25th International Meeting on Organic Geochemistry IMOG 2011

P-514
Molecular characterization of terrestrial, permafrost-derived
organic matter along a soil-river-ocean transect (Lena Delta, NE
Siberia)
Maria Winterfeld 1,2 , Miguel Goni 3 , Gesine Mollenhauer 1,2
1 Alfred Wegener Institute for Polar and Marine Research, 27570 Bremerhaven, Germany, 2 Department of
Geosciences, University of Bremen, Klagenfurther Str., 28359 Bremen, Germany, 3 College of Oceanic &
Atmospheric Sciences, Oregon State University, 104 Ocean Administration Building, COAS, Corvallis, OR
97331, United States of America (corresponding author:Maria.Winterfeld@awi.de)
About 50% of the global soil organic carbon (OC) is
stored in Arctic permafrost soils [1]. In response to
global climate warming vast amounts of this mainly
freeze-locked, old OC will likely be remobilized and
released during permafrost thawing. However, until
now the fate of organic matter released from
permafrost and its possible feedbacks for the global
carbon cycle are hardly understood. It is rather
unknown which proportions of the previously frozen
OC will be released into the atmosphere as carbon
dioxide or methane or remain fixed in soils and
tundra/taiga biomass. Likewise, it is unknown how
much of the OC will be exported in
particulate/dissolved state via fluvial runoff and
coastal erosion and become further degraded in the
riverine and oceanic water column.
In recent years, there have been few studies along
the East Siberian Shelf Seas qualitatively
investigating permafrost OC exported to the ocean on
a molecular level (e.g. [2]). These studies mainly
focused on the analysis of terrestrial lipids found in
sediments and particulate organic carbon (POC) from
the oceanic water column in order to investigate the
sources, transport processes and degradation of
terrigenous OC on the shelves. Nevertheless, in these
studies the original molecular composition of the
terrestrial OC source, the permafrost soils, was not
analysed although such characterization is essential
to study the fate of terrestrial OC in the Arctic.
In order to characterize the molecular composition of
permafrost soils as well as potential compositional
changes during transport from land to ocean, we
analyzed biomarkers from soil samples, suspended
particulate matter (SPM) and sediments from the
Lena Delta and adjacent Buor Khaya Bay, NE Siberia.
The soil samples were analyzed for their biomarker
composition including leaf wax & soil derived lipids,
and lignin phenols to identify those permafrost
compounds that should also be detectable in riverine
and shelf-derived surface water POC and sediments,
respectively. Here, we report the lignin phenol
composition of soil samples, POC, and sediments and
use the acid/aldehyde ratios ([Ad/Al]) of lignin phenols
in soils to determine the degree of oxidative lignin
degradation (e.g. [3]) before it is exported to the
ocean. Furthermore, we report syringyl/vanillyl (S/V)
and cinnamyl/vanillyl (C/V) ratios of soil, POC and
sediments in order to distinguish between different
vegetation types (i.e. angiosperm vs. gymnosperm
and woody vs. non-woody plants, e.g. [4]). This will
help distinguishing spatially different terrestrial OC
sources since the southern Lena River catchment is
mainly characterized by taiga forest whereas the Lena
Delta is characterized by tundra vegetation. With
these results, we provide new molecular data for
determining the current state of permafrost-derived
OC transferred from land to ocean in the Lena Delta
region.
References
[1] Tarnocai, C., Canadell, J.G., Schuur, E.A.G.,
Kuhry, P., Mazhitova, G. & Zimov, S. (2009). Soil
organic carbon pools in the northern circumpolar
permafrost region. Global Biogeochemical Cycles 20,
doi: 10.1029/2008GB003327.
[2] Vonk, J.E., Sánchez-García, L., Semiletov,
I., Dudarev, O., Eglinton, T., Andersson, A. &
Gustafsson, Ö. (2010). Molecular and radiocarbon
constraints on sources and degradation of terrestrial
organic carbon along the Kolyma paleoriver transect,
East Siberian Sea. Biogeosciences 7, 3153-3166.
[3] Goñi, M.A., Yunker, M.B., Macdonald, R.W.
& Eglinton, T.I. (2005). The supply and preservation
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[4] Hedges, J.I. & Ertel J.R. (1982). Lignin
geochemistry of a Late Quaternary sediment core
from Lake Washington. Geochimica et Cosmochimica
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