Natural Volatile Organic Compounds Research Articles

Interference Effect of Tree Spacing on Natural Volatile Organic Compound Concentrations Measured Using Passive Samplers

Research highlights: The increasing rates of mental health disorders during the COVID-19 pandemic have popularized the notion of access to natural environments as a solution, leading to a surge in demand for urban green spaces. The concentration of natural volatile organic compounds (NVOCs) in forests, resulting from plant metabolism, plays a crucial role in forest-based healing and ecosystem health. Background and objectives: This study aimed to investigate how tree spacing influences NVOC concentrations within forest ecosystems using passive samplers, thereby enhancing the understanding of optimal forest management practices to promote human health benefits. Methods: We employed passive samplers to investigate tree spacing effects on NVOC concentrations. We placed passive samplers among trees in the study area to measure NVOC concentrations in individual trees and analyzed the relationship between NVOC concentration and tree spacing and structure. Results: A multiple regression analysis using distance decay models showed that a tree spacing of 2.7–3 m had a significant impact on NVOC concentrations. These findings provide a better understanding of how tree structure, tree spacing, and microclimate within the forest influence NVOC concentration. Conclusion: These findings have important implications for forest management and the design of forest landscapes to promote human health and well-being by considering the spatial distribution of NVOC concentrations.

Volatile organic composition of five Rubiaceae species: Insights into their phytochemical diversity

Natural volatile organic compounds (VOCs) obtained from five Rubiaceae plants native to south China, namely Damnacanthus indicus, Hamelia patens, Exallage chrysotricha, Psychotria serpens, and Spermacoce pusilla, were isolated and characterized in this study. The analysis revealed that each plant contained 71, 57, 80, 73, and 70 volatile organic chemical compounds, respectively. The main VOCs shared by five plants was palmitate (10.20%–36.26%). Methyl salicylate, caryophyllene oxide, tetradecanoic acid, 6,10,14-trimethyl-2-pentadecanone, pentadecanoic acid, pentacosane, pentadecanal, nonanal, hexadecanoic acid methyl ester, phytol, linalool, and (E)-β-ionone were shared by at least 4 Rubiaceae plants in this study. Besides, each of the five plants has its main components as follows: 12.81% ethyl linoleate and 6.13% (E)-13-octadecenoic acid for D. indicus; 35.17% methyl salicylate for H. patens; 9.50% (Z, Z)-9,12-octadecadienoic acid and 7.56% endo-borneol for E. chrysotricha; 13.93% methyl salicylate for P. serpens; 6.19% humulene and 6.08% humulene oxide II for S. pusilla. This research provides insights into the phytochemical diversity and classification of Rubiaceae plants, laying a solid foundation for future natural product development in the Rubiaceae family.

Mechanisms of methyl 2-methylbutyrate suppression on Aspergillus flavus growth and aflatoxin B1 biosynthesis

Aspergillus flavus and subsequently produced carcinogenic aflatoxins frequently contaminate postharvest food crops, resulting in a threat to global food safety. Chemical preservatives are currently the main antifungal agents. However, fungal resistance effect, biological toxicity, and environmental contamination limit their practical applications. The application of natural volatile organic compounds has great potential for controlling fungal and mycotoxin contamination of postharvest food crops. This study therefore investigated the antifungal and anti-aflatoxigenic activities of the volatile compound, methyl 2-methylbutyrate (M2M), against Aspergillus flavus and its potential mechanisms. M2M effectively inhibited A. flavus mycelia growth, with a minimum inhibitory concentration of 2.0 μL/mL. Moreover, M2M also suppressed aflatoxin production, sclerotia production, and the pathogenicity on peanut and corn flour. RNA-Seq results showed that 2899 differentially expressed genes (DEGs), and DEGs involved in ergosterol synthesis, cell wall structure, glycolysis, citric acid cycle, mitogen activated protein kinase signaling pathway, DNA replication, and aflatoxin biosynthesis, were down-regulated in A. flavus. Further studies showed that M2M strongly damaged the cell membrane and cell wall integrity, reduced ATP levels, and induced reactive oxygen species (ROS) accumulation and DNA damage. Notably, a GATA type zinc finger transcription factor, AfSreA (AFLA_132440), which is essential for A. flavus growth and aflatoxin production, was identified. The growth and aflatoxin yield in the ΔAfSreA strain decreased by 94.94 % and 71.82 %, respectively. Additionally, deletion of AfSreA destroyed cell wall integrity and decreased expressions of genes involved in aflatoxin biosynthesis. Taken together, our results identified the antifungal and anti-aflatoxigenic mechanisms of M2M against A. flavus, and confirmed the potential of M2M in protecting peanut and corn from fungal contamination.

Superflux of an organic adlayer towards its local reactive immobilization

On-surface mass transport is the key process determining the kinetics and dynamics of on-surface reactions, including the formation of nanostructures, catalysis, or surface cleaning. Volatile organic compounds (VOC) localized on a majority of surfaces dramatically change their properties and act as reactants in many surface reactions. However, the fundamental question “How far and how fast can the molecules travel on the surface to react?” remains open. Here we show that isoprene, the natural VOC, can travel ~1 μm s−1, i.e., centimeters per day, quickly filling low-concentration areas if they become locally depleted. We show that VOC have high surface adhesion on ceramic surfaces and simultaneously high mobility providing a steady flow of resource material for focused electron beam synthesis, which is applicable also on rough or porous surfaces. Our work established the mass transport of reactants on solid surfaces and explored a route for nanofabrication using the natural VOC layer.

Natural product 2-Phenylethanol inhibits ATP synthesis of P. infestans by blocking the oxidative phosphorylation pathway to prevent potato late blight

Potato tuber rots caused by the late blight pathogens oomycete Phytophthora infestans results in severe postharvest losses in transit and storage. Natural volatile organic compounds (VOCs) produced by antagonistic microorganisms have good biocontrol effects. However, VOCs for controlling potato late blight largely remains scarcity, the antimicrobial mechanisms were not entirely clear. In this study, an antagonistic yeast Candida quercitrusa strain Cq-1 was reported that had strong anti-oomycete activity on P. infestans. Its natural VOCs are mainly attributable to the inhibitory ability at the inhibition rate of 85.94%. Mycelial growth of P. infestans and lesions on postharvest potato tubers were inhibited after exposure to its VOCs by storage simulation assay. Furthermore, 2-Phenylethanol (C8H10O) (2-PE) was identified as one of the primary components of VOCs in C. quercitrusa through GC-MS. Hyphal growth of P. infestans following 2-PE treatment was malformed and shriveling. Mechanism investigations revealed that 2-PE blocked the oxidative phosphorylation pathway from RNA-seq analysis, the down-regulation of relevant genes was validated by qPCR, eventually causing a 68.08% reduction in ATP contents, thereby leading to ATP depletion and ultimate mortality of P. infestans. Hence, 2-PE suggesting potential application to protect postharvest potato tubers from late blight.

Natural Volatile Organic Compounds (NVOCs) Are Greater and More Diverse in UK Forests Compared with a Public Garden

Forest bathing is based upon a Japanese practice known as Shinrin–Yoku and is a nature-based therapy involving mindful walks through ancient woodland to reduce stress and anxiety. One proposed mechanism behind the effectiveness of Forest bathing is based on the potential mental and physical health benefits of the natural volatile organic compounds (NVOCs) that fill the forest understory. Surprisingly little is known about the concentrations and diversity of plant NVOCs in ambient air particularly in the UK and this study aims to increase that knowledge. Air samples were collected in July 2022 in a UK forest and compared with samples from a walled garden environment. The samples were collected over a 2 h time period and analysed using GC-MS and showed clear differences in the chemical composition of the air. This study revealed NVOCs including limonene, carvone, terpenes, terpenoids and sesquiterpenoids were present within a UK forest but were either not present or present at little to low levels in the control setting of a walled garden. This study also found that the typical 2 h duration of a Forest bathing session was a long enough sampling period to detect these NVOCs, indicating that Forest bathers could benefit from exposure to NVOCs.

The Retention and Chemical Composition of NVOCs (Natural volatile organic compounds) in a Warm Temperate Forest

The Retention and Chemical Composition of NVOCs (Natural volatile organic compounds) in a Warm Temperate Forest

Impact of Climate-Driven Land-Use Change on O3 and PM Pollution by Driving BVOC Emissions in China in 2050

This study predicted three future land-use type scenarios in 2050 (including the Shared Socioeconomic Pathway SSP126, SSP585, and carbon scenario) based on the Land-Use Harmonization (LUH2) project and the future evolution of land-use types considering China’s carbon neutrality background. The contribution of land-use changes to terrestrial natural source biogenic volatile organic compounds (BVOCs), as well as O3 and PM concentrations, were determined. Under the SSP126 pathway, meteorological changes would increase BVOC emissions in China by 1.0 TgC in 2050, compared with 2015, while land-use changes would increase them by 1.5–7.1 TgC. The impact of land-use changes on O3 and PM concentrations would be less than 3.6% in 2050 and greater in summer. Regional differences must be considered when calculating future environmental background concentrations of pollutants. Due to more afforestation measures under the SSP126 scenario, the impact of land-use change on pollutants was more obvious under the SSP126 pathway than under the SSP585 pathway. Under the carbon scenario, the increase in PM concentration caused by land-use changes would pose a risk to air quality compliance; thus, it is necessary to consider reducing or offsetting this potential risk through anthropogenic emission control measures.

Antifungal activity of 1-octen-3-ol against Monilinia fructicola and its ability in enhancing disease resistance of peach fruit

Peach fruit is susceptible to decay caused by Monilinia fructicola infection. Synthetic fungicides are effective for inhibiting this pathogen and rot rate, but more and more attentions to the safety and pollution that chemicals compel us to find other methods to control M. fructicola disease. Natural volatile organic compound was considered as a potential way to reduce pathogen infection. 1-Octen-3-ol, a natural product from plant or fungi, can inhibit several pathogens growth. In this study, it is found that 1-octen-3-ol fumigation not only inhibited development of M. fructicola in vitro but also effectively reduced brown rot caused by the pathogen in vivo. The results showed 37.20, 55.80 and 74.40 μg mL −1 1-octen-3-ol fumigation could inhibit the extension of M. fructicola hyphae and significantly reduce the ergosterol content of mycelium. The results of microscopy, it can be seen that 1-octen-3-ol destroyed the hyphae morphology and cell structure. The spore apoptosis rate and reactive oxygen species (ROS) increased, and the mitochondrial membrane potential (MMP) decreased. Moreover, 55.80 μg mL −1 1-octen-3-ol fumigation could significantly reduce disease incidence and lesion diameter of fruit. Chitinase and β-1,3-glucanase activities were enhanced, and expression of ICS1 , NPR1 , TGA1 , PR1 were up-regulated, as well as down-regulation of AOS , COI1 and MYC2 . These results indicate that 1-octen-3-ol treatment is a promising approach to control brown rot, which is related to the activation of salicylic acid (SA) signal to enhance fruit disease resistance besides direct destruction of pathogen. • Volatile 1-octen-3-ol could inhibit Monilinia fructicola in vitro. • 1-octen-3-ol destroyed the integrity of fungal biofilm and respiratory energy metabolism. • 1-octen-3-ol treatment effectively inhibited brown rot development in peach fruit. • 1-octen-3-ol may induce disease resistance via activation of SA signal pathway of peach fruit.

Fumigation of three major soil pests (Agriotes lineatus, Diabrotica virgifera virgifera, Phyllopertha horticola) with 3-octanone and 1-octen-3-ol enantiomers

ABSTRACT New pest management solutions are needed to control soil invertebrates (insects, nematodes, mollusks) in order to implement the goals of the European Green Deal. Natural volatile organic compounds (VOCs) such as 1-octen-3-ol and 3-octanone, emitted by the entomopathogenic fungus Metarhizium brunneum could be part of the solution. Three major crop pests, Agriotes lineatus (wireworm), Diabrotica virgifera virgifera (corn rootworm) and Phyllopertha horticola (garden chafer), were susceptible to fumigation with 1-octen-3-ol and 3-octanone. The toxicity of the VOCs was tested in soil-free arenas and in soils which differed in moisture content and porosity. The mortality rates were dependent on the interaction between the VOC treatment, dose and pest species. The insects differed in their sensitivity to these VOCs. A dose of 1.25 µl of 1-octen-3-ol applied in a closed glass tube was sufficient to kill D. v. virgifera and P. horticola in soil trials whereas 5 µl was needed to kill A. lineatus. The highest dose (20 µl) was highly toxic to all insects. Soil moisture content slightly influenced mortality rates whereas porosity had no obvious impact. The mode of action of the VOCs is unknown but the compounds are likely to cause tissue damage and loss of body fluids. This may explain the shrivelled appearance of corn rootworm and garden chafer and melanisation in wireworm. Both 1-octen-3-ol and 3-octanone show promise as biofumigants.

Path of coordinated control of PM<sub>2.5</sub> and ozone in China

<p indent="0mm">Since the <italic>Air Pollution Prevention and Control Action Plan</italic> was issued in 2013, air quality in China has significantly improved. But the concentration of fine particulate matter (PM_2.5) remains 3 times higher than the guideline value of the WHO (World Health Organization, 2015), and the rising concentration of ozone (O₃) that has caused premature death and economic losses neutralized the environmental benefits brought in by partial reductions of PM_2.5. The coordinated control of PM_2.5 and O₃, hence, has been put at the top of the agenda for China’s air pollution prevention and control. Given nitrogen oxides (NO_{<italic>x</italic>}) and volatile organic compounds (VOCs) are major precursors of both PM_2.5 and O₃, reducing the emissions of NO_{<italic>x</italic>} and VOCs is considered as the key to the coordinated control of PM_2.5 and O₃. Focused on the common precursors of PM_2.5 and O₃, our research conducted qualitative analysis of the effects of reduced emissions of NO_{<italic>x</italic>} and VOCs, and suggested China’s path to coordinated control of PM_2.5 and O₃. The results are expected to be adopted as scientific bases by administrative authorities for relevant policy-making. Our research was based on the WRF-CAMx model and scenario analysis was used. Different scenarios where NO_{<italic>x</italic>}<italic> </italic>and VOCs emissions were reduced to different degrees were set to simulate the changes of concentrations of PM_2.5 and O₃ across China and in key areas. The indicator of sensitivity was introduced to quantitively evaluate the responsiveness of PM_2.5 and O₃ concentrations to the reduced emissions of NO_{<italic>x</italic>} and VOCs. The effects of reduced emissions of NO_{<italic>x</italic>} and VOCs on the concentrations of PM_2.5 and O₃ were revealed directly in the research. As suggested by simulation results, the reduction of NO_{<italic>x</italic>} or VOCs emission can contribute to the decrease of the concentration of PM_2.5 nationwide and in key areas. If at the same ratio of reduction, the reduction of NO_{<italic>x</italic>} emission can lead to a larger decrease of PM_2.5 concentration. The change of O₃ concentration nationwide or in key areas varies under different NO_{<italic>x</italic>} and VOCs emission reduction scenarios. From the perspective of the whole country, a small ratio of NO_{<italic>x</italic>}<italic> </italic>emission reduction may lead to the rise of O₃ concentration in some areas, but the O₃ concentration declines on the whole, and the rate of decline rises with the further reduction of NO_{<italic>x</italic>} emission. The reduction of VOCs emission can decrease the O₃ concentration nationwide, but the effect is less obvious than the reduction of NO_{<italic>x</italic>} emission. For the Pearl River Delta area, the reduced emission of VOCs is more effective for the decrease of O₃ concentration. For the “2+26” cities, the Yangtze River Delta, and the Fenwei Plain, if on a small scale, the reduction of VOCs is more effective for the decrease of O₃ concentration than that of NO_{<italic>x</italic>}. But due to the existence of natural VOCs, the proportion of artificial VOCs to the total emission of VOCs reduces as the artificial VOCs continues to decline, and hence, the benefit of the reduction of VOCs becomes less obvious than that of NO_{<italic>x</italic>}. Sensitivity results were in agreement with the concentration changes. Based on the abovementioned results, to realize the balance of the benefits of NO_{<italic>x</italic>} and VOCs emissions reduction between the local and global and between the short term and the long term, we suggest that the continuous reduction of NO_{<italic>x</italic>} emission should be regarded as the focus of coordinated control of PM_2.5 and O₃ in terms of both the whole country and key areas and the reduction of VOCs emission is the key to the improvement of O₃ pollutions in key areas in the short term, which should be incorporated in the medium-to-long-term design of China’s path to coordinated control of air pollutions.

Usage of Natural Volatile Organic Compounds as Biological Modulators of Disease.

Plants produce a wide variety of natural volatile organic compounds (NVOCs), many of which are unique to each species. These compounds serve many purposes, such as fending off herbivores and adapting to changes in temperature and water supply. Interestingly, although NVOCs are synthesized to deter herbivores, many of these compounds have been found to possess several therapeutic qualities, such as promoting nerve stability, enhancing sleep, and suppressing hyperresponsiveness, in addition to acting as antioxidants and anti-inflammatory agents. Therefore, many NVOCs are promising drug candidates for disease treatment and prevention. Given their volatile nature, these compounds can be administered to patients through inhalation, which is often more comfortable and convenient than other administration routes. However, the development of NVOC-based drug candidates requires a careful evaluation of the molecular mechanisms that drive their therapeutic properties to avoid potential adverse effects. Furthermore, even compounds that appear generally safe might have toxic effects depending on their dose, and therefore their toxicological assessment is also critical. In order to enhance the usage of NVOCs this short review focuses not only on the biological activities and therapeutic mode of action of representative NVOCs but also their toxic effects.

Statistical Evidence for Managing Forest Density in Consideration of Natural Volatile Organic Compounds

Rapid deforestation, coupled with the growing population seeking forest therapy, urges the necessity for research on how to maximize forests’ therapeutic functions when cultivating damaged or unmanaged forests. This study was formulated to provide a basis for forest stand density management to maximize the therapeutic effects of forests with a focus on natural volatile organic compounds (NVOCs), a representative component of forest therapy through analysis of variance and regression analyses. The results of this study revealed all studied stand densities yield the highest total NVOC (TNVOC) emissions in summer, especially in the study site which has a forest density of 700/ha. In addition, treeless areas (0/ha) were found to have the most significant difference in average NVOC emissions when cultivated at a density of 700/ha. When managing forests with a density of 900/ha to 1000/ha, it has been shown that it is most desirable, in terms of therapeutic function efficiency, to control a density of 500/ha to 700/ha. Finally, regression equations for the five experimental sites with significant explanatory power were derived. Based on the results of the conducted analyses, 700/ha of forest density is recommended to maximize the therapeutic effects of forests, compared to other ranges of forest density.

\u03b1-Terpineol fumigation alleviates negative plant-soil feedbacks of Panax notoginseng via suppressing Ascomycota and enriching antagonistic bacteria

The accumulation of soil-borne pathogens is the main driving factor of negative plant-soil feedbacks (NPSFs), which seriously restricts the sustainable development of agriculture. Using natural volatile organic compounds (VOCs) from plants or microorganisms as biofumigants is an emerging strategy to alleviate NPSFs in an environmentally-friendly way. Here, we identified α-terpineol from the VOCs of pine needles, confirmed the ability of α-terpineol fumigation in alleviating the NPSF of Panax notoginseng via significantly reducing seed decay rate, and also deciphered the underlying mechanism by which the soil microbial community is modified. α-Terpineol fumigation could suppress culturable fungi but enrich bacteria in a dose-dependent manner. Network analysis with high-throughput sequencing data revealed that α-terpineol could distinctly modify both fungal and bacterial communities. In detail, α-terpineol significantly suppressed the relative abundance of Ascomycota from 64.04 to 32.26%, but enriched the relative abundance of Proteobacteria, Acidobacteria and Actinobacteria. Subnetwork analysis further demonstrated that α-terpineol could directly or indirectly suppress fungal pathogens and enrich plant growth-promoting rhizobacteria (PGPRs). In vitro fumigation and co-culture experiments with culturable isolates validated these findings. The antagonism between beneficial bacteria and pathogens, and the synergistic growth promotion among α-terpineol-enriched bacteria might be involved in soil microbial community assembly. In summary, α-terpineol fumigation could directly or indirectly modify the soil microbial community to alleviate NPSFs, especially by suppressing fungal pathogens and enriching beneficial bacteria. This study suggests that VOCs from natural products are worth developing as biofumigants due to their multiple functions in modifying the soil microbial community.

Prediction of Natural Volatile Organic Compounds Emitted by Bamboo Groves in Urban Forests

Due to the COVID-19 outbreak, people in countries around the world including the United Kingdom, Denmark, Canada, and South Korea are seeking physiological and psychological healing by visiting forests as stay-at-home orders continue. NVOCs (natural volatile organic compounds), a major healing factor of forests, have several positive effects on human health. This study specifically researched the NVOC characteristics of bamboo groves. This study revealed that α-pinene, 3-carene, and camphene were observed to emit the most, and the largest amount of NVOC emitted was seen during the early morning and late afternoon within bamboo groves. Furthermore, NVOC emission was found to have normal correlations with temperature and humidity, and inverse correlations with solar radiation, PAR (photosynthetically active radiation), and wind speed. A regression analysis conducted to predict the effect of microclimate factors on NVOC emissions resulted in a regression equation with 82.9% explanatory power, finding that PAR, temperature, and humidity had a significant effect on NVOC emission prediction. In conclusion, this study investigated NVOC emission of bamboo groves, examined the relationship between NVOC emissions and microclimate factors, and derived a prediction equation of NVOC emissions to figure out bamboo groves’ forest healing effects. These results are expected to provide a basis for establishing more effective forest healing programs in bamboo groves.

Metabolomic analyses revealed multifaceted effects of hexanal on Aspergillus flavus growth.

Hexanal, a natural volatile organic compound, exerts antifungal activity against Aspergillus flavus; however, the mechanisms underlying these effects are unclear. In this study, we found that the growth of A. flavus mycelium was completely inhibited following exposure to 0.4 μL/mL hexanal (minimal inhibitory concentration). A detailed metabolomics survey was performed to identify changes in metabolite production by A. flavus cells after exposure to 1/2 the minimal inhibitory concentration of hexanal for 6 h, which revealed significant differences in 70 metabolites, including 20 upregulated and 50 downregulated metabolites. Among them, levels of L-malic acid, α-linolenic acid, phosphatidylcholine, D-ribose, riboflavin, D-mannitol, D-sorbitol, and deoxyinosine were significantly reduced. The metabolomics results suggest that the metabolites are mainly involved in the tricarboxylic acid cycle (TCA), ABC transport system, and membrane synthesis in A. flavus cells. Hexanal treatment reduced succinate dehydrogenase and mitochondrial dehydrogenase activity and stimulated superoxide anion and hydrogen peroxide accumulation in A. flavus mycelia. Increases in the electric conductivity and A260nm of the culture supernatant indicated cell membrane leakage. Therefore, hexanal appears to disrupt cell membrane synthesis, induce mitochondrial dysfunction, and increase oxidative stress in A. flavus mycelia. KEY POINTS: • Metabolite changes of A. flavus mycelia were identified after hexanal treatment. • Most differential metabolites were downregulated in hexanal-treated A. flavus. • An antifungal model of hexanal against A. flavus was proposed.

Volatile allosteric antagonists of mosquito odorant receptors inhibit human-host attraction

Odorant-dependent behaviors in insects are triggered by the binding of odorant ligands to the variable subunits of heteromeric olfactory receptors. Previous studies have shown, however, that specific odor binding to ORco, the common subunit of odorant receptor heteromers, may allosterically alter olfactory receptor function and profoundly affect subsequent behavioral responses. Using an insect cell–based screening platform, we identified and characterized several antagonists of the odorant receptor coreceptor of the African malaria vector Anopheles gambiae (AgamORco) in a small collection of natural volatile organic compounds. Because some of the identified antagonists were previously shown to strongly repel Anopheles and Culex mosquitoes, we examined the bioactivities of the identified antagonists against Aedes, the third major genus of the Culicidae family. The tested antagonists inhibited the function of Ae. aegypti ORco ex vivo and repelled adult Asian tiger mosquitoes (Ae. albopictus). Binary mixtures of specific antagonists elicited higher repellency than single antagonists, and binding competition assays suggested that this enhanced repellence is due to antagonist interaction with distinct ORco sites. Our results also suggest that the enhanced mosquito repellency by antagonist mixtures is due to additive rather than synergistic effects of the specific antagonist combinations on ORco function. Taken together, these findings provide novel insights concerning the molecular aspects of odorant receptor function. Moreover, our results demonstrate that a simple screening assay may be used for the identification of allosteric modifiers of olfactory-driven behaviors capable of providing enhanced personal protection against multiple mosquito-borne infectious diseases.

Is It Possible to Predict the Concentration of Natural Volatile Organic Compounds in Forest Atmosphere?

We aimed to understand the correlation between the microclimate environment within a forest and NVOC (Natural volatile organic compounds) concentration and the concentration of NVOC more efficiently through the prediction model method. In this study, 380 samples were collected and analyzed to examine the characteristics of NVOC emitted from a birch forest. NVOC were analyzed in May and July 2019, and measurements were performed at three different locations. Using a pump and stainless-steel tube filled with Tenax-TA, 9 L of NVOC was collected at a speed of 150 mL/h. The analysis of NVOC composition in the forest showed that it comprised α-pinene 27% and camphor 10%. Evaluation of the correlation between the NVOC concentration and the microclimate in the forests showed that the concentration increased markedly with the increase in temperature and humidity, and the concentration decreased with the increase in wind velocity. Nineteen substances in total including α-pinene and β-pinene were detected at high concentrations during the sunset. The results of the study site analysis presented a significant regression model with a R2 as high as 60.1%, confirming that the regression model of the concentration prediction of NVOC in birch forest has significant explanatory power.

Biogenetic study of the emissions of species: Pinus radiata, Eucalyptus globulus Labill and Alnus acuminata in Riobamba canton, Ecuador

Background: Air pollution is one of the biggest problems in the world, and it is generated by industrial production, vehicular flow and use of fossil fuels, leaving aside other important emission sources such as vegetation. The aim of this research is to quantify the emissions of natural volatile organic compounds produced by the forest species: Eucalyptus globulus L., Pinus radiata and Alnus acuminata in Riobamba, Ecuador. Methods: Identification of plant coverings in the years 2014 and 2017was performed using geographic information systems tools, complemented with the application of the Guenther model for the calculation of monoterpenes and other organic volatile compounds; thus, to analyze the relationship between meteorological variables and concentrations of volatile organic compounds and nitrogen dioxide per species. Results: Mathematical calculation of emissions in Riobamba showed that Eucalyptus globulus L. registered higher emissions in the years 2014-2017, followed by Pinus radiata and Alnus acuminata. These emissions are due to the vegetation cover covering each species. The analysis of volatile organic compounds in forest plantations in air is directly related to the emissions represented in the environment and correlated with the meteorological variables of temperature, global solar radiation and wind velocity. The proposed method manages to estimate concentrations of monoterpenes and volatile organic compounds for the two examined seasons, presenting the influence of the species introduced in this study such as Eucalyptus globulus L. and Pinus radiata, with a reduction in their emissions (less area found in the year 2017, with respect to 2014). However, the emission of Alnus acuminata can be quantified only in 2017, since in 2014 no records of this species were found. Conclusions: Volatile organic compound concentrations in the air are directly related to the emissions represented spatially and correlated with the meteorological variables of temperature, global solar radiation and wind velocity.

Biogenetic study of the emissions of species: Pinus radiata, Eucalyptus globulus Labill and Alnus acuminata in Riobamba canton, Ecuador.

Background: Air pollution is one of the biggest problems in the world, and it is generated by industrial production, vehicular flow and use of fossil fuels, leaving aside other important emission sources such as vegetation. The aim of this research is to quantify the emissions of natural volatile organic compounds produced by the forest species: Eucalyptus globulus L., Pinus radiata and Alnus acuminata in Riobamba, Ecuador. Methods: Identification of plant coverings in the years 2014 and 2017was performed using geographic information systems tools, complemented with the application of the Guenther model for the calculation of monoterpenes and other organic volatile compounds; thus, to analyze the relationship between meteorological variables and concentrations of volatile organic compounds and nitrogen dioxide per species. Results: Mathematical calculation of emissions in Riobamba showed that Eucalyptus globulus L. registered higher emissions in the years 2014-2017, followed by Pinus radiata and Alnus acuminata. These emissions are due to the vegetation cover covering each species. The analysis of volatile organic compounds in forest plantations in air is directly related to the emissions represented in the environment and correlated with the meteorological variables of temperature, global solar radiation and wind velocity. The proposed method manages to estimate concentrations of monoterpenes and volatile organic compounds for the two examined seasons, presenting the influence of the species introduced in this study such as Eucalyptus globulus L. and Pinus radiata, with a reduction in their emissions (less area found in the year 2017, with respect to 2014). However, the emission of Alnus acuminata can be quantified only in 2017, since in 2014 no records of this species were found. Conclusions: Volatile organic compound concentrations in the air are directly related to the emissions represented spatially and correlated with the meteorological variables of temperature, global solar radiation and wind velocity.