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Volume 15, No. 2, April 2015, Pages 465-478 PDF(3.47 MB)  
doi: 10.4209/aaqr.2014.02.0028   

Characterization of Black Carbon Aerosols over Darjeeling - A High Altitude Himalayan Station in Eastern India

Chirantan Sarkar1, Abhijit Chatterjee1,2,3, Ajay Kumar Singh2, Sanjay Kumar Ghosh2,3, Sibaji Raha1,2,3

1 Environmental Sciences Section, Bose Institute, P 1/12 CIT Scheme-VIIM, Kolkata 700 054, India
2 Center for Astroparticle Physics and Space Science, Bose Institute, Saltlake, Sector-V, Kolkata 700 091, India
3 National Facility on Astroparticle Physics and Space Science, Bose Institute, 16, AJC Bose Road, Darjeeling 734 101, India

 

Highlights
  • First time long-term study of black carbon aerosols at eastern Himalaya, India.
  • Vehicular emissions are major source of black carbon through out the year.
  • Effect of local emission, long range and mountain wind transport was studied.
  • BC over Darjeeling was higher than other high altitude stations of India and Nepal.
  • BC over Darjeeling was higher and comparable with some Indian metro cities.

Abstract

 

A continuous monitoring of black carbon (BC) aerosols was carried over a high altitude station Darjeeling (27°01′N, 88°15′E; 2200 m a.s.l.) at eastern part of Himalaya in India during January 2010–December 2011. In this article, we have presented the results of our analysis of the data collected during this interval. This study is focused on the investigation of the temporal variations, potential sources, long-range transport of BC aerosols along with the meteorological impact on these aerosols. BC is found to exhibit strong seasonal variation with the maximum concentration during premonsoon (5.0 ± 1.1 µg/m3) followed by winter (3.9 ± 2.2 µg/m3), postmonsoon (2.9 ± 1.0 µg/m3) and minimum during monsoon (1.7 ± 0.7 µg/m3). BC concentration varied between 0.2–12.8 µg/m3 with an average of 3.4 ± 1.9 µg/m3 over the entire period of study. The diurnal variation of BC aerosol shows sharp morning and evening peaks associated to the local anthropogenic activities as well as the impact of up-slope mountain wind. Amongst the long distant sources, BC concentration associated with the transport from Middle East countries and passing over South West countries like Pakistan, Afghanistan and Indo-Gangetic Plain is found to be comparatively higher. It is observed that the contributions of local emissions, long-range transport and mountain wind transport are approximately 56%, 27% and 17%, respectively, towards the total BC loading over Darjeeling during premonsoon. Fossil fuel emissions during premonsoon and biomass burning during winter are the major sources of BC with the overall dominance of fossil fuel burning throughout the entire study period. The BC concentration over Darjeeling is found to be much higher than any other high altitude stations in India and Nepal and even higher and comparable with some of the metro-cities in India.

 

 

Keywords: Black carbon; Himalaya; Darjeeling; Fossil fuel; Biomass.

 

 

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