@article {2698, title = {Permafrost Organic Carbon Mobilization From the Watershed to the Colville River Delta: Evidence From 14C Ramped Pyrolysis and Lignin Biomarkers}, journal = {Geophysical Research Letters}, volume = {44}, year = {2017}, month = {Apr-11-2019}, pages = {11,491 - 11,500}, abstract = {The deposition of terrestrial-derived permafrost particulate organic carbon (POC) has been recorded in major Arctic river deltas. However, associated transport pathways of permafrost POC from the watershed to the coast have not been well constrained. Here we utilized a combination of ramped pyrolysis-oxidation radiocarbon analysis (RPO 14C) along with lignin biomarkers, to track the linkages between soils and river and delta sediments. Surface and deep soils showed distinct RPO thermographs which may be related to degradation and organo-mineral interaction. Soil material in the bed load of the river channel was mostly derived from deep old permafrost. Both surface and deep soils were transported and deposited to the coast. Hydrodynamic sorting and barrier island protection played important roles in terrestrial-derived permafrost POC deposition near the coast. On a large scale, ice processes (e.g., ice gauging and strudel scour) and ocean currents controlled the transport and distribution of permafrost POC on the Beaufort Shelf.}, keywords = {Arctic, carbon cycling, Colville River, Lignin, permafrost, pyrolysis}, issn = {0094-8276}, doi = {10.1002/grl.v44.2210.1002/2017GL075543}, url = {https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017GL075543}, author = {Zhang, Xiaowen and Bianchi, Thomas S. and Cui, Xingqian and Rosenheim, Brad E. and Ping, Chien-Lu and Hanna, Andrea J. M. and Kanevskiy, Mikhail and Schreiner, Kathryn M. and Allison, Mead A.} } @article {2573, title = {Historical records of organic matter supply and degradation status in the East Siberian Sea}, journal = {Organic Geochemistry}, volume = {91}, year = {2016}, month = {Jan-01-2016}, pages = {16 - 30}, abstract = {Destabilization and degradation of permafrost carbon in the Arctic regions could constitute a positive feedback to climate change. A better understanding of its fate upon discharge to the Arctic shelf is therefore needed. In this study, bulk carbon isotopes as well as terrigenous and marine biomarkers were used to construct two centennial records in the East Siberian Sea. Differences in topsoil and Pleistocene Ice Complex Deposit permafrost concentrations, modeled using δ13C and Δ14C, were larger between inner and outer shelf than the changes over time. Similarly, lignin-derived phenol and cutin acid concentrations differed by a factor of ten between the two stations, but did not change significantly over time, consistent with the dual-carbon isotope model. High molecular weight (HMW) n-alkane and n-alkanoic acid concentrations displayed a smaller difference between the two stations (factor of 3{\textendash}6). By contrast, the fraction for marine OC drastically decreased during burial with a half-life of 19{\textendash}27 years. Vegetation and degradation proxies suggested supply of highly degraded gymnosperm wood tissues. Lipid Carbon Preference Index (CPI) values indicated more extensively degraded HMW n-alkanes on the outer shelf with no change over time, whereas n-alkanoic acids appeared to be less degraded toward the core top with no large differences between the stations. Taken together, our results show larger across-shelf changes than down-core trends. Further investigation is required to establish whether the observed spatial differences are due to different sources for the two depositional settings or, alternatively, a consequence of hydrodynamic sorting combined with selective degradation during cross-shelf transport.}, keywords = {210Pb, Arctic, East Siberian Arctic Shelf, HMW wax lipids, Lignin, Monte Carlo, δ13C, Δ14C}, issn = {01466380}, doi = {10.1016/j.orggeochem.2015.10.008}, url = {https://doi.org/10.1016/j.orggeochem.2015.10.008}, author = {Broder, Lisa and Tesi, Tommaso and Andersson, August and Eglinton, Timothy I. and Semiletov, Igor P. and Dudarev, Oleg V. and Roos, Per and Gustafsson, ?rjan} }