Source identification of the Arctic sea ice proxy IP25

Abstract

Analysis of the organic geochemical biomarker IP 25 in marine sediments is an established method for carrying out palaeo sea ice reconstructions for the Arctic. Such reconstructions cover timescales from decades back to the early Pleistocene, and are critical for understanding past climate conditions on Earth and for informing climate prediction models. Key attributes of IP 25 include its strict association with Arctic sea ice together with its ubiquity and stability in underlying marine sediments; however, the sources of IP 25 have remained undetermined. Here we report the identification of IP 25 in three (or four) relatively minor (o5%) sea ice diatoms isolated from mixed assemblages collected from the Canadian Arctic. In contrast, IP 25 was absent in the dominant taxa. Chemical and taxonomical investigations suggest that the IP 25 -containing taxa represent the majority of producers and are distributed pan-Arctic, thus establishing the widespread applicability of the IP 25 proxy for palaeo Arctic sea ice reconstruction.

Carbon geochemistry of plankton-dominated samples in the Laptev and East Siberian shelves: contrasts in suspended particle composition

“…4b) further highlights the different regimes observed in ice-free and icedominated surface waters. IP25 is a proxy of sea ice based on a highly branched monounsaturated isoprenoid alkene found in some sea ice diatoms which, however, generally account for 5 % of the total sea ice taxa (Belt et al, 2007;Brown et al, 2014). The IP25 concentrations varied by several orders of magnitude over the study area showing low concentrations in the open-water western region while the sea-ice-dominated surface waters to the east exhibited high concentrations especially at station 31b ( Fig.…”

“…Species include Pleurosigma stuxbergii var. rhomboide, Haslea crucigeroides (and/or Haslea spicula) and Haslea kjellmanii (Brown et al, 2014). Briefly, lipids were extracted via sonication using a dichloromethane/methanol solution (2 : 1 v/v × 3).…”

Identification of paleo Arctic winter sea ice limits and the marginal ice zone: Optimised biomarker-based reconstructions of late Quaternary Arctic sea ice

“…1; Belt et al, 2007), a C 25 highly branched isoprenoid (HBI) lipid made uniquely by certain Arctic sea ice-dwelling diatoms (Brown et al, 2014), has been suggested to provide a more direct measure of past sea ice when detected in underlying sediments (see Belt and Müller, 2013 for a recent review). Importantly, IP 25 has been identified in sediments from a large number of surface sediments from seasonally ice-covered Arctic locations and downcore records spanning timescales from recent decades (Müller et al, 2011;Stoynova et al, 2013;Xiao et al, 2013;Navarro-Rodriguez et al, 2013), the Holocene (Vare et al, 2009;Müller et al, 2012) and even longer Knies et al, 2014;Müller and Stein, 2014).…”

The emergence of modern sea ice cover in the Arctic Ocean

“…1). In recent years, the analysis of the biomarker IP 25 ('Ice Proxy with 25 carbon atoms') 14 , a mono-unsaturated highly branched isoprenoid lipid biosynthesized by certain sea ice diatoms 15 , has become an established proxy method for the reconstruction of Arctic sea ice 16 . The presence (absence) of IP 25 in Arctic marine sediments is especially sensitive to the past occurrence (absence) of sea ice 16 , while abundance variations are usually consistent with corresponding directional changes in sea ice cover 16 .…”