Source identification and distribution reveals the potential of the geochemical Antarctic sea ice proxy IPSO25

• Published in: Nature communications Vol. 7; no. 1; p. 12655
• Main Authors: Belt, S. T., Smik, L., Brown, T. A., Kim, J.-H., Rowland, S. J., Allen, C. S., Gal, J.-K., Shin, K.-H., Lee, J. I., Taylor, K. W. R.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 30.08.2016; Nature Publishing Group; Nature Portfolio
• Subjects: 704/106/125; 704/106/2738; 704/172/169/209; Biomarkers; Humanities and Social Sciences; Ice; Lipids; multidisciplinary; Plankton; Science; Science (multidisciplinary); Sediments; South Korea; Weddell Sea; Bellingshausen Sea; Antarctic Peninsula; United Kingdom > UK; Arctic region; Southern Ocean; Ross Sea; Antarctica
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms12655

The presence of a di-unsaturated highly branched isoprenoid (HBI) lipid biomarker (diene II) in Southern Ocean sediments has previously been proposed as a proxy measure of palaeo Antarctic sea ice. Here we show that a source of diene II is the sympagic diatom Berkeleya adeliensis Medlin. Furthermore, the propensity for B. adeliensis to flourish in platelet ice is reflected by an offshore downward gradient in diene II concentration in >100 surface sediments from Antarctic coastal and near-coastal environments. Since platelet ice formation is strongly associated with super-cooled freshwater inflow, we further hypothesize that sedimentary diene II provides a potentially sensitive proxy indicator of landfast sea ice influenced by meltwater discharge from nearby glaciers and ice shelves, and re-examination of some previous diene II downcore records supports this hypothesis. The term IPSO 25 —Ice Proxy for the Southern Ocean with 25 carbon atoms—is proposed as a proxy name for diene II. The sedimentary presence of the diatom lipid diene II (hereafter IPSO 25 ) has been proposed as a proxy for palaeo Antarctic sea ice. Here, the authors identify a source of IPSO 25 and hypothesize that its sedimentary distribution may provide proxy evidence of landfast ice influenced by freshwater discharge.