Aerosol composition and sources in the central Arctic Ocean during ASCOS
Date
2011
Authors
Chang, R. Y. -W
Leck, C.
Graus, M.
Mueller, M.
Paatero, J.
Burkhart, J. F.
Stohl, A.
Orr, L. H.
Hayden, K.
Li, S. -M
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Abstract
Measurements of submicron aerosol chemical composition were made over the central Arctic
Ocean from 5 August to 8 September 2008 as a part of the Arctic Summer Cloud Ocean Study
(ASCOS) using an aerosol mass spectrometer (AMS). The median levels of sulphate and
organics for the entire study were 0.051 and 0.055 mu gm(-3), respectively. Positive
matrix factorisation was performed on the entire mass spectral time series and this
enabled marine biogenic and continental sources of particles to be separated. These
factors accounted for 33% and 36% of the sampled ambient aerosol mass, respectively, and
they were both predominantly composed of sulphate, with 47% of the sulphate apportioned
to marine biogenic sources and 48% to continental sources, by mass. Within the marine
biogenic factor, the ratio of methane sulphonate to sulphate was 0.25+/-0.02, consistent
with values reported in the literature. The organic component of the continental factor
was more oxidised than that of the marine biogenic factor, suggesting that it had a
longer photochemical lifetime than the organics in the marine biogenic factor. The
remaining ambient aerosol mass was apportioned to an organic-rich factor that could have
arisen from a combination of marine and continental sources. In particular, given that
the factor does not correlate with common tracers of continental influence, we cannot
rule out that the organic factor arises from a primary marine source.
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Citation
Chang, R. Y. -W, C. Leck, M. Graus, M. Mueller, et al. 2011. "Aerosol composition and sources in the central Arctic Ocean during ASCOS." Atmospheric Chemistry and Physics 11(20): 10619-10636.