@article {2738,
	title = {Remobilization of old permafrost carbon to Chukchi Sea sediments during the end of the last deglaciation},
	journal = {Global Biogeochemical Cycles},
	year = {2018},
	month = {Jan-12-2019},
	abstract = {Climate warming is expected to destabilize permafrost carbon (PF-C) by thaw-erosion and deepening of the seasonally thawed active layer and thereby promote PF-C mineralization to CO2 and CH4. A similar PF-C remobilization might have contributed to the increase in atmospheric CO2 during deglacial warming after the last glacial maximum. Using carbon isotopes and terrestrial biomarkers (Δ14C, δ13C, and lignin phenols), this study quantifies deposition of terrestrial carbon originating from permafrost in sediments from the Chukchi Sea (core SWERUS-L2-4-PC1). The sediment core reconstructs remobilization of permafrost carbon during the late Aller{\o}d warm period starting at 13,000 cal years before present (BP), the Younger Dryas, and the early Holocene warming until 11,000 cal years BP and compares this period with the late Holocene, from 3,650 years BP until present. Dual-carbon-isotope-based source apportionment demonstrates that Ice Complex Deposit{\textemdash}ice- and carbon-rich permafrost from the late Pleistocene (also referred to as Yedoma){\textemdash}was the dominant source of organic carbon (66 {\textpm} 8\%; mean {\textpm} standard deviation) to sediments during the end of the deglaciation, with fluxes more than twice as high (8.0 {\textpm} 4.6 g{\textperiodcentered}m-2{\textperiodcentered}year-1) as in the late Holocene (3.1 {\textpm} 1.0 g{\textperiodcentered}m-2{\textperiodcentered}year-1). These results are consistent with late deglacial PF-C remobilization observed in a Laptev Sea record, yet in contrast with PF-C sources, which at that location were dominated by active layer material from the Lena River watershed. Release of dormant PF-C from erosion of coastal permafrost during the end of the last deglaciation indicates vulnerability of Ice Complex Deposit in response to future warming and sea level changes.},
	keywords = {carbon isotope, climate change feedback, coastal erosion, Deglaciation, past carbon cycling, permafrost},
	issn = {0886-6236},
	doi = {10.1029/2018GB005969},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2018GB005969https://onlinelibrary.wiley.com/doi/pdf/10.1029/2018GB005969https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1029\%2F2018GB005969https://onlinelibrary.wiley.com/doi/pdf/10.1029/2018GB005969},
	author = {Martens, Jannik and Wild, Birgit and Pearce, Christof and Tesi, Tommaso and Andersson, August and Broder, Lisa and O{\textquoteright}Regan, Matt and Jakobsson, Martin and Sk{\"o}ld, Martin and Gemery, Laura and Cronin, Thomas M. and Semiletov, Igor and Dudarev, Oleg V. and Gustafsson, {\"O}rjan}
}
@article {2882,
	title = {Carbon geochemistry of plankton-dominated samples in the Laptev and East Siberian shelves: contrasts in suspended particle composition},
	journal = {Ocean Science},
	volume = {13},
	year = {2017},
	month = {Jan-01-2017},
	pages = {735 - 748},
	abstract = {Recent Arctic studies suggest that sea ice decline and permafrost thawing will affect phytoplankton dynamics and stimulate heterotrophic communities. However, in what way the plankton composition will change as the warming proceeds remains elusive. Here we investigate the chemical signature of the plankton-dominated fraction of particulate organic matter (POM) collected along the Siberian Shelf. POM (> 10 {\textmu}m) samples were analysed using molecular biomarkers (CuO oxidation and IP25) and dual-carbon isotopes (δ13C and Δ14C). In addition, surface water chemical properties were integrated with the POM (> 10 {\textmu}m) dataset to understand the link between plankton composition and environmental conditions.

δ13C and Δ14C exhibited a large variability in the POM (> 10 {\textmu}m) distribution while the content of terrestrial biomarkers in the POM was negligible. In the Laptev Sea (LS), δ13C and Δ14C of POM (> 10 {\textmu}m) suggested a heterotrophic environment in which dissolved organic carbon (DOC) from the Lena River was the primary source of metabolisable carbon. Within the Lena plume, terrestrial DOC probably became part of the food web via bacteria uptake and subsequently transferred to relatively other heterotrophic communities (e.g. dinoflagellates). Moving eastwards toward the sea-ice-dominated East Siberian Sea (ESS), the system became progressively more autotrophic. Comparison between δ13C of POM (> 10 {\textmu}m) samples and CO2aq concentrations revealed that the carbon isotope fractionation increased moving towards the easternmost and most productive stations.

In a warming scenario characterised by enhanced terrestrial DOC release (thawing permafrost) and progressive sea ice decline, heterotrophic conditions might persist in the LS while the nutrient-rich Pacific inflow will likely stimulate greater primary productivity in the ESS. The contrasting trophic conditions will result in a sharp gradient in δ13C between the LS and ESS, similar to what is documented in our semi-synoptic study.},
	doi = {10.5194/os-13-735-2017},
	url = {https://os.copernicus.org/articles/13/735/2017/},
	author = {Tesi, Tommaso and Geibel, Marc C. and Pearce, Christof and Panova, Elena and Vonk, Jorien E. and Karlsson, Emma and Salvado, Joan A. and Krus{\r a}, Martin and Broder, Lisa and Humborg, Christoph and Semiletov, Igor and Gustafsson, {\"O}rjan}
}
@article {2572,
	title = {Fate of terrigenous organic matter across the Laptev Sea from the mouth of the Lena River to the deep sea of the Arctic interior},
	journal = {Biogeosciences},
	volume = {13},
	year = {2016},
	month = {Jan-01-2016},
	pages = {5003 - 5019},
	abstract = {Ongoing global warming in high latitudes may cause an increasing supply of permafrost-derived organic carbon through both river discharge and coastal erosion to the Arctic shelves. Mobilized permafrost carbon can be either buried in sediments, transported to the deep sea or degraded to CO2 and outgassed, potentially constituting a positive feedback to climate change.

This study aims to assess the fate of terrigenous organic carbon (TerrOC) in the Arctic marine environment by exploring how it changes in concentration, composition and degradation status across the wide Laptev Sea shelf. We analyzed a suite of terrestrial biomarkers as well as source-diagnostic bulk carbon isotopes (δ13C, Δ14C) in surface sediments from a Laptev Sea transect spanning more than 800 km from the Lena River mouth (< 10 m water depth) across the shelf to the slope and rise (2000{\textendash}3000 m water depth). These data provide a broad view on different TerrOC pools and their behavior during cross-shelf transport. The concentrations of lignin phenols, cutin acids and high-molecular-weight (HMW) wax lipids (tracers of vascular plants) decrease by 89{\textendash}99 \% along the transect. Molecular-based degradation proxies for TerrOC (e.g., the carbon preference index of HMW lipids, the HMW acids / alkanes ratio and the acid / aldehyde ratio of lignin phenols) display a trend to more degraded TerrOC with increasing distance from the coast. We infer that the degree of degradation of permafrost-derived TerrOC is a function of the time spent under oxic conditions during protracted cross-shelf transport. Future work should therefore seek to constrain cross-shelf transport times in order to compute a TerrOC degradation rate and thereby help to quantify potential carbon{\textendash}climate feedbacks.},
	doi = {10.5194/bg-13-5003-201610.5194/bg-13-5003-2016},
	url = {http://www.biogeosciences.net/13/5003/2016},
	author = {Broder, Lisa and Tesi, Tommaso and Salvad?, Joan A. and Semiletov, Igor P. and Dudarev, Oleg V. and Gustafsson, ?rjan}
}
@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}
}
