Effect of ikaite precipitation on phosphate removal in sea ice
Ikaite (CaCO3·6H2O) precipitation in sea ice has been shown to affect CO2 exchange between the atmosphere and ocean. A laboratory study indicates that it could also co-precipitate phosphate from sea ice, which has the potential to affect sea-ice biogeochemical processes. However, the relative importance of ikaite precipitation on phosphate removal under sea-ice conditions remains unknown. We investigated ikaite precipitation in both frost flowers and seaice (under two scenarios: flooded by seawater and non-flooded) in an outdoor sea-ice mesocosm experiment, and in sea ice under natural conditions in north-eastern Greenland. The ice mesocosm experiment showed that ikaite was highly enriched in frost flowers with a concentration of up to 350 µmol·kg–1. Ikaite was also detected in the surface layer of sea ice, ranging from ca. 13 µmol·kg–1 in the non-flooded ice to ca. 95 µmol·kg–1 in the flooded ice. However, under all these conditions, no phosphate co-precipitation with ikaite was observed. The field study in Greenland showed similar results: ikaite was detected in surface ice with an average concentration of 13.8 µmol·kg–1, but no phosphate removal due to ikaite precipitation was observed. These results suggest that the impact of ikaite precipitation on phosphate and the sea-ice ecosystem might not be as significant as imagined previously.
Cox G.F.N. & Weeks W.F. 1983. Equations for determining the gas and brine volumes in sea-ice samples. Journal of Glaciology 29, 306–316, doi: 10.3189/S0022143000008364.
Deming J.W. & Collins R.E. 2017. Sea ice as a habitat for Bacteria, Archaea and viruses. In D.N. Thomas (ed.): Sea ice. Pp. 326–351. Oxford: Blackwell Science.
Dieckmann G.S., Nehrke G., Papadimitriou S., Göttlicher J., Steininger R., Kennedy H., Wolf-Gladrow D. & Thomas D.N. 2008. Calcium carbonate as ikaite crystals in Antarctic sea ice. Geophysical Research Letters 35, L08501, doi: 10.1029/2008GL033540.
Dieckmann G.S., Nehrke G., Uhlig C., Göttlicher J., Gerland S., Granskog M.A. & Thomas D.N. 2010. Brief communication: Ikaite (CaCO3.6H2O) discovered in Arctic sea ice. The Cryosphere 4, 227–230, doi: 10.5194/tc-4-227-2010.
Fischer M., Thomas D.N., Krell A., Nehrke G., Göttlicher J., Norman L., Meiners K.M., Riaux-Gobin C. & Dieckmann G.S. 2013. Quantification of ikaite in Antarctic sea ice. Antarctic Science 25, 421–432, doi: 10.1017/S0954102012001150.
Fripiat F., Meiners K., Vancoppenolle M., Papadimitriou S., ThomasD., Ackley S., Arrigo K., Carnat G., Cozzi S., Delille B., Dieckmann G., Dunbar R., Fransson A., Kattner G., Kennedy H., Lannuzel D., Munro D., NomuraD., Rintala J.-M. & Tison J.-L. 2017. Macro-nutrient concentrations in Antarctic pack ice: overall patterns and overlooked processes. Elementa—Science of the Anthropocene 5, article no. 13, doi: 10.1525/elementa.217.
Galley R.J., Else B.G.T., Geilfus N.-X., Hare A.A., Babb D., Papakyriakou T., Barber D.G. & Rysgaard S. 2015. Micrometeorological and thermal control of frost flower growth and decay on young sea ice. Arctic 68, 79–92, doi: 10.14430/arctic4457.
Geilfus N.-X., Carnat G., Dieckmann G.S., Halden N., Nehrke G., Papakyriakou T., Tison J.-L. & Delille B. 2013. First estimates of the contribution of CaCO3 precipitation to the release of CO2 to the atmosphere during young sea ice growth. Journal of Geophysical Research—Oceans 118, 244–255, doi: 10.1029/2012JC007980.
Gleitz M., Loeff M.R.v.d., Thomas D.N., Dieckmann G.S. & Millero F.J. 1995. Comparison of summer and winter inorganic carbon, oxygen and nutrient concentrations in Antarctic sea ice brine. Marine Chemistry 51, 81–91, doi: 10.1016/0304-4203(95)00053-T.
Hare A.A., Wang F., Barber D., Geilfus N.-X., Galley R.J. & Rysgaard S. 2013. pH evolution in sea ice grown at an outdoor experimental facility. Marine Chemistry 154, 46–54, doi: 10.1016/j.marchem.2013.04.007.
Hu Y.-B., Dieckmann G.S., Wolf-Gladrow D.A. & Nehrke G.2014. Laboratory study on coprecipitation of phosphate with ikaite in sea ice. Journal of Geophysical Research—Oceans 119, 7007–7015, doi: 10.1002/2014JC010079.
Loose B., Miller L.A., Elliott S. & Papakyriakou T. 2011. Sea ice biogeochemistry and material transport across the frozen interface. Oceanography 24, 202–218, doi: 10.5670/oceanog.2011.72.
Millero F.J. 2006. Chemical oceanography. Boca Raton, FL: CRC Press.
Murphy J. & Riley J.P. 1962. A modified single solution method for the determination of phosphate in natural waters. Analytica Chimica Acta 27, 31–36, doi: 10.1016/S0003-2670(00)88444-5.
Nomura D., Nishioka J., Granskog M.A., Krell A., Matoba S., Toyota T., Hattori H. & Shirasawa K. 2010. Nutrient distributions associated with snow and sediment-laden layers in sea ice of the southern Sea of Okhotsk. Marine Chemistry 119, 1–8, doi: 10.1016/j.marchem.2009.11.005.
Papadimitriou S., Kennedy H., Kennedy P. & Thomas D.N. 2014. Kinetics of ikaite precipitation and dissolution in seawater-derived brines at sub-zero temperatures to 265 K. Geochimica et Cosmochimica Acta 140, 199–211, doi: 10.1016/j.gca.2014.05.031.
Rysgaard S., Glud R.N., Lennert K., Cooper M., Halden N., Leakey R.J.G., Hawthorne F.C. & Barber D. 2012. Ikaite crystals in melting sea ice—implications for pCO2 and pH levels in Arctic surface waters. The Cryosphere 6, 901–908, doi: 10.5194/tc-6-901-2012.
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