Gaseous pollutants over different sites in a metropolitan region (Pune) over India

Abstract

The various gaseous pollutants (ozone, nitrogen oxides, carbon monoxide and Volatile Organic Compounds) were measured at 9 different micro—environments (i.e. Urban area, semi urban area, industrial area, residential area, agricultural area, etc.) over Pune city in the year 2017 (January–December). The urban area had the highest concentration of ozone (during Mar to May), attributed mainly due to the high concentration of the precursor gases like nitrogen oxide (NOx) and carbon monoxide (CO). The diurnal patterns of CO and NOx show inverse relation with Ozone at all the locations indicating that during ozone production these gases are utilized. However, NOx at the urban locations is found to be high even during the day when generally the ozone concentrations were high. The airport area of the city showed higher concentration of Ozone after 12 am (early morning hours). VOC’s such as benzene, toluene, ethylbenzene and xylenes are also found to play a role in the formation of the tropospheric ozone. The maximum increment reactivity of different VOCs enables in determining the ozone forming potential at each of our locations. Toluene is found to have the highest ozone forming potential amongst the VOCs in most of the locations. The distribution of pollutants and its potential sources over this Metropolitan region is illustrated in detail in this paper.