25th International Meeting on Organic Geochemistry IMOG 2011

P-233
Branched GDGTs in the Yenisei river catchment; the trans-
Siberian CBT/MBT signature of river and lake particulate matter
Cindy De Jonge 1 , Alina Stadnitskaia 1 , Georgy Charkashov 2 , Andrei Fedotov 3 , Alexander
Vasiliev 4 , Jaap S. Sinninghe Damsté 1
1 Department of Marine Organic Biogeochemistry, Royal Netherlands Institute for Sea Research (Royal
NIOZ), Texel, Netherlands, 2 All-Russian Research Institute for Geology and Mineral Resources of the World
Ocean (VNIIOkeangeologia), Ministry of Nat, St.Petersburg, Russian Federation, 3 Limnological Institute,
Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russian Federation, 4 Earth Cryosphere
Institute Siberian Branch of Russian Academy of Science, Tumen, Russian Federation (corresponding
author:cindy.de.jonge@nioz.nl)
Continental temperature reconstructions are
hampered by a lack of quantitative temperature
proxies. Weijers et al. (2007) described proxies that
allow to estimate both palaeo-soil-pH as palaeocontinental-temperature
based on branched GDGT
membrane lipid distributions [the methylation index of
branched tetraethers (MBT) and the cyclisation ratio
of branched GDGTs (CBT)]. These soil-derived lipids
can be recovered from ocean sediments, providing an
opportunity to reconstruct long-term climate changes.
In order to test the applicability of these new proxies,
they need to be further tested in geographically
contrasting settings, as for instance the Arctic region.
Therefore, we performed a detailed study on the
sources of soil GDGTs, mode of their transport, and
re-deposition in the Yenisei river – Kara Sea system
(Fig. 1). The Yenisei starts in the Asian Tuva and
flows through the Central Siberian Plateau into the
Arctic Ocean through the Kara Sea, covering different
climatic zones and biomes (tundra, taiga/boreal
forest). We determined BIT (Branched and Isoprenoid
Tetraether) and MBT/CBT indices in suspended
particulate matter (SPM) of the Yenisei river and their
geographical variation.
At 36 sites, 20 to 100L of water was sampled and
filtered to collect the SPM. Not only the Yenisei river
and its main tributaries were sampled, but also a
number of lakes in the Yenisei catchment. The BITindex,
describing the relative abundance of branched
GDGTs over aquatically produced crenarchaeol, of
the river SPM ranges between 0.18 and 1.00 (mean is
0.87), with values