Distribution Of Volatile Organic Compounds Research Articles

Distribution of volatile organic compounds by distance from industrial complexes and potential health impact on the residents

ABSTRACT Volatile organic compounds (VOCs) are the air pollutants emitted from the petrochemical industry known to pose adverse health effects on workers. The database based on the third phase of The Environmental Health Study in the Korean National Industrial Complexes (EHSNIC) in Ulsan conducted from 2018 to 2021 was used. Subjects were divided into the exposed and control group according to the estimated pollution level and distances from the industrial complexes. Ambient benzene, ethylbenzene, and xylene were significantly higher in the exposed group compared to the controls, as well as their metabolites. Risk of chronic disease and atopic dermatitis was higher in the exposed group which was supported by higher serum inflammatory markers and high hazard index of the exposed region. These results can draw attention to people engaged with environmental plans and used as primary data when making policies to reduce pollutant levels around industrial complexes.

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.

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.

Spatial distribution of volatile organic compounds in contaminated soil and distinct microbial effect driven by aerobic and anaerobic conditions

The vertical distribution of 35 volatile organic compounds (VOCs) was investigated in soil columns from two obsolete industrial sites in Eastern China. The total concentrations of ΣVOCs in surface soils (0–20 cm) were 134–1664 ng g−1. Contamination of VOCs in surface soil exhibited remarkable variability, closely related to previous production activities at the sampling sites. Additionally, the concentrations of ΣVOCs varied with increasing soil depth from 0 to 10 m. Soils at depth of 2 m showed ΣVOCs concentrations of 127–47,389 ng g−1. Among the studied VOCs, xylene was the predominant contaminant in subsoils (2 m), with concentrations ranging from n.d. to 45,400 ng g−1. Chlorinated alkanes and olefins demonstrated a greater downward migration ability compared to monoaromatic hydrocarbons, likely due to their lower hydrophobicity. As a result, this vertical distribution of VOCs led to a high ecological risk in both the surface and deep soil. Notably, the risk quotient (RQ) of xylene in subsoil (2 m, RQ up to 319) was much higher than that in surface soil. Furthermore, distinct effects of VOCs on soil microbes were observed under aerobic and anaerobic conditions. Specifically, after the 30-d incubation of xylene-contaminated soil, Ilumatobacter was enriched under aerobic condition, whereas Anaerolineaceae was enriched under anaerobic condition. Moreover, xylene contamination significantly affected methylotrophy and methanol oxidation functions for aerobic soil (t-test, p < 0.05). However, aromatic compound degradation and ammonification were significantly enhanced by xylene in anaerobic soil (t-test, p < 0.05). These findings suggest that specific VOC compound has distinct microbial ecological effects under different oxygen content conditions in soil. Therefore, when conducting soil risk assessments of VOCs, it is crucial to consider their ecological effects at different soil depths.

Characteristics of Volatile Organic Compounds Distribution in Downtown Ansan Near Industrial Complexes

There are four industrial complexes located around Ansan City, which is one of the areas with the highest VOCs emissions in Gyeonggi region based on the emissions provided by the clean policy support system (CAPSS), Korea. In this study, proton transfer reaction time-of-flight mass spectrometer (PTR-TOF-MS) was used to determine the distribution of volatile organic compounds (VOCs) in urban areas near industrial complexes in Ansan City in 2023 (May to June). The PTR-TOF-MS was operated over the mass range of 10-400amu at a drift tube pressure of 2.3mbar and temperature 80&lt;sup&gt;o&lt;/sup&gt;C (E/N ~ 130Td) that enabled the collection of VOC data at 0.1Hz resolution. The mixing ratio calculations for methanol, acetaldehyde, acetonitrile, acetone, acetic acid, dimethyl sulfide, isoprene, methyl vinyl ketone (MVK), methyl ethyl ketone (MEK), benzene, toluene, styrene, xylene, trimethylbenzene and pinene reported in this study were done using the sensitivity factors obtained from the PTR-TOF-MS calibrations. As a result of the intensive measurement in springtime, among the substances constituting VOCs, methanol was the most abundant with 16.27±7.13 ppb, followed by acetone, acetaldehyde, acetic acid, methyl ethyl ketone (MEK), toluene, and xylene. VOCs compositions were dominated by oxidized VOCs, with CxHyO1 at 74%, CxHyO2 at 11%, aromatic CxHy at 10.5%, and CxHyN at 3.1%, respectively. As a result of the diurnal variations and conditional probability function (CPF) analysis, it was found that toluene and MEK were locally greatly influenced by industrial complexes distributed around Ansan City. Related with the ozone creating contribution, the ratio of VOCs to nitrogen oxide (NOx) was 6.5 (1.4 to 18.2), which appeared in the NOx-limited (4:1) and the VOCs-limited (15:1). Therefore it is suggested that the management of emission source NOx and VOCs are very important for the reduction of ozone in Ansan.

Appropriate control measure design by rapidly identifying risk areas of volatile organic compounds during the remediation excavation at an organic contaminated site.

Many organic contaminated sites require on-site remediation; excavation remediation processes can release many volatile organic compounds (VOCs) which are key atmospheric pollutants. It is therefore important to rapidly identify VOCs during excavation and map their risk areas for human health protection. In this study, we developed a rapid analysis and assessment method, aiming to and reveal the real-time distribution of VOCs, evaluate their human health risks by quantitative models, and design appropriate control measures. Through on-site diagonal distribution sampling and analysis, VOCs concentration showed a decreasing trend within 5 m from the excavation point and then increased after 5 m with the increase in distance from the excavation point (p < 0.05). The concentrations of VOCs near the dominant wind direction were higher than the concentrations of surrounding pollutants. In contrast with conventional solid-phase adsorption (SPA) and thermal desorption gas chromatography-mass spectrometry (TD-GC/MS) methods for determining the composition and concentration of VOCs, the rapid measurement of VOCs by photo-ionization detector (PID) fitted well with the chemical analysis and modeling assessment of cancer/non-cancer risk. The targeting area was assessed as mild-risk (PID < 10ppm), moderate-risk (PID from 10 to 40ppm), and heavy-risk (PID > 40ppm) areas. Similarly, the human health risks also decreased gradually with the distance from the excavation point, with the main risk area located in the dominant wind direction. The results of rapid PID assessment were comparable to conventional risk evaluation, demonstrating its feasibility in rapidly identifying VOCs releases and assessing the human health risks. This study also suggested appropriate control measures that are important guidance for personal protection during the remediation excavation process.

Insights into flavor formation of braised chicken: Based on E-nose, GC–MS, GC-IMS, and UPLC-Q-Exactive-MS/MS

Effects of braising duration on volatile organic compounds (VOCs) and lipids in chicken were investigated. Aroma profiles identified by an electronic nose were effective in differentiating braising stages. During braising process, a total of 25 key VOCs were detected in braised chicken, and sample braised for 210 min exhibited the highest level of key VOCs. Additionally, a gas chromatography mass spectrometry fingerprint was established to evaluate the distribution of VOCs throughout the braising process. Partial least square discriminant analysis indicated that 2-heptanone, 3-methyl-2-butanone, octanal, nonanal, butanal, (E)-2-pentenal, 1-octen-3-ol, 1-hexanol, pentanal, hexanal, and 1-pentanol significantly affected flavor characteristics of braised chicken. Furthermore, 88 differential lipids were screened, and glycerolipids metabolic was found to be main metabolic pathway during braising process. Triglycerides (TG) and phosphatidyl ethanolamine (PE), such as TG (16:0/18:1/18:2), TG (18:0/18:1/18:2), TG (18:1/18:2/18:3), TG (18:1/18:1/18:2), PE (O-18:2/18:2), PE(O-18:2/18:1), and TG (16:0/16:1/18:2), played a vital role in the generation of VOCs.

One-third of global population at cancer risk due to elevated volatile organic compounds levels

Outdoor air pollution, particularly volatile organic compounds (VOCs), significantly contributes to the global health burden. Previous analyses of VOC exposure have typically focused on regional and national scales, thereby limiting global health burden assessments. In this study, we utilized a global chemistry-climate model to simulate VOC distributions and estimate related cancer risks from 2000 to 2019. Our findings indicated a 10.2% rise in global VOC emissions during this period, with substantial increases in Sub-Saharan Africa, the Rest of Asia, and China, but decreases in the U.S. and Europe due to reductions in the transportation and residential sectors. Carcinogenic VOCs such as benzene, formaldehyde, and acetaldehyde contributed to a lifetime cancer burden affecting 0.60 [95% confidence interval (95CI): 0.40–0.81] to 0.85 [95CI: 0.56–1.14] million individuals globally. We projected that between 36.4% and 39.7% of the global population was exposed to harmful VOC levels, with the highest exposure rates found in China (82.8–84.3%) and considerably lower exposure in Europe (1.7–5.8%). Open agricultural burning in less-developed regions amplified VOC-induced cancer burdens. Significant disparities in cancer burdens between high-income and low-to-middle-income countries were identified throughout the study period, primarily due to unequal population growth and VOC emissions. These findings underscore health disparities among different income nations and emphasize the persistent need to address the environmental injustice related to air pollution exposure.

Vertical distribution of VOCs in the boundary layer of the Lhasa valley and its impact on ozone pollution

To investigate the vertical distribution of volatile organic compounds (VOCs) concentrations in the Lhasa valley region, an intensive measurement campaign was first conducted in summer using a tethered balloon. The results showed that the average concentration of surface VOCs was 49.1 ± 30.1 ppbv, alkanes and aromatics were the main components. Notably, a very large discrepancy in VOCs was obtained between the wet (71.6 ± 25.9 ppbv) and dry (25.6 ± 8.0 ppbv) episodes, which was attributed to the atmospheric stability and diffusion capacity. Moreover, the total VOC (TVOCs) concentration declined under fluctuations, but it rapidly increased with height in the afternoon during the wet episode (2.50 ppbv/100 m, R2 = 0.47). According to the PMF results, combustion was the dominant emission source, additionally, the contribution of solvent coating in the wet episode and the background in the dry episode increased with height. Moreover, the O3 concentration increased with height, and the decrease in LNOx-OH could effectively prevent the occurrence of high O3 values. This study indicated that low wind speeds and high humidity levels highly likely cause the accumulation of atmospheric VOCs under static and stable conditions, while the control of high O3 concentrations must still greatly consider summertime NOx emissions in Lhasa.

Development of a CFD model indicating the quantitative relationship among reactor dimension, bed flow unevenness, and performance for VOCs biofilters

ABSTRACT This study presents a Computational Fluid Dynamics (CFD) based biofiltration model to investigate the airflow distribution and the impact of bed flow unevenness (BFU) on the removal of Volatile Organic Compounds (VOCs) in biofilters. The biofiltration model consists of a gas flow sub-model and a VOCs removal sub-model, which were validated by pilot-scale experiments. The model was used to examine the quantitative relationship among reactor dimensions, including the width to height ratio of the filter bed and empty bed residence time (EBRT), BFU, and performance for VOCs biofilters. Simulation results demonstrate that the flow unevenness index (FUI) of the packing layer changes from 0.06 to 0.48 m2‧s−1 with reactor dimension changes. With an increase in the width to height ratio at a constant EBRT, FUI increases, BFU changes, and flow velocity fluctuation on the cross-section becomes larger, leading to a reduction of about 10% in VOCs removal efficiency. Concentration distribution of VOCs becomes uneven in the horizontal direction. At a constant width to height ratio of the filter bed, an increase in EBRT causes an increase in FUI, leading to a decrease in VOCs removal efficiency. When the width to height ratio is 0.5, velocity fluctuation of filter bed cross-section is small, the concentration of VOCs decreases evenly across the filter bed layer, and FUI is at a low level (0.06–0.11 m2‧s−1). Implication: In this manuscript, a biofiltration model of VOCs biofilter based on CFD has constructed and validated. And the manuscript gave the quantitative relationship among reactor dimension, bed flow unevenness and performance for VOCs biofilters for the first time. This study can lead to enhanced VOCs removal efficiency and improved overall performance of biofilters in practical engineering applications.

Effect of microstructure in mesoporous adsorbents on the adsorption of low concentrations of VOCs: An experimental and simulation study

This study evaluated the adsorption of five volatile organic compounds (VOCs) on Opoka, precipitated silica, and palygorskite, to elucidate the effect of their pore size on VOCs adsorption. The adsorption capacity of these adsorbents is not only highly correlated with their surface area and pore volume, but also notably improved by the presence of micropores. The variation in adsorption capacity for different VOCs was primarily influenced by their boiling point and polarity. Palygorskite, which had the smallest total pore volume (0.357 cm3/g) but the largest micropore volume (0.043 cm3/g) among the three adsorbents, exhibited the highest adsorption capacity for all tested VOCs. Additionally, the study constructed slit pore models of palygorskite with micropores (0.5 and 1.5 nm) and mesopores (3.0 and 6.0 nm), calculated and discussed the heat of adsorption, concentration distribution, and interaction energy of VOCs adsorbed on different pore models. The results revealed that the adsorption heat, concentration distribution, total interaction energy, and van der Waals energy decrease with increasing pore size. The concentration of VOCs in 0.5 nm pore was nearly three times that in 6.0 nm pore. This work can also provide guidance for further research on using adsorbents with mixed microporous and mesoporous structures to control VOCs.

Characteristics comparison of gaseous and particle-phase VOCs released by smoldering mosquito coils and their health risks

Mosquito coils have been widely used in tropical and subtropical regions, particularly in rural areas. However, their emissions, primarily volatile organic compounds (VOCs) and particulate matters (PMs), have raised concerns about their potential health impact. This study provides new insights into the characteristics of VOCs and PMs produced by three representative Chinese mosquito coils, revealing stark differences in VOCs found in the gas phase compared to the particle phase. Results showed that during the use of mosquito coils, the indoor concentrations of total volatile organic compounds (TVOCs) and PM2.5 can surge to 2.35–3.33 times and 1.59–7.42 times above the acceptable standards, respectively. Detailed characterization of VOCs using GC/MS suggested that PMs concentrations significantly impact the distribution of VOCs in gas and particle phases. A key finding of this study is the difference in VOCs composition between the gas and particle phases. The particle phase VOCs demonstrated a higher species number and average relative molecular weight across the three tested mosquito coil brands, and the carcinogens they contained were entirely distinct from those found in the gaseous phase. For instance, gaseous VOCs were predominantly alkanes (60.29–74.75 wt%), while the dominant particle-phase VOCs for the three mosquito coils were alkanes (33.56 wt%), esters (51.76 wt%) and aromatics (35.51 wt%), respectively. Health risk assessments indicated that while gaseous VOCs contribute predominantly to both non-carcinogenic and carcinogenic risks, the role of particle-phase VOCs, particularly from mosquito coils producing more PMs, cannot be discounted. This study conducted a detailed evaluation of the various forms of pollutants generated by mosquito coils, providing crucial references for future assessments of pollution emanating from similar sources.

Imaging VOC distribution and tracing emission sources in surface water by a mobile shipborne spray inlet proton transfer reaction mass spectrometry

Volatile organic compound (VOC) pollution in surface water can affect the growth of microorganisms and even cause damage to human health. Quickly obtaining VOC distribution and tracing emission sources are of great significance to ensure the security of water quality. In this study, we developed a mobile shipborne spray inlet proton transfer reaction mass spectrometry (S-SI-PTR-MS) instrument for rapid and on-line detection of volatile organic compounds (VOCs) in surface water. It mainly consists of a shipborne platform, a spray inlet system, a proton transfer reaction mass spectrometer, and geographic information software (GIS). During the navigation, VOCs in water can be quickly extracted to gaseous state by the SI system and transferred into the proton transfer reaction mass spectrometry (PTR-MS) for detection. The GIS can receive VOC and longitude-latitude data at the same time. And then the identification and concentration information can be shown on an electronic map in real time. The limit of detection and response time were 1.32 μg/L∼9.43 μg/L and 56 s∼114 s, respectively. The spatial resolution is 0.14 m in a common navigation experiment (5 km/h, dwell time=0.1 s), allowing for high-resolution monitoring of VOCs in water. Finally, field experiments were performed on the lower Nanfeihe River and some surfaces of Chaohu Lake in China. During tracing pollution in Nanfeihe River, two VOC emission sources in the downstream were located, nearing a sewage outlet and a wharf, respectively. During imaging VOC distribution in the Chaohu Lake, we found the areas with high-concentration VOCs were mainly along the ship channel. The newly developed S-SI-PTR-MS can monitor water quality in surface water in real time and has the potential to assist environmental protection enforcement.

Vertical evolution of the concentrations and sources of volatile organic compounds in the lower boundary layer in urban Beijing in summer

Exploring the vertical variations in volatile organic compounds (VOCs) in the atmosphere and quantifying the sources of VOCs at different heights can help control atmospheric photochemical pollution in summer. Here, VOCs were vertically detected at three heights (47 m, 200 m and 320 m) along a 325 m tower of the Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, in the mornings (8:00) and afternoons (15:00) from May 19 to June 18, 2021. The VOC concentrations in Beijing in summer were 16.2 ± 5.6 ppbv, 14.7 ± 2.5 ppbv and 14.9 ± 3.8 ppbv at 47 m, 200 m and 320 m, respectively, and alkanes accounted for the largest proportion at all heights (>56%). The vertical gradients of the VOC concentrations and components did not significantly change, which was consistent with the summer observations of other stations in North China in recent years, but these results significantly differed from observations from more than a decade ago. To determine the reason for this, a classification based on atmospheric stability was performed, revealing that the vertical distribution of VOCs was uniform in convective and stable conditions and decreased with increasing height in neutral condition. With the transition of atmospheric stability from neutral to convective to stable, the contributions of fuel combustion sources and solvent use sources gradually increased, while those of biogenic sources and background sources gradually decreased. With increasing height, the contributions of background sources increased, those of biogenic sources, solvent use and gasoline vehicular emissions decreased, and those of fuel combustion and industrial emissions remained basically unchanged. The above results indicated that with air pollution treatment, the potential for reducing emissions of VOCs in Beijing has decreased. Therefore, regional joint prevention and control are the main ways to control VOC pollution in Beijing.

Pollution Characteristics and Risk Assessment of Volatile Organic Compounds in Songhua Lake, China

In order to assess the dangers to human health and the environment from Songhua Lake's volatile organic compounds (VOCs) pollution. A total of 18 VOCs were found in the water samples that were collected at 26 sampling locations in Songhua Lake utilizing the purge and trap technique and gas chromatography-mass spectrometry (GC-MS). Toluene and naphthalene had the highest detection rates among them, reaching 96.15%; trans-1,2-dichloroethylene, 1,2-dichloroethane, and isopropyl benzene had the lowest rates, only 3.85%. The maximum and average concentrations of 1,1-dichloroethane were 20.93 μg/L and 4.16 μg/L, respectively, the maximum concentration of isopropyl benzene was only 0.02 μg/L, and the average concentration was also the lowest. The spatial distribution of VOCs in Song Hua Lake was typically described as "high in the northwest and low in the southeast," with a concentration range of 0.00 to 23.21 μg/L. An examination of the current situation reveals that human activity-related ecological deterioration is the primary cause of the VOCs contamination in Songhua Lake. The results of the risk assessment revealed that there were only moderate ecological risks to aquatic organisms and that the non-carcinogenic and carcinogenic risk indices of Songhua Lake were within the safe range. Additionally, there were no non-carcinogenic or carcinogenic threats to the health of people as a whole.

Proposal of a Gas Sensor-Based Device for Detecting Adulteration in Essential Oil of Cistus ladanifer

Essential oils are a valuable raw material for several industries. Low-cost methods cannot detect its adulteration; specialised equipment is required. In this paper, we proposed the use of gas sensors to detect the adulteration process in the essential oil of Cistus ladanifer. Gas sensors are used in a measuring chamber to measure pure and adulterated oils. We compare the suitability of the tested sensors for detecting adulterated oil and the required measuring time. A total of five samples are determined, with a measuring time of 12 h. Each gas sensor is configured to be sensitive to different compounds. Even though sensors are not specific to detect the volatile organic compounds (VOCs) present in the essential oil, our objective is to evaluate if these VOCs might interact with the sensors as an interferent. Results indicate that various gas sensors sensitive to the same chemical compound offered different values. It might indicate that the interaction of VOCs is different among the tested sensors or that the location of the sensors and the heterogeneous distribution of VOCs along the measurement chamber impact the data. Regarding the performed analyses, we can affirm that identifying the adulterated essential oil is possible using the generated data. Moreover, the results suggest that most of the data, even for different compounds and sensors, are highly correlated, allowing a reduction in the studied variables. According to the high correlation, data are reduced, and 100% of correct classification can be obtained even when only the MQ3 and MQ8 are used.

Integrated Sustainable Management of Petrochemical Industrial Air Pollution.

The emission inventory, emission factor, and spatial concentration distribution of volatile organic compounds (VOCs) from a petrochemical industry (aromatics plant) were intensively evaluated in this study to elucidate the potential sources of BTX emission and their contribution to ambient concentrations. Five emission groups were quantified through direct measurement and emission models. These data were then used as input for the AERMOD dispersion model for the source apportionment analysis. The source to ambient contribution analysis revealed that a wastewater treatment facility and organic liquid storage tank were major contributors accounting for about 20.6-88.4% and 10.3-75.4% to BTX environmental concentrations, respectively. The highest annual ambient concentrations of benzene (B), toluene (T), and xylenes (X) were predicted as 9.0, 2.8, and 57.9 µg/m3 at the fence line of the plant boundary, respectively. These findings assist policymakers in prioritizing the appropriate control measures to the right source by considering not just the amount released but also their contribution to ambient concentrations. This study suggested that the wastewater treatment unit should be changed to the closed system which will benefit reduction in its emission (45.05%) as well as effectively minimizing ambient VOC concentration by 49.96% compared to its normal operation.

Profile of atmospheric VOC over the Yellow Sea, China: A tale of distribution, constraints, and sources

In the winter of 2018–2019, 75 air samples were collected through four ship-borne measurements in the Yellow Sea (YS) to assess the levels, confinement processes, and source distribution of volatile organic compounds (VOCs). A total of 41 were eventually detected, which mainly were non-methane hydrocarbons (NMHCs), volatile halogenated hydrocarbons (VHCs), oxygenated volatile organic compounds (OVOCs), and volatile organic sulfur compounds (VSCs). Aromatics (31.93 %) and alkenes (11.04 %) in the atmosphere of the YS accounted for a larger proportion of NMHCs compared with the coastal areas. C3-C5 alkanes, propylene, and chloroform exhibited strong latitudinal gradients and opposite latitudinal distributions in the North and South YS, highlighting the strong contribution of regional outflow to YS's atmosphere. The level of Σ41VOCs increased significantly during the heavy pollution period with some chemical monomers detected, which was further enhanced by the emissions from industrial parks near the Liaodong Peninsula and the Shandong Peninsula. Five main VOC sources were identified by the Positive matrix factorization (PMF) model, which were industrial emissions (13.33 %), fuel use and volatilization (6.67 %), Freon R-22 emissions (33.33 %), oil and gas production (20.00 %), and solvent volatilization (26.67 %). These observations revealed the strong causal relationship between coastal air mass transport and the atmosphere in the marginal sea and emphasized that full attention should be paid to the unintentional and unorganized emission of chemical monomers in the industrial process.

Seasonal Characteristics of Volatile Organic Compounds in Seoul, Korea: Major Sources and Contribution to Secondary Organic Aerosol Formation

Volatile organic compounds (VOCs) are major pollutants that cause air pollution and are precursors that react in the air to produce secondary organic aerosol (SOA). This study attempted to elucidate the distribution characteristics of VOCs in the atmosphere of Seoul by measuring 34 types of VOCs in real time in the winter of 2020 and summer of 2021. The objectives of this research are as follows: (1) understand the characteristics of VOCs in Seoul and the difference between winter and summer compositions, (2) identify the main sources of VOCs in winter and summer, and (3) estimate the contribution of VOCs to the SOA formation potential in Seoul. Total VOC concentrations were found to be higher in summer (7.61 ± 4.22 ppb) than in winter (6.35 ± 4.11 ppb). To further specify the cause of the difference in major VOC components in winter and summer, a cause analysis was performed using the ratio between marker components, and an emission source analysis of VOCs was performed by applying the positive matrix factorization model (PMF). The source distribution of VOCs in Seoul was attributed to five factors: solvent usage, vehicle exhaust, industry/burning of fossil fuels, petrochemical industry, and road emission (winter)/gasoline-related (summer). The contribution of VOCs to SOA formation was estimated using the secondary organic aerosol formation potential. The results showed that toluene was the primary contributor to SOA formation in both winter and summer. In the summer, solvent usage containing high proportion of ethylbenzene and xylenes contributed more than twice as much to SOA formation compared to the winter.

Explication on distribution patterns of volatile organic compounds in petro-chemistry and oil refineries of China using a species-transport model and health risk assessment

Volatile organic compounds (VOCs) from industrial emissions have attracted great attention due to their negative effects on human, but there is lack of deterministic air quality model for VOC emissions. In this study, airborne VOCs from a typical petrochemical and oil refinery region, Lanzhou, Gansu province of China, were on-site measured. The regional pollution patterns were investigated using a species transport model and the health risks were evaluated. The spatial distribution of VOCs showed that 87.5 % of the airborne VOCs were benzene, toluene, ethylbenzene, and xylene having higher concentration (146 μg/m3) in the north direction oil refinery industrial areas. The concentrations of toluene and benzene were as high as 41.5 and 33.3 μg/m3 in the 4 km2 area away from the petrochemical emission source, respectively, and the concentration of o−/m + p-xylene was up to 79.7 μg/m3. Based on the measured concentration data, the numerical results showed that the accumulation of high concentration of VOC species by mass transfer in the region is related to the atmospheric diffusion driven by downward-moving air over the valley areas. Non-carcinogenic risk assessments showed that airborne benzene exposure had acceptable hazard quotient of 0.185 for adults, which was 1.8 times of children's (0.102), whereas it was found that a high carcinogenic risk (>10−4) from benzene in several sampling sites and diffuse distance become significant for carcinogenic risk. This study verified the effectiveness of VOC atmospheric diffusion model through a large number of on-site monitoring data, providing data support for model-based risk assessment.