Aromatic VOCs at Major Road Junctions of a Metropolis in India: Measurements Using TD-GC-FID and PTR-TOF-MS Instruments

Abstract

Ambient mass concentrations of benzene and toluene were measured at 12 different road junctions of Ahmedabad city in India during the pre-monsoon season of year 2015. A Thermal Desorption-Gas Chromatography-Flame Ionization Detector (TD-GC-FID) technique was used for the analysis of aromatic volatile organic compounds (VOCs) in air samples. In each of both inner and outer ring roads, air samples were collected at 6 sites to investigate the spatial variation of benzene and toluene. The mass concentrations of benzene and toluene show strong site-to-site and day-to-day variations. The average mass concentration of benzene varied in the ranges of 11-35 µg m -3 and 4-12 µg m -3 along the inner and outer roads, respectively. The mass concentration of toluene varied in the ranges of 43-142 µg m -3 and 11-28 µg m -3 along the inner and outer roads, respectively. Overall, the mass concentrations of VOCs along the inner road were 3-5 times higher than those measured along the outer road.The mass concentrations of benzene and toluene show good correlation suggesting their common emission sources (mostly vehicular). However, the enhancement ratios of ∆Toluene/∆Benzene (~4.0 µg µg -1 ) along both the roads were higher than the typical ratios (1.5-3.5 µg µg -1 ) reported for vehicular emissions. The higher values of ∆Toluene/∆Benzene are due to the emissions of VOCs also from industrial and other non-traffic sources. During the daytime, the lower mass concentrations of VOCs and lower ∆Toluene/∆Benzene (~2 µg µg -1 ) indicate the role of photochemical aging. The combined diurnal trend of ∆Toluene/∆Benzene agrees well with that measured at central Ahmedabad using the proton-transfer-reaction time of flight mass spectrometer (PTR-TOF-MS). However, compared to weekdays, the mass concentrations of VOCs show reduction and increase during the Sunday and Saturday, respectively. The mass concentration of VOCs and their ratio were towards the higher side of data reported for different urban sites of the world.

Emissions of non-methane volatile organic compounds from a landfill site in a major city of India: impact on local air quality

“…Poor air quality is a serious problem in many cities of the world due to the large emissions of both gaseous and particulate pollutants from a variety of anthropogenic activities ( Carmichael et al., 2009 ; Baudic et al., 2016 ; Wang et al., 2017 ; Dias and Tchepel, 2018 ; Shah et al., 2019 ). The fast urbanization, industrial-economic growth, transportation rate, and use of fossil fuels have resulted in the increasing concentrations of key air pollutants in the South Asia region ( Sahu et al., 2016a , 2016b , 2020a ; Srivastava, 2005 ; Yadav et al., 2019 , 2017 ). Volatile organic compounds (VOCs) are important components of urban air pollution.…”

“…In major cities, aromatic VOCs are released mainly from the combustion of fossil fuels in gasoline and diesel engines, gasoline evaporation, solvent usage and bio-decomposition of wastes in landfill areas ( Chan et al., 2002 ; Filella and Penuelas, 2006 ; Ortiz et al., 2002 ; Sahu et al., 2016a ). Typically, congested traffic and stagnant wind conditions are the major factors favoring accumulations of pollutants, resulting in their concentrations ( Ho et al., 2004 ).…”

“…However, mostly focused on traffic-related emissions, benzene and toluene concentrations are reported for different urban regions of the world (e.g., Barletta et al., 2005 ; Chaudhary and Kumar, 2012 ; Civan et al., 2011 ; Keymeulen et al., 2001 ; Miller et al., 2011 ; Parra et al., 2006 ; Shaw et al., 2015 ; Tiwari et al., 2010 ; Velasco et al., 2007 ). The measurement-based studies of aromatic VOCs are limited only to a few cities of India (e.g., Hoque et al., 2008 ; Lal et al., 2012 ; Majumdar et al., 2011 ; Sahu et al., 2016a , 2016b ; Sahu et al., 2010 ; Sahu and Lal, 2006a , 2006b ; Srivastava, 2005 ). However, the measurements of VOCs near specific emission sources such as landfill, major road junction, etc.…”

Characteristic wavelength selection of volatile organic compounds infrared spectra based on improved interval partial least squares

“…7 As the atmospheric pollution incidents caused by VOCs become increasingly serious and prominent, it's necessary to establish a real-time continuous VOCs monitoring system to con¯rm the information of speci¯c VOCs and control the emission of them. Classical VOC analytical methods include chemical methods, liquid chromatography (LC), 14 gas chromatography-mass spectrometry (GC-MS), 15 gas chromatography-°ame ionization detector (GC-FID), 16 photo-ionization detection (PID) 17 and so on. With the continuous progress of sensors and computer technology, various online real-time VOCs detection technologies and corresponding portable instruments have been developed.…”

Indoor Air Pollution Levels in Decorated Residences and Public Places over Xi’an, China

“…Exposure to VOCs has been associated with acute and chronic health problems, such as asthma and sick building syndrome symptoms (Madureira et al, 2015;Mendes et al, 2015;Tham, 2016;Huang et al, 2016;Sahu et al, 2016). Bocskay, et al (2010) reported that prenatal exposures to carcinogenic polycyclic aromatic hydrocarbons (PAHs) were positively associated with stable chromosomal aberrations.…”