Abundant Volatile Organic Compounds Research Articles

Methylotrophic bacteria from rice paddy soils: mineral-nitrogen-utilizing isolates richness in bulk soil and rhizosphere.

Methanol, the second most abundant volatile organic compound, primarily released from plants, is a major culprit disturbing atmospheric chemistry. Interestingly, ubiquitously found methanol-utilizing bacteria, play a vital role in mitigating atmospheric methanol effects. Despite being extensively characterized, the effect of nitrogen sources on the richness of methanol-utilizers in the bulk soil and rhizosphere is largely unknown. Therefore, the current study was planned to isolate, characterize and explore the richness of cultivable methylotrophs from the bulk soil and rhizosphere of a paddy field using media with varying nitrogen sources. Our data revealed that more genera of methylotrophs, including Methylobacterium, Ancylobacter, Achromobacter, Xanthobacter, Moraxella, and Klebsiella were enriched with the nitrate-based medium compared to only two genera, Hyphomicrobium and Methylobacterium, enriched with the ammonium-based medium. The richness of methylotrophic bacteria also differed substantially in the bulk soil as compared to the rhizosphere. Growth characterization revealed that majority of the newly isolated methanol-utilizing strains in this study exhibited better growth at 37°C instead of 30 or 45°C. Moreover, Hyphomicrobium sp. FSA2 was the only strain capable of utilizing methanol even at elevated temperature 45°C, showing its adaptability to a wide range of temperatures. Differential carbon substrate utilization profiling revealed the facultative nature of all isolated methanol-utilizer strains with Xanthobacter sp. TS3, being an important methanol-utilizer capable of degrading toxic compounds such as acetone and ethylene glycol. Overall, our study suggests the role of nutrients and plant-microbial interaction in shaping the composition of methanol-utilizers in terrestrial environment.

Assessing acetone for the GISS ModelE2.1 Earth system model

Abstract. Acetone is an abundant volatile organic compound (VOC) in the atmosphere, with important influences on ozone and oxidation capacity. Direct sources include chemical production from other VOCs and anthropogenic emissions, terrestrial vegetation, biomass-burning emissions, and ocean production. Sinks include chemical loss, deposition onto the land surface, and ocean uptake. Acetone also has a lifetime that is long enough to allow transport and reactions with other compounds remote from its sources. The NASA Goddard Institute for Space Studies (GISS) Earth system model ModelE2.1 simulates a variety of Earth system interactions. Previously, acetone had a very simplistic representation in the ModelE chemical scheme. This study assesses a more sophisticated acetone scheme in which acetone is a full 3-dimensional tracer with explicit sources, sinks, and atmospheric transport. We first evaluate the new global acetone budget in the context of past literature. Estimated source and sink fluxes fall within the range of previous models, although total atmospheric burden and lifetime are at the lower end of the published literature. Acetone's new representation in ModelE2.1 also results in more realistic spatial and vertical distributions, which we compare against previous models and field observations. The seasonality of acetone-related processes was also studied in conjunction with field measurements, and these comparisons show promising agreement but also shortcomings at high-emission urban locations, where the model's resolution is too coarse to capture the true behavior. Finally, we conduct a variety of sensitivity studies that explore the influence of key parameters on the acetone budget and its global distribution. An impactful finding is that the production of acetone from precursor hydrocarbon oxidation has strong leverage on the overall chemical source, indicating the importance of accurate molar yields. Overall, our implementation is one that corroborates with previous studies and marks a significant improvement in the development of the acetone tracer in GISS ModelE2.1.

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

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

Investigation on the source of VOCs emission from indoor construction materials using electronic sensors and TD-GC-MS

Indoor air quality (IAQ) is critical to the health and wellbeing of people. As the majority of people spend greater amounts of time indoors, either in office spaces or households, the level of air pollutants in such environments is critical. Building materials and furniture are known sources of air pollutants such as Volatile Organic Compounds (VOCs) and may be associated with discomfort, detrimental health of the occupants, etc. In this study, the VOCs found in a brand new office complex were monitored over a period of 6 months, with an emphasis on monitoring and quantifying harmful VOCs and identifying their emission source. Air samples were taken from a closed, unoccupied office space on a weekly basis and analysed using Thermal Desorption-Gas Chromatography-Mass Spectrometry (TD-GC-MS), while continuous monitoring of the air quality was performed using two commercially available IAQ sensors. To identify the source of the emitted VOCs, pieces of all construction material that were used in the office, including flooring, finished wall material, and adhesive glues, were removed, and placed in air-tight glass containers prior to analysis confirming that the source of VOCs is indeed the flooring. Identified compounds included mainly material origin VOCs such as BTEX (benzene, toluene, ethylbenzene, xylene) and styrene, but also common VOCs such as acetone and propan-2-ol. Of significant importance was the concentration of toluene that was found to be the most abundant VOC in both the flooring material and the indoor air.

Traceability tagging of volatile organic compound sources and their contributions to ozone formation in Suzhou using vehicle-based portable single-photon ionization mass spectrometry

BackgroundIn recent decades, there has been an increasing global preoccupation with atmospheric volatile organic compounds (VOCs). Given the significant impact of VOCs as pollutants and essential precursors of ozone (O3) in urban and industrial areas, it is imperative to identify and quantify the sources of their emissions to facilitate the development and implementation of effective environmental control strategies.MethodsA mobile laboratory vehicle equipped with a single-photon ionization–time-of-flight mass spectrometer (SPI–TOFMS) and a navigation system was employed to establish the traceability of VOCs that contribute to the formation of ozone in Suzhou Industrial Park. The method exhibited a favorable detection limit of 0.090 ppbv, accompanied by a mass resolution of 1500 for the instrument and a correlation coefficient ≥ 0.990. A positive matrix factorization (PMF) model was utilized to determine the source appointment of the VOCs.ResultsThe study tentatively traced and identified the VOCs emissions source and their contribution to ozone formation in Suzhou. Using the PMF model, the sources of VOCs were profiled: three primary sources of VOCs were identified, namely, vehicular emissions, an industrial solvent, and biofuel combustion. Alkanes groups were found to be the most abundant VOCs species, accounting for 60% of the total VOCs, followed by aromatics and alkenes. Maximum incremental reactivity (MIR) quantifies the impact of photochemical reaction mechanism on the potential ozone formation.ConclusionsThe findings of this study complement existing knowledge on the pollution status of atmospheric VOCs and highlight the correlation with ozone formation potential in Suzhou. The aforementioned sources were identified as the primary factors responsible for the pollution in Suzhou. The successful implementation of SPI–TOFMS has demonstrated a promising methodology that is well-suited for the real-time and online monitoring of VOCs in the atmosphere. In addition, a library for identifying VOC fingerprints from the same plant was established. This library serves as a comprehensive resource for establishing on-site VOC traceability, estimating source apportionment, and evaluating their impact on ozone formation.

Integrated transcriptomics and metabolomics analysis provides insights into aromatic volatiles formation in Cinnamomum cassia bark at different harvesting times.

Cinnamomum cassia Presl, classified in the Lauraceae family, is widely used as a spice, but also in medicine, cosmetics, and food. Aroma is an important factor affecting the medicinal and flavoring properties of C. cassia, and is mainly determined by volatile organic compounds (VOCs); however, little is known about the composition of aromatic VOCs in C. cassia and their potential molecular regulatory mechanisms. Here, integrated transcriptomic and volatile metabolomic analyses were employed to provide insights into the formation regularity of aromatic VOCs in C. cassia bark at five different harvesting times. The bark thickness and volatile oil content were significantly increased along with the development of the bark. A total of 724 differentially accumulated volatiles (DAVs) were identified in the bark samples, most of which were terpenoids. Venn analysis of the top 100 VOCs in each period showed that twenty-eight aromatic VOCs were significantly accumulated in different harvesting times. The most abundant VOC, cinnamaldehyde, peaked at 120 months after planting (MAP) and dominated the aroma qualities. Five terpenoids, α-copaene, β-bourbonene, α-cubebene, α-funebrene, and δ-cadinene, that peaked at 240 MAP could also be important in creating C. cassia's characteristic aroma. A list of 43,412 differentially expressed genes (DEGs) involved in the biosynthetic pathways of aromatic VOCs were identified, including phenylpropanoids, mevalonic acid (MVA) and methylerythritol phosphate (MEP). A gene-metabolite regulatory network for terpenoid and phenylpropanoid metabolism was constructed to show the key candidate structural genes and transcription factors involved in the biosynthesis of terpenoids and phenylpropanoids. The results of our research revealed the composition and changes of aromatic VOCs in C. cassia bark at different harvesting stages, differentiated the characteristic aroma components of cinnamon, and illuminated the molecular mechanism of aroma formation. These foundational results will provide technical guidance for the quality breeding of C. cassia.

The microbial and metabolite composition of Gouda cheese made from pasteurized milk is determined by the processing chain

Gouda cheeses of different production batches and ripening times often differ in metabolite composition, which may be due to the starter culture mixture applied or the growth of non-starter lactic acid bacteria (NSLAB) upon maturation. Therefore, a single Gouda cheese production batch was systematically investigated from the thermized milk to the mature cheeses, ripened for up to 100 weeks, to identify the main bacterial species and metabolites and their dynamics during the whole production and ripening. As this seemed to be starter culture strain- and NSLAB-dependent, it requested a detailed, longitudinal, and quantitative investigation. Hereto, microbial colony enumeration, high-throughput full-length 16S rRNA gene sequencing, and a metabolomic approach were combined. Culture-dependently, Lactococcus lactis was the most abundant species from its addition as part of the starter culture up to the first two months of cheese ripening. Afterward, the NSLAB Lacticaseibacillus paracasei became the main species during ripening. The milk was a possible inoculation source for the latter species, despite pasteurization. Culture-independently, the starter LAB Lactococcus cremoris and Lc. lactis were the most abundant species in the cheese core throughout the whole fermentation and ripening phases up to 100 weeks. The cheese rind from 40 until 100 weeks of ripening was characterized by a high relative abundance of the NSLAB Tetragenococcus halophilus and Loigolactobacillus rennini, which both came from the brine. These species were linked with the production of the biogenic amines cadaverine and putrescine. The most abundant volatile organic compound was acetoin, an indicator of citrate and lactose fermentation during the production day, whereas the concentrations of free amino acids were an indicator of the ripening time.

Evaluation of urinary limonene metabolites as biomarkers of exposure to greenness

Exposure to plants is known to improve physical and mental health and living in areas of high vegetation is associated with better health. The addition of quantitative measures of greenness exposure at individual-level to other objective and subjective study measures will help establish cause-and-effect relationships between greenspaces and human health. Because limonene is one of the most abundant biogenic volatile organic compounds emitted by plants, we hypothesized that urinary metabolites of inhaled limonene can serve as biomarkers of exposure to greenness. To test our hypothesis, we analyzed urine samples collected from eight human volunteers after limonene inhalation or after greenness exposure using liquid chromatography-high resolution mass spectrometry-based profiling. Eighteen isomers of nine metabolites were detected in urine after limonene inhalation, and their kinetic parameters were estimated using nonlinear mixed effect models. Urinary levels of most abundant limonene metabolites were elevated after brief exposure to a forested area, and the ratio of urinary limonene metabolites provided evidence of recent exposure. The identities and structures of these metabolites were validated using stable isotope tracing and tandem mass spectral comparison. Together, these data suggest that urinary metabolites of limonene, especially uroterpenol glucuronide and dihydroperillic acid glucuronide, could be used as individualized biomarkers of greenness exposure.

Compositional Characteristics, Fatty Acid Profile, Phenolic Content and Volatile Organic Compounds (VOCs) of Feta Cheese Made in Mountainous Grasslands and Plains of Greece

The study aimed to compare the physicochemical composition, fatty acid profile, phenolic content and volatile organic compounds (VOCs) of feta cheese produced in two regions in Greece (mountainous grasslands and plains). The VOC profiles of forage in the mountainous grasslands were also investigated in order to detect any relationship between the two profiles. Forbs were found to be the major functional group in the mountainous area and the most abundant VOCs were aldehydes, alcohols, and terpenes. Significant variations were observed between the main compositional features of the two types of cheeses, with the cheese produced from the milk of ewes and goats grazing in the mountainous region having a higher moisture content, lower fat content, and higher protein content. A total of 34 VOCs were identified and the most abundant groups in the cheese samples were esters, hydrocarbons, and alcohols. The fatty acid profile, phenolic content, and terpene profile of the cheese were also affected by the type of pasture. The cheese produced from the milk of ewes and goats grazing in the mountainous region also had a higher content of conjugated linoleic acid (CLA) and a lower content of saturated fatty acids (SFAs). These findings suggest that the grasslands grazed by ewes and goats in the mountainous region have a positive impact on the nutritional quality of feta cheese.

Selenium speciation and volatile flavor compound profiles in the edible flowers, stems, and leaves of selenium-hyperaccumulating vegetable Cardamine violifolia.

Cardamine violifolia is a unique selenium (Se)-hyperaccumulating vegetable in China. The total Se content and Se speciation of three edible parts, including flowers, stems, and leaves were detected by HPLC-ICP-MS. Volatile organic compounds (VOCs) greatly impact food flavor. The VOCs of three samples were analyzed by E-nose, HS-GC-IMS, and HS-SPME-GC-MS. The results showed that the total Se content in flowers was significantly higher than that in leaves and was the lowest in stems. Organic Se accounts for more than 98% of the total Se content, primarily selenocystine, followed by methyl selenocysteine. A total of 102 VOCs were identified from C. violifolia, mainly esters, aldehydes, alcohols, and ketones. Flowers contained abundant VOCs, while stems and leaves contained fewer but similar profiles. Moreover, multivariate statistical analysis was applied to investigate the VOC variations and marker VOCs. This work can provide useful knowledge for understanding the Se characteristics and flavor of C. violifolia.

Anaerobic Isoprene-Degrading Microorganisms and their Impact on Microbial Methane Dynamics in Deep-Sea Carbonates and Eucalyptus-Leaf Sediments

Isoprene, a highly abundant biogenic volatile organic compound, has emerged as a crucial yet overlooked factor in addressing climate change. Despite its widespread production in all forms of life, comprehensive data on its global biogeochemical cycle remain scarce. Isoprene's reactivity in the atmosphere influences methane concentrations, with detrimental implications for climate, air quality, and health. Conversely, methane is abundant in marine and terrestrial subsurface environments, where deep-sea carbonates serve as hotspots for microorganisms performing anaerobic methane oxidation—an essential process in long-term methane storage and removal from the marine carbon cycle. Recent studies by Beckmann et al. (2020), Prouty et al. (2020) have shed light on novel metabolic pathways utilized by microbial communities in carbonates for methane oxidation. Similarly, in terrestrial environments, eucalyptus trees, as the highest emitters of isoprene, may harbor microorganisms capable of metabolizing isoprene alongside methane-oxidation and formation in eukalyptus leaf detritus. However, little is known about the fate of isoprene and the potential microbial communities involved in its metabolism within deep-sea carbonates and eucalyptus-leaf sediments, potentially impacting methane metabolism. Our study aims to unravel the anaerobic pathways of microbial isoprene degradation and investigate the effects of isoprene abundance and degradation on microbial methane production and oxidation. We detected anaerobic isoprene-degradation in deep-sea carbonates and terrestrial eukalyptus-leave sediments, where methane oxidation and methane formation was pronounced. Surprisingly, the presence of isoprene inhibited mcirobial methane-oxidation as well as methane-formation, suggesting an substantial impact of the presence of isoprene on methane cycling and storage. We are currently characterizing and isolating the microorganisms involved in the isoprene and methane metabolism in these enrichment cultures.

Identification of geographical origin of winter jujube based on GC–MS coupled with machine-learning algorithms

Headspace solid-phase microextraction (HS-SPME) combined with gas chromatography–mass (GC–MS) is the most often used technique for the analysis of volatile organic compounds (VOCs). When coupled with machine-learning algorithms, the two provide the means to differentiate the volatile metabolome of foods from different origins. In this study, the volatile metabolites of winter jujube, a fruit protected by China and the European Union (EU) based on geographical indications (GI), was analyzed by HS-SPME–GC–MS. Extreme gradient boosting (XGBoost) was applied, for the first time, to evaluate differences in winter jujube grown in four distinct regions. Locational differences yielded 33 VOCs that differed by functionality and concentration with a recurrence probability of ≥ 60%. Zhanhua winter jujube contained the most abundant VOCs, with Yuncheng winter jujube the least. The 33 winter jujube VOCs were analyzed by random forest (RF), support vector machine (SVM), and XGBoost to identify the place of origin. The discrimination rates were about 85% using RF, about 93% using SVM, and about 98% with XGBoost. Compared to RF and SVM algorithms, XGBoost was more efficient, producing higher accuracy rates, and providing new opportunities for origin traceability.

Measurement report: Source apportionment and environmental impacts of volatile organic compounds (VOCs) in Lhasa, a highland city in China

Abstract. Hypoxia and adverse health outcomes might be affected by O3 pollution in the highland city of Lhasa. NOx emissions can amplify the role of volatile organic compounds (VOCs) in the secondary production of O3 under the conditions of high ultraviolet (UV) radiation levels and unfavourable dispersion patterns in the Lhasa River valley. Here, online C2–C11 VOC measurements, accompanied by other parameters concerning the O3 chemical budget, were first obtained and employed to identify the key VOC species and key sources of VOCs in terms of the loss rate against OH radicals (LOH), ozone formation potential (OFP), secondary organic aerosol potential (SOAP), and toxicity. Oxygenated VOCs (OVOCs) not only were the most abundant VOCs but also dominated LOH, OFP, and toxicity. Isoprene and anthropogenic VOCs were further identified as precursors of these OVOCs. Aromatics accounted for 5 % of the total VOCs (TVOCs) but contributed 88 % to the SOAP and 10 % to the toxicity. As the primary oxidative intermediates of aromatics were not well characterized by our measurements, the environmental impact of aromatics could be underestimated by our data. Source appointment and ternary analysis of benzene, toluene, and ethylbenzene confirmed the combined contribution of traffic emissions, solvent usage, and biomass burning. This suggests that O3 precursors are mainly from sources associated with residents' lives, except for solvent usage emissions which contribute to aromatics. Preliminary comparisons between source spectrums of transport sector emissions with positive matrix factorization (PMF)-decomposed ones and our measured ones suggest that vehicle emission patterns of VOCs at high altitude generally follow the ground-level impression. More quantitative data are required to further confirm this point though. Emission reduction strategy analysis for O3 pollution control highlighted multiple benefits of the simultaneous reduction in NOx originating from diesel vehicle emissions, biomass burning, and background sources (possibly dominated by incense burning). The notable biogenic emission contribution to the OFP was also first confirmed in our study, and this highlights the side effects of the government's pursuit of a greener city.

Composition Characteristics of VOCs in the Atmosphere of the Beibei Urban District of Chongqing: Insights from Long-Term Monitoring

Reducing anthropogenic volatile organic compounds (VOCs) is the most effective way to mitigate O3 pollution, which has increased over the past decades in China. From 2012 to 2017, special stainless-steel cylinders were used to collect ambient air samples from the urban area of Beibei district, Chongqing. Three-step pre-concentration gas chromatography–mass spectrometry was used to detect the collected air samples. The composition, concentration, photochemical reactivity, and sources of VOCs in Beibei were analyzed. During the observation period, the annual average VOC concentration was 31.3 ppbv, which was at an intermediate range compared to other cities in China. Alkanes (36.8%) and aromatics (35.6%) were the most abundant VOC groups, followed by halo-hydrocarbons (14.4%) and alkenes (12.6%). The overall trend of seasonal distribution of VOC concentration was high in summer and autumn, and low in winter and spring, with a statistically significant difference between summer and winter concentrations. The ozone formation potential (OFP) showed that alkenes were the most active species, followed by aromatics and alkanes, and summer was the season with the highest OFP (131.6 ppbv). Three major emission sources were identified through principal component analysis (PCA), i.e., vehicle exhaust emissions (66.2%), fuel oil evaporation (24.8%), and industrial sources (9.0%). To ameliorate the air quality within the study area, concerted efforts should be directed towards curtailing traffic emissions and mitigating the release of alkenes, particularly emphasizing more stringent interventions during the summer season.

Identification of priority pollutants at an integrated iron and steel facility based on environmental and health impacts in the Yangtze River Delta region, China

Emissions from the iron and steel industry are a major source of air pollution. To investigate the composition characteristics, estimate the secondary transformation potential, and assess the ecological risk and human health risks of air pollutants from iron and steel industry, field measurements of volatile organic compounds (VOCs) and trace metals (TMs) were conducted simultaneously from 2020 to 2022 in the Yangtze River Delta (YRD) region, China. The average mixing concentration of VOCs (Σ64VOCs) was 58.2 ppbv. Alkanes, alkenes and aromatics were the major components. Benzene and ethylene were the most abundant VOC species. In the O3 season, the calculated OH loss rates (LOH) and ozone formation potential (OFP) were 10.87 S−1 and 181.74 ppbv, respectively, which increased 39.54% and 21.51% compared to the non-O3 season. Furthermore, the O3-VOCs-NOx sensitivity indicated that O3 formation was under the VOCs-limited regime. The average concentration of total 10 trace metals (Σ10TMs) was 226.8 ng m−3, Zn, Pb and Mn were the top abundant TM species. The results also found that Se was extremely contaminated; Pb and Zn was heavily to extremely contaminated; Cu, As and Ni were moderately to heavily contaminated. For lifetime cancer risk, the cumulative carcinogenic risks were 1.84E-5 for children, 6.14E-5 for adults and 1.83E-5 for workers. The carcinogenic risks of individual chemicals cannot be ignored, especially for Cr, Ni, benzene and 1,3-butadiene. The hazard index values for workers and residents were 0.53 and 2.23, respectively, suggesting a high non-carcinogenic risks to the exposed population. These findings deepen the understanding of the pollutant character of the iron and steel industry, and provide theoretical support for policy development on O3 pollution treatment and human health in the YRD region, China. For the study area, we recommend utilizing high-quality raw coal, reducing the volatile hydrocarbon content in the sinter feed, and installing absorption device for highly reactive VOC components at the exhaust outlet.

UV-Vis spectrophotometric determination of isoprene in atmosphere based on Diels–Alder reaction

ABSTRACT Isoprene is the most abundant biogenic volatile organic compound in the atmosphere. Till now, chromatography is the main detection method for isoprene, dependent on sophisticated instruments and complex operations. An UV-Vis spectrophotometric method based on the Diels–Alder (D-A) reaction was developed to detect isoprene in the atmosphere. The fast D-A reaction between the probe 4-phenyl−1,2,4-triazolin−3,5-dione (PTAD) and isoprene may cause absorbance decrease, which enable it to detect isoprene in solution at 118 nmol·L−1 level. Further, isoprene in air at the level of ppbv was detected using this method. Compared with chromatography this method has the advantages of low cost, fast and less dependence on instrument.

Characterisation of volatile organic compounds in hospital indoor air and exposure health risk determination

Several volatile organic compounds (VOCs) have impacts on human health, but little is known about the concentrations of VOCs in the hospital environment. This study characterised VOCs present in clinical assessment rooms. More than 600 samples of air were collected over 31 months (2017–2020) at two hospital sites in Leicester, United Kingdom, and analysed by comprehensive two-dimensional gas chromatography, making this the largest hospital environment database worldwide on VOCs and first such UK study. The most abundant VOCs found were 2-propanol, ethyl chloride, acetone and hexane, with respective mean concentrations of 696.6 μgm−3, 436.5 μgm−3, 83.9 μgm−3 and 58.5 μgm−3. Acetone, 2-propanol and hexane concentrations were 4, 9 and 30-fold higher respectively compared to similar studies performed in other hospitals. Our results showed that the most frequently detected VOCs, with the highest concentrations, were most likely released by healthcare activities, or related to ingress of vehicle emissions. Hazard quotient (HQ) and cancer risk (CR) were calculated to identify the potential risk of VOCs exposure to the health of healthcare workers. No HQs were measured above 1, compared to inhaled US EPA and OEHHA health guidelines for non-cancer chemicals. For both hospitals, trichloroethylene CR were calculated above 1E-06 by using inhaled US EPA cancer risk values, leading to possible risks to healthcare workers with long-term exposure. More studies of this type, including measurements of VOCs such as formaldehyde that we were unable to include in this study, are needed to better characterise exposures and risks, both to healthcare workers and patients.

Volatilom und Transkriptom des Speisepilzes Agrocybe aegerita

Mushrooms are part of the human diet since time immemorial, appreciated for their nutritional value and especially for their delicious flavors. Hundreds of volatile organic compounds (VOCs) have been identified in fungi contributing to the unique aroma of each species. Generally, studies on mushroom VOCs are carried out with chopped fruiting bodies of more or less one developmental stage. For determine fungal aromas for assessment of the food quality this procedure might be adequate. Nonetheless, for analysis of the biological role of fungal VOCs in context of inter alia VOC biosynthesis or fungal communication this approach can suffer from drawbacks. First of all, damaging fruiting bodies can lead to VOC artefacts due to cell disruption and the occurrence of unnatural enzymatic reactions. Furthermore, fungal VOC profiles are dynamic, changing with ongoing development. For better understanding of the biological function of fungal VOCs it is therefore helpful to know which volatile patterns are characteristic for a certain developmental stage.Against this background, an approach was developed enabling on one hand the cultivation of fungi during different developmental stages, including the growth of fruiting bodies, and on the other hand the non‐invasive analysis of VOCs in the headspace (HS) of fungal cultures. These requirements were complied with modified crystallizing dishes for culture purposes and a HS‐ SPME‐GC‐MS approach to analyze the VOCs. This method was applied to analyze the volatilomes of the dikaryotic strain C. aegerita AAE‐3 and four monokaryotic offspring siblings with different fruiting phenotypes throughout ten life stages. At early stages, in the HS of all tested strains alcohols and ketones, such as oct‐1‐en‐3‐ol, 2‐methylbutan‐1‐ol and cyclopentanone, were the most prominent VOCs. Particularly counting for the dikaryon, the volatilome altered with continued fruiting body development exhibiting remarkable changes during sporulation. Here, sesquiterpenes, especially Δ6‐protoilludene, α‐cubebene and δ‐cadinene, were the most abundant VOCs in the HS of C. aegerita AAE‐3. After sporulation, the amount of sesquiterpenes decreased along with the appearance of other VOCs including octan‐3‐one. In contrast, less VOCs were present in the HS of the monokaryotic strains of which all were as well detectable in the HS of the dikaryon. The changes of the volatilome were the fundament for a subsequent transcriptome analysis aiming to identify enzymes involved in fungal VOC biosynthesis, especially regarding C8 VOC formation, which is, despite the fact that these substances are ubiquitous found in fungi, still barely understood. The transcriptomic study was carried out with seven developmental stages of C. aegerita AAE‐3, which during the volatilome study exhibited interesting volatile patterns. Additionally, fruiting bodies (five stages) and mycelia (seven stages) samples were harvested separately to get further insights about the putative origin of the VOCs observed in the HS of C. aegerita. Combining transcriptome and volatilome data, enzymes putatively involved in the biosynthesis of C8 oxylipins in C. aegerita including lipoxygenases (LOXs), dioxygenases (DOXs), hydroperoxide lyases (HPLs), alcohol dehydrogenases (ADHs) and ene‐ reductases could be identified. Especially the putative DOX AAE3_13098, the putative HPLs AAE3_05330 and AAE3_09203, the putative ADHs AAE3_00054 and AAE3_06559 as well as the putative ene‐reductase AAE3_15349 exhibit remarkable transcriptomic patterns making these enzymes highly interesting for future characterization studies. Furthermore, the study showed that the mycelium is probably the main source for sesquiterpenes observed during sporulation in the HS of C. aegerita AAE‐3 cultures whereas changes in the Cs profile detected in late stages of development are probably due to the activity of enzymes located in the fruiting bodies.

Multiple source apportionments, secondary transformation potential and human exposure of VOCs: A case study in a megacity of China

The Central Plain City Cluster represented by Zhengzhou is one of the most haze-polluted regions, especially for the heating period. As critical precursors of Secondary Organic Aerosol (SOA) and Ozone, the ambient Volatile Organic Compounds (VOCs) emitted from anthropogenic activities have aroused widespread concern. This study provided a revealing insight on the concentration level, chemical composition, multiple source apportionments (SAs), SOA formation potential (SOAp) and exposed health risk of VOCs before and during heating periods at a megacity site. The average concentrations of TVOCs during clear days before heating, pollution days before heating, clear days during heating, and pollution days during heating were 37.81 ± 17.21, 54.48 ± 17.83, 39.27 ± 16.38 and 63.98 ± 22.42 ppbv, respectively. Compared with the before heating period, the concentration of TVOCs increased by 3.9% and 17.4% on clear days and polluted days during the heating period, respectively. Among them, alkanes were the most abundant species of VOCs, followed by halocarbons and alkenes. The multiply SAs methods were applied to identify potential sources, and the contributions of source structures were reasonable and credible by comparing PMF and emission inventory. Vehicular exhaust was the largest contributor during the non-heating period (33.2%), while for the heating period, combustion source contributed the most to VOCs emission (24.2%). In terms of the contribution to SOAp formation, aromatics were the most abundant VOCs species, and combustion (29.4%) was the major source, followed by solvent usage (26.5%) and vehicular exhaust (24.6%). The non-carcinogenic risks of VOCs sources were significantly lower than the acceptable safety threshold, while all the specific VOCs sources posed carcinogenic risks except for biogenic emission. The ways of analysis and assessment in this study can highlight the need for more effective control strategies related to VOCs anthropogenic activities during the heating period in megacities of Central China.

Terpenoid VOC profiles and functional characterization of terpene synthases in diploid and tetraploid cytotypes of Chrysanthemum indicum L

Chrysanthemum indicum L. is a valuable medicinal plant with diploid and tetraploid forms that are widely distributed in central and southern China, and it contains abundant volatile organic compounds (VOCs). Despite the discovery of some terpene synthase (TPS) in C. indicum (i.e., CiTPS) in previous studies, many TPSs and their corresponding terpene biosynthesis pathways have yet to be discovered. In the present study, terpenoid VOCs in different tissues from two cytotypes of C. indicum were analyzed. We identified 52 types of terpenoid VOCs and systematically investigated the content and distribution of these compounds in various tissues. The two cytotypes of C. indicum exhibited different volatile terpenoid profiles. The content of monoterpenes and sesquiterpenes in the two cytotypes showed an opposite trend. In addition, four full-length candidate TPSs (named CiTPS5–8) were cloned from Ci-GD4x, and their homologous TPS genes were screened based on the genome data of Ci-HB2x. These eight TPSs displayed various tissue expression patterns and were discovered to produce 22 terpenoids, 5 of which are monoterpenes and 17 are sesquiterpenes. We further proposed corresponding terpene synthesis pathways, which can enable the establishment of an understanding of the volatile terpenoid profiles of C. indicum with different cytotypes. This knowledge may provide a further understanding of germplasm in C. indicum and may be useful for biotechnology applications of Chrysanthemum plants.