Concentrations Of Volatile Organic Compounds Research Articles

Fundamental insights and recent advances in catalytic oxidation processes using ozone for the control of volatile organic compounds.

The development of technologies for highly efficient treatment of emissions containing low concentrations of volatile organic compounds (VOCs) remains an important challenge. Catalytic oxidation with ozone (catalytic ozonation) is useful for the oxidative decomposition of VOCs, particularly aromatic compounds, under ambient temperature conditions. Only inexpensive transition metal oxides are required as catalysts, and Mn-based catalysts are widely used for catalytic ozonation. This review describes the oxidation reaction mechanisms, reaction pathways of aromatic hydrocarbons, and dependence of the catalytic ozonation activity on the reaction conditions. The reasons why Mn oxides are effective in catalytic ozonation are also explained. The structure of the catalytic active sites and the types of supporting materials contributing to the reaction are also discussed in detail, with the aim of establishing a VOC control technology. In addition, recent progress in catalytic oxidation processes using ozone as an oxidant has been outlined, focusing on catalyst materials and reaction conditions.

Characterization of VOCs emissions and associated health risks inherent to the packaging and printing industries in Shandong Province, China

Comprehensive volatile organic compounds (VOCs) emission control is imperative to decreasing occupational health risks and environmental impact of the packaging and printing industries. In this work, we investigated the VOCs emission characteristics and concentrations of individual contaminants generated by the packaging and printing industries, with regard to various categories, processes, and geographic regions. VOCs emissions, ozone formation potential (OFP), and associated health risks were assessed at 10 representative packaging and printing firms across several cities in Shandong Province, China. Plastic packaging enterprises had the greatest levels of unorganized VOCs emissions, consisting predominantly of oxygenated volatile organic compounds (OVOCs), followed by alkanes and halocarbons. From metal and paper packaging enterprises, OVOCs, alkanes, and aromatics were significant components of unorganized VOCs emissions. Aromatics, halocarbons, and OVOCs contributed significantly to OFP in workshops. The potential carcinogenic risk associated with VOCs in the packaging and printing industries was not significant. However, according to the findings in this study, the workshop environment may provide a comparatively elevated non-carcinogenic risk attributable to ethyl acetate, isopropanol, acrolein, 1,1,2-Trichloroethane, 1,2-Dichloropropane, and naphthalene exposure. In particular, the endocrine-disrupting and genetic toxic effects caused by benzene, toluene, styrene, and naphthalene should not be overlooked. Thus, it is essential to provide precedence to the working environment conditions of workshop laborers, while also undertaking scientific and systematic measures to mitigate the detrimental impacts of VOCs on the environment and human welfare.

Impact of a minimally processing route for the production of infant formulas on their sensory properties

Infant formulas (IFs), the sole adequate substitute to human milk, undergo several thermal treatments during production that can damage milk proteins and promote the formation of Maillard reaction products, modifying nutritional and sensory properties. The aim of this study was to determine the impact of a minimally processing route based on membrane filtration associated with different levels of heat treatment, on the odor, taste, texture and color attributes of IFs, then to compare with those of commercial milks. Three experimental IFs (produced with membrane filtration associated with low - T-, medium - T+, or high thermal treatments - T+++) were evaluated. Triangular tests conducted with a panel of 50 adults highlighted clear disparities between all the IFs. The same panel applied the Check-All-That-Apply method to evaluate the IFs: the range of variability between T- and T+++ was similar to that between the 2 commercial IFs, and the sensory characteristics of the experimental IFs were not far from the commercial brands for flavor and texture attributes. Analysis performed on the citation frequencies for each descriptor differentiated T-/T+ from T+++, but all the experimental IFs were described with positive sensory characteristics, unlike one commercial IF. Volatile organic compounds (VOCs) content of IFs with low and high thermal treatments were analyzed. Forty VOCs were identified by gas chromatography-mass spectrometry. T- contained a higher quantity of VOCs than T+++, except for benzaldehyde (Maillard reaction product), and aldehydes (oxidation-related products) were the most represented compounds. In conclusion, the processing was associated with sensory differences among IFs, but no marked difference in flavors was found according to CATA and physicochemical analysis. Additionally, no unpleasant sensory descriptors were noted. This shows that the minimally processed route leads to IFs that could fit well within the market from a sensory point of view.

An absorption model of volatile organic compound by plant leaf: The most influential site in the absorption pathway

Plant leaves absorb some kinds of volatile organic compounds (VOCs) and can contribute to air purification, as revealed by recent exposure experiments conducted at environmentally realistic concentrations in ppb (v/v). However, the mechanisms underlying VOC absorption by plants remain unclear. In this study, we applied Fick's first law of diffusion to a VOC absorption model for plant leaves to account for the VOC diffusion process via stomata, air-liquid partitioning, partitioning into the plasma membrane, and metabolic conversion of the VOC in plant cells. The resistance and concentration of VOCs at individual sites were determined using previously reported absorption data for aliphatic aldehydes and ketones in three plant species and the leaf morphology parameters obtained from leaf cross-section micrographs. The highest resistance occurred at the metabolic site (rmet), suggesting that VOC metabolic capacity is the most influential factor in VOC absorption. The resistance of stomata (rs) or plasma membrane (rpl) was the second highest, depending on compound family. Using the absorption rate data of Q. acutissima, it is revealed that metabolic site resistance rmet for methyl vinyl ketone is affected by light intensity. Thus, our VOC absorption model can determine the most influential site in the absorption pathway both for different VOCs and plant species. Our model can contribute to the development of plant-based strategies for controlling air pollution.

Seasonal and height dynamics of volatile organic compounds in rubber plantation: Impacts on ozone and secondary organic aerosol formation

Rubber trees emit a range of volatile organic compounds (VOCs), including isoprene, monoterpenes, and sesquiterpenes, as part of their natural metabolism. These VOCs can significantly influence air quality through photochemical reactions that produce ozone and secondary organic aerosols (SOAs). This study examines the impact of VOCs detected in a rubber tree plantation in Northeastern Thailand on air quality, highlighting their role in atmospheric reactions that lead to the formation of ozone and SOAs. VOCs were collected at varying heights and seasons using Tenax-TA tubes paired with an atmospheric sampler pump and identified by gas chromatography–mass spectrometry. In total, 100 VOCs were identified, including alkanes, alkenes, terpenes, aromatics, and oxygenated VOCs. Principal Coordinate Analysis (PCoA) revealed distinct seasonal VOC profiles, with hydrocarbons, peaking in summer and terpenes in the rainy season. The Linear Mixed-Effects (LME) model indicates that VOC concentrations are more influenced by seasonal changes than by sampling heights. Secondary organic aerosol potential (SOAP) and ozone formation potential (OFP) of selected VOC species were also determined. The total SOAP ranged from 67.24 μg/m3 in summer to 17.87 μg/m3 in winter, while the total OFP ranged from 377.87 μg/m3 in summer to 139.39 μg/m3 in winter. Additionally, positive matrix factorization (PMF) analysis identified four main VOC sources: gasoline combustion (18.3 %), microbial activity (38.6 %), monoterpene emissions during latex production (15.0 %), and industrial sources (28.1 %). These findings provide essential information for managing air pollution in rubber tree plantations. By adopting focused air quality management strategies, plantation operators can mitigate the adverse effects of VOCs, promoting a healthier and more sustainable future.

Exposure to volatile organic compounds in offices and in residential and educational buildings in the European Union between 2010 and 2023: A systematic review and health risk assessment

Chronic exposure to indoor volatile organic compounds (VOCs) can result in several adverse effects including cancers. We review reports of levels of VOCs in offices and in residential and educational buildings in the member states of the European Union (EU) published between 2010 and 2023. We use these data to assess the risk to population health by estimating lifetime exposure to indoor VOCs and resulting non-cancer and cancer risks and, from that, the burden of cancer attributable to VOC exposure and associated economic losses. Our systematic review identified 1783 articles, of which 184 were examined in detail, with 58 yielding relevant data. After combining data on VOC concentrations separately for EU countries and building types, non-cancer and cancer risks were assessed in terms of hazard quotient and lifetime excess cancer risk (LECR) using probabilistic Monte Carlo Simulations. The LECR was used to estimate disability adjusted life years (DALYs) from VOC-related cancers and associated costs. We find that the LECR associated with formaldehyde exposure was above the acceptable risk level (ARL) in France and Germany and that of from exposure to benzene was also above the ARL in Spanish females. The sum of DALYs and related costs/1,000,000 population/year from exposure to acetaldehyde, benzene, formaldehyde, tetrachloroethylene, and trichloroethylene were 4.02 and €41,010, respectively, in France, those from exposure to acetaldehyde, benzene, carbon tetrachloride, formaldehyde, and trichloroethylene were 3.91 and €39,590 in Germany, and those from exposure to benzene were 0.1 and €1030 in Spain. Taken as a whole, these findings show that indoor exposure to VOCs remains a public health concern in the EU. Although the EU has set limits for certain VOCs, further measures are needed to restrict the use of these chemicals in consumer products.

Are there any differences in the quality of high-mountain green tea before and after the first new leaves unfold? A comprehensive study based on E-sensors, whole metabolomics and sensory evaluation

High-mountain green tea, where the first new leaf hasn't yet unfurled, is prized for perceived superior quality, but this hasn't yet been verified by experimentation. Electronic sensors, whole metabolomics and sensory evaluation were employed to assess the quality of yymj (tea buds with a newly unfurled leaf) and qymj (tea buds without new leaves). The qymj proved to have significant advantages in aroma, color and shape, but still had some shortcomings in umami, bitterness and sourness. Differences in the content of volatile organic compounds (including alcohols, hydrocarbons and lipids) and nonvolatile organic compounds (flavonoids, amino acids, sugars, and phenolic acids) quality of high-mountain green teas with different maturity levels and provides well explained these quality differences. This study establishes a systematic approach to study the quality of high-mountain green tea at different maturity levels, and provides important reference information for consumers, governments and tea farmers.

Evaluating DIY air cleaner variability and potential for post-construction emission of aromatic VOCs during wildfire events

While do-it-yourself (DIY) air cleaners such as the Corsi-Rosenthal Box (CR Box) are an increasingly popular choice for low-cost, accessible air cleaning during a wildfire event, construction and performance variability remains a concern. Using the same set of instructions, materials, and location of assembly, seven CR Boxes are constructed by individuals with no prior DIY air cleaner experience and clean air delivery rates (CADRs) are experimentally determined for each of the devices. Against a challenge aerosol consisting of fresh smoke generated via pine needle combustion, average number-based, PM2.5 CR Box CADRs range from 313–396 m3/h (relative standard deviation = 7.6 %). Over this modest range of observed variability, constructed units outperform many higher-cost commercial air cleaners. A review of the literature demonstrates that across studies, substantial CADR variability is observed (285–1448 m3/h); differences in materials (including filter type) used during air cleaner construction, challenge aerosols tested, and evaluation protocol are major contributors to variability. To evaluate the potential for exposure to aromatic volatile organic compounds (VOCs) from CR Box materials, we place three devices in a large chamber for 24–72 hours immediately following construction. Toluene and C8 aromatics (ethylbenzene and xylenes) are emitted at 2289 and 89 μg/h, respectively, with emission rates decreasing by 94 % and 82 % after 12 hours. Using experimentally determined PM2.5 CADRs and VOC emission rates, a hypothetical wildfire event impacting the bedroom of a home is modeled at four outdoor air exchange rates (AERs) to assess tradeoffs between building airtightness, particle removal effectiveness, and VOC off-gassing from a newly built CR Box. PM2.5 effectiveness ranges from 0.88 to 0.95, depending on AER (0.1–1 h−1). While modeled maximum VOC concentrations remain orders of magnitude below short-term permissible exposure limits at all AERs considered, modeled and observed VOC dynamics imply that an off-gassing period of ∼6–12 hours would avoid episodic emission of VOCs at rates that may cause accumulation in excess of the lower-limit of toluene odor threshold estimates.

Sources of organic gases and aerosol particles and their roles in nighttime particle growth at a rural forested site in southwest Germany

Abstract. The composition, sources and chemical transformation of volatile organic compounds (VOCs) and organic aerosol (OA) particles were investigated during July–August 2021 at a rural forested site in southwest Germany, 10 km north of the city of Karlsruhe. VOCs and semi-volatile OA particles were measured with a proton-transfer-reaction mass spectrometer coupled to the CHemical Analysis of aeRosols ONline particle inlet (CHARON–PTR-MS). The CHARON-measured OA mass accounted for 62 ± 18 % on average of the total OA mass (4.2 ± 2.8 µg m−3) measured concurrently with an aerosol mass spectrometer (AMS). The total concentrations of measured VOCs ranged from 7.6 to 88.9 ppb with an average of 31.2 ± 13.4 ppb. Positive matrix factorization (PMF) was used to identify major source factors of VOCs and OA particles. Three types of oxygenated VOC (OVOC), namely aromatic OVOCs, biogenic OVOCs and aged OVOCs, contributed on average 11 % ± 9 %, 37 % ± 29 % and 29 % ± 21 % of total VOC concentrations, respectively. The results of AMS–PMF indicated substantial contributions of oxygenated organic compounds to OA particle mass. Three secondary OA (SOA) factors determined by CHARON–PMF analysis, namely aromatic SOA (5 % ± 7 %), daytime biogenic SOA (17 % ± 17 %) and nighttime biogenic SOA (28 % ± 21 %), consistently showed high contributions to the total CHARON-measured OA mass. Nighttime particle growth was observed regularly in this area, which was mainly attributed to the semi-volatile organic compounds and organic nitrates formed from the oxidation of monoterpenes and sesquiterpenes. This study presents the major sources, real-time transformations of VOCs and OA particles, and nighttime particle formation characteristics for central European forested areas.

Fermentation Performance Evaluation of Lactic Acid Bacteria Strains for Sichuan Radish Paocai Production.

Fermented vegetable products play a significant role in various cuisines, and understanding the fermentation dynamics of lactic acid bacteria (LAB) strains is essential for optimizing their production and quality. Here, we sought to investigate the fermentation performance of five LAB strains isolated from Sichuan paocai as starters for paocai. Sensory evaluation revealed that the inoculation of radish paocai samples with LAB strains effectively improved the overall liking and sensory satisfaction of participants, increasing the scores to varying degrees in terms of taste, flavor, texture, and coloration. Lactiplantibacillus plantarum and Lacticaseibacillus rhamnosus exhibited a good salt resistance in radish juice and could grow in a medium containing 10% NaCl. Four indicator strains commonly found in contaminated paocai were effectively inhibited by fermented LAB broths, which improved the edibility and safe production of paocai. Compared to spontaneous fermentation (CK), radish paocai inoculated with LAB showed a significantly accelerated acid production rate, shortening the fermentation period by approximately two days. The contents of titratable total acids, organic acids, and free amino acids were higher in the inoculated samples and were enriched in the taste of radish paocai. The content of volatile organic compounds in the inoculated samples was higher than that in CK. Based on OPLS-DA analysis, 31 key indicators of paocai quality were screened and used to rank the fermentation performances of the five strains using the TOPSIS method; here, Lpb. plantarum and Lcb. rhamnosus achieved the highest scores. This study provides a reference for selecting LAB strains as efficient and secure fermentation starters to optimize paocai quality.

A study of neurological functions in construction work painters

BackgroundPainters are constantly exposed to organic solvents containing volatile organic compounds (VOCs), a primary source of indoor air pollution. Prolonged exposure to solvents generates significant health repercussions on pulmonary and neurological functioning. Few studies have assessed the neurological function of unorganized sector painters objectively, especially in developing nations. The current research evaluates the effects of organic solvents on neurological functions in painters working in unorganized sectors like construction sites in Chennai. MethodsA validated questionnaire was used to assess solvent-exposed neurological symptoms in full-time painters (n = 75) aged 25–55, stratified by years of exposure (≤10 years, >10 years). A subset of 35 painters underwent bilateral median nerve motor and sensory nerve conduction studies. Personal exposure monitors measured VOC concentration during the painting processes. ResultsToluene and benzene concentrations were greater in paint scraping. 47% of painters reported neurological symptoms, and those with >10 years of experience had a higher AOR (95%CI): 3.4 (1.3, 9.6). 13% had diplopia, 18% had ocular discomfort. Painters with more than 10 years of experience had longer motor and sensory onset latency of the left median nerve, as well as decreased bilateral sensory conduction velocities (Right median nerve: 53.8 ± 13.9 vs 64.2 ± 5.2; Left median nerve: 55.75 ± 6.5 vs 64.3 ± 6.2). ConclusionPaint emits toluene, a major solvent. The impact of occupational exposure to organic solvents on neurological functions has been observed to exhibit a progressive deterioration over time. Health awareness and strict protective measure legislation are needed to reduce morbidity and mortality in these unorganized sectors.

Anthropogenic-driven changes in concentrations and sources of winter volatile organic compounds in an urban environment in the Yangtze River Delta of China between 2013 and 2021

Volatile organic compounds (VOCs) serve as crucial precursors to surface ozone and secondary organic aerosols (SOA). In response to severe air pollution challenges, China has implemented key air quality control policies from 2013 to 2021. Despite these efforts, a comprehensive understanding of the chemical composition and sources of urban atmospheric VOCs and their responses to emission reduction measures remains limited. Our study focuses on analyzing VOCs composition and concentrations during the winters of 2013 and 2021 through online field observations in urban Nanjing, a typical city in the Yangtze River Delta region of China. Using a machine learning approach, we found a notable reduction in total VOCs concentration from 52.4 ± 30.4 ppb to 33.9 ± 21.6 ppb between the two years, with dominant contributions (approximately 94.3 %) associated with anthropogenic emission control. Furthermore, alkanes emerged as the major contributors (48.6 %) to such anthropogenic-driven decline. The total SOA formation potential decreased by approximately 27.4 %, with aromatics identified as the major contributing species. Positive matrix factorization analysis identified six sources. In 2013, prominent contributors were solid fuel combustion (43.6 %), vehicle emission (16.7 %), and paint and solvent use (12.8 %). By 2021, major sources shifted to solid fuel combustion (31.9 %), liquefied petroleum gas and natural gas (26.8 %), and vehicle emission (25.5 %). Solid fuel combustion emerged as the primary driver for total VOCs reduction. The lifetime carcinogenic risk in 2021 decreased by 72.6 % relative to 2013, emphasizing the need to address liquefied petroleum gas and natural gas source, and vehicle emissions for improved human health. Our findings contribute critical insights for policymakers working on effective air quality management.

Numerical prediction model for long- and short-term concentration of indoor volatile organic compounds from building materials

ABSTRACT Emission models of volatile organic compounds (VOCs) from individual indoor building materials have been developed and validated. However, multiple indoor building materials release VOCs simultaneously, and neither single building material nor multiple building material emission models can predict the entire release cycle of VOCs accurately. This study established a long- and short-term numerical prediction model for indoor VOC concentration. The model includes an attenuation coefficient θ. To describe the decay rate of the total VOC content, which is mainly influenced by time, and by designing experiments and testing in environmental warehouses under different seasonal conditions, the value of θ was first obtained. Then, after successfully plotting the emission curve of indoor pollutant concentration over time through numerical solution and using θ, the VOC content was corrected for various seasonal conditions. On the basis of this model, an exposure dose integration algorithm was proposed to evaluate the environmental health risks, as an application of this model. In comparison with previous research results and experimental data, this model has better predictive performance.

Stable Cd(II)-based coordination polymer as a multifunctional fluorescent sensor for ascorbic acid, acetylacetone and nitrofuran antibiotics

The concentrations of hazardous volatile organic compounds (VOCs), pharmaceutical antibiotics and biomolecules in water systems are closely related with public health and ecological security. Thus, the convenient and accurate detection of these harmful items can not only reflect the state of human health but also evaluate the level of homologous contamination in the environment. To this end, a new Cd(II)-CP ({[Cd3L2(bmoe)]·DMF}n) with excellent luminescence properties was designed by employing the semi-rigid tricarboxylic acid 4-(2′,3′-dicarboxylphenoxy) (H3L) and N-donor ligand 1,1′-bis(1H-benzimidazolyl) oxydiethane (bmoe). The as-prepared Cd-CP features the unique uninodal sql topology. Benefiting from its great stability in the aqueous system, Cd-CP serves as a versatile multifunctional fluorescent sensor for different analytes, ascorbic acid (AA), nitrofuran antibiotics nitrofurantoin (NFT) and nitrofurazone (NFZ) and acetylacetone (ACAC). The established methods are characterized with impressive low detection limits, ultrafast response time, high sensitivity, strong anti-interference ability, as well as reliable reproducibility. Experimental and theoretical calculation reveals that the collaborative effects of Förster resonance energy transfer (FRET), inner-filter effect (IFE) and photoinduced electron transfer (PET) are the most probable causes behind the quenching of the CP's fluorescence signal.

Field and intervention study on indoor environment in professional classrooms

To study the variation of environment in the professional classroom during lecture hours, multiple field experiments and intervention experiments on indoor and outdoor temperatures were conducted in a university professional classroom in Shaoxing during the spring. Environmental data, including indoor and outdoor temperatures, relative, and CO2 concentrations, were recorded every 5 min. Volatile organic compounds (VOC) were sampled, and indoor air quality was evaluated repeatedly. Results showed that the classroom’s average indoor air temperature ranged from 17.8–29.2 ℃, the average indoor relative humidity from 34.5%–91.0%, the average CO2 concentrations from 921.6–1805.2 ppmv, and total VOC concentrations from 330–682 ppbm. The subjective evaluation conducted during the intervention experiments indicated a significant increase in perceived odor intensity upon entering the classroom. When the CO2 concentration reached 2000 ppmv, the satisfaction and acceptability of the air quality for the subjects and invitees decreased significantly. In the temperature range of 17–31 ℃, the CO2 emission rate of human body was estimated to increase by 0.78 L/h for every 1 ℃ increase in temperature. To maintain the indoor CO2 concentration at 1000 ppmv, the required ventilation rate for each person must be increased by 0.25 ± 0.3 L/s.

An Assessment of the Contribution of Vehicular Traffic to Ambient Air Quality - A Case Study of Nairobi Expressway Corridor

Abstract In this study, the vehicular air pollution from the Nairobi Expressway corridor was estimated by simulation using AERMOD dispersion model. The Vehicle Kilometer Travelled (VKT), emission factors, and traffic data were used to estimate the pollutants from vehicular traffic.. The highest modelled 24-hour and annual concentrations of PM2.5 were 0.274 µg/m3 and 0.152 µg/m3, whereas the highest 24-hour and annual concentrations of PM10 were 0.405 µg/m3 and 0.225 µg/m3, respectively. The maximum 24-hour and annual concentrations of Total Volatile Organic Compounds (TVOCs) were 20.8 µg/m3 and 11.5 µg/m3, respectively, whereas the maximum 8-hour and annual concentrations of carbon monoxide (CO) were 319 µg/m3 and 177 µg/m3, respectively. The highest modeled 24-hour and annual concentrations of NO2 were 28.2 µg/m3 and 15.7 µg/m3, respectively. The 24-hour average measured TVOCs values showed that Nairobi expressway traffic contributed 3.5 percent to the measured TVOCs concentration value, but CO accounted for 55 percent of the measured value. According to the simulated PM2.5 and PM10 concentration values, Nairobi expressway traffic contributed 1.1 and 1.6 percent, respectively, to the 24-hour average measured concentration levels.

Sensing volatile organic compounds with CVD graphene: insights from quartz crystal microbalance and surface plasmon resonance studies

This study explores the sensing capabilities of chemical vapor deposition (CVD)-grown graphene in detecting volatile organic compounds (VOCs) through quartz crystal microbalance (QCM) and surface plasmon resonance (SPR) techniques. Two distinct sensing devices were developed, each tailored for QCM and SPR transducing mechanisms, utilizing CVD graphene as the sensing element. The sensors demonstrated consistent and reproducible responses when exposed to various concentrations of dichloromethane, chloroform, carbon tetrachloride, benzene, toluene, and m-xylene. Notably, both sensors exhibited unparalleled sensitivity to dichloromethane, with the graphene-coated SPR sensor displaying a sensitivity value of 294 × 10−3 ppm−1 and a limit of detection (LOD) value of 10.62 ppm. Additionally, the SPR sensor showcased remarkably swift response and recovery times, both under 3 sec. Results indicate that the adsorption of VOC molecules on the CVD graphene surface increases with the rising dipole moments and vapor pressure values of the molecules. The utilization of CVD graphene in both sensing approaches demonstrates good reproducibility in detecting ultralow concentrations of VOCs at room temperature.

Significant contributions of the petroleum industry to volatile organic compounds and ozone pollution: Insights from year-long observations in the Yellow River Delta

The petroleum industry is a significant source of anthropogenic volatile organic compounds (VOCs), but up to now, its exact impact on urban VOCs and ozone (O3) remains unclear. This study conducted year-long VOC observations in Dongying, China, a petroleum industrial region. The VOCs from the petroleum industry (oil and gas volatilization and petrochemical production) were identified by employing the positive matrix factorization model, and their contribution to O3 formation was quantitatively evaluated using an observation-based chemical box model. The observed annual average concentration of VOCs was 68.6 ± 63.5 ppbv, with a maximum daily average of 335.3 ppbv. The petroleum industry accounted for 66.5% of total VOCs, contributing 54.9% from oil and gas evaporation and 11.6% from petrochemical production. Model results indicated that VOCs from the petroleum industry contributed to 31% of net O3 production, with 21.3% and 34.2% contributions to HO2+NO and RO2+NO pathways, respectively. The larger impact on the RO2 pathway is primarily due to the fact that OH+VOCs account for 86.9% of the primary source of RO2. This study highlights the critical role of controlling VOCs from the petroleum industry in urban O3 pollution, especially those from previously overlooked low-reactivity alkanes.

Characterization of the volatile organic compounds and sensory properties of fermented soymilks as affected by carbohydrates and starter cultures

Soymilks were fermented by two starter cultures and with different levels of added glucose or lactose respectively. GC-MS, HS-GC-IMS and GC × GC-TOFMS were compared and the latter reported much more volatile organic compounds (VOCs). The VOCs profiles of the fermented soymilks were divided into four groups using principal component analysis and hierarchical clustering analysis. Based on the variable importance in the projection value greater than 1.0 and one way ANOVA (P < 0.05), 22 VOCs were respectively identified as the critical differential VOCs in starter culture A and B fermented soymilk, and the concentrations of the critical differential VOCs changed in different patterns in response to the addition of carbohydrates. Four significant metabolic pathways were involved via the metabolite set enrichment analysis, including the glycolysis/gluconeogenesis, pyruvate metabolism. Among critical differential VOCs, there were 11 and 13 aroma-active compounds with odor activity values greater than 1.0, for starter culture A and B fermented soymilks respectively. The deductive sensory properties of the fermented soymilks as affected by carbohydrate addition were evaluated. This study provides experimental and theoretical bases for improving flavor quality of fermented soymilks.

Sansevieria trifasciata's specific metabolite improves tolerance and efficiency for particulate matter and volatile organic compound removal

Phytoremediation has become famous for removing particulate matter (PM) and volatile organic compounds (VOCs), but the ability is affected by plant health. Lately, the priming technique was a simple approach to studying improving plant tolerance against abiotic stress by specific metabolites that accumulated, known as “memory”, but the mechanism underlying this mechanism and how long this “memory” was retained in the plant was a lack of study. Sansevieria trifasciata was primed for one week for PM and VOC stress to improve plant efficiency on PM and VOC. After that, the plant was recovered for two- or five-weeks, then re-exposed to the same stress with similar PM and VOC concentrations from cigarette smoke. Primed S. trifasciata showed improved removal of PMs entirely within 2 h and VOC within 24 h. The primed plant can maintain a malondialdehyde (MDA) level and retain the “memory” for two weeks. Metabolomics analysis showed that an ornithine-related compound was accumulated as a responsive metabolite under exposure to PM and VOC stress. Exogenous ornithine can maintain plant efficiency and prevent stress by increasing proline and antioxidant enzymes. This study is the first to demonstrate plant “memory” mechanisms under PM and VOC stress.