Abstract
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) (15μmolCO2gOC-1day-1) compared to the Laptev Sea Buor-Khaya Bay (LS-BKB) (2.4μmolCO2gOC-1day-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 (r2=0.93-0.96, p<0.01, linear regression) and two wax lipid-based degradation proxies (r2=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.
Original language | English |
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Pages (from-to) | 11-22 |
Number of pages | 12 |
Journal | Marine Chemistry |
Volume | 170 |
DOIs | |
Publication status | Published - 1 Mar 2015 |
Keywords
- Arctic Ocean
- Coastal shelf
- Continental margin
- CuO oxidation
- Decomposition
- Incubations
- Lignin
- Organic geochemistry
- Organic matter lability
- Permafrost
- Reactivity
- Remineralization
- Sediment
- Terrestrial organic carbon
- Wax lipids
ASJC Scopus subject areas
- Oceanography
- Chemistry(all)
- Environmental Chemistry
- Water Science and Technology