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Titel |
Effect of biomass burning over the western North Pacific Rim: wintertime maxima of anhydrosugars in ambient aerosols from Okinawa |
VerfasserIn |
C. Zhu, K. Kawamura, B. Kunwar |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1680-7316
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Digitales Dokument |
URL |
Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 4 ; Nr. 15, no. 4 (2015-02-24), S.1959-1973 |
Datensatznummer |
250119453
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Publikation (Nr.) |
copernicus.org/acp-15-1959-2015.pdf |
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Zusammenfassung |
Biomass burning (BB) largely modifies the chemical composition of
atmospheric aerosols on the globe. We collected aerosol samples (TSP) at
Cape Hedo, on subtropical Okinawa Island, from October 2009 to February 2012 to
study anhydrosugars as BB tracers. Levoglucosan was detected as the dominant
anhydrosugar followed by its isomers, mannosan and galactosan. We found a
clear seasonal trend of levoglucosan and mannosan with winter maxima and
summer minima. Positive correlation was found between levoglucosan and
nss-K+ (r = 0.38, p < 0.001); the latter is another BB tracer.
The analyses of air mass trajectories and fire spots demonstrated that the
seasonal variations of anhydrosugars are caused by long-range transport of
BB emissions from the Asian continent. We found winter maxima of
anhydrosugars, which may be associated with open burning and domestic
heating and cooking in northern and northeastern China, Mongolia and Russia and
with the enhanced westerly winds. The monthly averaged levoglucosan / mannosan
ratios were lower (2.1–4.8) in May–June and higher (13.3–13.9) in
November–December. The lower values may be associated with softwood burning
in northern China, Korea and southwestern Japan whereas the higher values are
probably caused by agricultural waste burning of maize straw in the North
China Plain. Anhydrosugars comprised 0.22% of water-soluble organic
carbon (WSOC) and 0.13% of organic carbon (OC). The highest values to
WSOC (0.37%) and OC (0.25%) were found in winter, again indicating an
important BB contribution to Okinawa aerosols in winter. This study provides
useful information to better understand the effect of East Asian biomass
burning on the air quality in the western North Pacific Rim. |
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