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Organic iodine in Antarctic sea ice: A comparison between winter in the Weddell Sea and summer in the Amundsen Sea
Author(s) -
Granfors Anna,
Ahnoff Martin,
Mills Matthew M.,
Abrahamsson Katarina
Publication year - 2014
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
eISSN - 2169-8961
pISSN - 2169-8953
DOI - 10.1002/2014jg002727
Subject(s) - sea ice , antarctic sea ice , oceanography , arctic ice pack , snow , cryosphere , environmental science , fast ice , climatology , atmospheric sciences , geology , geomorphology
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 (CH 3 I, CH 2 ClI, CH 2 BrI, and CH 2 I 2 ) 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 chlorophyll a biomass indicated a biological origin. We suggest that CH 3 I is formed biotically in sea ice during both summer and winter. For CH 2 ClI, CH 2 BrI, and CH 2 I 2 , an additional abiotic source at the snow/ice interface in winter is suggested. Elevated air concentrations of CH 3 I and CH 2 ClI during winter indicate that they are enriched in lower troposphere and may take part in the formation of IO at polar sunrise.