Long term studies on characteristics of black carbon aerosols over a tropical urban station Pune, India

Continuous monitoring of surface black carbon (BC) was carried out using an Aethalometer in Pune, an inland urban tropical location in SW India. BC data for the period of 6 years (2005-2010) was studied and compared with that reported from different Indian locations. The mean BC concentration for the 6 year period was 3.58 ± 1.55 μg/m3 with maximum concentration occurring during winter and minimum during monsoon season in each year. Various characteristics of temporal variation of BC aerosols are discussed. Mean annual mass fraction of BC to TSP was 2.9%. The similarity of diurnal variation as well as significantly good correlation of BC with PM1.0 showed that BC lies mainly in the fine size. Also, a good correlation with other anthropogenically originated chemical components of aerosol like NO3−, NH4+ and nonsea salt fractions of SO42 − and K+ indicated the presence of common source like fossil-fuel/biomass burning. Effects of meteorological parameters such as temperature, wind speed, rainfall and mixing ratio on BC are discussed. In addition, some of the optical properties of aerosols e.g. aerosol optical depths (AOD), single scattering albedo (SSA), and Angstrom Coefficient are correlated with surface BC concentrations.