Distinctive ¹³C isotopic signature distinguishes a novel sea ice biomarker in Arctic sediments and sediment traps

Simon T. Belt (1) , Guillaume Massé (1) , Lindsay L. Vare (1) , Steven J. Rowland (1) , Michel Poulin (2) , Marie-Alexandrine Sicre (3) , Makoto Sampei (4) , Louis Fortier (4)

1 School of Earth, Ocean and Environmental Sciences [Plymouth]
2 Canadian Museum of Nature (CANADA)
3 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]
4 Québec-Océan

A C₂₅ highly branched isoprenoid (HBI) monoene hydrocarbon, designated IP₂₅ , has been proposed previously to originate from diatoms living in Arctic sea ice, while the presence of IP₂₅ in sediments has been suggested to be a proxy for the occurrence of former Arctic sea ice. Here, we show that the ¹³C isotopic composition of IP₂₅ in sea ice, in sediment trap material collected under sea ice, and in high latitude northern sediments, is distinctive (isotopically 'heavy') and distinguishable from that of organic matter of planktonic or terrigenous origin. Mean δ¹³C values for IP₂₅ were − 22.3 ± 0.4‰ (sea ice), −19.6 ± 1.1‰ (sediment traps) and −19.3 ± 2.3‰ (sediments). These measurements, therefore, support further the proposed use of IP_{25 25} as an Arctic sea ice proxy.

Mots clés: Arctic; Isotopes; Biomarker; IP₂₅; δ¹³C; Sea Ice; Sediment

Domaines: Océan, Atmosphère; Géochimie

Simon T. Belt, Guillaume Massé, Lindsay L. Vare, Steven J. Rowland, Michel Poulin, et al.. Distinctive ¹³C isotopic signature distinguishes a novel sea ice biomarker in Arctic sediments and sediment traps. Marine Chemistry, 2008, 112 (3-4), pp.158 - 167. ⟨10.1016/j.marchem.2008.09.002⟩. ⟨hal-03427331⟩