Macromolecular composition of terrestrial and marine organic matter in sediments across the East Siberian Arctic Shelf

• Main Authors: Sparkes, Robert B., Selver, Ayça Doǧrul, Gustafsson, Orjan, Semiletov, Igor P., Haghipour, Negar, Wacker, Lukas, Eglinton, Timothy I., Talbot, Helen M.
• Other Authors: Mühendislik Fakültesi, orcid:0000-0001-8223-0536, orcid:0000-0003-0756-0150, orcid:0000-0003-1189-142X
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Gesellschaft MBH 2016
• Subjects: Lena River; Old Carbon; Laptev Sea; Permafrost; Coastal; Degradation; Delta-C-13; Erosion; Alaska; Ocean; Arctic; Arctic Ocean; laptev; lena river; permafrost; Swedish Polar Research Secretariat; Siberia
• Online Access: https://hdl.handle.net/20.500.12462/6683; https://doi.org/10.12697/10.5194/tc-10-2485-2016

Selver, Ayça Dogrul (Balikesir Author) Mobilisation of terrestrial organic carbon (terrOC) from permafrost environments in eastern Siberia has the potential to deliver significant amounts of carbon to the Arctic Ocean, via both fluvial and coastal erosion. Eroded terrOC can be degraded during offshore transport or deposited across the wide East Siberian Arctic Shelf (ESAS). Most studies of terrOC on the ESAS have concentrated on solvent-extractable organic matter, but this represents only a small proportion of the total terrOC load. In this study we have used pyrolysis-gas chromatography-mass spectrometry (py-GCMS) to study all major groups of macromolecular components of the terrOC; this is the first time that this technique has been applied to the ESAS. This has shown that there is a strong offshore trend from terrestrial phenols, aromatics and cyclopentenones to marine pyridines. There is good agreement between proportion phenols measured using py-GCMS and independent quantification of lignin phenol concentrations (r(2) = 0.67, p < 0.01, n = 24). Furfurals, thought to represent carbohydrates, show no offshore trend and are likely found in both marine and terrestrial organic matter. We have also collected new radiocarbon data for bulk OC (C-14(OC)) which, when coupled with previous measurements, allows us to produce the most comprehensive C-14(OC) map of the ESAS to date. Combining the C-14(OC) and py-GCMS data suggests that the aromatics group of compounds is likely sourced from old, aged terrOC, in contrast to the phenols group, which is likely sourced from modern woody material. We propose that an index of the relative proportions of phenols and pyridines can be used as a novel terrestrial vs. marine proxy measurement for macromolecular organic matter. Principal component analysis found that various terrestrial vs. marine proxies show different patterns across the ESAS, and it shows that multiple river-ocean transects of surface sediments transition from river-dominated to coastalerosion-dominated to marine-dominated signatures. NERC research grant - NE/I024798/1 NE/I027967/1 Ministry of National Education - Turkey Government of the Russian Federation - 14.Z50.31.0012 Knut & Alice Wallenberg Foundation Russian Academy of Sciences Swedish Research Council - 621-2004-4039 621-2007-4631 621-2013-5297 US National Oceanic and Atmospheric Administration (OAR Climate Program Office) - NA08OAR4600758 Russian Foundation for Basic Research (RFBR) - 08-05-13572 08-05-00191-a 07-05-00050a Swedish Polar Research Secretariat Nordic Council of Ministers National Science Foundation (NSF) - OPP ARC 0909546 NERC Natural Environment Research Council - NE/I024798/1 NE/I027967/1