Sources and light absorption of water-soluble organic carbon aerosols in the outflow from northern China 1Department of Applied Environmental Science (ITM) and the Bolin Centre for Climate Research, Stockholm University, 106 91 Stockholm, Sweden
07 Feb 2014
2Department of Earth and Environmental Sciences, Korea University, 136-701 Seoul, South Korea
Received: 09 Jul 2013 – Published in Atmos. Chem. Phys. Discuss.: 25 Jul 2013 Abstract. High loadings of anthropogenic carbonaceous aerosols in Chinese air influence
the air quality for over one billion people and impact the regional climate.
A large fraction (17–80%) of this aerosol carbon is water-soluble,
promoting cloud formation and thus climate cooling. Recent findings, however,
suggest that water-soluble carbonaceous aerosols also absorb sunlight,
bringing additional direct and indirect climate warming effects, yet the
extent and nature of light absorption by this water-soluble "brown carbon"
and its relation to sources is poorly understood. Here, we combine source
estimates constrained by dual carbon isotopes with light-absorption
measurements of water-soluble organic carbon (WSOC) for a March 2011 campaign
at the Korea Climate Observatory at Gosan (KCOG), a receptor station in SE
Yellow Sea for the outflow from northern China. The mass absorption cross
section at 365 nm (MAC365) of WSOC for air masses from N. China were in
general higher (0.8–1.1 m2 g−1), than from other source regions
(0.3–0.8 m2 g−1). However, this effect corresponds to only
2–10% of the radiative forcing caused by light absorption by elemental
carbon. Radiocarbon constraints show that the WSOC in Chinese outflow had
significantly higher fraction fossil sources (30–50%) compared to
previous findings in S. Asia, N. America and Europe. Stable carbon
(δ13C) measurements were consistent with aging during long-range
air mass transport for this large fraction of carbonaceous aerosols.
Revised: 11 Dec 2013 – Accepted: 05 Jan 2014 – Published: 07 Feb 2014
Citation: Kirillova, E. N., Andersson, A., Han, J., Lee, M., and Gustafsson, Ö.: Sources and light absorption of water-soluble organic carbon aerosols in the outflow from northern China, Atmos. Chem. Phys., 14, 1413-1422, doi:10.5194/acp-14-1413-2014, 2014.