Study on Black Carbon and Its Characterisation at an Urban Location, Hyderabad during 2010 to 2012

A seven channel Aethalometer (AE31) was used to measure the black carbon (BC) mass concentrations at the premises of National Remote Sensing Centre (NRSC), Hyderabad during the period 2010-2012 to characterize BC temporal concentration and source identification. Diurnal variation of BC shows varied amplitude of BC mass concentration with peak during mornings and nights with minimum during afternoons of all the study periods (2010-2012). Highest absorption coefficient at 520 nm (babs = 38.79 Mm-1) was observed during post monsoon season of 2011 and lowest value observed (babs = 22.06 Mm-1) during winter season of 2010. Absorption Angstrom Exponents (AAE) were analysed in the lower (370 nm-520 nm) and higher wavelength (590 nm-950 nm) region to explain the BC origin. A few number of days with high contrasting AAE in lower and higher wavelengths, responsible for the bio fuel generated BC were found during the study period. Study revealed that majority of the study period, AAE values are around 1, attributed to mainly vehicular emission. Highest AAE of 1.57 (370 nm-950 nm) was observed on 4 January, 2012. Three representative days of pre-monsoon, post-monsoon and winter were considered for analyzing daily variations of AAE in conjunction with back trajectories from NOAA HYSPLIT model to confirm the source of BC as biomass burning origin.