GDGT distributions on the East Siberian Arctic Shelf: implications for organic carbon export, burial and degradationShow others and affiliations
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2015 (English)In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 12, no 12, p. 3753-3768
Article in journal (Refereed) Published
Abstract [en]
Siberian permafrost contains a globally significant pool of organic carbon (OC) that is vulnerable to enhanced warming and subsequent release into the contemporary carbon cycle. OC release by both fluvial and coastal erosion has been reported in the region, but the behaviour of this material in the Arctic Ocean is insufficiently understood. The balance between OC deposition and degradation on the East Siberian Arctic Shelf (ESAS) influences the climate-carbon cycle feedback in this area. In this study we couple measurements of glycerol dialkyl glycerol tetraethers (GDGTs) with bulk geochemical observations to improve knowledge of the sources of OC to the ESAS, the behaviour of specific biomarkers on the shelf and the balance between delivery and removal of different carbon pools. Branched GDGT (brGDGT) concentrations were highest close to river mouths, yet low in ’ice complex’ permafrost deposits, supporting recent observations that brGDGTs are mostly delivered by fluvial erosion, and may be a tracer for this in complex sedimentary environments. BrGDGT concentrations and the branched and isoprenoidal tetraether (BIT) index reduced quickly offshore, demonstrating a rapid reduction in river influence. Stable carbon isotope ratios changed at a different rate to the BIT index, suggesting not only that OC on the shelf is sourced from fluvial erosion but also that erosion of coastal sediments delivers substantial quantities of OC to the Arctic Ocean. A model of OC export from fluvial, coastal and marine sources is able to recreate the biomarker and bulk observations and provide estimates for the influence of fluvial and coastal OC across the whole shelf. The model shows that coastal erosion delivers 43 % of the OC and 87 % of the mineral sediment to the ESAS, but that rivers deliver 72 % of brGDGTs, indicating that brGDGTs can be used as a proxy for river-derived sediment.
Place, publisher, year, edition, pages
2015. Vol. 12, no 12, p. 3753-3768
Keywords [en]
dialkyl glycerol tetraethers buor-khaya bay se laptev sea bit index particulate matter marine-sediments polar-regions old carbon ocean river Environmental Sciences & Ecology Geology
Research subject
SWEDARCTIC 2008, ISSS-08
Identifiers
URN: urn:nbn:se:polar:diva-2158DOI: 10.5194/bg-12-3753-2015OAI: oai:DiVA.org:polar-2158DiVA, id: diva2:851691
Funder
Swedish Polar Research Secretariat
Note
ISI Document Delivery No.: CL6ZL Times Cited: 0 Cited Reference Count: 71 Sparkes, R. B. Selver, A. Dogrul Bischoff, J. Talbot, H. M. Gustafsson, O. Semiletov, I. P. Dudarev, O. V. van Dongen, B. E. NERC [NE/I024798/1, NE/I027967/1]; Ministry of National Education of Turkey; government of the Russian Federation [p220/mega-grant 2013-220-04-157, 14, Z50.31,0012/03.19.2014]; Swedish Royal Academy of Sciences through Knut and Alice Wallenberg Foundation; Knut and Alice Wallenberg Foundation; Far Eastern Branch of the Russian Academy of Sciences; Swedish Research Council; US National Oceanic and Atmospheric Administration; Russian Foundation of Basic Research; Swedish Polar Research Secretariat; Nordic Council of Ministers; US National Science Foundation We gratefully acknowledge receipt of a NERC research grant (NE/I024798/1 and NE/I027967/1) to B. E. van Dongen and H. M. Talbot, a PhD studentship to A. Dogrul Selver funded by the Ministry of National Education of Turkey, a research grant (p220/mega-grant 2013-220-04-157 #14, Z50.31,0012/03.19.2014) from the government of the Russian Federation to I. P. Semiletov and O. V. Dudarev, and financial support as an academy research fellow to O. Gustafsson from the Swedish Royal Academy of Sciences through a grant from the Knut and Alice Wallenberg Foundation. We thank the crew and personnel of the R/V Yakob Smirnitskyi and all colleagues in the International Siberian Shelf Study (ISSS) programme for support, including sampling. We thank P. Lythgoe (University of Manchester) for invaluable assistance with LC-MS and T. Tesi for providing the ice complex samples for the Kolyma catchment area. The ISSS programme is supported by the Knut and Alice Wallenberg Foundation, the Far Eastern Branch of the Russian Academy of Sciences, the Swedish Research Council, the US National Oceanic and Atmospheric Administration, the Russian Foundation of Basic Research, the Swedish Polar Research Secretariat, the Nordic Council of Ministers and the US National Science Foundation. We thank one of the anonymous reviewers for their constructive comments, and another for their generous endorsement. 0 Copernicus gesellschaft mbh Gottingen 1726-4189
2015-09-072015-09-072017-12-04