Emission Rates Of Volatile Organic Compounds Research Articles

Human health impacts and indoor chemical reactions of VOCs from cleaning products and occupants

Occupants and indoor activities are sources of volatile organic compounds (VOCs). We propose a framework to simulate the pollutant pathway using the INCA-Indoor© model and VOC emission rates to derive dynamic concentrations, and the USEtox model to evaluate health impacts in DALYs (Disability-Adjusted Life Years). The applicability of the framework is tested on a case study, and the effect of indoor chemical reactions on health impacts is assessed. In this case study, health impacts were of 0.3 μDALY/day without and 0.4 μDALY/day (13 s/day) with indoor air chemistry (+28 %) out of which 12 % were linked to occupant breath and skin emissions. Cleaning activities led to the highest impacts without chemical reactions (terpinolene, responsible for 0.14 μDALY/day), but indoor air chemistry led to high impacts linked to formaldehyde formation (0.18 μDALY/day). These reactions led to the formation of more formaldehyde, hence leading to 20% more impacts, in summer than in winter. Occupants’ contribution to CO2 concentrations exceeded recommended limits under the given occupancy and ventilation scenario. Secondary organic aerosol (SOA) formation affected indoor particulate matter mass concentrations by up to a factor 1.2 and their number concentrations by up to a factor 25,000 in the presence of VOC emissions. Results of this study indicate that chemical reactions and SOA formation are important factors to consider in indoor air quality impact assessment. A larger number of activities and scenarios can be tested to improve the robustness of the conclusions, since, under different scenarios (for e.g. activities with lower emission rates) and with more complete toxicity data, these conclusions are likely to change.

VOC emission rates from an indoor surface using a flux chamber and PTR-MS

Arising from the Chemical Assessment of Surfaces and Air (CASA) 2022 study at the National Institute of Standards and Technology (NIST) Net-Zero Energy Residential Test Facility (NZERTF), this paper presents the first evaluation of indoor surface emissions to a house measured with a surface flux chamber coupled to an online, non-targeted volatile organic compound (VOC) mass spectrometric detection. These surface emissions are compared to those assessed using ambient, whole house indoor VOC measurements and the outdoor air change rate. Chamber emission rates varied by almost four orders of magnitude across 35 quantified VOCs. The whole house emissions measured by campaign-long ambient measurements and the flux chamber emissions (when scaled to the painted surface area of the house) are similar, with an average ratio between the two of 1.3 ± 1.0. The general agreement between these two approaches indicates that the flux chamber was not solely measuring primary emissions from building materials located below the chamber. Rather, the results suggest that over the 12-year house lifetime, VOCs have been widely distributed around the house, migrating from their primary sources to secondary surface reservoirs. With the house in a quasi-steady state, the thermodynamic activities (i.e., the vapor pressures) of the VOCs within the different reservoirs become similar. Emissions of aromatics and monoterpenes have declined since the house was built, whereas aldehyde emissions have remained relatively constant.

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.

Bedroom Concentrations and Emissions of Volatile Organic Compounds during Sleep.

Because humans spend about one-third of their time asleep in their bedrooms and are themselves emission sources of volatile organic compounds (VOCs), it is important to specifically characterize the composition of the bedroom air that they experience during sleep. This work uses real-time indoor and outdoor measurements of volatile organic compounds (VOCs) to examine concentration enhancements in bedroom air during sleep and to calculate VOC emission rates associated with sleeping occupants. Gaseous VOCs were measured with proton-transfer reaction time-of-flight mass spectrometry during a multiweek residential monitoring campaign under normal occupancy conditions. Results indicate high emissions of nearly 100 VOCs and other species in the bedroom during sleeping periods as compared to the levels in other rooms of the same residence. Air change rates for the bedroom and, correspondingly, emission rates of sleeping-associated VOCs were determined for two bounding conditions: (1) air exchange between the bedroom and outdoors only and (2) air exchange between the bedroom and other indoor spaces only (as represented by measurements in the kitchen). VOCs from skin oil oxidation and personal care products were present, revealing that many emission pathways can be important occupant-associated emission factors affecting bedroom air composition in addition to direct emissions from building materials and furnishings.

Drought induces moderate, diverse changes in the odour of grassland species

Plants react to drought stress with numerous changes including altered emissions of volatile organic compounds (VOC) from leaves, which provide protection against oxidative tissue damage and mediate numerous biotic interactions. Despite the share of grasslands in the terrestrial biosphere, their importance as carbon sinks and their contribution to global biodiversity, little is known about the influence of drought on VOC profiles of grassland species. Using coupled gas chromatography-mass spectrometry, we analysed the odorants emitted by 22 European grassland species exposed to an eight-week-lasting drought treatment (DT; 30% water holding capacity, WHC). We focused on the odorants emitted during the light phase from whole plant shoots in their vegetative stage. Emission rates were standardised to the dry weight of each shoot. Well-watered (WW) plants (70% WHC) served as control. Drought-induced significant changes included an increase in total emission rates of plant VOC in six and a decrease in three species. Diverging effects on the number of emitted VOC (chemical richness) or on the Shannon diversity of the VOC profiles were detected in 13 species. Biosynthetic pathways-targeted analyses revealed 13 species showing drought-induced higher emission rates of VOC from one, two, three, or four major biosynthetic pathways (lipoxygenase, shikimate, mevalonate and methylerythritol phosphate pathway), while six species exhibited reduced emission rates from one or two of these pathways. Similarity trees of odorant profiles and their drought-induced changes based on a biosynthetically informed distance metric did not match species phylogeny. However, a phylogenetic signal was detected for the amount of terpenoids released by the studied species under WW and DT conditions. A comparative analysis of emission rates of single compounds released by WW and DT plants revealed significant VOC profile dissimilarities in four species only. The moderate drought-induced changes in the odorant emissions of grassland species are discussed with respect to their impact on trophic interactions across the food web. (294 words)

Jingle bells, what are those smells? Indoor VOC emissions from a live Christmas tree

Every year in the United States conifers are purchased to serve as Christmas trees in homes where they emit volatile organic compounds (VOCs) to the indoor environment. Although many studies have measured the ecosystem-level emissions of VOCs from conifers outdoors (characterizing monoterpene, isoprene, and aldehyde emissions), little is known about VOC emission rates once a conifer is brought indoors. Using a proton transfer reaction-mass spectrometer we characterized the VOCs emitted from a freshly cut Douglas Fir for 17 days in an environmentally controlled chamber. Ozone injections were also performed to analyze indoor chemistry that may occur. Introduction of the tree into the chamber increased the response of 52 mass spectra signals detected by the PTR-MS by at least 500 counts per second (cps) compared to background levels, with concentrations sharply decreasing after the first two days. Monoterpenes were emitted from the tree at a rate of 12.4 mg h−1 the first day and fell to 1 mg h−1 by day three. Overall, monoterpene emissions from this Douglas fir were initially comparable to other strong indoor monoterpene sources (fragranced products and air fresheners) but decayed quickly and, within days, were smaller than other common indoor sources. Addition of ozone to the chamber resulted in decreased monoterpene concentrations that coincided with modest increases in formaldehyde. Four other emitted VOCs were tentatively identified due to their large increase within the first few hours of the tree placed in the chamber, behavior during ozonation, or pattern of accumulation over time.

Seasonal and Elevational Variability in Dwarf Birch VOC Emissions in Greenlandic Tundra

AbstractRising temperatures amplify biogenic volatile organic compound (VOC) emissions from Arctic vegetation, causing feedbacks to the climate system. Changes in climate also alter plant physiology and vegetation composition, all of which can influence VOC emissions. Moreover, leaf development and biotic stresses cause highly variable emissions during the growing season. Therefore, linking VOC emissions with plant traits and tracking responses to climate change might provide better understanding of VOC emission regulation under future conditions. We measured VOC emissions and other plant traits in dwarf birch (Betula glandulosa) at two elevations in Narsarsuaq, South Greenland. The measurements were performed in warming experiments that have run since 2016. We collected VOCs using the branch enclosure method from early June until late July 2019 (n = 200). Emissions of green leaf volatiles (GLVs), oxygenated monoterpenes (oMTs), and homoterpenes followed a seasonal trend. VOC emission rates and the diversity of the VOC blend decreased at the end of the measurement period. Differences in VOC emission rates between elevations were pronounced early in the season. Majority of the traits did not explain the variation in VOC emissions. We show strong seasonal variability in VOC emissions within the growing season, which is likely driven by leaf phenology. While the diversity of VOCs was greater at the milder low‐elevation site, VOC emission rates were higher or similar at the harsher high‐elevation site, showing stronger VOC emission potentials than previously assumed. Seasonal variations in the emissions of VOCs are crucial for accurate predictions of current and future VOC emissions from arctic ecosystems.

Emission of volatile organic compounds from residential biomass burning and their rapid chemical transformations

Biomass combustion releases a complex array of Volatile Organic Compounds (VOCs) that pose significant challenges to air quality and human health. Although biomass burning has been extensively studied at ecosystem levels, understanding the atmospheric transformation and impact on air quality of emissions in urban environments remains challenging due to complex sources and burning materials. In this study, we investigate the VOC emission rates and atmospheric chemical processing of predominantly wood burning emissions in a small urban centre in Greece. Ioannina is situated in a valley within the Dinaric Alps and experiences intense atmospheric pollution accumulation during winter due to its topography and high wood burning activity. During pollution event days, the ambient mixing ratios of key VOC species were found to be similar to those reported for major urban centres worldwide. Positive matrix factorisation (PMF) analysis revealed that biomass burning was the dominant emission source (>50 %), representing two thirds of OH reactivity, which indicates a highly reactive atmospheric mixture. Calculated OH reactivity ranges from 5 s−1 to an unprecedented 278 s−1, and averages at 93 ± 66 s−1 at 9 PM, indicating the presence of exceptionally reactive VOCs. The highly pronounced photochemical formation of organic acids coincided with the formation of ozone, highlighting the significance of secondary formation of pollutants in poorly ventilated urban areas. Our findings underscore the pressing need to transition from wood burning to environmentally friendly sources of energy in poorly ventilated urban areas, in order to improve air quality and safeguard public health.

Variations in VOCs Emissions and Their O3 and SOA Formation Potential among Different Ages of Plant Foliage.

Volatile organic compounds (VOCs) emitted by plant foliage play an important role in ozone (O3) and secondary organic aerosol (SOA) formation. Their emissions can be influenced by the leaf age. We explored the VOCs emissions and their effects on the formation of O3 and SOA from plant foliage in different ages. VOCs emissions from the young, mature, and senescent leaves of Ginkgo biloba, Ligustrum lucidum, and Forsythia suspensa were measured using the dynamic enclosure system and the TD-GC-MS technique. Based on the emission rates of quantified compounds, their potential to form O3 and SOA was estimated. Results showed that there were significant differences in the VOCs emission rate and their composition among leaves in different ages. The emission rate of the total VOCs by young leaves was the highest, while the lowest by senescent leaves. Monoterpenes were the dominant VOCs category, and isoprene emission had the lowest contribution for the leaves at each age. With increasing leaf age, the proportion of monoterpenes emission increased, and the proportion of sesquiterpenes decreased. The variations of isoprene and other VOCs were different. The potentials of total VOCs, isoprene, monoterpenes, sesquiterpenes, and other VOCs to form O3 (OFP) and SOA (SOAP) varied significantly among leaves at different ages. The total OFP and SOAP were the highest by young leaves, while the lowest by senescent leaves. With increasing leaf age, the contribution of monoterpenes to OFP and SOAP also increased, while that of sesquiterpenes decreased. Our study will provide support for the more accurate parameterization of the emission model and help to understand the VOCs emissions and study the precise prevention and control of complex air pollution at different times.

Indoor monoterpene emission rates from commercial cannabis cultivation facilities in Colorado

ABSTRACT In 2019, an air emissions field sampling study was conducted by the Colorado Department of Public Health and Environment’s Air Pollution Control Division (APCD) at four commercial cannabis cultivation facilities. Measurements of ambient biogenic volatile organic compounds (VOC) concentrations were collected from various growing stages of cannabis (vegetative and flowering) and during post-harvest activities (drying and trimming). These data were then used to determine room-specific biogenic VOC emission rates for three of the facilities from the vegetative stage of the life cycle through post-harvest activities. This study shows that the magnitude of biogenic VOC emissions within a cannabis cultivation facility varies widely with the highest emission rates of up to 7.18E–1 kg/hr found during mechanical trimming and up to 2.33E–1 kg/hr in the drying rooms. These were up to an order of magnitude higher than emission rates found in the cultivation rooms. For example, Facility A vegetative room had an emissions rate of 1.46E–2 kg/hr. Normalized by the amount of biomass present, the drying rooms had the highest VOC emissions rates, with a maximum rate of 1.6E–3 kg/hr/kg biomass. The flowering room rates were found to be up to 3.25E–4 kg/hr/kg biomass and drying rooms up to 1.16E–3 kg/hr/kg biomass. When normalized by plant count, emission rates in the flower rooms ranged from 8.11E–6 to 3.62E–4 kg/hr/plant. The dominant monoterpenes from sampling were β-myrcene, terpinolene, and D-limonene. These data suggest that the variability in emission rates across cannabis production will create a challenge in establishing a generalized emission factor for all facilities. Across the industry, cannabis cultivation conditions and strategies can vary widely impacting the amount and type of VOC emissions. Minimizing uncertainties for VOC emission from cannabis facilities requires site-specific information on air exchange rates, plant counts, cannabis strains, biomass, and if hand or mechanical processing is used. Implications: This study found that the magnitude of biogenic VOC emissions within a cannabis cultivation varies widely throughout rooms found in the facility, with the highest emissions found during post-harvest activities (i.e. trimming) and the lowest rates in the vegetative room. These data suggest that the large emission sources of VOCs are found post-harvest and emission inventories based solely on cultivation emissions will underestimate total biogenic VOC emissions from indoor cannabis cultivation facilities. The dominant measured terpenes throughout all facilities from cultivation to post harvest were: β-myrcene, terpinolene, and D-limonene.

Volatile organic compound release across a permafrost-affected peatland

As the permafrost region experiences unprecedented climate warming, accelerated decomposition rates are potentially switching these cold landscapes to a hotspot of carbon emissions. In addition to the more widely studied greenhouse gases, carbon dioxide and methane, permafrost-affected soils may also be a source of volatile organic compounds (VOCs), but these reactive trace gases have so far received little attention. Nevertheless, VOCs can i) prolong the lifetime of atmospheric methane, ii) contribute to hazardous ozone production, and iii) lead to the formation of secondary organic aerosols. Consequently, changing VOC emissions may exert significant impacts on climate forcing factors that can both exacerbate or mitigate future climate change. Here, we conducted in situ measurements of soil and pond VOC emissions across an actively degrading permafrost-affected peatland in subarctic Norway. We used a permafrost thaw gradient as a space-for-time substitute that covered bare soil and vegetated peat plateaus, underlain by intact permafrost, and increasingly degraded permafrost landscapes: thaw slumps, thaw ponds, and vegetated thaw ponds. Results showed that every peatland landscape type was an important source of atmospheric VOCs, emitting a large variety of compounds, such as methanol, acetone, monoterpenes, sesquiterpenes, isoprene, hydrocarbons, and oxygenated VOCs. VOC composition varied considerably across the measurement period and across the permafrost thaw gradient. We observed enhanced terpenoid emissions following thaw slump degradation, highlighting the potential atmospheric impacts of permafrost thaw, due to the high chemical reactivities of terpenoid compounds. Higher VOC emission rates were observed in summer (June, July and August) compared to early autumn (September). Overall, our study demonstrates that VOCs are being emitted in significant quantities and with largely similar compositions upon permafrost thawing, inundation, and subsequent vegetation development, despite major differences in microclimate, hydrological regime, vegetation, and permafrost occurrence.

Effect of farm Hazard Analysis and Critical Control Point (farm HACCP) certification efforts on emissions of volatile organic compounds from livestock sheds in Japan.

"Farm HACCP" incorporates the concept of Hazard Analysis and Critical Control Points (HACCP) into farm animal husbandry and sanitation management to ensure the safety of livestock products and improve productivity. Implementing farm HACCP may reduce the emission of volatile organic compounds (VOCs), which are derived from livestock manure and are responsible for odors, PM2.5 , and photochemical oxidants. In this study, the effects of implementing farm HACCP on the emissions, composition, and environmental impact of VOCs from sheds were evaluated. VOCs in swine, dairy cattle, and hen sheds were measured before and after implementing farm HACCP. After implementing farm HACCP, the concentrations in the sheds were 55%-80% lower than the concentration in the sheds before. Odor activity values decreased in the cattle and hen sheds, whereas they increased in the swine shed. In addition, OH radical reactivity, an indicator of reactivity with OH radicals, decreased in all sheds. Finally, the emission rates of VOCs from each shed were estimated to be 42%-97% lower. These results suggest that implementing farm HACCP can reduce emissions of VOCs from livestock industries.

Temperature dependence of volatile organic compound emissions from surface coatings: Inter-species difference observed in real indoor environments and mechanistic understanding

Coatings often cover two-thirds of the surfaces in indoor environments and represent important sources of indoor volatile organic compounds (VOCs). Temperature is known to affect VOC emission rates from coatings, yet inter-species difference in the temperature dependence still needs to be understood. Based on time-resolved VOC measurements in an indoor air campaign conducted in residences in Beijing, China, we identified dibasic ester (DBE), a solvent mixture often used in coatings, and found that the concentration ratios of DBE components exhibited strong temperature dependence in an apartment when the indoor temperature declined stepwise over a multiweek period. To interpret the observational results, we developed a simplified mechanistic model relating the temperature dependence of VOC emission rates from coated surfaces to the temperature dependence of the diffusion coefficient of the emitted VOCs in the coating layer and further to a predicable molecular property of the emitted VOCs, molar volumes at 0 K, based on the free-volume theory. This correlation was quantitatively verified using the DBE data as well as using the data of alkanes, another set of VOCs that might be emitted from coatings, observed in two apartments in the same campaign. Given that indoor temperature varies considerably over seasons and across regions, the correlation proposed herein may help better predict indoor VOC emissions from coatings.

Volatile Compound Emissions from Stereolithography Three-Dimensional Printed Cured Resin Models for Biomedical Applications.

Stereolithography three-dimensional printing is used increasingly in biomedical applications to create components for use in healthcare and therapy. The exposure of patients to volatile organic compounds (VOCs) emitted from cured resins represents an element of concern in such applications. Here, we investigate the biocompatibility in relation to inhalation exposure of volatile emissions of three different cured commercial resins for use in printing a mouthpiece adapter for sampling exhaled breath. VOC emission rates were estimated based on direct analysis using a microchamber/thermal extractor coupled to a proton transfer reaction-mass spectrometer. Complementary analyses using comprehensive gas chromatography-mass spectrometry aided compound identification. Major VOCs emitted from the cured resins were associated with polymerization agents, additives, and postprocessing procedures and included alcohols, aldehydes, ketones, hydrocarbons, esters, and terpenes. Total VOC emissions from cubes printed using the general-purpose resin were approximately an order of magnitude higher than those of the cubes printed using resins dedicated to biomedical applications at the respective test temperatures (40 and 25 °C). Daily inhalation exposures were estimated and compared with daily tolerable intake levels or standard thresholds of toxicological concerns. The two resins intended for biomedical applications were deemed suitable for fabricating an adapter mouthpiece for use in breath research. The general-purpose resin was unsuitable, with daily inhalation exposures for breath sampling applications at 40 °C estimated at 310 μg day-1 for propylene glycol (tolerable intake (TI) limit of 190 μg day-1) and 1254 μg day-1 for methyl acrylate (TI of 43 μg day-1).

Distribution characteristics, air-water exchange, ozone formation potential and health risk assessments of VOCs emitted from typical coking wastewater treatment process

Coking industry has been considered as important source of volatile organic compounds (VOCs) emissions. However, few studies have emphasized the occurrence and adverse effects of VOCs from coking wastewater treatment processes. In this research, pollution profiles of both air and water phase VOCs in a typical coking wastewater treatment plant were investigated in terms of distribution characteristics, air-water exchange, ozone formation potential (OFP) and associated human health risks. Thirty VOCs were detected in the air phase, in which benzene and naphthalene were found to be the major VOCs with total contribution of 87.81 %. Nineteen VOCs were detected in the water phase, in which benzene, naphthalene and toluene contribute most to total VOCs with total contribution of 75.1 %. The regulating tank (RT) was the major source of VOCs, and the emission rate of total VOCs from all unites was 2711.03 g/d with annual emission of 0.99 t. The emission factor was estimated to be 1.36 g VOCs/m3 wastewater. The air-water exchange was assessed using the Fugacity model, and water-to-air volatilization was predominant based on the net flux of air-water exchange. OFP evaluated by emission factor indicated that the total OFP in RT was the highest (1.52 g O3/m3 wastewater), and toluene contributed 41.8 % of the total OFP, followed by naphthalene accounting for 38.7 % The total carcinogenic risks were in the range of 8.60 × 10−6 to 2.18 × 10−3, in which the RT exceeded the significant risk threshold (>1 × 10−4). The non-carcinogenic risks of hazard quotient value in RT also exceeded the risk threshold (>1), and naphthalene was the major contributor accounting for 79.02 %. These results not only provided comprehensive knowledge on pollution profiles and environmental risks of VOCs during coking wastewater treatment processes, but also facilitated the implement of VOCs regulation and occupational health protection strategies in coking industries.

Estimation of Anthropogenic VOCs Emission Based on Volatile Chemical Products: A Canadian Perspective.

Volatile organic compounds (VOCs) in urban areas are of great interest due to their significant role in forming ground-level ozone and adverse public health effects. Emission inventories usually compile the outdoor VOCs emission sources (e.g., traffic and industrial emissions). However, considering emissions from volatile chemical products (e.g., solvents, printing ink, personal care products) is challenging because of scattered data and the lack of an effective method to estimate the VOCs emission rate from these chemical products. This paper aims to systematically analyse potential sources of VOCs emission in Canada's built environment, including volatile chemical products. Also, spatial variation of VOCs level in the ambient atmosphere is examined to understand the VOC relationship with ozone and secondary organic aerosol formation. The study shows that VOCs level may vary among everyday microenvironments (e.g., residential areas, offices, and retail stores) depending on the frequency of product consumption, building age, ventilation condition, and background ambient concentration in the atmosphere. However, it is very difficult to establish VOC speciation and apportionment to different volatile chemical products that contribute most significantly to exposure and target subpopulations with elevated levels. Thus, tracer compounds can be used to identify inventory sources at the consumer end. A critical overview highlights the limitations of existing VOC estimation methods and possible approaches to control VOC emissions. The findings provide crucial information to establish an emission inventory framework for volatile chemical products at a national scale and enable policymakers to limit VOCs emission from various volatile chemical products.

Experimental evaluation on liquid area sources: Influence of wind velocity and temperature on the wind tunnel sampling of VOCs emissions from wastewater treatment plants

The investigation of Volatile Organic Compounds (VOCs) emission from wastewater basins is a challenging issue. In particular, the quantification of an accurate emission rate appears quite tricky, since the release of VOC compounds from this type of source, and the subsequent dispersion into the atmosphere, is ruled by different complex phenomena, potentially affected by a variety of external chemical and physical parameters. In this regard, the wind velocity and the liquid temperature represent variables that are worth investigating. Given this, the present paper discusses an experimental study aimed at evaluating the influence of these variables on the emission rate of VOCs (i.e. acetone, toluene and butanol) in solution with water at low concentrations (0.5 mL/L and 5 mL/L). The experimental trials are conducted using a wind tunnel system, changing the sweep air flow from 0.02 m/s to about 0.06 m/s and the liquid temperature from 20 °C to 35 °C. This study reveals that while the wind velocity seems to slightly influence the emission rate of VOCs estimated by wind tunnel sampling, the effect of the temperature appears much more significant. This behaviour is also confirmed by experimental trials conducted on real-case industrial wastewater, coming from an equalization tank. In view of this, the approach commonly applied to evaluate the influence of wind velocity (i.e. a dependence of the odour emission rate on the square root of the wind velocity) appears not fully consistent with the experimental results obtained at low concentrations by wind tunnel sampling. Also, the influence of temperature seems more pronounced in the case of butanol, in accordance with the theoretical trend of Henry constant as a function of temperature.

Volatile organic compound emissions from the human body: Decoupling and comparison between whole-body skin and breath emissions

The human body can affect indoor air by emitting volatile organic compounds (VOCs) through breath and skin. However, studies on the quantitative characteristics of skin VOC emissions are scarce compared to those on the characteristics of breath emissions. Moreover, the species and emission rates of VOCs emitted from the breath and whole-body skin of a single person have rarely been reported. In this study, VOCs emitted from the whole-body skin and breath of 14 young adults under controlled conditions were decoupled and measured. The number of VOC species emitted from each study participant's whole-body skin and breath ranged 38–69 and 28–55, respectively, with total emission rates of all detected VOCs of 164–518 and 286–1030 μg/h, respectively. The VOCs in the high-detection rate intervals also had higher emission rates, increasing their importance in human body emissions. There were 9–26 common VOCs and 25–47 different VOCs between the skin and breath emissions. Acetone was detected in both the skin and breath emissions of all study participants, with the highest emission rate in each participant's whole-body emissions. Ketones, siloxanes, aldehydes, and alcohols contributed the most to the whole-body skin emission rates of each study participant, whereas ketones and alkenes alone accounted for most of the breath emission rates. Analysis of the generation mechanisms found that endogenous and exogenous VOCs were dominant in breath and skin emissions, respectively. These results can enrich the qualitative and quantitative characteristics of breath and skin emissions and improve understanding of emission mechanisms.

Volatile organic compound emissions from subarctic mosses and lichens

Plant volatile organic compound (VOC) emissions can drive important climate feedbacks. Although mosses and lichens are important components of plant communities, their VOC emissions are poorly understood. It is crucial to obtain more knowledge on moss and lichen VOCs to improve ecosystem VOC emission models. This is especially relevant at high latitudes, where mosses and lichens are abundant and VOC emissions are expected to increase in response to climate change. In this study, we examined VOC emissions from four common moss (Hylocomium splendens, Pleurozium schreberi, Sphagnum warnstorfii, and Tomentypnum nitens) and lichen (Cladonia arbuscula, Cladonia mitis, Cladonia pleurota, and Nephroma arcticum) species in the Subarctic using gas chromatography-mass spectrometry (GC-MS) and proton-transfer-reaction time-of-flight mass spectrometry. Moss and lichen VOC emissions were dominated by low molecular weight (LMW) VOCs, such as acetone and acetaldehyde, as well as hydrocarbons (HCs) and oxygenated VOCs (oVOCs). Of the studied mosses, S. warnstrofii had the highest and H. splendens had the lowest total VOC emission rates. The VOC emission blends of P. schreberi, S. warnstrofii, and T. nitens were clearly distinct from one another. Of the lichens, N. arcticum had a different VOC blend than the Cladonia spp. N. arcticum also had higher emission rates of HCs, oVOCs, and other GC-MS-based VOCs, but lower LMW VOC emission rates than the other lichen species. Our study demonstrates that mosses and lichens emit considerable amounts of various VOCs and that these emissions are species dependent.

Relationships between Volatile Organic Compounds Released by Wheat Plants Following Artificial Stress and Their Potential Influence on Natural Pest Management

There is an urgent need to establish new agro-technical practices that require the delivery of effective, natural, ecological, and verified solutions. The evaluation of possible applications in the field of cropping and farming in recent years has resulted in numerous products and approaches, which may potentially reduce our dependence on artificial pesticides. A major requirement to help establish these new agro-technical practices is to determine their efficiency. Here we present a study that investigates the relationship between volatile organic compounds (VOCs) released by Triticum sp. plants under two artificial stress conditions. We discuss their effectiveness in natural pest management and for use in monitoring crop health. Two varieties of spring wheat, “Kandela” and “Serenada”, were exposed to either mechanical (deliberate) wounding, to imitate the stress caused by insect attack, or exposure to methyl jasmonate, a defence volatile used by plants. Both stress factors caused an increased release of green leaf volatiles (C6 aldehydes and alcohols) and other volatile compounds, such as (E)-β-ocimene, linalool, β-caryophyllene, and (E)-β-farnesene. VOC emission rates are reported at three time points (24, 48, and 72 h) following a stress factor. Correlation coefficients between the emitted plant’s VOCs indicate the potential of monitoring just one single compound from the combination of volatiles emitted by plants to predict the overall condition of a crop. This has major implications for the development of a chemically specific and fieldable analytical sensor that could be used to provide an array of volatile monitoring stations delivering information continuously and in real-time. Finally, we demonstrate the effectiveness of the volatiles released by damaged spring wheat for pest management by exposing a shield bug (Bishop’s Mitre (Aelia acuminata L.), Hemiptera: Pentatomidae), to them.