In:
The Cryosphere, Copernicus GmbH, Vol. 12, No. 10 ( 2018-10-11), p. 3293-3309
Kurzfassung:
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.
Materialart:
Online-Ressource
ISSN:
1994-0424
DOI:
10.5194/tc-12-3293-2018
DOI:
10.5194/tc-12-3293-2018-supplement
Sprache:
Englisch
Verlag:
Copernicus GmbH
Publikationsdatum:
2018
ZDB Id:
2393169-3
