Highly Branched Isoprenoids as Proxies for Variable Sea Ice Conditions in the Southern Ocean

G. Massé1,3, S.T. Belt3, X. Crosta2, S. Schmidt2, I. Snape4, D.N. Thomas5 and Steven J. Rowland3


1

LOCEAN, UMR7159, Université Pierre et Marie Curie, France
2 EPOC, UMR5805, Université Bordeaux 1, France
3 Biogeochemistry Research Centre, University of Plymouth, U.K.
4 Australian Antarctic Division, Australia
5 School of Ocean Sciences, Bangor University, U.K.

Presented at: 25th IMOG, Interlaken, Switzerland, 18-23 September 2011

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Introduction

Reconstruction of the historical and palaeo-environmental occurrence of sea ice is key to understanding climate change. Numerous sediment proxies of historical and palaeo-sea ice occurrence have been proposed. Amongst these is a hydrocarbon designated IP25 (I, Figure 1) synthesised by sympagic sea-ice diatoms. IP25 has a widespread occurrence in Arctic sea ice but it has never been reported in the Antarctic. However, a number of related chemicals (HBIs) have been reported in Antarctic sea ice diatom samples and sediments.

In the present study, we report the presence of a di-unsaturated HBI (II) in Antarctic sea ice and other poly-unsaturated HBIs (e.g. III-VI) in Antarctic phytoplankton. Using differences in structures and isotopic compositions, we assign the origins of HBI isomers present in recent sediments collected from the Adélie Land area in the Eastern Antarctic Continental Shelf area.

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