Mass absorption efficiency of light absorbing organic aerosols from source region of paddy-residue burning emissions in the Indo-Gangetic Plain. (January 2016)

• Record Type: Journal Article
• Authors: Srinivas, B.; Rastogi, N.; Sarin, M.M.; Singh, A.; Singh, D.
• Is Part Of: Atmospheric environment. Volume 125:Part B(2016)
• Page Start: 360
• Page End: 370
• Publication Date: 2016-01
• Subjects: Brown carbon -- Biomass burning -- WSOC -- Carbonaceous aerosols -- India -- South Asia; Air -- Pollution -- Periodicals; Air -- Pollution -- Meteorological aspects -- Periodicals; 551.51
• DOI: 10.1016/j.atmosenv.2015.07.017
• Languages: English
• ISSNs: 1352-2310

Abstract

Abstract: The mass absorption efficiency (MAE) of light absorbing water-soluble organics, representing a significant fraction of brown carbon (BrC), has been studied in fine mode aerosols (PM2.5 ) from a source region (Patiala: 30.2 °N, 76.3 °E) of biomass burning emissions (BBEs) in the Indo-Gangetic Plain (IGP). The mass absorption coefficient of BrC at 365 nm ( b abs-365 ), assessed from absorption spectra of aqueous extracts, exhibits significant linear relationship with water-soluble organic carbon (WSOC) for day (R 2 = 0.37) and night time (R 2 = 0.77) samples; and slope of regression lines provides a measure of MAE of BrC (daytime: ∼0.75 m 2 g −1 and night time: 1.13 m 2 g −1 ). A close similarity in the temporal variability of b abs-365 (for BrC) and K + in all samples suggests their common source from BBEs. The b abs-365 of BrC follows a power law ( b abs-λ ≈ λ −α ; where α = angstrom exponent) and averages around 5.2 ± 2.0 M m −1 (where M = 10 −6 ). A significant decrease in the MAE of BrC from the source region (this study) to the downwind oceanic region (over Bay of Bengal, Srinivas and Sarin, 2013 ) could be attributed to relative increase in the contribution of non-absorbing WSOC and/or photo-bleaching of BrC during long-range atmospheric transport. The atmospheric radiative forcing due to BrC over the study site accounts for ∼40% of that from elemental carbon (EC). Highlights: Atmospheric brown carbon (BrC) from paddy-crop residue burning has been studied. Temporal variability of mass absorption coefficient of BrC and K + are similar. MAE of BrC decreases from source region of emission to downwind oceanic region. Atmospheric radiative forcing due to BrC accounts for ∼40% of that due to BC.