Abstract:
This work presents short-term investigations to assess variations in PM2.5, PM10, SO2, NO2, O3, CO, BC, light NMHCs (ethane, ethylene, propane, propylene, and acetylene) and solar radiation at Bhubaneswar, during two special events in consecutive years: Diwali (2021 & 2022) and partial solar eclipse (2022). During 2022, PM levels were affected by meteorology and simultaneous occurrence of solar eclipse on the day after Diwali day (DDay). Interesting atmospheric chemistry was observed due to emissions from crackers during Diwali night influencing solar flux on post-D-day, which in turn had an impact on the pollutant levels. NO2, SO2, CO, and O3 were below prescribed safety limits for both years, however, BC and NMHC concentrations were high on D-day due to contribution from crackers, biomass, and jute burning as a ritual in the state. Also, a sharp increase in CO and NO2 concentrations was noticed exactly during the most intense phase of eclipse due to cooling of atmosphere. The oxidant levels reduced as a result of sudden drop in the solar intensity during the event. In comparison to alkanes, the alkenes exhibited high O3-forming potential (97-98%) during both the years. However, in 2022 the photo-oxidation process of alkenes was affected due to reduced solar flux on D-day. Further O3 concentration on 2022 D-Day was comparatively lower (10%) than 2021 D-day with a reduction in surface O3 concentration (43.50%) almost 2 h after the eclipse. Thus, O3 chemistry during Diwali can be attributed to both natural phenomena and man-made activities.