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Dual carbon isotope characterization of total organic carbon in wintertime carbonaceous aerosols from northern India
Author(s) -
Bikkina Srinivas,
Andersson August,
Sarin M. M.,
Sheesley R. J.,
Kirillova E.,
Rengarajan R.,
Sudheer A. K.,
Ram K.,
Gustafsson Örjan
Publication year - 2016
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2016jd024880
Subject(s) - environmental science , aerosol , total organic carbon , troposphere , atmospheric sciences , isotopes of carbon , environmental chemistry , isotopes of nitrogen , geology , nitrogen , chemistry , meteorology , geography , organic chemistry
Large‐scale emissions of carbonaceous aerosols (CA) from South Asia impact both regional climate and air quality, yet their sources are not well constrained. Here we use source‐diagnostic stable and radiocarbon isotopes (δ 13 C and Δ 14 C) to characterize CA sources at a semiurban site (Hisar: 29.2°N, 75.2°E) in the NW Indo‐Gangetic Plain (IGP) and a remote high‐altitude location in the Himalayan foothills (Manora Peak: 29.4°N, 79.5°E, 1950 m above sea level) in northern India during winter. The Δ 14 C of total aerosol organic carbon (TOC) varied from −178‰ to −63‰ at Hisar and from −198‰ to −1‰ at Manora Peak. The absence of significant differences in the 14 C‐based fraction biomass of TOC between Hisar (0.81 ± 0.03) and Manora Peak (0.82 ± 0.07) reveals that biomass burning/biogenic emissions (BBEs) are the dominant sources of CA at both sites. Combining this information with δ 13 C, other chemical tracers (K + /OC and SO 4 2− /EC) and air mass back trajectory analyses indicate similar source regions in the IGP (e.g., Punjab and Haryana). These results highlight that CA from BBEs in the IGP are not only confined to the atmospheric boundary layer but also extend to higher elevations of the troposphere, where the synoptic‐scale circulations could substantially influence their abundances both to the Himalayas and over the downwind oceanic regions such as the Indian Ocean. Given the vast emissions of CA from postharvest crop residue combustion practices in the IGP during early Northeast Monsoon, this information is important for both improved process and model understanding of climate and health effects, as well as in guiding policy decision aiming at reducing emissions.