Roadside BTEX Profiles in the Atmosphere at a Terai Region of Northern India

Abstract

Transportation has turned into an escalating source that causes severe adverse effects on air quality. Over the last few decades, there has been a dramatic increase in the number of publications on traffic-related volatile organic compounds (VOCs), which indicates that automobiles in urban regions are the dominant source of benzene, toluene, ethylbenzene and xylene, commonly called BTEX. A monitoring program was designed and implemented to characterize roadside levels of BTEX during November, 2014 – February, 2015 at Gorakhpur – a terai belt of north India, on both weekdays and weekends. Samples of the air were collected at two sites namely, Nausad Traffic Junction (NTJ) and Golghar Traffic Junction (GTJ). Besides this, air samples were also collected at different distances (3 m, 10 m, 20 m, 30 m respectively) from the road. BTEX were sampled by SKC activated charcoal tubes and analyzed by GC–FID (Gas Chromatography- Flame Ionization Detector). Total BTEX concentration ranged from 9.8 - 61.3 μg m^-3 at roadside sites, Gorakhpur. The total mean BTEX at Golghar traffic junction (GTJ) and Nausad traffic junction (NTJ) were 36.6 μg m^-3 and 18.1 μg m^-3 respectively. The concentrations of BTEX were plotted against distance from the road. The coefficient of determination (R² values) for benzene, toluene, ethylbenzene and xylene were found to be 0.65, 0.98, 0.98 and 0.92 respectively. The average T/B and X/E ratios of both the sites together were 2.3 and 1.2 respectively. The higher traffic volume and traffic congestion on weekdays lead to remarkably higher BTEX levels than those observed on Sunday at both the sites. Toluene was found to be dominant followed by benzene, xylene and ethylbenzene. Appropriate traffic management and vehicle emission control should be applied to reduce the VOC pollution in the city.