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Composition and fate of terrigenous organic matter along the Arctic land-ocean continuum in East Siberia: Insights from biomarkers and carbon isotopes
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2014 (English)In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 0016-1258, Vol. 133Article in journal (Refereed) Published
Abstract [en]

Climate warming is predicted to translocate terrigenous organic carbon (TerrOC) to the Arctic Ocean and affect the marine biogeochemistry at high latitudes. The magnitude of this translocation is currently unknown, so is the climate response. The fate of the remobilized TerrOC across the Arctic shelves represents an unconstrained component of this feedback. The present study investigated the fate of permafrost carbon along the land-ocean continuum by characterizing the TerrOC composition in three different terrestrial carbon pools from Siberian permafrost (surface organic rich horizon, mineral soil active layer, and Ice Complex deposit) and marine sediments collected on the extensive East Siberian Arctic Shelf (ESAS). High levels of lignin phenols and cutin acids were measured in all terrestrial samples analyzed indicating that these compounds can be used to trace the heterogeneous terrigenous material entering the Arctic Ocean. In ESAS sediments, comparison of these terrigenous biomarkers with other TerrOC proxies (bulk delta C-13/delta C-14 and HMW lipid biomarkers) highlighted contrasting across-shelf trends. These differences could indicate that TerrOC in the ESAS is made up of several pools that exhibit contrasting reactivity toward oxidation during the transport. In this reactive spectrum, lignin is the most reactive, decreasing up to three orders of magnitude from the inner-to the outer-shelf while the decrease of HMW wax lipid biomarkers was considerably less pronounced. Alternatively, degradation might be negligible while sediment sorting during the across-shelf transport could be the major physical forcing that redistributes different TerrOC pools characterized by different matrix-association. Despite the marked decrease shown by lignin, the fingerprint of lignin phenols such as the acid: aldehyde ratio of vanillyl and syringyl phenols showed a lack of any across-shelf trends and exhibited an extremely wide range of values in all terrestrial samples. By contrast, the 3,5-dihydroxybenzoic: vanillyl phenols ratio exhibited a clear across-shelf trend suggesting either increasing degradation with distance from the coast or TerrOC sorting along the sediment dispersal system. The ratio of syringyl: vanillyl phenols indicated that gymnosperm tissues are more important than angiosperm tissues in surface sediments, in particular off the Lena River mouth, consistent with the vegetation in its watershed. Conversely, the fingerprint of p-hydroxybenzenes suggests lack of substantial input of moss-derived material. Finally, autochthonous lipid-and protein-derived CuO reaction products displayed a strong along-shelf gradient likely reflecting the inflow of nutrient-rich Pacific waters from the Bering Strait that stimulate primary productivity in the eastern ESAS. In particular short-chain fatty acids showed a clear frontal/transition zone between Pacific-influenced and river-influenced waters approximately along the 160 degrees E longitude. Considering the labile nature of phytoplankton, priming and co-metabolism processes might stimulate degradation of TerrOC in the easternmost region of the Siberian shelf. This study demonstrated the need to consider multiple TerrOC proxies at isotopic/molecular levels to differentiate the fate for different allocthonous components in Arctic sediments and the need to assess how these TerrOC pools are distributed in different density, size, and settling fractions to better discriminate between the extent of hydrodynamic sorting versus degradation. (C) 2014 Elsevier Ltd. All rights reserved.

Place, publisher, year, edition, pages
2014. Vol. 133
Keyword [en]
permafrost-affected soils oxide oxidation-products alkaline cuo oxidation oxygen exposure time gulf-of-mexico buor-khaya bay laptev sea washington margin river discharge sediment transport Geochemistry & Geophysics
Research subject
SWEDARCTIC 2008, ISSS-08
Identifiers
URN: urn:nbn:se:polar:diva-1936DOI: 10.1016/j.gca.2014.02.045OAI: oai:DiVA.org:polar-1936DiVA: diva2:810354
Note

ISI Document Delivery No.: AF6OE Times Cited: 2 Cited Reference Count: 114 Tesi, Tommaso Semiletov, Igor Hugelius, Gustaf Dudarev, Oleg Kuhry, Peter Gustafsson, Orjan Knut and Alice Wallenberg Foundation; Far Eastern Branch of the Russian Academy of Sciences; Swedish Research Council (VR) [621-2004-4039, 621-2007-4631]; US National Oceanic and Atmospheric Administration (OAR Climate Program Office) [NA08OAR 4600758]; Russian Foundation of Basic Research [08-05-13572, 08-05-00191-a, 07-05-00050a]; Swedish Polar Research Secretariat; Nordic Council of Ministers; US National Science Foundation [OPP ARC 0909546]; Academy Research Fellow from the Swedish Royal Academy of Sciences through a grant from the Knut and Alice Wallenberg Foundation; EU [PIEF-GA-2011-300259]; ESF CryoCarb project (Swedish Research Council; VR Contract) [824-2009-7357]; EU 7FP PAGE21 project [282700] We thank crew and personnel of the R/V Yakob Smirnitskyi and TB0012. The ISSS-08 expedition was supported by the Knut and Alice Wallenberg Foundation, Headquarters of the Far Eastern Branch of the Russian Academy of Sciences, the Swedish Research Council (VR Contract No. 621-2004-4039 and 621-2007-4631), the US National Oceanic and Atmospheric Administration (OAR Climate Program Office, NA08OAR 4600758/Siberian Shelf Study), the Russian Foundation of Basic Research (08-05-13572, 08-05-00191-a, and 07-05-00050a), the Swedish Polar Research Secretariat, the Nordic Council of Ministers and the US National Science Foundation (OPP ARC 0909546). O. Gustafsson acknowledges financial support as an Academy Research Fellow from the Swedish Royal Academy of Sciences through a grant from the Knut and Alice Wallenberg Foundation. T. Tesi acknowledges EU financial support as Marie Curie fellow (contract no. PIEF-GA-2011-300259).). Field sampling and simple geochemical analyses of inland soil profiles and Yedoma exposures by G. Hugelius and P. Kuhry were financed by the ESF CryoCarb project (Swedish Research Council; VR Contract No. 824-2009-7357) for the Kolyma samples, and the EU 7FP PAGE21 project (Grant Agreement No. 282700) and the EU 7FP PATTERN project (INTERACT Transnational Access program) for the Lena and Indigyrka samples. We also thank three anonymous reviewers for their constructive comments. 2 Pergamon-elsevier science ltd Oxford Geochemistry & Geophysics

Available from: 2015-05-07 Created: 2015-05-06 Last updated: 2015-05-26

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