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Titel |
A snow pack source of aldehydes and acetone in West Antarctica between 76 and 90 degrees S |
VerfasserIn |
M. M. Frey, R. C. Bales, D. Belle-Oudry |
Konferenz |
EGU General Assembly 2009
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Medientyp |
Artikel
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Sprache |
Englisch
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 11 (2009) |
Datensatznummer |
250030377
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Zusammenfassung |
The investigation of snow-atmosphere exchange of many chemical species driven by physical
and photochemical processes is key for understanding atmospheric chemistry above snow
covered regions and has important implications for ice core interpretation. A number of
recent field and modeling studies indicates that a source of aldehydes and ketones exists
in polar snowpacks, and the emission of these species may significantly impact
organic and HO2 radical levels in the overlying boundary layer. However, most of the
studies took place in the northern hemisphere and only few data are available from
Antarctica.
Here we present new measurements from the US International Trans-Antarctic Scientific
Expedition (ITASE) carried out in summers of 2000-2003. 1-2 day average mixing ratios of
formaldehyde (CH2O), acetaldehyde (CH3CHO) and acetone (CH3COCH3) were determined
in ambient and firn air across the West Antarctic Ice Sheet (WAIS) between 76-S and 90-S.
Organic chemical species were collected on 2,4-Dinitrophenylhydrazine (DNPH) filter
cartridges and analyzed after elution using HPLC. Median (range) ambient levels of CH2O,
CH3CHO and CH3COCH3 were 65 (15-205) pptv, 35 (10-195) pptv and 65 (25-150) pptv,
respectively. Firn air concentrations of CH2O and CH3CHO were increased up
to 15fold compared to ambient air, suggesting significant emission fluxes, while
CH3COCH3 gradients between the air above and below the snow surface were less
pronounced..
We discuss implications for the oxidation capacity of the WAIS boundary layer and for
the interpretation of ongoing surface studies at the WAIS Divide deep coring site. |
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