title: Source identification of the Arctic sea ice proxy IP25.
abstract: Analysis of the organic geochemical biomarker IP25 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 IP25 include its strict association with Arctic sea ice together with its ubiquity and stability in underlying marine sediments; however, the sources of IP25 have remained undetermined. Here we report the identification of IP25 in three (or four) relatively minor (<5%) sea ice diatoms isolated from mixed assemblages collected from the Canadian Arctic. In contrast, IP25 was absent in the dominant taxa. Chemical and taxonomical investigations suggest that the IP25-containing taxa represent the majority of producers and are distributed pan-Arctic, thus establishing the widespread applicability of the IP25 proxy for palaeo Arctic sea ice reconstruction.
authors.affiliation: Biogeochemistry Research Centre, School of Geography, Earth and Environmental Sciences, University of Plymouth, Plymouth PL4 8AA, UK.
authors.forename: T A
authors.initials: TA
authors.lastname: Brown
authors.affiliation: Biogeochemistry Research Centre, School of Geography, Earth and Environmental Sciences, University of Plymouth, Plymouth PL4 8AA, UK.
authors.forename: S T
authors.initials: ST
authors.lastname: Belt
authors.affiliation: Institute of Oceanology Polish Academy of Sciences, Powstańców Warszawy 55, 81-712 Sopot, Poland.
authors.forename: A
authors.initials: A
authors.lastname: Tatarek
authors.affiliation: Centre for Earth Observation Science, University of Manitoba, 535 Wallace Building, 125 Dysart Road, Winnipeg, Canada R3T 2N2.
authors.forename: C J
authors.initials: CJ
authors.lastname: Mundy