Biomarker distributions in surface sediments from the Central Arctic Ocean and adjacent marginal seas

• Main Authors: Xiao, Xiaotong, Stein, Ruediger, Fahl, Kirsten, Müller, Juliane
• Format: Dataset
• Language: English
• Published: PANGAEA 2015
• Subjects: 2,10,14-Trimethyl-6-enyl-7-(3-methylpent-1-enyl)pentadecene; per unit mass total organic carbon; 2,6,10,14-Tetramethyl-7-(3-methylpent-4-enyl)pentadecane; 24-ethylcholest-5-en-3beta-ol; 24-Methylcholest-5-en-3beta-ol; 24-Methylcholesta-5,22E-dien-3beta-ol; 4alpha,23,24-Trimethyl-5alpha-cholest-22E-en-3beta-ol; ARA2B; ARA2B-11_BOX-01; ARA2B-15; ARA2B-16a_BOX-01; ARA2B-16B; ARA2B-18A; ARA2B-18B; ARA2B-1A; ARA2B-1B; ARA2B-2; ARA2B-3A; ARA2B-3B; ARA2B-8_BOX-01; ARA2B-9_BOX-01; ARA3B; ARA3B_01; ARA3B_08MUC-02; ARA3B_09MUC-02; ARA3B_10MUC-02; ARA3B_11MUC-02; ARA3B_12; ARA3B_13MUC-01; ARA3B_14MUC-01; ARA3B_15b; ARA3B_16MUC-01; ARA3B_18MUC-01; ARA3B_19MUC-02; ARA3B_26; ARA3B_27; ARA3B_28; ARA3B_29MUC-02; ARA3B_30MUC-01; ARA3B_38aMUC-01; ARA3B_41MUC-03; Araon; Arctic Ocean; ARK-XI/1; ARK-XIV/1a; Arctic; Barents Sea; Chukchi; Phytoplankton; Sea ice
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.819526; https://doi.org/10.1594/PANGAEA.819526

Records of the spatial and temporal variability of Arctic Ocean sea ice are of significance for understanding the causes of the dramatic decrease in Arctic sea-ice cover of recent years. In this context, the newly developed sea-ice proxy IP25, a mono-unsaturated highly branched isoprenoid alkene with 25 carbon atoms biosynthesized specifically by sea-ice associated diatoms and only found in Arctic and sub-Arctic marine sediments, has been used to reconstruct the recent spatial sea-ice distribution. The phytoplankton biomarkers 24S-brassicasterol and dinosterol were determined alongside IP25 to distinguish ice-free or permanent ice conditions, and to estimate the sea-ice conditions semi-quantitatively by means of the phytoplankton-IP25 index (PIP25). Within our study, for the first time a comprehensive data set of these biomarkers was produced using fresh and deep-frozen surface sediment samples from the Central Arctic Ocean proper (>80°N latitude) characterised by a permanent ice cover today and recently obtained surface sediment samples from the Chukchi Plateau/Basin partly covered by perennial sea ice. In addition, published and new data from other Arctic and sub-Arctic regions were added to generate overview distribution maps of IP25 and phytoplankton biomarkers across major parts of the modern Arctic Ocean. These comprehensive biomarker data indicate perennial sea-ice cover in the Central Arctic, ice-free conditions in the Barents Sea and variable sea-ice situations in other marginal seas. The low but more than zero values of biomarkers in the Central Arctic supported the low in-situ productivity there. The PIP25 index values reflect modern sea-ice conditions better than IP25 alone and show a positive correlation with spring/summer sea ice. When calculating and interpreting PIP25 index as a (semi-quantitative) proxy for reconstructions of present and past Arctic sea-ice conditions from different Arctic/sub-Arctic areas, information of the source of phytoplankton biomarkers and the possible presence of ...