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Gautam Alok Sagar,Sanjeev Kumar,Sneha Gautam,Aryan Anand,Ranjit Kumar,Abhishek Joshi,Kuldeep Bauddh,Karan Singh 한국기상학회 2021 Asia-Pacific Journal of Atmospheric Sciences Vol.57 No.4
The present paper designed to understand the variations in the atmospheric pollutants viz. PM10, PM2.5, SO2, NO2, and CO during the COVID-19 pandemic over eight most polluted Indian cities (Mumbai, Delhi, Bangalore, Hyderabad, Lucknow, Chandigarh, Kolkata, and Ahmedabad). A significant reduction in the PM2.5 (63%), PM10 (56%), NO2 (50%), SO2 (9%), and CO (59%) were observed over Major Dhyan Chand Stadium. At Chhatrapati Shivaji International Airport, a decline of 44% in PM2.5 and 50% in PM10 was seen just a week during the initial phase of the lockdown. Gaseous pollutants (NO2, SO2 & CO) dropped up-to 36, 16, and 41%, respectively. The Air Quality Index (AQI) shows a dramatic change from 7% to 67% during observation at Chandigarh and Ballygunge during the inspection. Whereas, Ahmedabad, Worli, Income Tax Office, Talkatora, Lalbagh, and Ballygaunge have showed a significant change in AQI from 25.76% to 68.55%. However, Zoo Park, CST, Central School, and Victoria show relatively low variation in AQI in the range of 3.0% to 14.50% as compare to 2019 after lockdown. Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) analysis suggested that long range transportation of pollutants were also a part and parcel contributing to changes in AQI which were majorly coming from the regions of Iran, Afghanistan, Saudi Arabia, as well as a regional grant from Indian Gangatic plains and Delhi Non-capital region.
K. Sandeep,R. S. Negi,A. S. Panicker,Alok Sagar Gautam,D. S. Bhist,G. Beig,B. S. Murthy,R. Latha,Santosh Singh,S. Das 한국기상학회 2020 Asia-Pacific Journal of Atmospheric Sciences Vol.56 No.3
Extraction of organic carbon (OC) and elemental carbon (EC) were carried out over Srinagar, India, an ecologically sensitive semi-urban site in Garhwal Himalays. The PM2.5 sampling was carried out during January to December, 2017 over the site. The OC and EC were extracted from PM2.5 samples using a thermo optical OC/EC analyzer. Highest OC and EC concncentrations were found during postmonsoon (17.67 ± 1.1 μg/m3 OC and 6.34 ± 0.75 EC) and Winter (17.31 ± 3.045 μg/m3 OC and 6.32 ± 0.585 μg/m3 EC) seasons are attributed to boundary layer dynamics and anthropogenic activities. The lower concentration of OC/ EC was observed during monsoon season (11.64 ± 1.75 μgm−3 OC and 3.46 ± 0.19μgm−3 EC) owing to wet scavenging of aerosols and minimum count of forest fire/biomass buring incidences. Both pre-monsoon and post-monsoon season concentrations are also influenced by biomass burning in the IGP (Indo-Gangetic Plain) region and forest fires in the adjecent areas. The OC/EC ratio sounds that vehicular exhaust and biomass burning are the major source of OC/EC over the site. Generation of secondary organic carbon (SOC) at the region causes variability in OC/EC ratio in different seasons. It is found that 24–32% of PM2.5 is contributed by carbonaceous aerosols (OC and EC) over Srinagar. The pivotal role of meteorology in modulating OC/ EC concentrations has been illustared in detail.