HR: 08:45h
AN: C31A-04    [Abstracts]
TI: Frozen Quaternary Deposits of the Laptev Sea Region as a Reservoir of Organic Carbon: Total Content and Composition.
AU: * Kholodov, A
EM: akholodov@gi.alaska.edu
AF: University of Alaska Fairbanks, 903 Koyukuk Dr., Fairbanks, AK 99775, United States
AU: * Kholodov, A
EM: akholodov@gi.alaska.edu
AF: Institute of physical chemical and biological problems of soil science RAS, 2 Institutskaya str., Pushchino, 142290, Russian Federation
AU: Schirrmeister, L
EM: schirrmeister@awi.de
AF: Alfred Wegener Institute for Polar and Marine Research Potsdam branch, Telegrafenberg A43, Potsdam, 14473, Germany
AU: Shirshova, L
EM: shirshova@issp.psn.ru
AF: Institute of physical chemical and biological problems of soil science RAS, 2 Institutskaya str., Pushchino, 142290, Russian Federation
AU: Zolotareva, B
EM: akholodov@mil.ru
AF: Institute of physical chemical and biological problems of soil science RAS, 2 Institutskaya str., Pushchino, 142290, Russian Federation
AU: Meyer, H
EM: hano.meyer@awi.de
AF: Alfred Wegener Institute for Polar and Marine Research Potsdam branch, Telegrafenberg A43, Potsdam, 14473, Germany
AU: Knoblauch, C
EM: Christian.Knoblauch@uni-hamburg.de
AF: Soil Science Institute Hamburg University, 2 Allende-Platz, Hamburg, 20146, Germany
AU: Fahl, K
EM: kfahl@awi-bremerhaven.de
AF: Alfred Wegener Institute for Polar and Marine Research, 26 Am Alten Haven, Bremerhaven, 27569, Germany
AB: Permafrost is a significant reservoir and potential source of ancient organic matter (OM) such as plant remains, humified organics, etc. and greenhouse gases. In according with different estimations 1 cubic meter of frozen deposits in this region consists up to 10 kg of Corg. Due to the degradation of permafrost under the both modern geological processes and global warming, this organic carbon is easily released into the present biogeochemical cycle Humus parameters, elementary and isotopic composition of OM, dissolved organic carbon content and some biomarkers in the following types of quaternary deposits were determined: Middle Pleistocene deposits contain 1-2% of TOC and characterised by the ratios of C/N 5-7,5 (syncryogenic) and 10-12 (epycryogenic). Late Pleistocene syncryogenic deposits composed by true syncryogenic deposits and buried soils. The former characterized by the 1-2% of TOC and C/N ratio 9-11 the later 4-16% of TOC and 12-16 C/N ratio. Late Pleistocene-Holocene taberal deposits. TOC – 1%, C/N - 10-12 Holocene alas deposits. TOC 4-6%, C/N - 10-12. Main part of total carbon is organic origin. Carbonates consist only 31 – 20 %. The following conclusions can be done: More transformed OM is in the buried soils and alas deposits. OM of syncryogenic deposits is a most labile. TOC and stage of organic matter transformation in the syncryogenic deposits depends on ratio of sedimentation and freezing rate. Decreasing of freezing rate leads to the more deposition and to deeper transformation of OM. Most transformed OM is in alas deposits and buried soils. About 20% of TOC presented by humus. Syncryogenic and taberal deposits are not so matured (humus content 15%). Content of organic matter potentially available to be dissolved in the water is low in the all investigated deposits. It consists approximately the 1-1,5% of TOC in Ice Complex deposits and 2-3% in alas and taberal deposits. Determination of biomarkers composition (n-alkanes, fatty acids and sterols) in alas and taberal deposits was carried out. Main part of organic matter in investigated deposits is presented by n-alkanes (37-74%, generally 55-60%). Fatty acids and sterols consist 13-22 and 2-7% correspondingly. On the base of the analyses conclusions about the main source of organic matter in the all investigated deposits can be done. Predomination of odd carbon-numbered long-chain n-alkanes (with 25-35 carbon atoms) and saturated fatty acids with long carbon chain (> C22) are character for terrestrial higher plants. There is a positive correlation of TOC and long-chain alkanes. All investigated deposits characterized by the low values of isotope C13 (from -24 to -24) what reflects the low decomposition of organic matter. Research was supported by RFBR (05-05-64062).
DE: 0428 Carbon cycling (4806)
DE: 0702 Permafrost (0475)
DE: 0793 Biogeochemistry (0412, 0414, 1615, 4805, 4912)
SC: Cryosphere [C]
MN: 2007 Fall Meeting