Search Results (25)

This study investigates the emission characteristics and environmental impacts of pollutants from bagasse-fired biomass boilers through the integrated field monitoring of two sugarcane processing plants in Guangxi, China. Comprehensive analyses of flue gas components, including PM_2.5, NOx, CO, heavy metals, VOCs, HCl, and HF, revealed distinct physicochemical and emission profiles. Bagasse exhibited lower C, H, and S content but higher moisture (47~53%) and O (24~30%) levels compared to coal, reducing the calorific values (8.93~11.89 MJ/kg). Particulate matter removal efficiency exceeded 98% (water film dust collector) and 95% (bag filter), while NOx removal varied (10~56%) due to water solubility differences. Heavy metals (Cu, Cr, Ni, Pb) in fuel migrated to fly ash and flue gas, with Hg and Mn showing notable volatility. VOC speciation identified oxygenated compounds (OVOCs, 87%) as dominant in small boilers, while aromatics (60%) and alkenes (34%) prevailed in larger systems. Ozone formation potential (OFP: 3.34~4.39 mg/m³) and secondary organic aerosol formation potential (SOAFP: 0.33~1.9 mg/m³) highlighted aromatic hydrocarbons (e.g., benzene, xylene) as critical contributors to secondary pollution. Despite compliance with current emission standards (e.g., PM < 20 mg/m³), elevated CO (>1000 mg/m³) in large boilers indicated incomplete combustion. This work underscores the necessity of tailored control strategies for OVOCs, aromatics, and heavy metals, advocating for stricter fuel quality and clear emission standards to align biomass energy utilization with environmental sustainability goals. Full article

Many US states have adopted regulations to divert food waste from landfills to composts. While this may lower greenhouse emissions from landfills, volatile organic compound (VOC) emissions from compost may contain hazardous air pollutants or produce odors, posing potential public health concerns. Effective methods to analyze speciated VOCs in compost are needed to better understand VOC source generation. Here, a two-component compost sampling method was developed and employed consisting of a chilled impinger and pump apparatus to trap water-soluble VOCs, and dual sorbent tubes to capture hydrophobic VOCs in yard and food/yard waste compost. VOCs were measured via headspace gas chromatography with flame ionization detection (HS-GC-FID) and thermal desorption–gas chromatography–mass spectrometry (TD-GC-MS). Overall, there was higher VOC generation within higher-temperature compost piles, with concentrations ranging up to 27,000 ppm for ethanol and 3500 ppm for methanol. Alpha-pinene and D-limonene were seen in these piles with concentrations over 1600 ppb. Methanol and ethanol were more than one thousand times as concentrated in mixed food/yard waste than yard waste alone, while terpenes were seen in slightly higher concentrations for yard waste than the mixed food/yard waste. Methanol was observed to be higher than permissible indoor levels and may pose potential health risks. Full article

This study investigates the chemical complexity and toxicity of volatile organic compounds (VOCs) emitted from national petrochemical industrial parks and their effects on air quality in an industrial area of Nanjing, China. Field measurements were conducted from 1 December 2022, to 17 April 2023, focusing on VOC concentrations and speciations, diurnal variations, ozone formation potential (OFP), source identification, and associated health risks. The results revealed an average total VOC (TVOC) concentration of 15.9 ± 12.9 ppb and an average OFP of 90.1 ± 109.5 μg m⁻³. Alkanes constituted the largest fraction of VOCs, accounting for 44.1%, while alkenes emerged as the primary contributors to OFP, comprising 52.8%. TVOC concentrations peaked before dawn, a pattern attributed to early morning industrial activities and nighttime heavy vehicle operations. During periods classified as clean, when ozone levels were below 160 μg m⁻³, both TVOC (15.9 ± 12.9 ppb) and OFP (90.4 ± 110.0 μg m⁻³) concentrations were higher than those during polluted hours. The analysis identified the key sources of VOC emissions, including automobile exhaust, oil and gas evaporation, and industrial discharges, with additional potential pollution sources identified in adjacent regions. Health risk assessments indicated that acrolein exceeded the non-carcinogenic risk threshold at specific times. Moreover, trichloromethane, 1,3-butadiene, 1,2-dichloroethane, and benzene were found to surpass the acceptable lifetime carcinogenic risk level (1 × 10⁻⁶) during certain periods. These findings highlight the urgent need for enhanced monitoring and regulatory measures aimed at mitigating VOC emissions and protecting public health in industrial areas. In the context of complex air pollution in urban industrial areas, policymakers should focus on controlling industrial and vehicle emissions, which can not only reduce secondary pollution, but also inhibit the harm of toxic substances on human health. Full article

Background: The fragrance and aroma of Rosaceae plants are complex traits influenced by a multitude of factors, with genetic variation standing out as a key determinant which is largely impacted by polyploidy. Polyploidy serves as a crucial evolutionary mechanism in plants, significantly boosting genetic diversity and fostering speciation. Objective: This review focuses on the Rosaceae family, emphasizing how polyploidy influences the production of volatile organic compounds (VOCs), which are essential for the aromatic characteristics of economically important fruits like strawberries, apples, and cherries. The review delves into the biochemical pathways responsible for VOC biosynthesis, particularly highlighting the roles of terpenoids, esters alcohols, aldehydes, ketones, phenolics, hydrocarbons, alongside the genetic mechanisms that regulate these pathways. Key enzymes, such as terpene synthases and alcohol acyltransferases, are central to this process. This review further explores how polyploidy and hybridization can lead to the development of novel metabolic pathways, contributing to greater phenotypic diversity and complexity in fruit aromas. It underscores the importance of gene dosage effects, isoenzyme diversity, and regulatory elements in determining VOC profiles. Conclusions: These findings provide valuable insights for breeding strategies aimed at improving fruit quality and aligning with consumer preferences. Present review not only elucidates the complex interplay between genomic evolution and fruit aroma but also offers a framework for future investigations in plant biology and agricultural innovation. Full article

Volatile organic compound (VOC) emissions to the atmosphere cause air pollution associated with adverse health outcomes. Volatile chemical products (VCPs) have emerged as a VOC emission category that is poorly characterized by air pollution models. VCPs are present throughout developed economies in manufactured products that include paints, cleaning agents, printing inks, adhesives and pesticides. Air quality models must accurately represent the atmospheric chemistry of VCPs to develop reliable air quality plans. We develop a chemical mechanism for oxidant formation by VCP compounds that is compatible with version 6 of the Carbon Bond (CB6) mechanism. We analyzed a recent U.S. VCP emission inventory and found that ~67% of the emissions mass can be well-represented by existing CB6 mechanism species but ~33% could be better represented by adding 16 emitted VCP species including alcohols, ethers, esters, alkanes and siloxanes. For larger alkanes, an important VCP category, our mechanism explicitly represents temperature-dependent organic nitrate formation and autoxidation via 1,6 H-shift reactions consistent with current knowledge. We characterized the ozone forming potential of each added VCP species and compared it to the current practice of representing VCP species by surrogate species. Nine of the sixteen added VCP species are less reactive than the current practice, namely i-propanol, dimethyl ether, methyl formate, ethyl formate, methyl acetate, larger esters, i-butane, large alkanes and siloxanes. These less reactive VCP species are characterized by having OH-reactions that form un-reactive products. A total of 7 of the 16 VCP species are more reactive than current practice, namely n-propanol, ethylene glycol, propylene glycol, larger alcohols, diethyl ether, larger ethers and ethyl acetate. These more reactive VCP species are characterized as containing functional groups that promote faster OH-reaction. The VCP chemical mechanism for CB6 can improve how VCP impacts to oxidants are represented and will be incorporated to CB7. Changes in oxidant formation resulting from the mechanism update will depend on how VCP emissions are speciated for modeling, which is uncertain, and impacts may go in opposite directions for specific categories of VCP emissions that have unique chemical speciation characteristics. We provide guidance to help modelers implement the VCP mechanism update. Full article

Industrial emissions of trace gases and VOCs can be an important contributor to air quality in cities. Disentangling different point sources from each other and characterizing their emissions can be particularly challenging in dense industrial areas, such as Detroit, Dearborn and surrounding areas in Southeast Michigan (SEMI). Here, we leverage mobile measurements of trace gases and speciated volatile organic compounds (VOCs) to identify emitting sites. We characterize their complicated emissions fingerprints based on a core set of chemical ratios. We report chemical ratios for 7 source types including automakers, steel manufacturers, chemical refineries, industrial chemical use (cleaning; coatings; etc.), chemical waste sites, compressor stations, and more. The source dataset includes visits to over 85 distinct point sources. As expected, we find similarities between the different types of facilities, but observe variability between them and even at individual facilities day-to-day. Certain larger sites are better thought of as a collection of individual point sources. These results demonstrate the power of mobile laboratories over stationary sampling in dense industrial areas. Full article

Air quality is a prevalent concern due to its imposing health risks. The state of Utah, USA, at times over the last 20 years has suffered from some of the worst air quality in the nation. The propensity for the state of Utah to experience elevated concentrations of particulate matter and ozone can in part be attributed to its unique geography that features dry, mountainous topography. Valleys in Utah create ideal environments for extended cold-pool events. In this review, we summarize the research executed in Utah over the past 20 years (2002–2022) by dividing the state into six regions: Utah Valley, Summit County, Southern Utah (regions south of Utah Valley), Cache Valley, Uinta Basin, and Salt Lake Valley. We review the published literature chronologically and provide a summary of each region identifying areas where additional research is warranted. We found that the research effort is weighted towards Uinta Basin and Salt Lake Valley, with the other regions in Utah only adding up to 20% of the research effort. We identified a need for more source apportionment studies, speciated volatile organic compound (VOC) studies, and ozone isopleths. Where ozone isopleths are not able to be created, measurement of glyoxal and formaldehyde concentrations could serve as surrogates for more expensive studies to inform ozone mitigation policies. Full article

Volatile Organic Compounds (VOCs) are prevalent emissions from a plethora of industries, known for their role in the formation of atmospheric ozone, thus contributing to secondary pollution. Both the United States and the European Union have presented various regulatory measures to mitigate VOC emissions. Nevertheless, the diversity of VOCs, some exhibiting carcinogenic properties, pose substantial challenges in devising comprehensive mitigation strategies. In light of this, the current study focuses on the synthetic rubber manufacturing industry, specifically analyzing VOCs with high emission volumes and elevated Photochemical Ozone Creation Potentials (POCPs). A total of 88 compounds, including PM-57 and TO-14A, were examined in this study. The Active and Passive monitoring methods, two out of the six recommended by the Environmental Protection Agency (EPA) for Fenceline monitoring, were employed. For business entity ‘A’, the Active method revealed the highest emission rates of n-butane (13.5%) and n-Pentane (12.8%). In contrast, the Passive method indicated styrene (9.4%) and toluene (8.1%) as the most prominently emitted compounds. Benzene, though detected at all points ranging from 1~3 µg/m³, is not manipulated in this industry, suggesting potential influence from neighboring enterprises. Compounds such as benzene, toluene, ethylbenzene, xylene, and styrene demonstrated convertible concentrations using both Active and Passive methods, detected within the range of 0~3 µg/m³. Notably, the average concentrations determined by both methods exhibited remarkable similarity. For business entity ‘B’, the Active method detected significant levels of n-hexane (45.0%) and methylcyclopentane (14.4%), whereas the Passive method identified high concentrations of n-hexane (37.7%) and isopentane (8.8%). A general pattern emerged where high concentrations were exhibited at points 9, 10, and 11, located within the production area, while points 1, 2, and 3 displayed lower concentrations, likely due to the influence of eastward wind patterns. In terms of compounds with high POCPs, business entity ‘A’ demonstrated substantial emission of n-butane (38.80%) and n-hexane (27.15%) using the Active method, and toluene (28.62%) and n-hexane (25.23%) via the Passive method. For business entity ‘B’, n-hexane emerged dominantly, detected at 84.57% using the Active method and 68.85% via the Passive method. This suggests that in the synthetic rubber manufacturing industry, n-hexane should be prioritized in formulating effective emission reduction strategies. Full article

While transportation emissions have declined over the past several decades, volatile organic compound (VOC) emissions from solvent use applications have increased as urban areas expand. In this work, the Canadian air quality model (GEM-MACH-TEB) is used to assess the importance of solvent emissions during the Michigan Ontario Ozone Source Experiment (MOOSE). Model predictions are compared to ozone and total mono-substituted aromatics (TOLU) observations collected in Windsor, Ontario. For summer 2018, model estimates of TOLU from solvent emissions are smaller (30% for an 8 h daytime average) in Windsor than estimates from positive matrix factorization (44% for a 24 h average). The use of updated U.S. solvent emissions from the EPA’s VCPy (Volatile Chemical Product framework) for summer 2021 simulations increases the solvent use source contribution over Detroit/Windsor (30–50% for an 8 h daytime average). This also provides a more uniform spatial distribution across the U.S./Canada border (30–50% for an 8 h daytime average). Long-chain alkanes are the dominant speciation in the model’s air pollutant emission inventory and in the observation-derived solvent use factor. Summertime 8 h daytime ozone decreased by 0.4% over Windsor for a 10% solvent use VOC emission reduction scenario. A 10% mobile NO_x emission reduction scenario resulted in a 0.6% O₃ decrease over Windsor and more widespread changes over the study region. Full article

The speciation of volatile organic compounds (VOCs) emitted from personal care products (PCPs) is complex and contributes to poor air quality and health risks to users via the inhalation exposure pathway. Detailed VOC emission profiles were generated for 26 sunscreen products; consequently, variability was observed between products, even though they were all designed for the same purpose. Some were found to contain fragrance compounds not labelled on their ingredients list. Five contaminant VOCs were identified (benzene, toluene, ethylbenzene, o-xylene, and p-xylene); headspace sampling of an additional 18 randomly selected products indicated that ethanol originating from fossil petroleum was a potential source. The gas phase emission rates of the VOCs were quantified for 15 of the most commonly emitted species using SIFT-MS. A wide range of emission rates were observed between the products. Usage estimates were made based on the recommended dose per body surface area, for which the total mass of VOCs emitted from one full-body application dose was in the range of 1.49 × 10³–4.52 × 10³ mg and 1.35 × 10²–4.11 × 10² mg for facial application (men aged 16+; children aged 2–4). Depending on age and sex, an estimated 9.8–30 mg of ethanol is inhaled from one facial application of sunscreen. Full article

The petroleum refining industry emits various volatile organic compounds (VOCs), including high-volatility benzene, which can have a significant impact on the local community. To address this issue, the US Environmental Protection Agency (EPA) has implemented a fenceline monitoring system to ensure that benzene concentrations at the fenceline do not exceed 9 μg/m³. However, there are various types of VOCs, and some with high potential atmospheric oxidation (POCP) values, that may cause secondary air pollution. This study found that both study sites exceeded the action level of benzene (9 μg/m³), and the locations where the level was exceeded were close to the crude distillation unit (CDU) (max concentration 34.07 μg/m³). Additionally, a significant amount of xylene with a high POCP was also released. The xylene emission rate of study site A was 27.71%, and the xylene emission rate of study site B was 46.75%. Therefore, it is necessary to reduce both high-volatility benzene and high-POCP xylene. In various industries that use organic solvents, it is important to prioritize VOCs for continuous measurement and analysis and to establish reduction strategies. Full article

Travellers may be exposed to a wide range of different air pollutants during their journeys. In this study, personal exposures within vehicles and during active travel were tested in real-world conditions across nine different transport modes on journeys from London Paddington to Oxford City Centre, in the United Kingdom. The modes tested covered cycling, walking, buses, coaches, trains and private cars. Such exposures are relevant to questions of traveller comfort and safety in the context of airborne diseases such as COVID-19 and a growing awareness of the health, safety and productivity effects of interior air quality. Pollutants measured were particle number (PN), particle mass (PM), carbon dioxide (CO₂) and speciated volatile organic compounds (VOCs), using devices carried on or with the traveller, with pumped sampling. Whilst only a relatively small number of journeys were assessed—inviting future work to assess their statistical significance—the current study highlights where a particular focus on exposure reduction should be placed. Real-time results showed that exposures were dominated by short-term spikes in ambient concentrations, such as when standing on a train platform, or at the roadside. The size distribution of particles varied significantly according to the situation. On average, the coach created the highest exposures overall; trains had mixed performance, while private cars and active transport typically had the lowest exposures. Sources of pollutants included both combustion products entering the vehicle and personal care products from other passengers, which were judged from desk research on the most likely source of each individual compound. Although more exposed to exhaust emissions while walking or cycling, the active traveller had the benefit of rapid dilution of these pollutants in the open air. An important variable in determining total exposure was the journey length, where the speed of the private car was advantageous compared to the relative slowness of the coach. Full article

The volatile organic compounds (VOCs) released from a plastic track can cause stimulation and damage to the human body; the temperature, relative humidity (RH) and air exchange rate (AER) have a significant impact on the release of VOCs from materials. In this study, we used a 0.1 m³ environmental chamber; a qualitative and quantitative analysis of VOCs released from a plastic track was conducted by gas chromatography-mass spectrometry with a temperature range of 23–60 °C, RH of 5–65% and AER of 0.5–1.5 h⁻¹. The formation rate, the speciation, the nature of the main compounds and the mass concentration of VOCs under different environmental conditions were determined. It is shown that with the increase of temperature, the concentration of some main VOCs gradually increased and the C_alkane and C_{oxygenated organic compounds} were larger by 736.13 μg·m⁻³ and 984.22 μg·m⁻³ at 60 °C, respectively. Additionally, with the increase of RH, the concentration of different VOCs gradually increased. Nonetheless, the change in RH had no effect on the concentration percentage of different VOCs in the total VOC. With the increase in AER, the concentration of different main VOCs significantly declined, as did the VOC detection rate. When the AER was increased from 0.5 h⁻¹ to 1.5 h⁻¹, the C_alkane decreased by 206.74–254.21 μg·m⁻³ and C_{oxygenated organic compounds} decreased by 73.06–241.82 μg·m⁻³, and the number of non-detected VOC monomers increased from 1 to 7–12 species. The conclusion is that the increase in temperature and RH can promote the emission of VOCs from a plastic track, while increasing AER significantly reduces the concentrations of VOCs. Environmental temperature mainly causes the changes in the concentrations of different VOCs, and RH is a main factor leading to the variation in the detection rate of main VOCs. Overall, the release of VOCs from a plastic track is affected by environmental temperature, AER and RH in sequence. Through this paper, we clarify the effects of ambient temperature, RH and AER on the emission of VOCs from a plastic track, and furthermore, we determine the release characteristics of plastic track VOCs. Full article

Intermediate volatility organic compounds (IVOCs) and semi-volatile organic compounds (SVOCs) have recently been proposed as important precursors of secondary organic aerosol (SOA). In the present work, 97 volatile organic compounds (VOCs) and 80 intermediate volatility and semi-volatile organic compounds (IVOCs and SVOCs) were measured by online gas chromatography-mass spectrometer/flame ionization detection (GC-MS/FID), and offline thermal desorption gas chromatography-mass spectrometer (TD-GC-MS), respectively. The average concentration of speciated VOCs, IVOCs, and SVOCs were 22.36 ± 9.02 μg m⁻³, 1.01 ± 0.32 μg m⁻³, and 0.10 ± 0.17 μg m⁻³. Alkanes and polycyclic aromatic hydrocarbons (PAHs) are the main compounds of total S/IVOCs. With the increase in molecular weight, the concentrations decreased in the gas phase, while increasing in the particle phase. Vehicular emission is the most significant source according to the carbon preference index (CPI) and the carbon of the most abundant alkane (C_max). The yield method was used to estimate SOA from the oxidation of VOCs and S/IVOCs. The estimated SOA mass from IVOCs and SVOCs (0.70 ± 0.57 μg m⁻³) was comparable to that of VOCs (0.62 ± 0.61 μg m⁻³), and the oxidation of PAHs and alkanes took up 28.70 ± 8.26% and 51.97 ± 20.77% of the total SOA estimation, respectively. Compared to previous work, our study provided detailed molecular information of ambient S/IVOC species and elucidated their importance on SOA formation. Despite their low concentration, S/IVOCs species are important SOA precursors which shared comparable contribution compared with VOCs. Full article

Secondary organic aerosols (SOA) are crucial components of ambient particulate matters. However, their composition and formation mechanisms remain uncertain. To investigate the SOA formation and evaluate various SOA estimation approaches, a comprehensive measurement was conducted at an urban site, Changzhou, in Yangtze River Delta (YRD) region. 98 kinds of volatile organic compounds (VOCs) were measured by an online gas chromatography-mass spectrometer/flame ionization detector (GC-MS/FID). Non-refractory submicron particulate matters (NR-PM₁) were measured by an Aerodyne Aerosol Chemical Speciation Monitor (ACSM). Both bottom-up approaches, i.e., VOCs oxidation yield method, and top-down approaches, i.e., elemental carbon (EC) tracer method and ACSM, combined with positive matrix factorization (PMF) method, were utilized to estimate SOA. ACSM-PMF method estimated the highest SOA concentration, followed by EC tracer method. SOA from VOCs oxidation yield method accounted for 43.2 ± 41.9% of that from EC tracer method, suggesting the existence of missing SOA precursors, e.g., semivolatile organic compounds. The influencing factors of SOA formation were investigated and a good correlation of SOA with odd oxygen rather than aerosol liquid water content was found, suggesting the importance of photochemical formation of SOA. Full article