Manisha Mishra, U.C. Kulshrestha This email address is being protected from spambots. You need JavaScript enabled to view it.

School of Environmental Sciences, Jawaharlal Nehru University, New Delhi – 110067, India

Received: November 13, 2020
Revised: May 17, 2021
Accepted: June 8, 2021

 Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.

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Mishra, M., Kulshrestha, U.C. (2021). Source Impact Analysis Using Char-EC/soot-EC Ratios in the Central Indo-Gangetic Plain (IGP) of India. Aerosol Air Qual. Res.


  • Char-EC/soot-EC ratio found to be good tracer for biomass burning sources.
  • Seasonal characteristics ratio of Char-EC/Soot- EC contrasted to OC/EC ratio.
  • OC, WSOC and EC constituted about 40% of fPM mass.
  • Post-monsoon levels of carbonaceous species were higher than winters.


This study reports one year (December 2016–November 2017) observations of carbonaceous aerosols in fine particulate matter (fPM; dia. < 2.5µm, n = 102 samples) over an urban location (Prayagraj) in central Indo-Gangetic Plain (IGP). The fPM concentrations exhibited a very large variability ranging from 22‒367 (Avg. ± SD: 149 ± 87) µg m-3 during the entire study period. The carbonaceous aerosols (Organic Carbon (OC), Water soluble OC (WSOC) and Elemental Carbon (EC)) constituted about 40% of the annual fPM mass. Furthermore, based on several diagnostic ratios (EC/fPM, OC/EC, char-EC/soot-EC, and WSOC/OC), the characteristic features of carbonaceous aerosols were inferred to be significantly different in each season. The variation in the abundance pattern of carbonaceous aerosols appears to have influence of emission sources, seasonal meteorology, and atmospheric chemistry. The trajectory analysis at the sampling site has revealed that higher concentration of fPM and carbonaceous aerosols, mainly during the post-monsoon and winter season, was associated with the northwesterly air masses originated from the northwestern part of India. However, during summer and monsoon seasons the study site was likely to have influence from air masses of mixed origins (continental/marine) with the dominance of local anthropogenic sources. The char-EC/soot-EC ratio coupled to OC/EC ratio has been utilized in this study for source impact identification. Accordingly, the cross plots of char-EC/soot-EC and OC/EC ratio indicated the more of influence biomass burning during winter and post-monsoon season. However, during the summer and monsoon season, the cross plot indicated the predominant impact of fossil-fuel combustion sources. This study highlights the utility of char-EC/soot-EC ratio as a better indicator to trace out the impact of biomass burning and fossil-fuel combustion sources of carbonaceous aerosols compared to OC/EC over the IGP region.

Keywords: Indo-Gangetic Plain, Carbonaceous aerosols, OC/EC ratio, Char-EC/soot-EC ratio, Secondary organic aerosol

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