Assessment of Indoor & Outdoor Black Carbon emissions in rural areas of Indo-Gangetic Plain: seasonal characteristics, source apportionment and radiative forcing

Black Carbon (BC) has been widely recognized as the second largest source of territorial and global climate change as well as a threat to human health. There has been serious concern of BC emission and its impact in Indo-Gangetic Plains (IGP) due to the use of biomass and fossil fuels for cooking, transportation and industrial activities. An attempt has been made to study indoor (Liquefied Petroleum Gas-LPG & Traditional cookstoves users households) and outdoor concentrations; seasonal characteristics; radiative forcing and source of apportionment of BC in three districts (Sitapur, Patna and Murshidabad) of IGP during January to December 2016. The seasonal concentrations of BC in LPG (traditional cookstoves) users households were 3.79 +/- 0.77 mu gm(-3) (25.36 +/- 5.01 mu gm(-3)) during the winter; 2.62 +/- 0.60 mu gm(-3) (16.36 +/- 3.68 mu gm(-3)) during the pre-monsoon; 2.02 +/- 0.355 mu gm(-3) (8.92 +/- 1.98 mu gm(-3)) during the monsoon and 2.19 +/- 0.47 mu gm(-3) (15.17 +/- 3.31 mu gm(-3)) during the post-monsoon seasons. However, the outdoor BC concentrations were 24.20 +/- 4.46, 19.80 +/- 4.34, 8.87 +/- 1.83, and 9.14 +/- 1.84 mu gm(-3) during winter, pre-monsoon, monsoon and post-monsoon seasons respectively. The negative radiative forcing (RF) at the surface suggests a cooling effect while a warming effect appears to be occurring at the top of the atmosphere. The atmospheric forcing of BC and aerosols also show a net warming effect in the selected study areas. The analysis of BC concentrations and fire episodes indicated that the emissions from biomass burning increases the pollution concentration. The backward trajectory analysis through the HYSPLIT model also suggests an additional source of pollutants during winter and pre-monsoon seasons from the northwest and northern region in the IGP.