Characteristics of Black Carbon aerosols over Patiala Northwestern part of the IGP: Source apportionment using cluster and CWT analysis

Abstract

The present study represents the variation in characteristics of Black Carbon aerosols over Patiala (Punjab), northwest region of the IGP, India during two separate periods i.e. October 2013–September 2014 and October 2015–September 2016. Averaged BC mass concentration were found to be 9.9 μg m−3, 6.6 μg m−3,3.4 μg m−3 and 2.8 μg m−3 during Autumn (Oct–Nov), Winter(Dec–March), Summer(Apr–June) and Monsoon (July–Aug) seasons respectively. During the entire study period, spectral dependence of aerosol mass absorption coefficient reveals that dominant source of BC is biomass burning during autumn season while there is mixed contribution from biomass, bio-fuel burning and fossil fuel combustion in rest of the seasons. These results are further supported by seasonal variations in Angstrom coefficient and Delta -C values. Averaged values of mass absorption efficiency of BC were found to be 3.8 m2g-1, 5.0 m2g-1, 5.6 m2g-1 and 7.1 m2g-1 during autumn, winter, summer and monsoon seasons respectively. Cluster & Concentration weighted trajectory (CWT) analysis suggests that potential sources of BC aerosol over the study region are local as well as transported from distant places mostly situated in the northwest, south-west and south-east side of the observation site depending upon the meteorological conditions and regional anthropogenic activities that varies with season. BC concentration derived from online MERRA-2 model for Patiala region and from global inventory EDGARHTAP site for agriculture waste burning further supports our findings.