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Atmosphere
Special Issues
VOC Sensing and Measurements
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VOC Sensing and Measurements

A special issue of Atmosphere (ISSN 2073-4433). This special issue belongs to the section "Air Quality".

Deadline for manuscript submissions: closed (4 November 2021) | Viewed by 31991

Special Issue Editor

Dr. Stéphane Le Calvé

E-Mail Website
Guest Editor
Institute of Chemistry and Processes for Energy, Environment and Health (ICPEES, UMR 7515), CNRS and University of Strasbourg, 25 rue Becquerel, 67087 Strasbourg, France
Interests: analytical chemistry; air quality; environment; instrumentation; microfluidics; nanomaterials
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear colleagues,

Volatile organic compounds include several families of chemical compounds (alkanes, alkenes, mono-aromatic compounds, ketones, aldehydes, ethers, etc.) which are widely used in numerous applications. They are, for example, used as solvents, additives to fuels, etc. Regarding their volatility, it is not surprising to find them in the atmosphere at concentrations varying between a few ppt and a few hundred ppb depending on the environments considered and the proximity of their emission sources.

Some VOCs are directly toxic to human health, which leads legislators to define specific threshold values for their concentrations in the air. They also participate in the formation of photochemical smog in the presence of nitrogen oxides and ultraviolet radiation to generate ozone, other organic pollutants, or secondary organic aerosols. Some VOCs take part in the greenhouse effect. Halogenated VOCs can contribute to the destruction of stratospheric ozone when their lifetimes in the atmosphere are long.

VOCs have thus a direct or indirect impact on the environment, which requires the development of high-performance measurement tools to detect them and the measurements in different atmospheric compartments to better understand their behavior in the atmosphere.

This Special Issue is dedicated to 1) the development of analytical methods or instruments for airborne VOC quantification applied in controlled laboratory conditions and/or in real environments and 2) the measurements of VOCs indoors or outdoors to determine their concentrations, their spatial distribution or their temporal variations.

The issue will explore new designs of VOC sampling and sensing to improve the analytical performances (sensitivity, time-resolution, selectivity, portability, etc.). On the other hand, the measurements of VOCs will be applied to various environments including indoor air, industrial areas, urban and rural sites.

The issue is focused on, but not limited to, the following topics related to VOCs:

  • Passive and active sampling techniques
  • Off-line analytical instruments
  • Analytical methods
  • Sensors and detectors
  • VOC measurements
  • Real-time
  • Indoor air quality
  • VOC exposure
  • VOC emissions
  • Microdevices

Dr. Stéphane Le Calvé
Guest Editor

Manuscript Submission Information

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Keywords

  • Passive and active sampling techniques
  • Off-line analytical instruments
  • Analytical methods
  • Sensors and detectors
  • VOC measurements
  • Real-time
  • Indoor air quality
  • VOC exposure
  • VOC emissions
  • Microdevices

Published Papers (11 papers)

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Research

10 pages, 1066 KiB  
Article
Leaf Fluxes of Carbon Dioxide, Methane and Biogenic Volatile Organic Compounds of the Urban Trees Platanus × acerifolia and Schinus molle in Santiago, Chile
by Iván Farías, Margarita Préndez and Horacio E. Bown
Atmosphere 2022, 13(2), 298; https://doi.org/10.3390/atmos13020298 - 10 Feb 2022
Cited by 1 | Viewed by 1821
Abstract
This study assessed leaf fluxes of CO2, CH4 and biogenic volatile organic compounds (BVOC) for two common urban tree species, Platanus × acerifolia (exotic) and Schinus molle (native), widely distributed in Santiago, Chile. The emission factors (EF) and the Photochemical [...] Read more.
This study assessed leaf fluxes of CO2, CH4 and biogenic volatile organic compounds (BVOC) for two common urban tree species, Platanus × acerifolia (exotic) and Schinus molle (native), widely distributed in Santiago, Chile. The emission factors (EF) and the Photochemical Ozone Creation Index (POCI) for S. molle and P. × acerifolia were estimated. The global EF was 6.4 times higher for P. × acerifolia compared with S. molle, with similar rates of photosynthesis for both species. Isoprene represented more than 86% of the total BVOCs leaf fluxes being 7.6 times greater for P. × acerifolia than S. molle. For P. × acerifolia, BVOCs represented 2% of total carbon fixation while representing 0.24% for S. molle. These results may suggest that plant species growing outside their ecological range may exhibit greater BVOCs leaf fluxes, proportional to photosynthesis, compared to well-adapted ones. The results found may contribute to better urban forest planning. Full article
(This article belongs to the Special Issue VOC Sensing and Measurements)
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15 pages, 7883 KiB  
Article
Ambient BTEX Concentrations during the COVID-19 Lockdown in a Peri-Urban Environment (Orléans, France)
by Min Cai, Yangang Ren, Rodrigo G. Gibilisco, Benoit Grosselin, Max R. McGillen, Chaoyang Xue, Abdelwahid Mellouki and Véronique Daële
Atmosphere 2022, 13(1), 10; https://doi.org/10.3390/atmos13010010 - 21 Dec 2021
Cited by 8 | Viewed by 2516
Abstract
During the period from 17 March to 10 May 2020, France saw dramatic shifts in domestic, industrial and transport activities as a national lockdown was introduced. So far, studies have generally focused on urban settings, by contrast, this work reports data for a [...] Read more.
During the period from 17 March to 10 May 2020, France saw dramatic shifts in domestic, industrial and transport activities as a national lockdown was introduced. So far, studies have generally focused on urban settings, by contrast, this work reports data for a peri-urban location. Air samples were collected and analyzed using a fully automated GC-MS-FID system in an air quality monitoring station situated in the suburbs of Orléans, France. Average concentrations of BTEX (benzene, toluene, ethylbenzene, and xylenes) before, during, and after lockdown, were 402 ± 143, 800 ± 378 and 851 ± 445 pptv, respectively. Diurnal variation in BTEX and correlations between each of its components were analyzed to determine its various sources. The toluene/benzene (T/B) and m,p-xylene/ethylbenzene (MP/E) ratios, photochemical ages were used to explore whether the BTEX were from local or more distant sources. Together with a host of complementary measurements including NOx, O3, black carbon, meteorological parameters, and anthropogenic activities, we were able to make some inferences on the sources of BTEX. The results suggest that although anomalous local anthropogenic activity can lead to significant changes in BTEX concentrations, pollution levels in Orléans are mostly dependent on meteorological conditions, specifically whether the winds are coming from the Paris region. It appears, based on these measurements, that the pollution in the Orléans area is very much tied to the nearby megacity of Paris, this may be true for other peri-urban sites with implications for city planning and pollution mitigation strategies. Full article
(This article belongs to the Special Issue VOC Sensing and Measurements)
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11 pages, 1419 KiB  
Article
Comparison of Volatile Organic Compound Concentrations in Ambient Air among Different Source Areas around Khon Kaen, Thailand
by Pornpun Sakunkoo, Saksit Phonphinyo, Naowarat Maneenin, Chananya Jirapornkul, Yuparat Limmongkon, Jetnapis Rayubkul, Sakesun Thongtip and Sarawut Sangkham
Atmosphere 2021, 12(12), 1694; https://doi.org/10.3390/atmos12121694 - 17 Dec 2021
Cited by 4 | Viewed by 3621
Abstract
Volatile organic compounds (VOCs) are a complex group of chemicals that pose a direct risk to human health. They also lead to the formation of other air pollution constituents, including fine particulate matter (PM2.5) and ground level ozone (O₃). The ambient [...] Read more.
Volatile organic compounds (VOCs) are a complex group of chemicals that pose a direct risk to human health. They also lead to the formation of other air pollution constituents, including fine particulate matter (PM2.5) and ground level ozone (O₃). The ambient air concentrations of 19 VOCs were measured using multi-day 24 h sampling at two urban sites and two rural sites in the area of Khon Kaen, Thailand. Results showed that most VOCs were at concentrations considered acceptable according to the 24 h average standards established by the Thai Pollution Control Department. The VOC acrolein, however, was detected at concentrations (0.69–1.15 μg/m3) in excess of the 24 h average standard (0.55 μg/m3). Two other VOCs, benzene and 1,3-butadiene, were also detected at elevated levels (1.73–2.75 and 0.18–0.40 μg/m3, respectively) that indicated the potential to exceed the 1-year average standard. VOC concentrations were highest in the urban market monitoring site, suggesting that vehicle exhaust and food preparation using cooking oil at high temperatures may have been potential sources of the elevated VOCs. Full article
(This article belongs to the Special Issue VOC Sensing and Measurements)
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24 pages, 5360 KiB  
Article
Air Quality Assessment in the Central Mediterranean Sea (Tyrrhenian Sea): Anthropic Impact and Miscellaneous Natural Sources, including Volcanic Contribution, on the Budget of Volatile Organic Compounds (VOCs)
by Francesca Vichi, Antonietta Ianniello, Massimiliano Frattoni, Andrea Imperiali, Giulio Esposito, Maria Concetta Tomasi Scianò, Mattia Perilli and Angelo Cecinato
Atmosphere 2021, 12(12), 1609; https://doi.org/10.3390/atmos12121609 - 02 Dec 2021
Cited by 7 | Viewed by 1873
Abstract
The results of air pollution assessment during a 2017 cruise of the research ship “Minerva Uno” in the Tyrrhenian Sea are reported. Volatile Organic Compounds (VOCs), Oxygenated Volatile Organic Compounds (OVOCs), and pollutants such as nitrogen oxides, ozone, and sulphur dioxide were monitored [...] Read more.
The results of air pollution assessment during a 2017 cruise of the research ship “Minerva Uno” in the Tyrrhenian Sea are reported. Volatile Organic Compounds (VOCs), Oxygenated Volatile Organic Compounds (OVOCs), and pollutants such as nitrogen oxides, ozone, and sulphur dioxide were monitored throughout the cruise. The shallow waters at ten sites of the investigated area were also analyzed. Organic compounds such as n-alkanes showed a bimodal distribution with a maximum at C5–C6 and C10–C11 at sites the most affected by anthropic impact, whereas remote sites showed a unimodal distribution with maximum at C10–C11. The most abundant atmospheric OVOC was acetone (3.66 μg/m3), accounting for 38%; formaldehyde (1.23 μg/m3) and acetaldehyde (0.99 μg/m3) made up about 22–29% of the total. The influence of some natural sources as volcanoes, in the southern part of the Tyrrhenian Sea near the Aeolian arc was studied. This source did not induce any noticeable effect on the total amount of hydrocarbons nor on the levels of trace gases such as CFCs, whereas the trends of sulphur dioxide seemed to confirm a possible contribution. The impact of underwater emissions was observed near the Panarea and Vulcano islands, where lower pHs, high levels of Fe and Mn, and diagnostic of vent activity, were measured. Full article
(This article belongs to the Special Issue VOC Sensing and Measurements)
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15 pages, 2769 KiB  
Article
Seasonal and Spatial Variation of Volatile Organic Compounds in Ambient Air of Almaty City, Kazakhstan
by Olga P. Ibragimova, Anara Omarova, Bauyrzhan Bukenov, Aray Zhakupbekova and Nassiba Baimatova
Atmosphere 2021, 12(12), 1592; https://doi.org/10.3390/atmos12121592 - 29 Nov 2021
Cited by 10 | Viewed by 3676
Abstract
Air pollution is one of the primary sources of risk to human health in the world. In this study, seasonal and spatial variations of multiple volatile organic compounds (VOCs) were measured at six sampling sites in Almaty, Kazakhstan. The seasonal and spatial variations [...] Read more.
Air pollution is one of the primary sources of risk to human health in the world. In this study, seasonal and spatial variations of multiple volatile organic compounds (VOCs) were measured at six sampling sites in Almaty, Kazakhstan. The seasonal and spatial variations of 19 VOCs were evaluated in 2020, including the periods before and after COVID-19 lockdown. The concentrations of 9 out of 19 VOCs had been changed significantly (p < 0.01) during 2020. The maximum concentrations of total VOCs (TVOCs) were observed on 15, 17, and 19 January and ranged from 233 to 420 µg m−3. The spatial distribution of TVOCs concentrations in the air during sampling seasons correlated with the elevation and increased from southern to northern part of Almaty, where Combined Heat and Power Plants are located. The sources of air pollution by VOCs were studied by correlations analysis and BTEX ratios. The ranges of toluene to benzene ratio and benzene, toluene, and ethylbenzene demonstrated two primary sources of BTEX in 2020: traffic emissions and biomass/biofuel/coal burning. Most of m-, p-xylenes to ethylbenzene ratios in this study were lower than 3 in all sampling periods, evidencing the presence of aged air masses at studied sampling sites from remote sources. Full article
(This article belongs to the Special Issue VOC Sensing and Measurements)
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13 pages, 6657 KiB  
Article
VOCs Fugitive Emission Characteristics and Health Risk Assessment from Typical Plywood Industry in the Yangtze River Delta Region, China
by Kun Hu, Zhiqiang Liu, Ming Wang, Bingjie Zhang, Haotian Lin, Xingdong Lu and Wentai Chen
Atmosphere 2021, 12(11), 1530; https://doi.org/10.3390/atmos12111530 - 20 Nov 2021
Cited by 5 | Viewed by 2036
Abstract
Volatile organic compounds (VOCs) emissions from the plywood manufacturing industry in China have received concerns during recent years. A total of 115 VOCs were measured in the adhesive-making, adhesive-coating, and hot-pressing workshops of the plywood manufacturing industry to investigate fugitive emission characteristics of [...] Read more.
Volatile organic compounds (VOCs) emissions from the plywood manufacturing industry in China have received concerns during recent years. A total of 115 VOCs were measured in the adhesive-making, adhesive-coating, and hot-pressing workshops of the plywood manufacturing industry to investigate fugitive emission characteristics of VOCs and assess their health risks to workers. The average concentration of total VOCs in workshops of the plywood manufacturing industry is 467 ± 359 μg/m3, whereas the value for ambient air is 81.4 μg/m3. For specific processes, the adhesive-coating and hot-pressing processes show higher VOCs concentrations (501 μg/m3–519 μg/m3) than the adhesive-making process (340 μg/m3). Formaldehyde, ethyl acetate, and dichloromethane are the three most abundant VOCs in workshops, with relative contributions to total VOCs of 55.9–63.1%, 4.3–11.0%, and 1.7–4.4%, respectively. For ozone formation potential (OFP) of VOCs, formaldehyde is the largest contributor (86.1%), followed by toluene, xylenes, and propanal. The non-cancer toxic risks (HI) and cancer risks of total VOCs (T-LCR) for three processes are calculated as 2.93–3.94 and 2.86–4.17 × 10−4 using the US EPA recommended methods, both significantly higher than threshold values (1.0 for HI and 10−4 for LCR), suggesting the highly toxic and cancer risks to workers. Formaldehyde contributes 68.1–78.2% and 91.4–93.9% of HI and T-LCR, respectively. The designed risk reduction scheme of VOCs based on air ventilation suggests that air ventilation rates of formaldehyde need to reach 4–5 times in 8 h in three processes to reduce T-LCR to 10−5. These results are useful for developing VOCs control measures and evaluating VOCs occupational health risk for workers in the plywood manufacturing industry. Full article
(This article belongs to the Special Issue VOC Sensing and Measurements)
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24 pages, 2826 KiB  
Article
High-Performance VOC Quantification for IAQ Monitoring Using Advanced Sensor Systems and Deep Learning
by Yannick Robin, Johannes Amann, Tobias Baur, Payman Goodarzi, Caroline Schultealbert, Tizian Schneider and Andreas Schütze
Atmosphere 2021, 12(11), 1487; https://doi.org/10.3390/atmos12111487 - 10 Nov 2021
Cited by 20 | Viewed by 3052
Abstract
With air quality being one target in the sustainable development goals set by the United Nations, accurate monitoring also of indoor air quality is more important than ever. Chemiresistive gas sensors are an inexpensive and promising solution for the monitoring of volatile organic [...] Read more.
With air quality being one target in the sustainable development goals set by the United Nations, accurate monitoring also of indoor air quality is more important than ever. Chemiresistive gas sensors are an inexpensive and promising solution for the monitoring of volatile organic compounds, which are of high concern indoors. To fully exploit the potential of these sensors, advanced operating modes, calibration, and data evaluation methods are required. This contribution outlines a systematic approach based on dynamic operation (temperature-cycled operation), randomized calibration (Latin hypercube sampling), and the use of advances in deep neural networks originally developed for natural language processing and computer vision, applying this approach to volatile organic compound measurements for indoor air quality monitoring. This paper discusses the pros and cons of deep neural networks for volatile organic compound monitoring in a laboratory environment by comparing the quantification accuracy of state-of-the-art data evaluation methods with a 10-layer deep convolutional neural network (TCOCNN). The overall performance of both methods was compared for complex gas mixtures with several volatile organic compounds, as well as interfering gases and changing ambient humidity in a comprehensive lab evaluation. Furthermore, both were tested under realistic conditions in the field with additional release tests of volatile organic compounds. The results obtained during field testing were compared with analytical measurements, namely the gold standard gas chromatography mass spectrometry analysis based on Tenax sampling, as well as two mobile systems, a gas chromatograph with photo-ionization detection for volatile organic compound monitoring and a gas chromatograph with a reducing compound photometer for the monitoring of hydrogen. The results showed that the TCOCNN outperforms state-of-the-art data evaluation methods, for example for critical pollutants such as formaldehyde, achieving an uncertainty of around 11 ppb even in complex mixtures, and offers a more robust volatile organic compound quantification in a laboratory environment, as well as in real ambient air for most targets. Full article
(This article belongs to the Special Issue VOC Sensing and Measurements)
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22 pages, 2300 KiB  
Article
Statistical Evidence for Managing Forest Density in Consideration of Natural Volatile Organic Compounds
by Yeji Choi, Geonwoo Kim, Sujin Park, Sangtae Lee, Soojin Kim and Eunsoo Kim
Atmosphere 2021, 12(9), 1113; https://doi.org/10.3390/atmos12091113 - 30 Aug 2021
Cited by 4 | Viewed by 2124
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue VOC Sensing and Measurements)
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19 pages, 1831 KiB  
Article
An Assessment of Indoor Air Quality in the Arrivals Hall of Beirut–Rafic Hariri International Airport: Monitoring of VOCs and NO2
by Tharwat Mokalled, Jocelyne Adjizian Gérard, Maher Abboud, Céline Liaud, Rouba Nasreddine and Stéphane Le Calvé
Atmosphere 2021, 12(3), 400; https://doi.org/10.3390/atmos12030400 - 20 Mar 2021
Cited by 6 | Viewed by 3462
Abstract
In Beirut–Rafic Hariri International Airport (RHIA), airport employees stay at least 12 h inside the airport’s buildings and suffer from respiratory symptoms. Additionally, direct openings exist between the apron and the arrivals hall providing a pathway for contaminated air to enter the buildings. [...] Read more.
In Beirut–Rafic Hariri International Airport (RHIA), airport employees stay at least 12 h inside the airport’s buildings and suffer from respiratory symptoms. Additionally, direct openings exist between the apron and the arrivals hall providing a pathway for contaminated air to enter the buildings. Hence, we study the impact of Beirut–RHIA’s activities on the indoor air of the arrivals hall (impact on employees and passengers) during June, November, and October 2014. Due to their impacts on air quality and human health, assessing of the concentrations of nitrogen dioxide (NO2) and Volatile Organic Compounds (VOCs) was the target of our study by using gas chromatographic techniques (GC-MS and GC-FID) for VOCs and calorimetric methods for NO2 concentrations. NO2 levels indicated a probable hazard to the health of passengers and employees, while measured VOC levels did not present any risks except for acrolein. This is the first study to assess the speciation of a large number of VOCs (46 VOCs) for airport indoor air while revealing a very interesting correlation between aircraft number and the concentrations of VOC groups (namely heavy alkanes, aldehydes and ketones, and monoaromatics). Moreover, this is the first study in Lebanon to assess the speciation of a large number of VOCs in indoor air. Full article
(This article belongs to the Special Issue VOC Sensing and Measurements)
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16 pages, 1918 KiB  
Article
Reproducibility of the Quantification of Reversible Wall Interactions in VOC Sampling Lines
by Guido Sassi, Bilal Alam Khan and Maricarmen Lecuna
Atmosphere 2021, 12(2), 280; https://doi.org/10.3390/atmos12020280 - 20 Feb 2021
Viewed by 2321
Abstract
Volatile Organic Compounds (VOCs) are widely measured at ppb and ppt level in many contexts, from therapeutic drug control in respiratory diseases to monitoring of climate change and indoor air quality. The need for accuracy is a common denominator in all these fields. [...] Read more.
Volatile Organic Compounds (VOCs) are widely measured at ppb and ppt level in many contexts, from therapeutic drug control in respiratory diseases to monitoring of climate change and indoor air quality. The need for accuracy is a common denominator in all these fields. The interactions between gas mixtures and solid surfaces in sampling lines and instruments play an important role in calculating the total uncertainty of the amount of VOC. The amount of substances in the gas mixture is affected by its reversible and irreversible interactions with the sampling line. The main aim of this paper is to propose and discuss a method to quantify the amount of substance segregated by reversible interactions on sampling lines. To validate the proposed method, the areic amount of a VOC (Acetone) is measured for a commercial test pipe (Sulfinert®) as the amount of substance per unit area of the internal surface of the test pipe segregated from the flowing gas mixture. Stainless steel coated by Sulfinert® was chosen as a test material because of its wide use and its limited irreversible and permeation effects. A certified gas mixture of Acetone in air with a nominal mole fraction of 10 µmol mol−1 was used for validation. Broad temperature control was used and the sensibility of the method to the temperature and the pressure has been evaluated to correct the bias due to physical condition. The sensitivity to the residence time and the Reynolds number of the gas flow has been evaluated to verify the reaching of equilibrium and the limits of the applicability of the method. The areic amount of Acetone at equilibrium on Sulfinert® coated pipe was measured as 40 nmol m−2, and an equilibrium constant value of around 0.2 m was calculated as the ratio between the superficial amount segregated on the wall and the amount concentration of Acetone in the mixture, both at the equilibrium. The observed reproducibility was better than 2.5%. This method is aimed to investigate VOC losses due to interactions for many VOC/material systems at a lower amount of substance levels. Full article
(This article belongs to the Special Issue VOC Sensing and Measurements)
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27 pages, 4774 KiB  
Article
Seasonal Variation of Biogenic and Anthropogenic VOCs in a Semi-Urban Area Near Sydney, Australia
by Jhonathan Ramirez-Gamboa, Clare Paton-Walsh, Ian Galbally, Jack Simmons, Elise-Andree Guerette, Alan D. Griffith, Scott D. Chambers and Alastair G. Williams
Atmosphere 2021, 12(1), 47; https://doi.org/10.3390/atmos12010047 - 31 Dec 2020
Cited by 10 | Viewed by 3498
Abstract
Volatile organic compounds (VOCs) play a key role in the formation of ozone and secondary organic aerosol, the two most important air pollutants in Sydney, Australia. Despite their importance, there are few available VOC measurements in the area. In this paper, we discuss [...] Read more.
Volatile organic compounds (VOCs) play a key role in the formation of ozone and secondary organic aerosol, the two most important air pollutants in Sydney, Australia. Despite their importance, there are few available VOC measurements in the area. In this paper, we discuss continuous GC-MS measurements of 10 selected VOCs between February (summer in the southern hemisphere) and June (winter in the southern hemisphere) of 2019 in a semi-urban area between natural eucalypt forest and the Sydney metropolitan fringe. Combined, isoprene, methacrolein, methyl-vinyl-ketone, α-pinene, p-cymene, eucalyptol, benzene, toluene xylene and tri-methylbenzene provide a reasonable representation of variability in the total biogenic VOC (BVOC) and anthropogenic VOC (AVOC) loading in the area. Seasonal changes in environmental conditions were reflected in observed BVOC concentrations, with a summer peak of 8 ppb, dropping to approximately 0.1 ppb in winter. Isoprene, and its immediate oxidation products methacrolein (MACR) and methyl-vinyl-ketone (MVK), dominated BVOC concentrations during summer and early autumn, while monoterpenes comprised the larger fraction during winter. Temperature and solar radiation drive most of the seasonal variation observed in BVOCs. Observed levels of isoprene, MACR and MVK in the atmosphere are closely related with variations in temperature and photosynthetically active radiation (PAR), but chemistry and meteorology may play a more important role for the monoterpenes. Using a nonlinear model, temperature explains 51% and PAR 38% of the isoprene, MACR and MVK variation. Eucalyptol dominated the observed monoterpene fraction (contributing ~75%), with p-cymene (20%) and α-pinene (5%) also present. AVOCs maintain an average concentration of ~0.4 ppb, with a slight decrease during autumn–winter. The low AVOC concentrations observed indicate a relatively small anthropogenic influence, generally occurring when (rare) northerly winds transport Sydney emissions to the measurement site. The site is influenced by domestic, commercial and vehicle AVOC emissions. Our observed AVOC concentrations can be explained by the seasonal changes in meteorology and the emissions in the area as listed in the NSW emissions inventory and thereby act as an independent validation of this inventory. We conclude that the variations in atmospheric composition observed during the seasons are an important variable to consider when formulating air pollution control policies over Sydney given the influence of biogenic sources during summer, autumn and winter. Full article
(This article belongs to the Special Issue VOC Sensing and Measurements)
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