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- Granfors, Anna, 1978
(författare)
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Biogenic Halocarbons in Polar Sea Ice
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Sea ice is to date a rather poorly investigated part of the cycling of volatile halogenated organic compounds, halocarbons. These compounds are natural sources of reactive iodine and bromine to the atmosphere, and are produced in the marine environment. The aim of this study was to determine the role of sea ice in terms of production and release of halocarbons to the atmosphere. Iodinated and brominated halocarbons were measured in polar sea ice as well as in snow, air, and seawater under the ice. Multiple samples were collected from the same location in order to cover variability. Studies were performed both in winter and summer, and seasonal variations were observed. Sea ice acted as a source of halocarbons both in winter and in summer. Biotic production was observed during summer, and depth distributions of halocarbons in the ice were related to ice algal biomass. Unexpectedly high concentrations of halocarbons were found at the surface of Antarctic winter sea ice. For bromoform (CHBr3) the concentration range was 0.2 - 20 nM in the top 10 cm of the ice. High concentrations were also found in the snow closest to the snow-ice interface. Our results suggest that an abiotic formation occurs in seasonal sea ice during polar night. This may lead to a winter accumulation of halocarbons in the marine boundary layer and enhance tropospheric ozone depletion in the polar spring.
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| 2. |
- Granfors, Anna, 1978, et al.
(författare)
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Organic iodine in Antarctic sea ice: a comparison between winter in the Weddell Sea and summer in the Amundsen Sea
- 2014
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Ingår i: Journal of Geophysical Research - Biogeosciences. - 0148-0227 .- 2156-2202. ; 119:12, s. 2276-2291
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Tidskriftsartikel (refereegranskat)abstract
- Recent studies have recognized sea ice as a source of reactive iodine to the Antarctic boundary layer. Volatile iodinated compounds (iodocarbons) are released from sea ice, and they have been suggested to contribute to the formation of iodine oxide (IO), which takes part in tropospheric ozone destruction in the polar spring. We measured iodocarbons (CH3I, CH2ClI, CH2BrI and CH2I2) in sea ice, snow, brine and air during two expeditions to Antarctica, OSO 10/11 to the Amundsen Sea during austral summer, and ANT XXIX/6 to the Weddell Sea in austral winter. These are the first reported measurements of iodocarbons from the Antarctic winter. Iodocarbons were enriched in sea ice in relation to seawater in both summer and winter. During summer the positive relationship to Chl a biomass indicated a biological origin. We suggest that CH3I is formed biotically in sea ice during both summer and winter. For CH2ClI, CH2BrI and CH2I2 an additional abiotic source at the snow-ice interface in winter is suggested . Elevated air concentrations of CH3I and CH2ClI during winter indicate that they are enriched in lower troposphere and may take part in formation of IO at polar sunrise.
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