25th International Meeting on Organic Geochemistry IMOG 2011

P-188
Impact of degradation on the lipid biomarkers of a Holocene
peat sequence in the Eastern European Russian Arctic
Rina Andersson 1 , Philip Meyers 2
1 Stockholm University, Stockholm, Sweden, 2 University of Michigan, Michigan, United States of America
(corresponding author:rina.garcia@geo.su.se)
To help characterize the organic matter content of a
core taken from a peat plateau deposit in the
Northeast European Russian Arctic, the
concentrations and carbon preference indices (CPI) of
the n-alkanols, n-alkanoic acids and n-alkanes were
measured. This peat profile is a complex system that
experienced a transition from a wet fen to a relatively
dry bog during the onset of permafrost in the late
Holocene (~2500 yr BP). In the profile, the n-alkanoic
acids are the most abundant lipids and their
concentration is higher in the fen peat area, especially
immediately before the transition to the bog peat
before permafrost aggradation. The CPI values of the
n-alkanes are higher in the non-humified peat bog
area and diminish with increasing depth, which is
consistent with progressively greater degradation.
However, the CPI values for the n-alkanols and nalkanoic
acids display a complex trend that increases
with depth in the humified peat area. This apparent
contradiction in degradation as indicated by the CPI
patterns of the n-alkane and the other lipid fractions
may indicate that n-alkanoic acids and n-alkanols are
secondary products of the microbial impact on other
plant leaf waxes (Zhou et al., 2010). Decomposition of
wax esters that release free fatty acids and free
alcohols can also occur during sedimentation
(Simoneit and Mazurek, 2007) or release of fatty
acids and alkanols can be the result of the hydrolysis
of the wax esters in the acidic conditions of the mire
(Ficken et al., 1998). An increase with depth in the
relative amounts of stanols – considered to be the
products of microbial alteration of their corresponding
stenols - is revealed by an increase in the
stanol/sterol ratio and suggests the progressive
alteration of the original sterol inputs in the zone of
the peat deposit that was previously a wet fen.
References
Ficken, K., Barber, K., and Eglington, G., 1998, Lipid
biomarker, δ 13 C and plant macrofossil
stratigraphy of a Scottish montane peat bog
over the last two millennia.: Organic
Geochemistry, v. 28, p. 217-237
Simoneit, B.R.T., and Mazurek, M.A., 2007, Organic
Matter of the Troposphere--II.: Natural
Background of biogenic lipid matter in
aerosols over the rural western United
States: Atmospheric Environment, v. 41, p.
4-24.
Zhou, W., Zheng, Y., Meyers, P.A., Jull, A.J.T., and
Xie, S., 2010, Postglacial climate-change
record in biomarker lipid compositions of the
Hani peat sequence, Northeastern China:
Earth and Planetary Science Letters, v. 294,
p. 37-46.
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