• Ayça Dogrul Selver

Student thesis: Phd


The Arctic Region is currently experiencing an amplified warming if compared to the rest of the world. The soils in this region store approximately half of the global soil organic carbon (OC), mainly locked in the permanently-frozen ground (permafrost). This carbon sink is sensitive to global warming meaning that the predicted warming will likely increase the thaw-release of this 'old' carbon. However, what happens to this remobilized OC once it is transported to the Arctic Ocean, including the potential conversion to greenhouse gasses causing a positive feedback to climate warming, remains unclear. In this work, we further investigate the fate of terrestrial derived OC (terrOC) in the Eurasian Arctic Region. The key findings of this work are: • Glycerol dialkyl glycerol tetraethers (GDGTs) and bacteriohopanepolyols (BHPs) are present in marine sediments of the Eurasian Arctic Region and the associated Branched and Isoprenoidal tetraether (BIT) and Rsoil indices can be used to trace terrOC in marine realm. However, a slight modification in the Rsoil index is suggested (R'soil). • Analyses indicate that the behaviour of BIT is largely controlled by a marine GDGT contribution while the R'soil index is mainly controlled by the removal of soil marker BHPs. Although both indices suggest a non-conservative behavior for the terrOC, this leads to differences in the estimations for the percentage terrOC present. A multi-proxy approach is essential since the use of a single-proxy approach can lead to over/under estimation.• Comparison of BIT and 13Csoc indices across the East Siberian Shelf indicates that the BIT index is possibly reflecting a predominantly fluvial input while 13Csoc represents a mixed fluvial and coastal erosion input.• The macromolecular terrOC composition varies along a west-east Eurasian Arctic climosequence and is mainly controlled by the river runoff of surface derived terrOC and wetland coverage (sphagnum vs. higher plants) but is not affected by the presence/absence of continuous permafrost. • The phenols/(phenols+pyridines) ratio was suggested as a proxy to trace terrOC at the macromolecular level along the Kolyma River-East Siberian Sea transect. The results indicate a non-conservative behavior of the macromolecular terrOC comparable to the bulk of the terrOC.All molecular analyses/based proxies used showed that the remobilized terrOC in the Eurasian Arctic region behaves non-conservatively potentially causing a positive feedback to global climate change.
Date of Award1 Aug 2015
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorBart Van Dongen (Supervisor), Stephen Boult (Supervisor) & Jonathan Lloyd (Supervisor)


  • East Siberian Sea
  • BIT index
  • macromolecular organic carbon
  • river-ocean transect
  • Kalix River
  • Rsoil index
  • BHPs
  • Arctic Region
  • Kolyma River
  • GDGTs
  • Terrestrial organic carbon

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