[A-CG42] 海洋表層－大気間の生物地球化学

[ACG42-01] 海氷内部でのブロモホルム生成と大気への放出について

*野村 大樹¹、大木 淳之¹、Ellen Damm²、Gerhard Dieckmann²、Bruno Delille³、Markus Frey⁴、Mats Granskog⁵、Klaus Meiners^6,7、Anna Silyakova⁸、田村 岳史⁹、Jean-Louis Tison¹⁰、山下 洋平¹¹ (1.北海道大学大学院水産科学研究院、2.Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany、3.Université de Liège, Liège, Belgium.、4.British Antarctic Survey, Cambridge, United Kingdom.、5.Norwegian Polar Institute, Tromsø, Norway.、6.Antarctic Climate andEcosystems Cooperative Research Centre, University of Tasmania, Hobart, Australia.、7.Australian Antarctic Division, Kingston, Australia.、8.Centre for Arctic Gas Hydrate, Environment and Climate, Tromsø, Norway.、9.国立極地研究所、10.Université Libre de Bruxelles, Bruxelles, Belgium.、11.北海道大学大学院地球環境科学研究院)

キーワード：海氷、ブロモホルム、極域海洋

Bromoform (CHBr₃) is one of the important bromine containing volatile halocarbons that are involved in ozone depletion in the atmosphere. Although the possible source of reactive bromine species from snow and sea ice has been discussed, mechanisms that control CHBr₃ production within sea ice and emission to the atmosphere remain unclear. Here, we show evidence of massive CHBr₃ production at sea ice surface-snow interfaces and its strong emission to the atmosphere from five field-campaigns to the Arctic Ocean, the Southern Ocean, and the Sea of Okhotsk in the winter and spring, in addition to supporting laboratory experiments. We found that the ice-related strong CHBr₃ emission was linked to the production of the CHBr₃ at the snow-sea ice interface through the haloform reaction. Our results suggest that sea ice acts as a strong CHBr₃ source for the atmosphere, indicating a significant contribution to the atmospheric bromine cycle.