Journal of Geophysical Research: Atmospheres

13C- and 14C-based study of sources and atmospheric processing of water-soluble organic carbon (WSOC) in South Asian aerosols

Authors

  • Elena N. Kirillova,

    Corresponding author
    1. Department of Applied Environmental Science (ITM) and the Bert Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden
    • Corresponding author: E. N. Kirillova and Örjan Gustafsson, Department of Applied Environmental Science (ITM) and the Bert Bolin Centre for Climate Research, Stockholm University, 10691 Stockholm, Sweden. (elena.kirillova@itm.su.se; orjan.gustafsson@itm.su.se)

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  • August Andersson,

    1. Department of Applied Environmental Science (ITM) and the Bert Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden
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  • Rebecca J. Sheesley,

    1. Department of Applied Environmental Science (ITM) and the Bert Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden
    2. Current affiliation: Department of Environmental Science, Baylor University, Waco, Texas, USA
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  • Martin Kruså,

    1. Department of Applied Environmental Science (ITM) and the Bert Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden
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  • P. S. Praveen,

    1. Maldives Climate Observatory at Hanimaadhoo (MCOH), Republic of the Maldives
    2. Current affiliation: Scripps Institute of Oceanography, Center for Clouds, Chemistry and Climate, University of California-San Diego, La Jolla, California, USA
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  • Krishnakant Budhavant,

    1. Maldives Climate Observatory at Hanimaadhoo (MCOH), Republic of the Maldives
    2. Indian Institute of Tropical Meteorology, Pune, Maharashtra, India
    3. Vishwakarma Institute of Technology, Pune, Maharashtra, India
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  • P. D. Safai,

    1. Indian Institute of Tropical Meteorology, Pune, Maharashtra, India
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  • P. S. P. Rao,

    1. Indian Institute of Tropical Meteorology, Pune, Maharashtra, India
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  • Örjan Gustafsson

    Corresponding author
    1. Department of Applied Environmental Science (ITM) and the Bert Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden
    • Corresponding author: E. N. Kirillova and Örjan Gustafsson, Department of Applied Environmental Science (ITM) and the Bert Bolin Centre for Climate Research, Stockholm University, 10691 Stockholm, Sweden. (elena.kirillova@itm.su.se; orjan.gustafsson@itm.su.se)

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Abstract

[1] Water-soluble organic carbon (WSOC) is typically a large component of carbonaceous aerosols with a high propensity for inducing cloud formation. The sources of WSOC, which may be both of primary and secondary origins, are in general poorly constrained. This study assesses the concentrations and dual-carbon isotope (14C and 13C) signatures of South Asian WSOC during a 15-month continuous campaign in 2008–2009. Total suspended particulate matter samples were collected at Sinhagad (SINH) India and at the Maldives Climate Observatory at Hanimaadhoo (MCOH). Monsoon-driven meteorology yields significant WSOC concentration differences between the dry winter season (0.94 ± 0.43 µg m−3 MCOH and 3.6 ± 2.3 µg m−3 SINH) and the summer monsoon season (0.10 ± 0.04 µg m−3 MCOH and 0.35 ± 0.21 µg m−3 SINH). Radiocarbon-based source apportionment of WSOC not only shows the dominance of biogenic/biomass combustion sources but also a substantial anthropogenic fossil-fuel contribution (17 ± 4% MCOH and 23 ± 4% SINH). Aerosols reaching MCOH after long-range over-ocean transport were enriched by 3–4‰ in δ13C-WSOC relative to SINH. This is consistent with particle-phase aging processes influencing the δ13C-WSOC signal in the South Asian regional receptor atmosphere.

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