M. Fischer1,6, D. N. Thomas2,3, A. Krell1, G. Nehrke1, J. Göttlicher4, L. Norman2, C. Riaux-Gobin5, and G. S. Dieckmann11Alfred Wegener Institute for Polar and Marine Reserach, Bremerhaven, Germany 2Ocean Sciences, College of Natural Sciences, Bangor University, Menai Bridge, UK 3Marine Centre, Finnish Environment Institute (SYKE), Helsinki, Finland 4Institute of Synchrotron Radiation (ISS), Synchrotron Radiation Source ANKA, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany 5USR3278, CRIOBE, CNRS-EPHE, Perpignan, France 6Faculty of Biology and Chemistry, University of Bremen, Bremen, Germany
Received: 18 Jan 2012 – Accepted for review: 25 Jan 2012 – Discussion started: 03 Feb 2012
Abstract. Calcium carbonate precipitation in sea ice can increase pCO2 during precipitation in winter and decrease pCO2 during dissolution in spring. CaCO3 precipitation in sea ice is thought to potentially drive significant CO2 uptake by the ocean. However, little is known about the quantitative spatial and temporal distribution of CaCO3 within sea ice. This is the first quantitative study of hydrous calcium carbonate, as ikaite, in sea ice and discusses its potential significance for the carbon cycle in polar oceans. Ice cores and brine samples were collected from pack and land fast sea ice between September and December 2007 during an expedition in the East Antarctic and another off Terre Adélie, Antarctica. Samples were analysed for CaCO3, Salinity, DOC, DON, Phosphate, and total alkalinity. A relationship between the measured parameters and CaCO3 precipitation could not be observed. We found calcium carbonate, as ikaite, mostly in the top layer of sea ice with values up to 126 mg ikaite per liter melted sea ice. This potentially represents a contribution between 0.12 and 9 Tg C to the annual carbon flux in polar oceans. The horizontal distribution of ikaite in sea ice was heterogenous. We also found the precipitate in the snow on top of the sea ice.
Fischer, M., Thomas, D. N., Krell, A., Nehrke, G., Göttlicher, J., Norman, L., Riaux-Gobin, C., and Dieckmann, G. S.: Quantification of ikaite in Antarctic sea ice, The Cryosphere Discuss., 6, 505-530, doi:10.5194/tcd-6-505-2012, 2012.