Characteristics Of Volatile Organic Compounds Research Articles

Pseudomonas synxantha volatile organic compounds: efficacy against Cadophora luteo-olivacea and Botrytis cinerea of kiwifruit

Volatile organic compounds (VOCs) are responsible for the antagonistic activity exerted by different biological control agents (BCAs). In this study, VOCs produced by Pseudomonas synxantha strain 117-2b were tested against two kiwifruit fungal postharvest pathogens: Cadophora luteo-olivacea and Botrytis cinerea, through in vitro and in vivo assays. In vitro results demonstrated that P. synxantha 117-2b VOCs inhibit mycelial growth of C. luteo-olivacea and B. cinerea by 56% and 42.8% after 14 and 5 days of exposition, respectively. In vivo assay demonstrated significant inhibitory effects. VOCs used as a biofumigant treatment reduced skin-pitting symptoms disease severity by 28.5% and gray mold incidence by 66.6%, with respect to the untreated control. BCA volatiles were analyzed by solid-phase microextraction coupled with gas chromatography–mass spectrometry (SPME–GC/MS), and among the detected compounds, 1-butanol, 3-methyl and 1-nonene resulted as the most produced. Their efficacy as pure synthetic compounds was assayed against mycelial growth of fungal pathogens by different concentrations (0.34, 0.56, and 1.12 µL mL−1 headspace). The effect of the application of VOCs as a biofumigant was also investigated as the expression level of seven defense-related genes of kiwifruit at different exposition times. The results indicated an enhancement of the expression of almost all the genes starting from 3 h of treatment. These results described P. synxantha VOCs characteristics and their potential as a promising method to adopt for protecting kiwifruit from postharvest diseases caused by C. luteo-olivacea and B. cinerea.

Development of a UAV-borne sorbent tube sampler and its application on the vertical profile measurement of volatile organic compounds

Vertical detection of volatile organic compounds (VOCs) is essential to expend our understanding of the distribution characteristics of VOCs and improve the predictive ability of existing air quality models. In this work, we report the development of a sorbent tube sampler based on an unmanned aerial vehicle (UAV) platform. Vertical profile measurement of VOCs with a vertical resolution of 25 m was achieved. The sampler consists of five lightweight VOC sorbent tubes and a 5-way solenoid valve, making it available for collecting five atmospheric VOC samples in a single flight with a time response of less than 30 min. The sampler weighed ∼ 1.45 kg and had dimensions of 240 mm × 220 mm × 100 mm with small penetration loss (< 10%) under 4-liter sampling conditions (flow rate of 200 mL/min). Commercialized SUMMA canisters were used as experimental controls to investigate the possible loss of self-made sampler for target compounds in the same sampling process. Comparison experiment on the ground showed that the concentration differences for all VOC species were lower than 0.14 μg/m3, proving the good reliability for VOCs measurements using sorbent tube sampler. The UAV platform also incorporated online instruments for meteorological parameters and O3 measurement. The sampler was successfully applied to characterize the vertical profiles of VOCs up to 100 m in October 2023 in the Huaihe River Basin of China. The UAV platform and the sorbent tube sampler demonstrate good performance and will be a valuable and reliable tool for vertical VOCs measurement.

Detection and treatment of VOCs in the food industry

Volatile organic compounds (VOCs) are common pollutants in the atmosphere, which will do some harm to the environment and the human body. At present, the detection and treatment of VOCs are mainly concentrated in chemical, petroleum, pharmaceutical, household and other industries, but few scholars have studied the management of VOCs emitted by food industry. According to the characteristics of VOCs emitted from food industry, this article summarizes the research progress of relevant detection methods (gas chromatography, gas chromatography-mass spectrometry, gas chromatography-ion mobility spectrometry, electronic nose technology) for VOCs emitted from food industry in recent years, focusing on the research progress, advantages, and disadvantages of destruction technology (combustion method, low temperature plasma technology, biological method), treatment and recovery technology (adsorption method, absorption method, condensation method, membrane separation method) and combination technology for VOCs emitted from food industry. Based on the understanding of various governance technologies and the relevant policy requirements of VOCs governance, the future research trends in this field are prospected.

Response of protonated, adduct, and fragmented ions in Vocus proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS)

Abstract. Volatile organic compounds (VOCs) affect secondary pollutant formation via active chemistry. Proton-transfer-reaction mass spectrometry (PTR-MS) is one of the most important techniques to study the highly variable spatial and temporal characteristics of VOCs. The response of protonated, adduct, and fragmented ions in PTR-MS in changing instrument settings and varying relative humidity (RH) requires rigorous characterization. Herein, we present dedicatedly designed laboratory experiments conducted to investigate the response of these ions for 21 VOCs, including 12 oxygenated VOCs and 2 nitriles, using the recently developed Vocus PTR-MS. Our results show that the focusing ion–molecule reactor (FIMR) axial voltage increases sensitivity by 3 to 4 orders of magnitude but does not significantly change the fractions of protonated ions. Reducing the FIMR pressure, however, substantially increases fragmentation. Applying a high radio frequency (RF) amplitude radially to the FIMR can enhance sensitivity by 1 to 2 orders of magnitude without affecting the protonated ion fractions. The change in big segmented quadrupole (BSQ) amplitude mainly affects sensitivity and protonated ion fraction by modifying ion transmission. The relationship between sensitivity and proton-transfer reaction rate constant is complicated by the influences from both ion transmission and protonated ion fraction. The protonated ions of most VOCs studied (19 out of 21) show less than 15 % variations in sensitivity as RH increases from ∼ 5% to ∼ 85 %, except for some long-chain aldehydes which show a positive RH variation of up to 30 %. Our results suggest that the Vocus PTR-MS can reliably quantify the majority of VOCs under ambient conditions with varying RH. However, caution is advised for small oxygenates such as formaldehyde and methanol due to their low sensitivity and for long-chain aldehydes due to their slight RH dependence and fragmentation.

Increased tuberculosis case detection in Tanzanian children and adults using African giant pouched rats.

African giant pouched rats, trained by Anti-Persoonsmijnen Ontmijnende Product Ontwikkeling (APOPO), have demonstrated their ability to detect tuberculosis (TB) from sputum. We assessed rat-based case detection and compared the mycobacterium bacillary load (MTB-load) in children versus adults. From January-December 2022, samples were collected prospectively from 69 Directly Observed Therapy (DOT) facilities' presumed TB patients. Using an average of five rats, APOPO re-evaluated patients with bacteriologically negative (sputum-smear microscopy or Xpert MTB/RIF) results. Rat-positive samples were tested using concentrated smear light-emitting diode microscopy to confirm TB detection before treatment initiation. The rats' identification of pulmonary TB is based on smelling TB-specific volatile organic compounds (VOCs) in sputum. Using STATA, Chi-square for oddsratio and confidence interval was calculated and evaluated: (1) the yield of rat-based TB detection compared to that of the health facilities; (2) rat-based TB detection in children versus adults; and (3) rats' ability to detect TB across MTB-loads and between children and adults. From 35,766 patients, 5.3% (1900/35,766) were smear-positive and 94.7% (33,866/35,766) were smear or Xpert-negatives at DOTS facility. Of those with negative results, 2029 TB cases were detected using rats, contributing to 52% (2029/3929 of total TB identified), which otherwise would have been missed. Compared to DOT facilities, rats were six-fold more likely to detect TB among Acid Fast Bacilli (AFB) 1+/scanty [90% (1829/2029) versus 60% (1139/1900), odds ratio, OR = 6.11, 95% confidence interval, CI: 5.14-7.26]; twice more likely to identify TB cases among children [71% (91/129) versus 51% (1795/3542), OR = 2.3, 95% CI: 1.59-3.42]; and twice more likely to identify TB cases among children with AFB 1+/scanty than adults with the same MTB-load [5% (86/1703) versus 3% (28/1067), OR = 2.0, 95% CI: 1.28-3.03]. Rats contributed over half of the TB cases identified in program settings, and children, especially those with a lower MTB-load, were more likely to be diagnosed with TB by rats. The chemical signatures, VOCs, were only available for adults, and further research describing the characteristics of VOCs in children versus adults may pave the way to enhance TB diagnosis in children.

Characteristics of Volatile Organic Compounds Emitted from Airport Sources and Their Effects on Ozone Production.

In recent years, commercial air transport has increased considerably. However, the compositions and source profiles of volatile organic compounds (VOCs) emitted from aircraft are still not clear. In this study, the characteristics of VOCs (including oxygenated VOCs (OVOCs)) emitted from airport sources were measured at Shenzhen Bao'an International Airport. The results showed that the compositions and proportions of VOC species showed significant differences as the aircraft operating state changed. OVOCs were the dominant species and accounted for 63.17%, 58.44%, and 51.60% of the total VOC mass concentration during the taxiing, approach, and take-off stages. Propionaldehyde and acetone were the main OVOCs, and dichloromethane and 1,2-dichloroethane were the main halohydrocarbons. Propane had the highest proportion among all alkanes, while toluene and benzene were the predominant aromatic hydrocarbons. Compared with the source profiles of VOCs from construction machinery, the proportions of halogenated hydrocarbons and alkanes emitted from aircraft were significantly higher, as were those of propionaldehyde and acetone. OVOCs were still the dominant VOC species in aircraft emissions, and their calculated ozone formation potential (OFP) was much higher than that of other VOC species at all stages of aircraft operations. Acetone, propionaldehyde, formaldehyde, acetaldehyde, and ethylene were the greatest contributors to ozone production. This study comprehensively measured the distribution characteristics of VOCs, and its results will aid in the construction of a source profile inventory of VOCs emitted from aircraft sources in real atmospheric environments.

Characterization and source apportionment of volatile organic compounds in Hong Kong: A 5-year study for three different archetypical sites

Initial success has been achieved in Hong Kong in controlling primary air pollutants, but ambient ozone levels kept increasing during the past three decades. Volatile organic compounds (VOCs) are important for mitigating ozone pollution as its major precursors. This study analyzed VOC characteristics of roadside, suburban, and rural sites in Hong Kong to investigate their compositions, concentrations, and source contributions. Here we show that the TVOC concentrations were 23.05 ± 13.24, 12.68 ± 15.36, and 5.16 ± 5.48 ppbv for roadside, suburban, and rural sites between May 2015 to June 2019, respectively. By using Positive Matrix Factorization (PMF) model, six sources were identified at the roadside site over five years: Liquefied petroleum gas (LPG) usage (33%–46%), gasoline evaporation (8%–31%), aged air mass (11%–28%), gasoline exhaust (5%–16%), diesel exhaust (2%–16%) and fuel filling (75–9%). Similarly, six sources were distinguished at the suburban site, including LPG usage (30%–33%), solvent usage (20%–26%), diesel exhaust (14%–26%), gasoline evaporation (8%–16%), aged air mass (4%–11%), and biogenic emissions (2%–5%). At the rural site, four sources were identified, including aged air mass (33%–51%), solvent usage (25%–30%), vehicular emissions (11%–28%), and biogenic emissions (6%–12%). The analysis further revealed that fuel filling and LPG usage were the primary contributors to OFP and OH reactivity at the roadside site, while solvent usage and biogenic emissions accounted for almost half of OFP and OH reactivity at the suburban and rural sites, respectively. These findings highlight the importance of identifying and characterizing VOC sources at different sites to help policymakers develop targeted measures for pollution mitigation in specific areas.

Characteristics and Source Apportionment of Volatile Organic Compounds in an Industrial Area at the Zhejiang–Shanghai Boundary, China

As “fuel” for atmospheric photochemical reactions, volatile organic compounds (VOCs) play a key role in the secondary generation of ozone (O3) and fine particulate matter (PM2.5, an aerodynamic diameter ≤ 2.5 μm). To determine the characteristics of VOCs in a high-level ozone period, comprehensive monitoring of O3 and its precursors (VOCs and NOx) was continuously conducted in an industrial area in Shanghai from 18 August to 30 September 2021. During the observation period, the average concentration of VOCs was 47.33 ppb, and alkanes (19.64 ppb) accounted for the highest proportion of TVOCs, followed by oxygenated volatile organic compounds (OVOCs) (13.61 ppb), alkenes (6.92 ppb), aromatics (4.65 ppb), halogenated hydrocarbons (1.60 ppb), and alkynes (0.91 ppb). Alkenes were the predominant components that contributed to the ozone formation potential (OFP), while aromatics such as xylene, toluene, and ethylbenzene contributed the most to the secondary organic aerosol production potential (SOAFP). During the study period, O3, NOx, and VOCs showed significant diurnal variations. Industrial processes were the main source of VOCs, and the second largest source of VOCs was vehicle exhaust. While the largest contribution to OFP was from vehicle exhaust, the second largest contribution was from liquid petroleum gas (LPG). High potential source contribution function (PSCF) values were observed in western and southeastern areas near the sampling sites. The results of a health risk evaluation showed that the Hazard Index was less than 1 and there was no non-carcinogenic risk, but 1,3-butadiene, benzene, chloroform, 1,2-dibromoethane, and carbon tetrachloride pose a potential carcinogenic risk to the population.

Release characteristics of volatile organic compounds at residential garbage collection points: a case study of Hangzhou, China.

With the implementation of garbage classification, perishable waste has become increasingly concentrated. This has led to a significant change in the VOC release characteristics at residential garbage collection points, posing a potential risk with unknown characteristics. This study investigated the release characteristics, odor pollution, and health risks of VOCs at garbage collection points under different classification effectiveness, seasons, garbage drop-off periods, and garbage collection point types. The results showed that the average concentration of VOCs released from the garbage sorting collection points (SPs) was 341.43 ± 261.16 μg/m3, and oxygenated compounds (e.g., ethyl acetate and acetone) were the main VOC components. The VOC concentration increased as the community classification effectiveness improved, and it was higher in summer (followed by spring, autumn, and winter). Moreover, the VOC concentrations were higher in the evenings than in the mornings and at centralized garbage collection points (CPs) than at SPs. Further, odor activity value (OAV) assessments indicated that acrolein, styrene, and ethyl acetate were the critical odorous components, with an average OAV of 0.87 ± 0.85, implying marginal odor pollution in some communities. Health risk assessments further revealed that trichloroethylene, benzene, and chlorotoluene were the critical health risk substances, with an average carcinogenic risk (CR) value of 10-6-10-4, and a non-carcinogenic risk (HI) value < 1. These results indicated that HIs were acceptable, but potential CRs existed in the communities. Therefore, VOC pollution prevention and control measures should be urgently strengthened at the garbage collection points in high pollution risk scenarios.

Pollution Characteristics，Source Analysis，and Activity Analysis of Atmospheric VOCs During Winter and Summer Pollution in Zhengzhou

In order to study the pollution characteristics of volatile organic compounds （VOCs）， continuous monitoring of VOCs in two pollution processes was conducted in June and December 2021 in Zhengzhou. Combined with meteorological conditions， the pollution characteristics， source contributions， and reactivity of VOCs in winter and summer were compared and analyzed. The results showed that the volume fraction of atmospheric VOCs in two episodes were （27.92±12.68）×10-9 and （24.30±5.93）×10-9， respectively. The volume fraction of atmospheric VOCs in the haze pollution process in winter was larger than that in the ozone pollution process in summer. The analysis results of winter sources were as follows： industrial source （27.0%）， motor vehicle source （22.5%）， combustion source （20.1%）， solvent use source （16.3%）， and oil and gas volatilization source （14.1%）. The analysis results of summer sources were as follows： motor vehicle source （24.8%）， industrial source （24.1%）， solvent source （17.4%）， oil and gas volatilization source （14.2%）， combustion source （11.2%）， and plant source （8.4%）. The results of the smog production model showed that the proportion of days in the synergistic control zone of VOCs during the two pollution processes in summer （66.7%） was smaller than that in winter （100.0%）. The secondary reaction activity results showed that the average ·OH loss rate （L·OH） values in winter and summer were 4.12 s-1 and 4.75 s-1， respectively. The average ozone formation potential （OFP） values in summer were 108.36 μg·m-3. The olefins were dominant in the top ten species due to L·OH and OFP contributions in summer. The total SOAFP values in winter in Zhengzhou were 54.38 μg·m-3. Among the top ten species contributing to SOAFP in winter， nine were aromatic hydrocarbons.

A study on distribution characteristics of volatile organic compounds in Paju industrial complex area, using proton transfer reaction-time of flight mass spectrometry

Paju City is located in the northwest of Gyeonggi-do, and its chemical emissions in 2020 were 1,287,917 kg, the 4th highest in Gyeonggi-do. In particular, the Munsan High-Tech Industrial Complex in Paju has LCD manufacturing plants and partner companies distributed in groups, and the volatile organic compounds used by these companies are causing many problems, such as causing bad odors, to the local community. In this sense, real-time analyzing equipment (proton-transfer-reaction time-of-flight mass spectrometry) was mounted on a vehicle for this study to look into the air quality around VOCs-using companies inside the High-tech Industrial Complex in Munsan, Paju from October 19 to October 21, 2020.According to measurement results, toluene was detected the most at 25.7 ppb, followed by carbon tetrachloride (17.6 ppb), ethylbenzene (17.2 ppb), and xylene (8.5 ppb), which demonstrates that there is a need to control these substances to resolve the issue with VOCs in the region. In particular, benzene designated as the air quality standard was detected at 1.0 ppb in some sites, which is below the threshold (1.5 ppb). However, it was detected at 2.1 to 4.4 ppb, exceeding the threshold in most sites. Thus, continuous monitoring is expected to keep VOCs under control in Paju Industrial Complex down the road, using real-time measuring equipment.

Investigation of atmospheric VOCs sources and ozone formation sensitivity during epidemic closure and control: A case study of Zhengzhou

This study investigates the pollution characteristics of volatile organic compounds (VOCs) and their impact on ozone formation in the urban area of Zhengzhou. The analysis is based on the air quality data collected during the epidemic control period (P3) from July 20 to August 22, 2021, as well as the same period in 2019 and 2020 (P1 and P2). The results reveal a decreasing trend in the O3 precursors, namely NO2 and VOCs, from 2019 to 2021. During the P3 period, the mean concentrations of NO2 and VOCs were 19 μg/m3 and 56 μg/m3, respectively, a decline of 32% and 36% compared to the levels in P2. However, the mean MDA8 concentration in P3 was 142 μg/m3, 25% higher than that in P2, and ozone-polluted days was 12 d, 6 days more than that in P2. The VOCs composition profiles were similar across three periods, with alkanes accounting for 34%, 36%, and 39% of TVOC, respectively. Six kinds of VOCs sources were quantified by positive matrix factorization (PMF), among which vehicle emissions contributed the most (29%), followed by solvent usage (23%) and industrial processes (22%). The contribution of industrial processes and vehicle emissions declined significantly in P3, while that of stationary combustion and LPG/NG sources increased. The net production rate P(Ox) increased in P3 compared to that in P2, getting closer to the ridge line, indicating that O3 formation was gradually transiting from VOCs control zone to synergistic control zone. Therefore, VOCs and NOx emissions should be reduced synchronously.

Differentiation analysis of VOCs in Kunming during rainy and dry seasons based on monitoring high temporal resolution

Volatile Organic Compounds (VOCs) play a pivotal role as precursors for O3 formation. 66 VOCs species in Kunming were observed for two consecutive years using an online monitoring system. Concentration characteristics of VOCs, ozone formation potential (OFP), sources and health risks in rainy and dry seasons were investigated. Our results showed that the concentrations of VOCs exhibited significant seasonal differences, with average concentrations of 31.43 ± 17.62 μg/m3 and 64.78 ± 36.38 μg/m3 in the rainy and dry seasons, respectively. Alkanes (16.83 ± 16.75 μg/m3) dominated the VOCs types throughout the monitoring period, followed by halogenated hydrocarbons (13.38 ± 16.20 μg/m3), olefins (10.77 ± 14.34 μg/m3), aromatics (6.64 ± 6.71 μg/m3), and alkynes (0.36 ± 0.37 μg/m3). The OFP values in rainy and dry seasons were 86.10 μg/m3 and 198.55 μg/m3, respectively. The most substantial contribution to OFP originated from olefins, which could be associated with crude oil refining activities around Kunming. Vehicles and petrochemicals were the main sources in Kunming based on PMF calculations. Biomass burning (10.63%) and biogenic emission (8.68%) were noted in dry and rainy seasons, respectively. HYSPLIT analysis established that Kunming's air quality was significantly affected by the southwestward air mass transmission, particularly through a large industrial park. In the dry season, Kunming is significantly more affected by air mass transport from this direction than in the rainy season. The carcinogenic risk of benzene was high as 10 × 10−6 and 2.4 × 10−6 in the rainy and dry seasons, respectively. In conclusion, Kunming's VOCs control measures should pay more attention to the influence of the upwind industrial park.

Combining with volatilomic profiling and chemometrics to explore the volatile characteristics in five different dried Zanthoxylum bungeanum maxim

Owing to the short picking period of the fresh Zanthoxylum bungeanum, the postharvest drying has become an essential operation before the storage and transportation of Z. bungeanum. To explore the effects of drying methods on volatile characteristics, the volatilomic profiling of five different dried Z. bungeanum was investigated by E-nose, HS-SPME-GC/MS, GC-IMS in combination with chemometrics. The results indicated that W1W, W2W and W5S sensors within E-nose analysis showed the strongest responses in both fresh and dried Z. bungeanum. According to the identification of volatile organic compounds (VOCs), terpenes, esters and alcohols played the major roles in the volatile formation of the fresh and dried Z. bungeanum. The samples derived from hot air drying showed the relatively similar features with the fresh sample based on the relative abundances of these major VOCs. According to the results of multiple factor analysis (MFA), GC-IMS showed the strongest ability in distinguishing the fresh and different dried samples. Compared with the high levels of terpenes in fresh group, the significant increasement of terpene alcohols and terpene esters from the degradation and transformation of bound terpenoids was the main characteristics of all dried Z. bungeanum. Using the GC-IMS datasets, a weighted correlation network analysis (WCNA) model was constructed to clarify the VOC characteristics in all detetected samples. Thereinto, 6 significantly correlated modules were identified in fresh and five different dried samples. Additionally, a total of 23 hub VOCs can be recognized as the potential biomarkers for better distinguishing the fresh and five different dried Z. bungeanum.

Emission characteristics of VOCs emitted from household stove combustion in the north of China

The emissions of volatile organic compounds (VOCs) arising from household stove combustion of different fuels common in North China were quantified. Using a dilution tunnel sampling system and gas chromatography-mass spectrometry analysis, 107 different C2–C12 VOCs were identified in flue gases of four household solid fuels (coal briquette, honeycomb briquette, wood, and cornstalk), whose emission factors were 670 ± 550, 1322 ± 686, 1200 ± 1923, 8670 ± 8380 mg kg−1, respectively. Alkenes and alkynes contributed the most to the VOC emitted from the combustion of honeycomb briquettes (50.1%), wood (46.3%), and cornstalks (56.9%). N-Alkanes were the dominant VOC (43.9%) from coal briquette combustion. Ethane and ethene were the most abundant individual species found in the flue gas of coal briquettes, wood, and cornstalks, accounting for 60.4%, 59.8%, and 67.9% of the emissions, respectively. The VOC emitted from coal briquettes, honeycomb briquettes, wood, and cornstalks exhibited significantly different chemical reactivities. The OH reactivity of the VOCs from cornstalk combustion was 9–270 times greater than that of the other fuels. The differences in the atmospheric reactivity of emissions would suggest that cornstalk combustion should be prioritised in any strategy to reduce ozone pollution.

Study on the emission characteristics of VOCs under the condition of biomass blending combustion

In order to understand the emission characteristics of volatile organic compounds (VOCs) in the flue gas under the mixed combustion of biomass, the study on the emission characteristics of VOCs in the flue gas was carried out on a 58 MW circulating fluidized bed (CFB) unit. The results show that the co-firing of biomass can significantly reduce the emissions of VOCs and NOx and SO2. Changes in blended fuel particle size and combustion temperature reduce VOCs emissions. The most obvious change in the emission reduction of VOCs is reflected in the increase of the biomass mixing ratio from 20 % to 30 %. Biomass contains less S and N elements is the reason for the reduction of NOx and SO2 emissions. The emission of pollutants such as VOCs was the lowest when the biomass blending ratio was 40 %. Based on the actual operation of the power plant, 30 % is the optimal mixing ratio. The analysis showed that the amount of VOCs components had a strong positive correlation with the proportion of biomass in the fuel. The emission of VOCs under the condition of biomass blending has different characteristics from coal-fired boilers and biomass boilers. Under the two different mixing ratios, benzene series accounted for the largest proportion of VOCs emissions, reaching 44.38 % (20 %) and 33.75 % (40 %), respectively. The emission of benzene series is dominated by benzene and toluene, the emission of alkanes is dominated by n-hexane, and the emission of esters is dominated by ethyl acetate. The ozone formation potential (OFP) was analyzed by the maximum incremental reactivity method. The contribution of ozone generation potential at 20 % and 40 % mixing ratios was mainly from benzene series, which contributed 69.88 % and 70.24 %, respectively, and alkanes. contribution can also account for 25.76 % and 17.75 %.

Characterization, source apportionment, and risk assessment of ambient volatile organic compounds in urban and background regions of Hainan Island, China

The pollution characteristics of volatile organic compounds (VOCs) in urban and background regions in Hainan province, China, were determined based on field measurements of CO, NO, NO2, O3, VOCs, and meteorological parameters conducted at Haikou (HK, an urban site) and Wuzhishan (WZS, a background site) in 2019. The annual average concentration of VOCs at HK was 13.1 ppb, which was 2.2 times higher than that at WZS (6.0 ppb). VOC concentrations at HK were higher in winter, whereas there was no significant monthly variation at WZS. Diurnal variations in VOCs were characterized by two peaks at HK, attributable to emissions during morning and evening rush-hour traffic. At WZS, the diurnal variations of VOCs were characterized by one peak at 13:00–16:00, corresponding to the high temperature and intense sunlight in the afternoon. The total O3 formation potential of ambient VOCs was 135.1 g g−1 at HK and 80.6 g g−1 at WZS, with the O3 formation potential of alkenes accounting for 53.4% and 47.2%, respectively. The potential source region of VOCs at both sites was likely the southeastern ocean region of China (i.e., Guangdong, Guangxi, Hunan, and Jiangxi provinces) and Vietnam, Cambodia, and Thailand. Using on an empirical kinetic modeling approach, O3 formation at HK occurred under a mixed-limited region, and at WZS under a NOx-limited region. Traffic emissions were the largest contributor to VOCs at HK, accounting for 38.7%, followed by solvents (19.6%), combustion (15.2%), industrial sources (15.0%), and plant sources (11.5%). At WZS, traffic accounted for 39.6% of VOCs, similar to HK, whereas the contribution of industrial sources (22.1%) was higher. Although there are few vehicles and little industry around WZS, the long-distance transport of VOCs emitted elsewhere by these sources had a significant influence on the region's VOCs. The contribution of plant sources of VOCs was 1.5 times higher at WZS (17.0%) than at HK. None of the VOC species posed significant non-carcinogenic or carcinogenic risks at either HK or WZS.

Effects of different inhibitors on emission characteristics, environmental impact and health risk of volatile organic compounds from asphalt binder

Volatile organic compounds (VOCs) of asphalt will cause adverse environmental impact and workers’ health risk, inhibitors can be used to reduce the emission of VOCs from asphalt. Three inhibitors, including activated carbon (AC), expanded graphite (EG) and hydrotalcite (MA), were used to modified asphalt in this work. The effects of inhibitors on the VOCs emission characteristics of asphalt were investigated at multiple levels of VOCs total concentration, groups distribution and components characteristics. 101 asphalt VOCs components were detected, among which alkane accounted for more than 50% of the total concentration, followed by aldehyde and benzene. AC with the largest specific surface area and pore capacity exhibited the best inhibitory effect on the emission of VOCs with total concentration inhibition rate of 45.58%, followed by MA, while excessive MA would have adverse effect. Over 90% of VOCs components emissions had been suppressed by AC and EG. And inhibitors had the best inhibitory effect on the emission of olefin and aldehyde in VOCs, followed by ketone, but had the worst inhibitory effect on alkane, which was due to the weak interactions between non-polar alkane and polar hydroxyl on the surface of inhibitors. Furthermore, the effects of different inhibitors on the environmental impact and health risk of VOCs from asphalt were also systematically studied. The highest total inhibition rate of OFP and SOAP from asphalt VOCs by AC was only 58.3% and 21.7%, which was ascribed to the limited suppression on OFP and SOAP generated by alkane and benzene. Meanwhile, the non-carcinogenic risk from asphalt VOCs was mainly caused by acrolein with a contribution rate of 80.0%, AC and EG can completely inhibit the emission of acrolein in asphalt VOCs, while MA showed the poor performance. The contribution rate of acetaldehyde to the carcinogenic risk of asphalt VOCs reached 93.7%, while inhibitors had limited inhibitory effects on its emissions. This study contributes to a deeper understanding of the correlation mechanism between inhibitors, emission reduction characteristics of asphalt VOCs and environmental-health benefits, which could provide theoretical support for the design of bituminous material with low environmental-health load.

Evaluation of volatile organic compounds emissions and rheological properties of Buton rock asphalt modified asphalt

With the booming construction of asphalt pavements, the volatile organic compounds (VOCs) emission becomes a growing threat to the environment and people’s health. This paper aimed to investigate the impact of Buton rock asphalt (BRA) on VOCs emissions and the high-temperature rheological properties of modified asphalt. The investigation encompassed four different levels of BRA content, heating temperatures, and exposure durations, which were subjected to range analysis to ascertain the emission characteristics of BRA modified asphalt in terms of VOCs. Furthermore, the high-temperature rheological properties were assessed through dynamic shear rheometer (DSR) tests, and the correlation between asphalt VOCs characteristics and performance indicators was analyzed. The results showed that the emissions of VOCs increase significantly with rising temperatures and longer exposure to light. However, the incorporation of a 50% BRA modifier effectively reduced VOCs emissions by 8.84% while improving the high-temperature properties of asphalt. Additionally, a positive correlation was observed between the emission behavior of asphalt VOCs and the rheological properties of BRA modified asphalt. Overall, this study provides valuable insights into the environmental effect of BRA modified asphalt and it’s potential as a sustainable alternative to traditional asphalt materials.

Characteristics and Health Risk Assessment of Volatile Organic Compounds in Different Functional Zones in Baoji in Summer

The situation of air pollution in Guanzhong Plain has been increasing in recent years; hence, it is very important to study the characteristics of volatile organic compounds (VOCs) and their health risks in urban functional zones. We analyzed 115 VOCs using gas chromatography-mass spectrometry/hydrogen ion flame detector (GC-MS/FID) and high performance liquid chromatography (HPLC) at four sampling sites in the traffic, comprehensive, industrial, and scenic zones of Baoji. We analyzed the main components and key species in the different functional zones. Ozone formation potential (OFP),·OH consumption rate (L·OH), and secondary organic aerosol formation potential (SOAFP) were used to evaluate the environmental impact, and the hazard index (HI) and lifetime cancer risk (LCR) methods were employed. The results revealed that the mean values of φ(TVOCs) in the traffic, comprehensive, industrial, and scenic zones were (59.63±23.85)×10-9, (42.92±11.88)×10-9, (60.27±24.09)×10-9, and (55.54±7.44)×10-9, respectively. The dominant contributors at the traffic zone were alkanes, and those at the other functional zones were OVOCs. Acetaldehyde, acetone, n-butane, and isopentane were abundant at different functional zones. According to the characteristic ratios of VOCs, the average ratio of toluene to benzene (T/B) at the traffic, comprehensive, industrial, and scenic zones were 1.84, 2.39, 1.28, and 1.64, respectively, and the ratio of iso-pentane to n-pentane (i/n) was mainly between 1 and 4. The results indicated that VOCs in Baoji were significantly affected by vehicle emissions and gasoline evaporation, biomass and coal combustion, and industrial coatings and foundry. The ratio of m/p-xylene to ethylbenzene (X/E) was lower than 2 at the four functional zones, and the minimum was 1.79 at the scenic zones; the results revealed that X/E was small, and the aging degree of air masses was high, indicating the influence of regional transport. According to the ratio of formaldehyde to acetaldehyde (C1/C2) and the ratio of acetaldehyde to propanal (C2/C3), it was suggested that there may have been evident anthropogenic emission sources, and the photochemical reaction had an important effect on aldehydes and ketones. Environmental impact assessment results revealed that OVOCs and alkenes contributed significantly to OFP and OFP from large to small was as follows:industrial zone>scenic zone>traffic zone>comprehensive zone. The range of L·OH in each functional zone was 8.77-15.82 s-1, with isoprene contributing the most in the industrial zone and acetaldehyde contributing the most at other functional zones. The SOAFP of each functional zone was as follows:scenic zone>comprehensive zone>traffic zone>industrial zone. Toluene, m/p-xylene, and isoprene were the notable species. According to the health risk assessment of EPA, the HI of toxic VOCs in all functional zones was lower than 1, which was at an acceptable level. However, the number of days with HI>1 in industrial zones accounted for 42.86% of the total sampling days, indicating a high risk. The lifetime carcinogenic risk (LCR) of the traffic, comprehensive, industrial, and scenic zones were 1.83×10-5, 1.21×10-5, 1.85×10-5, and 1.63×10-5, respectively, which were all in grade Ⅲ of the rating system, indicating a high probability of cancer risk. Species with LCR greater than 10-6 were formaldehyde; acetaldehyde; 1,2-dibromoethane; 1,2-dichloroethane; 1,2-dichloropropane; and chloroform.