An inter-laboratory investigation of the Arctic sea ice biomarker proxy IP25 in marine sediments: key outcomes and recommendations

We describe the results of an inter-laboratory investigation into the identification and quantification of the Arctic sea ice biomarker proxy IP25 in marine sediments. Seven laboratories took part in the study, which consisted of the analysis of IP25 in a series of sediment samples from different re...

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Bibliographic Details
Published in:Climate of the Past
Main Authors: Belt, S. T., Brown, T. A., Ampel, L., Cabedo-Sanz, P., Fahl, K., Kocis, J. J., Masse, G., Navarro-Rodriguez, A., Ruan, J., Xu, Y.
Other Authors: Belt, ST (reprint author), Univ Plymouth, Sch Geog Earth & Environm Sci, Biogeochem Res Ctr, Plymouth PL4 8AA, Devon, England., Univ Plymouth, Sch Geog Earth & Environm Sci, Biogeochem Res Ctr, Plymouth PL4 8AA, Devon, England., Stockholm Univ, Dept Geol Sci, S-10691 Stockholm, Sweden., Alfred Wegener Inst Polar & Marine Res, D-27568 Bremerhaven, Germany., Univ Massachusetts Amherst, Dept Geosci, Amherst, MA 01075 USA., CNRS, UMI 3376, TAKUVIK, Quebec City, PQ G1V 0A6, Canada., Univ Laval, Quebec City, PQ G1V 0A6, Canada., Peking Univ, Coll Urban & Environm Sci, MOE Key Lab Earth Surface Proc, Beijing 100871, Peoples R China.
Format: Journal/Newspaper
Language:English
Published: climate of the past 2014
Subjects:
HIGHLY BRANCHED ISOPRENOIDS
HOLOCENE CLIMATE
FRAM STRAIT
BARENTS SEA
RECONSTRUCTION
IDENTIFICATION
VARIABILITY
HISTORY
RECORDS
DIATOMS
Antarctic
Antarctic Peninsula
Arctic
Barents Sea
Southern Ocean
The Antarctic
Antarc*
Fram Strait
Iceland
Sea ice
Online Access:https://hdl.handle.net/20.500.11897/390610
https://doi.org/10.5194/cp-10-155-2014
Description
Summary:We describe the results of an inter-laboratory investigation into the identification and quantification of the Arctic sea ice biomarker proxy IP25 in marine sediments. Seven laboratories took part in the study, which consisted of the analysis of IP25 in a series of sediment samples from different regions of the Arctic, sub-Arctic and Antarctic, additional sediment extracts and purified standards. The results obtained allowed 4 key outcomes to be determined. First, IP25 was identified by all laboratories in sediments from the Canadian Arctic with inter-laboratory variation in IP25 concentration being substantially larger than within individual laboratories. This greater variation between laboratories was attributed to the difficulty in accurately determining instrumental response factors for IP25, even though laboratories were supplied with appropriate standards. Second, the identification of IP25 by 3 laboratories in sediment from SW Iceland that was believed to represent a blank, was interpreted as representing a better limit of detection or quantification for such laboratories, contamination or mis-identification. These alternatives could not be distinguished conclusively with the data available, although it is noted that the precision of these data was significantly poorer compared with the other IP25 concentration measurements. Third, 3 laboratories reported the occurrence of IP25 in a sediment sample from the Antarctic Peninsula even though this biomarker is believed to be absent from the Southern Ocean. This anomaly is attributed to a combined chromatographic and mass spectrometric interference that results from the presence of a di-unsaturated highly branched isoprenoid (HBI) pseudo-homologue of IP25 that occurs in Antarctic sediments. Finally, data are presented that suggest that extraction of IP25 is consistent between Accelerated Solvent Extraction (ASE) and sonication methods and that IP25 concentrations based on 7-hexylnonadecane as an internal standard are comparable using these methods. Recoveries of some more unsaturated HBIs and the internal standard 9-octylheptadecene, however, were lower with the ASE procedure, possibly due to partial degradation of these more reactive chemicals as a result of higher temperatures employed with this method. For future measurements, we recommend the use of reference sediment material with known concentration(s) of IP25 for determining and routinely monitoring instrumental response factors. Given the significance placed on the presence (or otherwise) of IP25 in marine sediments, some further recommendations pertaining to quality control are made that should also enable the two main anomalies identified here to be addressed. Geosciences, Multidisciplinary Meteorology & Atmospheric Sciences SCI(E) 2 ARTICLE sbelt@plymouth.ac.uk 1 155-166 10

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