Release of Black Carbon From Thawing Permafrost Estimated by Sequestration Fluxes in the East Siberian Arctic Shelf Recipient

Joan A. Salvadó*, Lisa Bröder, August Andersson, Igor P. Semiletov, Örjan Gustafsson

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review


Black carbon (BC) plays an important role in carbon burial in marine sediments globally. Yet the sequestration of BC in the Arctic Ocean is poorly understood. Here we assess the concentrations, fluxes, and sources of soot BC (SBC)—the most refractory component of BC—in sediments from the East Siberian Arctic Shelf (ESAS), the World's largest shelf sea system. SBC concentrations in the contemporary shelf sediments range from 0.1 to 2.1 mg g−1 dw, corresponding to 2–12% of total organic carbon. The 210Pb-derived fluxes of SBC (0.42–11 g m−2 yr−1) are higher or in the same range as fluxes reported for marine surface sediments closer to anthropogenic emissions. The total burial flux of SBC in the ESAS (~4,000 Gg yr−1) illustrates the great importance of this Arctic shelf in marine sequestration of SBC. The radiocarbon signal of the SBC shows more depleted yet also more uniform signatures (−721 to −896‰; average of −774 ± 62‰) than of the non-SBC pool (−304 to −728‰; average of −491 ± 163‰), suggesting that SBC is coming from an, on average, 5,900 ± 300 years older and more specific source than the non-SBC pool. We estimate that the atmospheric BC input to the ESAS is negligible (~0.6% of the SBC burial flux). Statistical source apportionment modeling suggests that the ESAS sedimentary SBC is remobilized by thawing of two permafrost carbon (PF/C) systems: surface soil permafrost (topsoil/PF; 25 ± 8%) and Pleistocene ice complex deposits (ICD/PF; 75 ± 8%). The SBC contribution to the total mobilized permafrost carbon (PF/C) increases with increasing distance from the coast (from 5 to 14%), indicating that the SBC is more recalcitrant than other forms of translocated PF/C. These results elucidate for the first time the key role of permafrost thaw in the transport of SBC to the Arctic Ocean. With ongoing global warming, these findings have implications for the biogeochemical carbon cycle, increasing the size of this refractory carbon pool in the Arctic Ocean.

Original languageEnglish
Pages (from-to)1501-1515
Number of pages15
JournalGlobal Biogeochemical Cycles
Issue number10
Publication statusPublished - 1 Oct 2017


We would like to thank the scientific crew and personnel of the International Siberian Shelf Study 2008 (ISSS-08) and the SWERUS-C3 expedition 2014. The ISSS-08 and SWERUS-C3 campaigns were supported by the Knut and Alice Wallenberg Foundation, the Headquarters of the Russian Academy of Sciences (RAS), the Far Eastern Branch of the RAS, the Swedish Research Council (VR contracts 621-2007-4631 and 621-2013-5297), the Swedish Polar Research Secretariat, the Russian Foundation of Basic Research (08-05-13572, 08-05-00191-a, and 07-05-00050a), the Nordic Council of Ministers Cryosphere-Climate-Carbon Initiative (project Defrost, contract 23001), the European Research Council (ERC-AdG project CC-TOP #695331 to Ö. Gustafsson), the U.S. National Science Foundation (OPP ARC 0909546), and partial funding of a PhD student position from the Climate Research School of the Bolin Centre for Climate Research at Stockholm University. I.P. Semiletov also thanks the Russian Government for support (megagrant #2013–220–04– 157 under contract 14.Z50.31.0012). J.A. Salvadó acknowledges EU financial support as a Marie Curie grant (FP7-PEOPLE-2012-IEF; project 328049). All data are available in tables and figures associated with the paper.

FundersFunder number
Horizon 2020 Framework Programme695331


    • Arctic Ocean
    • black carbon
    • permafrost


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