-dibromoethane and chloroform were considered probable risk species at another site. Considering both the environmental impact and health risk, we used entropy-weighting to calculate a comprehensive control index (CCI). This index identified 1,2-dichloroethane as the Level Ⅰ controlled pollutant species at two sites, and toluene at the other two sites. This study highlights the spatial heterogeneity in VOC pollution and health risks within the industrial park, providing valuable insights for targeted pollution control strategies.

Ambient volatile organic compounds in a typical industrial city in southern China: Impacts of aromatic hydrocarbons from new industry

New industrial parks, including fine chemical, medical manufacturers, etc., are emerging in modern cities in China, whereas their emissions and impacts have not been fully illuminated. In this study, ambient volatile organic compounds (VOCs) in Huizhou were measured in three functional zones, namely new industrial, roadside, and residential zones. The average mixing ratios of total VOCs were as follow: industrial (56.22 ± 15.06 ppbv) > roadside (39.30 ± 12.96 ppbv) > residential (26.03 ± 7.31 ppbv). The ozone formation potential (OFP) and secondary organic aerosol formation potential (SOAP) of VOCs in the industrial zone were 1.5–2.3 and 1.7–3.1 times those in the other zones, respectively. Aromatics contributed the most to OFP (39.8 % - 44.8 %) and SOAP (78.9 % - 91.0 %), with much less contributions to VOCs mixing ratios (18.3 % - 21.2 %). Naphthalene was the most abundant aromatic species across the three zones and ranked among the top contributors to OFP and SOAP among all VOCs species. Source apportionment identified that new industrial emissions and solvent use was the largest VOCs contributor in the industrial zone (53.9 %), traffic-related emissions dominated in the roadside zone (40.7 %), while new industrial and traffic-related emissions contributed similar in the residential zone (32.9 % and 34.7 %, respectively). The carcinogenic and non-carcinogenic risks of hazardous VOCs were above the acceptable threshold, primarily due to new industrial and traffic-related emissions. Our results suggested to strengthen the control of new industrial emissions and aromatics sources in Huizhou city to improve air quality and protect human health.

Pollution Characteristics and Source Apportionment of VOCs in Urban Areas of Shijiazhuang in Spring

Samples of ambient volatile organic compounds （VOCs） were collected using SUMMA canisters at three Country Control Sites in Shijiazhuang during the spring of 2019, 2021, and 2022, which were detected using gas chromatography/mass spectrometry （GC/MS）. To investigate the characteristics and temporal variations of VOCs mass concentration levels, the online monitoring data of ozone （O3） and PM2.5 at the same site were also collected. Subsequently, the ozone formation potential （OFP） and secondary organic aerosol formation potential （SOAFP） were utilized to assess the chemical activity of VOCs. Additionally, the potential source areas of VOCs in spring in Shijiazhuang were further identified using the potential source contribution factor （PSCF） method and concentration weight trajectory analysis （CWT）. Hence, the major VOCs sources were evaluated with the VOCs initial mixing ratio. The results demonstrated that the averaged concentration of VOCs during the polluted period and clean period of spring in Shijiazhuang were 191.17 μg·m-3 and 122.18 μg·m-3, respectively. Meanwhile, the OFP was 361.23 μg·m-3 during the polluted period and 266.96 μg·m-3 during the clean period, whereas the SOAFP was 1.98 μg·m-3 and 1.61 μg·m-3, respectively. Therefore, effective control of benzene, toluene, ethylbenzene, and xylene （BTEX） is crucial for reducing PM2.5 and O3 pollution. Based on the results obtained from weight PSCF and CWT, the potential source areas of VOCs were further identified to be primarily located in the eastern Yuhua District, the high-tech district, and the northern Luancheng District of Shijiazhuang. These areas were influenced not only by local emissions but also by transport from neighboring regions, in which consistency between the CWT and PSCF results further supported these findings. Furthermore, the results obtained from the benzene/toluene/ethylbenzene （B/T/E） and xylene/benzene （X/B） ratios indicated that the main sources of VOCs in Shijiazhuang in spring were vehicle exhaust sources and burning sources, leading to a more serious air mass aging phenomenon. Hence, controlling vehicle emissions and implementing regional cooperative measures are the effective strategies for optimizing the air quality of Shijiazhuang.

Source Profiles and Impact of Volatile Organic Compounds in Typical Industries in Luohe City

Ten typical industries in Luohe City were selected for the sampling of organized emissions of volatile organic compounds （VOCs）, and 114 VOCs components of each sample were detected to analyze their source characteristics and effects. The results showed that VOCs emissions of packaging and printing were mainly composed of OVOC （60.9%）. In terms of the industrial coating, aromatic hydrocarbons （42.4%） and OVOC （38.9%） were the main VOCs species. The emissions of the footwear, furniture manufacturing, and paper industries were mainly composed of OVOC （32.3% - 42.6%） and aromatic hydrocarbons （20.7% - 33.7%）, with noticeable halogenated hydrocarbons. Chemical and pharmaceutical industries mainly emitted halogenated hydrocarbons, with the proportions of 59.3% and 46.6%, respectively. The emissions of the brick industry were primarily composed of alkane （62.7%）, and OVOC （48.5%）, and halogenated hydrocarbons （19.7%） were the main contributors to VOCs emissions of the thermal industry. OVOC （48.1%） and alkane （29.4%） were the dominant species for the food manufacturing industry. In the packaging and printing industry, acetone （14.8%）, isopropanol （14.0%）, ethylacetate （11.1%）, and toluene （10.2%） were the characteristic VOCs species. The emissions of industrial coating were dominated by isopropanol （25.6%）, toluene （15.0%）, m/p-xylene （12.4%）, and acetone （7.1%）. In the furniture manufacturing industry, m/p-xylene （15.8%）, followed by hexanal （15.1%）, 1,2-dichloroethane （9.6%）, and acetone （8.4%） were the characteristic VOCs species. The emissions of the footwear industry were dominated by acetone （18.9%）, toluene （18.1%）, methylene chloride （8.0%）, and acetaldehyde （6.8%）. The characteristic species of the chemical industry were methylene chloride （23.9%）, 1,2-dichloroethane （14.7%）, acetone （12.7%）, and trichloromethane （11.1%）, and those for the pharmaceutical industry were bromoethane （36.7%）, acetone （19.2%）, benzene （5.0%）, and vinyl acetate （3.0%）. The emissions of the brick industry were mainly ethane, propane, ethylene, and benzene. Acetone, toluene, acetylene, and acetaldehyde were the primary VOCs species in the paper industry. The emissions of the food manufacturing industry were dominated by acetaldehyde, n-pentane, acrolein, and n-heptane. The emissions of the thermal industry were characterized by acetone, acetaldehyde , benzene, and toluene. Although different industries emitted various characteristic VOCs species, in general, acetone, isopropanol, benzene, toluene, m/p-xylene, ethane, acetaldehyde, and methylene chloride were the main characteristic species in most industries in Luohe. OVOC and aromatic hydrocarbons had higher contributions to ozone generation potential （OFP）, and aromatic hydrocarbons contributed over 80.0% to secondary organic aerosol formation potential （SOAP）. The source reactivity of ozone [SR（O3）] of the food and furniture manufacturing industries were higher, with values of 3.7 g·g-1 and 3.5 g·g-1, respectively, whereas the source reactivity of secondary organic aerosol SR（SOA） of the industrial coating, furniture manufacturing, and footwear industries were higher, with the values of 0.021, 0.017, and 0.014 g·g-1. Hence, the food manufacturing, industrial coating, and furniture manufacturing industries should be the primary industries for the collaborative control of PM2.5 and ozone in Luohe City, of which the furniture manufacturing industry was the top priority.

Characterization of emissions from rubber modified asphalt and their impact on environmental burden: Insights into composition variability and hazard assessment

Rubber modified asphalt (RMA) is a promising avenue for recycling waste tires but faces concerns over hazardous fumes emission during production and construction. This study employs a specialized apparatus to analyze RMA's emission behavior, focusing on crumb rubber size variations under thermal conditions. Ozone Formation Potential (OFP) and Secondary Organic Aerosol Formation Potential (SOAFP) were quantified to evaluate the environmental burden. Results indicate distinct periods of emission behavior for different pollutants, with H2S emissions primarily occurring within the initial 150 min while volatile organic compounds (VOCs) dominate within the first 270 min. The size of rubber particles and thermal exposure duration influence the VOCs microscopic emission characteristics and environmental burdens. Polycyclic aromatic hydrocarbons (PAHs) emerge as the primary contributors to OFP and SOAFP, accounting for nearly 65 % and 25 %−60 %, respectively. High molecular weight aliphatic hydrocarbons (ALHs) also significantly contribute to SOAFP, with PAHs dominating throughout, while ALHs peak during the middle stage. H2S emissions likely stem from rubber, while early VOC emissions originate from rubber, transitioning to petroleum asphalt during the middle and late stages. Asphalt fractions influence emission behavior and property evolution. These findings inform emission suppression strategies and highlight the need for tailored approaches to mitigate emissions effectively.

Temperature-dependent emissions dominate aerosol and ozone formation in Los Angeles.

Despite declines in transportation emissions, urban North America and Europe still face unhealthy air pollution levels. This has challenged conventional understanding of the sources of their volatile organic compound (VOC) precursors. Using airborne flux measurements to map emissions of a wide range of VOCs, we demonstrate that biogenic terpenoid emissions contribute ~60% of emitted VOC OH reactivity, ozone, and secondary organic aerosol formation potential in summertime Los Angeles and that this contribution strongly increases with temperature. This implies that control of nitrogen oxides is key to reducing ozone formation in Los Angeles. We also show some anthropogenic VOC emissions increase with temperature, which is an effect not represented in current inventories. Air pollution mitigation efforts must consider that climate warming will strongly change emission amounts and composition.

Organic Emissions of Volatile Chemical Products in Canada: Emission Inventories, Indoor-to-Outdoor Transfer, and Regional Impacts.

The contribution of volatile chemical products (VCPs) to ambient air pollution has increased following decades of regulating combustion sources. There is a research gap concerning the impact of indoor physicochemical phenomena on VCP emissions. In this work, a bottom-up speciated VCP emission inventory with indoor-outdoor resolution was developed for Canada, an industrialized country with low air pollution levels, whose major cities are among the largest urban areas in North America. VCPs were estimated to account for about 290 kilotons of gaseous organic emissions for a typical year in the 2010s, with more than 60% of emissions occurring indoors. Coatings and cleaners were the most emissive VCP categories. Oxygenated species and saturated aliphatics dominated the chemical profiles of most emissions. Less than 5% of VCP emissions were impacted by indoor physicochemical phenomena. VCP emissions were predicted to account for 0.8-3.2 s-1 of OH reactivity and 0.22-0.52 μg/m3 of secondary organic aerosol formation potential in major urban areas in Canada. Our predictions aligned with previous measurements concerning indoor and outdoor organic pollutant levels, underscoring the important air quality impacts of VCPs relative to other sources. Our results provide helpful insights for future research regarding VCP emissions, especially from indoor spaces.

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.

Impact of HO2∕RO2 ratio on highly oxygenated α-pinene photooxidation products and secondary organic aerosol formation potential

Abstract. Highly oxygenated molecules (HOMs) from the atmospheric oxidation of biogenic volatile organic compounds are important contributors to secondary organic aerosol (SOA). Organic peroxy radicals (RO2) and hydroperoxy radicals (HO2) are key species influencing the HOM product distribution. In laboratory studies, experimental requirements often result in overemphasis on RO2 cross-reactions compared to reactions of RO2 with HO2. We analyzed the photochemical formation of HOMs from α-pinene and their potential to contribute to SOA formation under high (≈1/1) and low (≈1/100) HO2/RO2 conditions. As HO2/RO2 > 1 is prevalent in the daytime atmosphere, sufficiently high HO2/RO2 is crucial to mimic atmospheric conditions and to prevent biases by low HO2/RO2 on the HOM product distribution and thus SOA yield. Experiments were performed under steady-state conditions in the new, continuously stirred tank reactor SAPHIR-STAR at Forschungszentrum Jülich. The HO2/RO2 ratio was increased by adding CO while keeping the OH concentration constant. We determined the HOM's SOA formation potential, considering its fraction remaining in the gas phase after seeding with (NH4)2SO4 aerosol. An increase in HO2/RO2 led to a reduction in SOA formation potential, with the main driver being a ∼ 60 % reduction in HOM-accretion products. We also observed a shift in HOM-monomer functionalization from carbonyl to hydroperoxide groups. We determined a reduction of the HOM's SOA formation potential by ∼ 30 % at HO2/RO2 ≈1/1 compared to HO2/RO2 ≈ 1/100. Particle-phase observations measured a similar decrease in SOA mass and yield. Our study shows that too low HO2/RO2 ratios compared to the atmosphere can lead to an overestimation of SOA yields.

Impacts of ethanol blended fuels and cold temperature on VOC emissions from gasoline vehicles in China

The Chinese central government has initiated pilot projects to promote the adoption of gasoline containing 10%v ethanol (E10). Vehicle emissions using ethanol blended fuels require investigation to estimate the environmental impacts of the initiative. Five fuel formulations were created using two blending methods (splash blending and match blending) to evaluate the impacts of formulations on speciated volatile organic compounds (VOCs) from exhaust emissions. Seven in-use vehicles covering China 4 to China 6 emission standards were recruited. Vehicle tests were conducted using the Worldwide Harmonized Test Cycle (WLTC) in a temperature-controlled chamber at 23 °C and −7 °C. Splash blended E10 fuels led to significant reductions in VOC emissions by 12%–75%. E10 fuels had a better performance of reducing VOC emissions in older model vehicles than in newer model vehicles. These results suggested that E10 fuel could be an option to mitigate the VOC emissions. Although replacing methyl tert-butyl ether (MTBE) with ethanol in regular gasoline had no significant effects on VOC emissions, the replacement led to lower aromatic emissions by 40%–60%. Alkanes and aromatics dominated approximately 90% of VOC emissions for all vehicle-fuel combinations. Cold temperature increased VOC emissions significantly, by 3–26 folds for all vehicle/fuel combinations at −7 °C. Aromatic emissions were increased by cold temperature, from 2 to 26 mg/km at 23 °C to 33–238 mg/km at −7 °C. OVOC emissions were not significantly affected by E10 fuel or cold temperature. The ozone formation potential (OFP) and secondary organic aerosol formation potential (SOAFP) of splash blended E10 fuels decreased by up to 76% and 81%, respectively, compared with those of E0 fuels. The results are useful to update VOC emission profiles of Chinese vehicles using ethanol blended gasoline and under low-temperature conditions.

Secondary Organic Aerosol Formation Potential from Vehicular Non-tailpipe Emissions under Real-World Driving Conditions.

Traffic emissions are a dominant source of secondary organic aerosol (SOA) in urban environments. Though tailpipe exhaust has drawn extensive attention, the impact of non-tailpipe emissions on atmospheric SOA has not been well studied. Here, a closure study was performed combining urban tunnel experiments and dynamometer tests using an oxidation flow reactor in situ photo-oxidation. Results show a significant gap between field and laboratory research; the average SOA formation potential from real-world fleet is 639 ± 156 mg kg fuel-1, higher than the reconstructed result (188 mg kg fuel-1) based on dynamometer tests coupled with fleet composition inside the tunnel. Considering the minimal variation of SOA/CO in emission standards, we also reconstruct CO and find the critical role of high-emitting events in the real-world SOA burden. Different profiles of organic gases are detected inside the tunnel than tailpipe exhaust, such as more abundant C6-C9 aromatics, C11-C16 species, and benzothiazoles, denoting contributions from non-tailpipe emissions to SOA formation. Using these surrogate chemical compounds, we roughly estimate that high-emitting, evaporative emission, and asphalt-related and tire sublimation share 14, 20, and 10% of the SOA budget, respectively, partially explaining the gap between field and laboratory research. These experimental results highlight the importance of non-tailpipe emissions to atmospheric SOA.

Online observation of light non-methane hydrocarbons (C2–C5) over the central Himalayas: Influence of the Indo-Gangetic Plain region

Studies pertaining to non-methane hydrocarbons (NMHCs) are very limited in South Asia, particularly at high-mountain sites. Therefore, online in-situ observations of light NMHCs (C2–C5) were conducted in the Central Himalayas (Nainital, 1958 m) from January 2017 to December 2020. Additionally, air samples were collected from an Indo-Gangetic Plain (IGP) site (Haldwani, 554 m), located about 18 km and the nearest source regions for the mountain site. The diurnal variations show daytime higher values at the mountain site, which is typical for a pristine site. Correlation analysis and percentage contributions confirm the major roles of biomass burning at the mountain site and Liquefied Petroleum Gas (LPG) emission, automobile and domestic combustion at the IGP site. Nevertheless, the anthropogenic influences also reaches the Himalayan site, mainly in spring, which is confirmed by the concentrated weighted trajectory (CWT) analysis. Such influences are limited to the IGP site in winter, primarily due to the shallower boundary layer. The estimated photochemical age varies from 9 days in winter to 16 days in summer-monsoon. It is shown that the hydroxyl radical reactivity, ozone formation potential (OFP) and secondary organic aerosol formation potential (SOAFP) are 4–6 times higher at the IGP site compared to the Himalayan site. Propylene, ethylene and n-butane are major contributor in these at both sites. Ethane is found to be most abundant (40%) at the Himalayan site, while propane (27%) at the IGP site. An assessment of percentage contribution of different NMHCs in emission inventories for the Himalayan region is suggested.

Elucidating contributions of volatile organic compounds to ozone formation using random forest during COVID-19 pandemic: A case study in China

Ozone has been reported to increase despite nitrogen oxides reductions during the COVID-19 pandemic, and ozone formation needs to be revisited using volatile organic compounds (VOCs), which are rarely measured during the pandemic. Here, a total of 98 VOCs species were monitored in an economy-active city in China from January 2021 to August 2022 to assess contributions to ozone formation during the pandemic. Total VOCs concentrations were 35.55 ± 21.47 ppb during the entire period, among which alkanes account for the largest fraction (13.78 ppb, 38.0%), followed by aromatics (6.16 ppb, 16.8%) and oxygenated VOCs (OVOCs, 5.69 ppb, 15.7%). Most VOCs groups (e.g., alkenes, OVOCs) and individual species (e.g., isoprene, methyl vinyl ketone) display obvious seasonal and diurnal variations, which are related to their sources and reactivities. No weekend effects of VOCs suggest limited influences from traffic emissions during pandemic. Aromatics and alkenes are the major contributors (39% and 33%) to ozone formation potential, largely driven by o/m/p-xylene (21%), ethylene (15%), toluene (9%). Secondary organic aerosol formation potential is dominated by toluene (>50%) despite its low proportion (5%). Further inclusion of VOCs and meteorology in the Random Forest model shows good ozone prediction performance (R2 = 0.77–0.86, RMSE = 11.95–19.91 μg/m3, MAE = 8.89–14.58 μg/m3). VOCs and NO2 contribute >50% of total importance with the largest difference in importance ratio of VOCs/NO2 in the summer and winter, implying ozone formation regime may vary. No seasonal variations in importance of meteorology are observed, while importance of other variables (e.g., PM2.5) is highest in the summer. This work identifies critical VOCs groups and species for ozone formation during the pandemic, and demonstrates the feasibility of machine learning algorithms in elucidation of ozone formation mechanisms.

Sources and Distribution of Light NMHCs in the Marine Boundary Layer of the Northern Indian Ocean During Winter: Implications to Aerosol Formation

AbstractNon‐methane hydrocarbons (NMHCs) are ubiquitous trace gases and profoundly affect the Earth's atmosphere and climate change. Mixing ratios of light NMHCs were measured over the northern Indian Ocean during winter‐2018 as part of the Integrated Campaign for Aerosols, gases, and Radiation Budget (ICARB‐2018). Higher levels of NMHCs over the coastal regions were due to the efficient transport of anthropogenic and biogenic air masses and higher air‐sea exchanges due to the higher biological productivity. Although oceanic emissions dominated the open ocean, the transport of aged continental air also influenced the levels of some NMHCs. The higher and lower propane/ethane ratios of 2.41 ± 0.34 and 1.13 ± 0.78 ppbv ppbv−1 over coastal and open oceans indicated the prevalence of fresh and aged air masses, respectively. Ethene and propene show a strong correlation, but the ethene/propene ratios over open ocean (2.2 ± 0.25 ppbv ppbv−1) were slightly lower than the coastal region (2.5 ± 0.34 ppbv ppbv−1). Principal component analysis reveals the major associated sources identified in this study are from oceanic and nearby anthropogenic sources, explaining nearly 51% and 21% of variance. Light alkenes accounted for ∼70% of the total ozone and secondary organic aerosol formation potential. A higher alkene/alkane ratio, strong correlation of alkene with organic aerosol mass, and new particle formation events highlight the role of alkenes in secondary aerosol formation over the equatorial Indian Ocean. Overall, the levels of NMHCs were much higher than those measured nearly two decades ago during the Indian Ocean Experiment (INDOEX)‐1999.

Spatial-temporal characteristics of ambient isoprene and monoterpene and their ozone and secondary organic aerosol formation potentials in China

Biogenic volatile organic compounds (BVOCs) are important precursors of forming ozone (O3) and secondary organic aerosols (SOA), which have important impacts on air quality and climate change. Using a literature search, this review analyzed the concentration levels and spatial-temporal distributions of isoprene and monoterpene in the atmosphere in China, mainly from biogenic emissions, and estimated their impact on O3 and SOA generation. The existing observations were mainly in the Beijing-Tianjin-Hebei region, the Pearl River Delta region, central China, and in remote mountainous areas. The results showed that isoprene is the dominant component of BVOCs in the atmosphere, and its ambient concentration is much higher than monoterpene. The site-average concentrations of isoprene and monoterpene were 0.004–3.80 and 0.0003–6.31 ppb, respectively. At vegetation sites, the concentrations of isoprene and monoterpene were 0.006–3.80 and 0.007–6.31 ppb, respectively, whereas they were 0.004–2.70 and 0.0003–1.10 ppb at urban sites. For urban sites, the higher concentrations of annual isoprene occurred mainly in several central megacities, in the Sichuan-Chongqing region, and in southern regions. For vegetation sites, higher concentrations mainly occurred in southern regions. Ambient concentrations of BVOCs in the western region were the lowest for both urban and vegetation sites. Both isoprene and monoterpene showed higher concentrations in summer. The potential of isoprene and monoterpene to form O3 were 0.05–57.21 and 0.003–72.35 ppb, while those that form SOA were 0.0002–0.21 and 0.0006–10.46 μg/m3, respectively. For urban sites, the average annual O3 formation potential (OFP) by isoprene and monoterpene were 8.70 and 2.58 ppb, and their SOA formation potential (SOAP) were 0.03 and 0.37 μg/m3. For vegetation sites, they were 7.95 and 5.31 ppb and 0.03 and 0.75 μg/m3, respectively. The annual average contributions of isoprene and monoterpene to O3 and SOA formation were higher in the Beijing-Tianjin-Hebei region, Pearl River Delta region, and central China, where experience severe air pollution in China.

Contribution of Ship Emission to Volatile Organic Compounds Based on One‐Year Monitoring at a Coastal Site in the Pearl River Delta Region

AbstractShip emission impacts ambient air quality, especially in coastal regions, by emitting air pollutants such as fine particles, nitrogen oxides (NOx), and sulfur dioxide (SO2), yet its contributions to volatile organic compounds (VOCs) and the formation of secondary organic aerosol (SOA) and ozone (O3) are much less constrained with the challenge in distinguish ship emission from land diesel emission. In this study, we conducted a 1‐year online measurement of VOCs with a 1‐hr resolution at a coastal site in south China's Pearl River Delta region, which holds three of the world's top 10 container ports. The results revealed that C10–C12 n‐alkanes, as typical diesel‐related emission tracers, were significantly enhanced and strongly related to oceanic air masses. Receptor modeling revealed two diesel‐related sources of land diesel emission and ship emission, which could be differentiated based on their source profiles, seasonal trends and air mass back trajectories. Ship emissions contributed 6.4%, 5.0%, and 13.6% of total VOC mixing ratios, ozone formation potentials (OFPs), and secondary organic aerosol formation potentials (SOAFPs), while these percentages were 3.4%, 14.7%, and 15.9% for land diesel emission, respectively. In particular, in July, ship emissions could contribute 21.7%, 14.6%, and 31.2% of VOCs, OFPs, and SOAFPs, respectively. Our results highlight the important contribution of diesel‐related emission VOCs in forming O3 and SOA in coastal regions, and ship emission is a non‐negligible source of VOCs, particularly after the strict control of land emission sources.

Significance of Volatile Organic Compounds to Secondary Pollution Formation and Health Risks Observed during a Summer Campaign in an Industrial Urban Area.

The chemical complexity and toxicity of volatile organic compounds (VOCs) are primarily encountered through intensive anthropogenic emissions in suburban areas. Here, pollution characteristics, impacts on secondary pollution formation, and health risks were investigated through continuous in-field measurements from 1-30 June 2020 in suburban Nanjing, adjacent to national petrochemical industrial parks in China. On average, the total VOCs concentration was 34.47 ± 16.08 ppb, which was comprised mostly by alkanes (41.8%) and halogenated hydrocarbons (29.4%). In contrast, aromatics (17.4%) dominated the ozone formation potential (OFP) and secondary organic aerosol formation potential (SOAFP) with 59.6% and 58.3%, respectively. Approximately 63.5% of VOCs were emitted from the petrochemical industry and from solvent usage based on source apportionment results, followed by biogenic emissions of 22.3% and vehicle emissions of 14.2%. Of the observed 46 VOC species, hexachlorobutadiene, dibromoethane, butadiene, tetrachloroethane, and vinyl chloride contributed as high as 98.8% of total carcinogenic risk, a large fraction of which was ascribed to the high-level emissions during ozone pollution episodes and nighttime. Therefore, the mitigation of VOC emissions from petrochemical industries would be an effective way to reduce secondary pollution and potential health risks in conurbation areas.

Different VOC species derived from fugitive emissions at various altitudes around petrochemical plant

Volatile organic compounds (VOCs) emitted from fugitive sources are crucial for environmental and health risk assessments. However, monitoring these emissions at ground level, according to traditional technical specifications, has made it challenging to identify polluted air masses and collect purposeful samples. In this study, we focused on utilizing an unmanned aerial vehicle system to obtain air samples around a petrochemical industrial park. We conducted a quantitative analysis of 108 VOC species and compared the results between aerial and ground-level samples. The findings indicated a higher presence of reactive compounds in the aerial samples. The sample pairs exhibited relatively homogeneous compositions of hydrocarbons with fewer than eight carbon atoms, suggesting a well-mixed condition for light compounds. Conversely, the aerial samples exclusively exhibited high mixing ratios of C8–C15 compounds, including branched paraffins and aldehydes. Based on the quantified VOCs, we evaluated the ozone formation potential (OFP) and secondary organic aerosol formation potential (SOAP). The results highlighted aldehydes, alkenes, and aromatics, particularly propanal, 2-butene, m/p-xylene, and benzaldehyde, as priority control compounds. Additionally, the semiquantitative concentrations of these non-quantitative C8–C15 species ranged from 1 to 15 ppbv, with a total content exceeding 150 ppbv, it indicated the significant contribution to ambient secondary pollution. These results provide valuable insights into the identification of potential emission sources and the assessment of environmental repercussions attributed to these intermediate-volatile organic compounds from fugitive emissions around petrochemical plant.

Pollution characteristics and secondary formation potential of volatile organic compounds in the multi-industrial city of Ulsan, Korea

The secondary formation of ozone and aerosols due to volatile organic compounds (VOCs) has drawn increased attention in Ulsan, a multi-industrial city in South Korea. In this study, 52 VOCs were measured at 40 sites in four industrial (petrochemical, nonferrous, automobile, and shipbuilding) complexes and five urban sites using passive air samplers. The concentration of aromatics (44.6 μg/m3) accounted for 70.3% of the total VOC concentration (63.4 μg/m3), which was significantly higher than those of alkanes (27.5% and 17.4 μg/m3) and alkenes (2.15% and 1.37 μg/m3). The highest concentrations of total VOCs and aromatics were observed at the shipbuilding industrial complex, whereas the concentration of alkanes and alkenes was the highest in the petrochemical industrial complex. The positive matrix factorization (PMF) model suggested five major VOC sources in urban areas: (1) petrochemical production processes, (2) fuel combustion and evaporation, (3) urban emissions sources, (4) solvent use, and (5) painting and metal surface coating. The PMF result indicated that the distances from the four industrial complexes substantially affected VOC pollution in the urban areas. Moreover, aromatics (e.g., m,p-xylenes, toluene, ethylbenzene, o-xylene, and 1,2,4-trimethylbenzene) exhibited higher ozone formation potential (OFP) and secondary organic aerosol formation potential (SOAFP), which were mainly emitted from solvent use and painting in the shipbuilding and automobile industrial complexes. The petrochemical industrial complex close to densely populated urban areas also contributed significantly to secondary formation potential. In conclusion, our study revealed that elevated levels of aromatics were associated with increased OFP and SOAFP. Additionally, the four industrial complexes exhibited varying impacts on pollution characteristics in urban areas. These findings have practical implications, as they can inform the development of industry-specific management strategies for mitigating VOC pollution and secondary formation in multi-industrial cities.

Process-specific volatile organic compounds emission characteristics, environmental impact and health risk assessments of the petrochemical industry in the Beijing-Tianjin-Hebei region.

Volatile organic compounds (VOCs) concentration, source profiles, O3 and SOA formation, and health risks were investigated in the petrochemical industry in Beijing-Tianjin-Hebei. The results showed that total VOCs concentrations were 547.1-1956.5μg·m-3, and alkanes were the most abundant group in all processes (31.4%-54.6%), followed by alkenes (20.6%-29.2%) and aromatics (10.1%-25.1%). Moreover, ethylene (11.3%), iso-pentane (7.1%), n-hexane (5.1%), benzene (4.9%) and 2,2-dimethylbutae (4.8%) were identified as the top five species released for the whole petrochemical industry. The coefficient of divergence between the source profiles from different processes was 0.49-0.73, indicating that most source profiles must not be similar. Moreover, because of the different raw materials and technologies used, the source profiles in this study are significantly different from those of other regions. The ozone and secondary organic aerosol formation potentials (OFPs and SOAPs) were evaluated, suggesting that ethylene, propylene, 1-butene, m,p-xylene, and 1,3-butadiene should be preferentially controlled to reduce OFPs. That benzene, toluene, ethylbenzene, m,p-xylene, isopropylbenzene, o-ethyltoluene, and 1,3,5-trimethylbenzene should be priority control compounds for SOAPs. Additionally, the total hazard ratio for non-cancer risk ranged from 0.9 to 7.7, and only living area was unlikely to be related to adverse health effects. Cancer risks associated with organic chemicals, rubber synthesis, oil refining, and wastewater collection and treatment have definite risks, whereas other processes have probable risks. This study provides a scientific basis for VOCs emission control and management and guides human health in the petrochemical industry.