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Volume 12, issue 10 | Copyright
The Cryosphere, 12, 3293-3309, 2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 11 Oct 2018

Research article | 11 Oct 2018

Carbonaceous material export from Siberian permafrost tracked across the Arctic Shelf using Raman spectroscopy

Robert B. Sparkes1, Melissa Maher1, Jerome Blewett2,a, Ayça Doğrul Selver2,3, Örjan Gustafsson4, Igor P. Semiletov5,6,7, and Bart E. van Dongen2 Robert B. Sparkes et al.
  • 1School of Science and the Environment, Manchester Metropolitan University, Manchester, UK
  • 2School of Earth and Environmental Sciences and Williamson Research Centre for Molecular Environmental Science, University of Manchester, Manchester, UK
  • 3Balıkesir University, Geological Engineering Department, Balıkesir, Turkey
  • 4Department of Environmental Science and Analytical Chemistry (ACES) and the Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden
  • 5Pacific Oceanological Institute Far Eastern Branch of the Russian Academy of Sciences, Vladivostok, Russia
  • 6International Arctic Research Center, University of Alaska, Fairbanks, USA
  • 7National Tomsk Research Polytechnic University, Tomsk, Russia
  • anow at: Organic Geochemistry Unit, School of Chemistry, Cabot Institute, University of Bristol, Bristol, UK

Abstract. Warming-induced erosion of permafrost from Eastern Siberia mobilises large amounts of organic carbon and delivers it to the East Siberian Arctic Shelf (ESAS). In this study Raman spectroscopy of carbonaceous material (CM) was used to characterise, identify and track the most recalcitrant fraction of the organic load: 1463 spectra were obtained from surface sediments collected across the ESAS and automatically analysed for their Raman peaks. Spectra were classified by their peak areas and widths into disordered, intermediate, mildly graphitised and highly graphitised groups and the distribution of these classes was investigated across the shelf. Disordered CM was most prevalent in a permafrost core from Kurungnakh Island and from areas known to have high rates of coastal erosion. Sediments from outflows of the Indigirka and Kolyma rivers were generally enriched in intermediate CM. These different sediment sources were identified and distinguished along an E–W transect using their Raman spectra, showing that sediment is not homogenised on the ESAS. Distal samples, from the ESAS slope, contained greater amounts of highly graphitised CM compared to the rest of the shelf, attributable to degradation or, more likely, winnowing processes offshore. The presence of all four spectral classes in distal sediments demonstrates that CM degrades much more slowly than lipid biomarkers and other traditional tracers of terrestrial organic matter and shows that alongside degradation of the more labile organic matter component there is also conservative transport of carbon across the shelf toward the deep ocean. Thus, carbon cycle calculations must consider the nature as well as the amount of carbon liberated from thawing permafrost and other erosional settings.

Publications Copernicus
Short summary
Ongoing climate change in the Siberian Arctic region has the potential to release large amounts of carbon, currently stored in permafrost, to the Arctic Shelf. Degradation can release this to the atmosphere as greenhouse gas. We used Raman spectroscopy to analyse a fraction of this carbon, carbonaceous material, a group that includes coal, lignite and graphite. We were able to trace this carbon from the river mouths and coastal erosion sites across the Arctic shelf for hundreds of kilometres.
Ongoing climate change in the Siberian Arctic region has the potential to release large amounts...