Journal
MARINE CHEMISTRY
Volume 170, Issue -, Pages 11-22Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.marchem.2014.12.005
Keywords
Organic matter lability; Reactivity; Decomposition; Remineralization; Terrestrial organic carbon; Incubations; Arctic Ocean; Coastal shelf; Continental margin; Permafrost; Wax lipids; Lignin; CuO oxidation; Organic geochemistry; Sediment
Categories
Funding
- Knut and Alice Wallenberg Foundation [2011.0027]
- Nordic Council of Ministries Cryosphere-Climate-Carbon Initiative (project Defrost) [23001]
- Headquarters of the Far Eastern Branch of the Russian Academy of Sciences, Government of the Russian Federation [2013-220-04-157]
- Swedish Research Council [621-2004-4039, 621-2007-4631, 621-2013-5297]
- US National Oceanic and Atmospheric Administration (Siberian Shelf Study)
- Russian Foundation of Basic Research [08-05-13572, 13-05-12028, 13-05-12041]
- Swedish Polar Research Secretariat
- US National Science Foundation [OPP ARC 0909546]
- President Grants for Government Support of Young Scientists of the Russian Federation [2575.2014.5]
- EU [PIEF-GA-2011-300259]
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Compositional studies of organic matter on the East Siberian Arctic Shelf (ESAS) suggest that different terrestrial carbon pools have different propensities for transport and/or degradation. The current study combined laboratory-based microbial degradation experiments with earlier published degradation-diagnostic composition of several classes of terrestrial biomarkers on the same sediments to investigate differences and driving forces of terrestrial organic matter (TerrOM) degradation in two biogeochemically-contrasting regimes of the ESAS. The incubation-based anaerobic degradation rates were consistently higher (by average factor of 6) in the East Siberian Sea Kolyma Paleoriver Channel (ESS-KPC) (15 mu mol CO2 g OC-1 day(-1)) compared to the Laptev Sea Buor-Khaya Bay (LS-BKB) (2.4 mu mol CO2 g OC-1 day(-1)). The reported molecular markers show similarities between the terrestrial carbon pools in the two systems, but impose contrasting degradation regimes in combination with the incubation results. For the LS-BKB, there was a strong relationship between the degradation rates and the three lignin phenol-based degradation proxies (r(2) = 0.93-0.96, p < 0.01, linear regression) and two wax lipid-based degradation proxies (r(2) = 0.71 and 0.66, p < 0.05, linear regression). In contrast, for the ESS-KPC system, there was no relationship between incubation-based degradation rates and molecular marker-based degradation status of TerrOM. A principal component analysis indicated that short-chain fatty acids and dicarboxylic acids from CuO oxidation are mainly of terrestrial origin in the LS-BKB, but mainly of marine origin in the ESS-KPC. Hence, the microbial degradation in the western (LS-BKB) system appears to be fueled by TerrOM whereas the eastern (ESS-KPC) system degradation appears to be driven by MarOM. By combining molecular fingerprinting of TerrOM degradation state with laboratory-based degradation studies on the same ESAS sediments, a picture evolves of two distinctly different modes of TerrOM degradation in different parts of the ESAS system. (C) 2014 Elsevier B.V. All rights reserved.
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