Abstract
Abstract. In the framework of the TRANSport Emissions and Mitigation in the East Mediterranean (TRANSEMED/ChArMEx) program, volatile organic compound (VOC) measurements were performed for the first time in Istanbul (Turkey) at an urban site in September 2014. One commercial gas chromatograph coupled to a flame ionization detector (GC–FID) and one proton transfer mass spectrometer (PTR-MS) were deployed. In addition, sorbent tubes and canisters were implemented within the megacity close to major emission sources. More than 70 species including non-methane hydrocarbons (NMHCs), oxygenated VOCs (OVOCs), and organic compounds of intermediate volatility (IVOCs) have been quantified. Among these compounds, 23 anthropogenic and biogenic species were continuously collected at the urban site. VOC concentrations show a great variability with maxima exceeding 10 ppb (i.e., n-butane, toluene, methanol, and acetaldehyde) and mean values between 0.1 (methacrolein + methyl vinyl ketone) and 4.9 ppb (methanol). OVOCs represent 43.9 % of the total VOC concentrations followed by alkanes (26.3 %), aromatic compounds (20.7 %), alkenes (4.8 %), terpenes (3.4 %), and acetonitrile (0.8 %). Five factors have been extracted from the Positive Matrix Factorization model (EPA PMF 5.0) and have been compared to source profiles established by near-field measurements and other external variables (meteorological parameters, NOx, CO, SO2, etc.). Surprisingly, road transport is not the dominant source, only explaining 15.8 % of measured VOC concentrations contrary to the local emission inventory. Other factors are toluene from solvent use (14.2 %), biogenic terpenes (7.8 %), natural gas evaporation (25.9 %) composed of butanes, and a last factor characterized by mixed regional emissions and composed of most of the species (36.3 %). The PMF model results point out the influence of industrial emissions while there is no clear evidence of the impact of ship emissions on the measured VOC distribution. For the latter additional measurements of organic compounds of lower volatility like IVOC would be helpful. The sensitivity of PMF results to input data (time resolution, meteorological period, peak episode, interpolation method) was tested. While some PMF runs do not perform as well statistically as the reference run, sensitivity tests show that the same factors (number and type) are found with slightly different factor contributions (up to 16 % of change). Finally, the emission ratios (ERs) of VOCs relative to carbon monoxide (CO) were established. These ratios are usually higher than the ones of other cities worldwide but in the same range of magnitude. These ERs and the road transport factor from PMF were used to estimate VOC emissions and to evaluate three downscaled global emissions inventories (EDGAR, ACCMIP, and MACCity). It was found that the total annual VOC anthropogenic emissions by global inventories were either within the same range by a factor of 2 to 3 for alkanes and aromatics or underestimated by an order of magnitude, especially for oxygenated VOCs.
Highlights
Clean air is a vital need for all living beings
Among the various types of air pollutants in the atmosphere, volatile organic compounds (VOCs) include hundreds of species grouped in different families and with lifetimes ranging from minutes to months
VOC measurements were performed in Istanbul (Turkey) at an urban site in Besiktas in September 2014
Summary
Clean air is a vital need for all living beings. air pollution continues to pose a significant threat to health worldwide (WHO, 2005; Nel, 2005; Batterman et al, 2014), air quality, climate change, ecosystems (crop yield loss, acidity of ecosystem) (Matson et al, 2002), and building corrosion (Primerano et al, 2000; Ferm et al, 2005; Varotsos et al, 2009). The World Health Organization (WHO) estimates that 4.2 million people die every year as a result of exposure to ambient (outdoor) air pollution and 3.8 million people from exposure to smoke from dirty cook stoves and fuels, and 91 % of the world’s population lives in places where air quality exceeds WHO guideline limits (WHO, 2018). Among the various types of air pollutants in the atmosphere, volatile organic compounds (VOCs) include hundreds of species grouped in different families (alkanes, alkenes, aromatics, alcohol, ketone, aldehydes, etc.) and with lifetimes ranging from minutes to months. They can be released directly into the atmosphere by anthropogenic (vehicular exhausts, evaporation of gasoline, solvent use, natural gas emissions, industrial process) and natural sources (vegetation, ocean). Even though biogenic emissions of VOC are more important than anthropogenic emissions at a global scale (Finlayson-Pitts and Pitts, 2000; Goldstein and Galbally, 2007; Müller, 1992), the latter are the most dominant in urban areas
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
