Assessment of tropospheric ozone at an industrial site of Chennai megacity

Abstract

This paper presents the temporal variation in surface-level ozone (O 3) measured at Gummidipoondi near Chennai, Tamilnadu. The site chosen for the present study has high potential for ozone generation sources, such as vehicular traffic and industrial activities. The site is also located near a hazardous waste management facility. The key sources of nitrogen oxides (NO x), which are considered to be an important precursor of O 3 , include hazardous waste incineration, trucks bringing the hazardous wastes, and vehicles plying on the nearby National Highway 16 (NH 16). The measurements clearly showed diurnal variation, with maximum values observed during the noon hours and minimum values observed when solar radiation was less. The data showed a marked seasonal variation in O 3 , with the highest hourly average O 3 concentration (497.2 µg/m 3) in the summer season. Consequently, in order to identify the long-range transport sources adding to the increased O 3 levels, backward trajectories were computed using the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model. It was found that the polluted air mass originated from the Southeast Asian region and the Indo-Gangetic Plain. The polluted air mass, which advected large amounts of carbon monoxide (CO) plumes, was analyzed using the Measurement of Pollution in the Troposphere (MOPITT) retrievals. The correlations of O 3 with temperature (r = 0.746; P < 0.01) and solar radiation (r = 0.751; P < 0.01) were strongly positive, and that with NO x was found to be negative. Stronger correlation of O 3 with NO x was observed during pre-monsoon months (r = 0.627; P < 0.01) and following hours of photochemical reactions. There were substantial differences in concentrations between weekdays and weekends, with higher nitric oxide (NO) and nitrogen dioxide (NO 2), but lower O 3 , concentrations on weekdays. A substantial weekday-weekend difference in O 3 , which was higher on weekends, appears to be attributable to lower daytime traffic activity and hence reduced emissions of NO x to a "NO x-saturated" atmosphere. Implications: The assessment of ground-level ozone in an industrial area with hazardous waste management facility is very important, as there is high possibility for more generation of tropospheric ozone. Since the location of the study area is coastal, wind plays a major role in O 3 transportation; hence, the effects of wind speed and wind direction have been studied in different seasons. When compared with the other studies carried out in different places across India, the present study area has recorded much greater O 3 mixing ratio. This study can be useful for setting up control strategies in such industrial areas.

Evaluation of the Major Air Pollutants Levels and Its Interactions With Meteorological Parameters in Ankara

“…Pollutants except O3 are directly associated with traffic pollution. Tropospheric O3 is known as a secondary pollutant due to the increasing of ozone formation by other pollutants in the atmosphere (Mohan et al, 2019). Combustion of fossil fuels, vehicle exhausts and industry cause emission of NOX, CO, SO2 and VOCs as a primary air pollutant.…”

“…In the troposphere O3 is formed or its concentration increases at the end of photochemical reactions (Bozkurt et al, 2018). The concentration of NOX and intensity of solar radiation extremely affect the formation and concentration of O3 (US EPA 2020a; Bozkurt et al, 2018;Mohan et al, 2019). As a result, the highest levels of ozone pollution occur during periods of sunny weather (WHO, 2000).…”

Characteristics of Ozone Pollution, Regional Distribution and Causes during 2014–2018 in Shandong Province, East China

“…Other studies have also shown that the ozone concentration is significantly positively correlated with solar radiation intensity [59,60]; however, most studies have discussed the daily or seasonal variations of ozone concentration, and fewer studies have focused on the relationship between interannual ozone concentration and solar radiation.…”

Physiological significance of pedospheric nitric oxide for root growth, development and organismic interactions

“…Its concentrations range between 0.05-0.22 ppb in the remote troposphere (Stratmann et al, 2016) and 0.5-73 ppm in the polluted troposphere (Mohan & Saranya, 2019). Because of the rapid development of agriculture, industry and mega-cities, anthropogenic activities have dramatically affected the release of NO into the atmosphere.…”