Size-segregated aerosol measurements during Diwali festival in an elevated background location

Abstract

Recent studies in the direction of identifying signatures of aerosol emission from fireworks stressed on the need of simultaneous measurements of mass, number and chemical compositional characteristics. Such an identification is tricky when the measurements are performed in an elevated background environment and/or in presence of an additional wide source term. This work studies the modifications in atmospheric aerosol characteristics due to firework induced emissions in Bathinda city of Punjab, North India. This study presents interpretations based on the results obtained from the measurements performed for 14 days covering the days of Diwali festival, 2021 as well as the baseline database gathered from a year-long campaign to measure mass concentration in different size-ranges. Highest mass concentration for the study duration was observed to be PM10- 382 μg/m3, PM2.5–299 μg/m3, PM1- 240 μg/m3, respectively in the month of November 2021. A clear increase of concentration was noted for Diwali days and the averaged concentration for PM10, PM2.5 and PM1 reached to 445 μg/m3, 363 μg/m3 and 304 μg/m3 on Diwali day, respectively. Number size distribution evolution analysis for the data measured from an optical particle counter (size range: 0.25–1 μm) showed that emissions for Diwali days occurred mostly at night times and in smaller size channels (<0.5 μm). Chemical compositional data of selected samples close to Diwali days was interpreted in terms of factor of increase of mass density of collected particles in different size-ranges. Mass density of elements K, Cl, S, Al, Zn, P, Mn, Pb, Br and Zr in PM1 samples was observed to be higher for Diwali days in comparison to their pre-Diwali levels. Few elements viz. Ba, Sr and Nb were found to be only present in the samples taken during Diwali days. In addition to Ba, Sr and Nb, elements V, Mg, Br and Se were observed to be present in PM2.5 and PM10 samples taken during the Diwali days. This study provides combined ambient aerosol characteristics during Diwali days when the air quality was affected by stubble burning as well.