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Systematic measurements of mass concentration and chemical composition of aerosols have been carried out at Kharagpur in the Indo-Gangetic Plains during winter to identify the major sources over the region and to examine the changes in aerosol characteristics during haze events. Aerosol concentration is significantly large at the site, more than two-fold that of the National Ambient Air Quality Standards for residential areas in India. The main sources of aerosols over the region are anthropogenic activities and mineral dust. Species like SO42-, NO3-, NH4+, BC, CI-, etc. are associated with anthropogenic sources, while Al, Fe, Ca, Na, Ti, Mn, etc. originate mainly from crustal sources. Though the site is only similar to 100 km away from the Bay of Bengal, oceanic contribution is insignificant (similar to 2%), mainly due to prevailing north/northeasterly winds. A mean chemical composition evolved for the location shows that the aerosol system is composed of 17% mineral dust, 18% water-soluble components, 6% black carbon and 23% particulate organic matter along with a residual fraction of 36%. This residual fraction is attributed to organic aerosols of natural or secondary origin and water content of aerosols. An uncertainty of the order of 6-45% is involved in these estimations. Nevertheless, this mean chemical composition can act as a realistic input chemical model in the estimation of aerosol radiative forcing for this region. Analysis indicates that anthropogenic influence can be comparable to or exceeds natural aerosols at the location. The total aerosol mass concentration as well as that of anthropogenic species revealed enhancement on hazy days. (C) 2011 Elsevier Ltd. All rights reserved.

来源平台：JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS