@article {2467,
	title = {Siberian Arctic black carbon sources constrained by model and observation},
	journal = {Proceedings of the National Academy of Sciences},
	volume = {114},
	year = {2017},
	month = {Feb-02-2018},
	pages = {E1054 - E1061},
	abstract = {Black carbon (BC) in haze and deposited on snow and ice can have strong effects on the radiative balance of the Arctic. There is a geographic bias in Arctic BC studies toward the Atlantic sector, with lack of observational constraints for the extensive Russian Siberian Arctic, spanning nearly half of the circum-Arctic. Here, 2 y of observations at Tiksi (East Siberian Arctic) establish a strong seasonality in both BC concentrations (8 ng.m-3 to 302 ng.m-3) and dual-isotope{\textendash}constrained sources (19 to 73\% contribution from biomass burning). Comparisons between observations and a dispersion model, coupled to an anthropogenic emissions inventory and a fire emissions inventory, give mixed results. In the European Arctic, this model has proven to simulate BC concentrations and source contributions well. However, the model is less successful in reproducing BC concentrations and sources for the Russian Arctic. Using a Bayesian approach, we show that, in contrast to earlier studies, contributions from gas flaring (6\%), power plants (9\%), and open fires (12\%) are relatively small, with the major sources instead being domestic (35\%) and transport (38\%). The observation-based evaluation of reported emissions identifies errors in spatial allocation of BC sources in the inventory and highlights the importance of improving emission distribution and source attribution, to develop reliable mitigation strategies for efficient reduction of BC impact on the Russian Arctic, one of the fastest-warming regions on Earth.},
	keywords = {Arctic haze, atmospheric transport modeling, carbon isotopes, Climate change, emission inventory},
	issn = {0027-8424},
	doi = {10.1073/pnas.1613401114},
	url = {http://www.pnas.org/lookup/doi/10.1073/pnas.1613401114https://syndication.highwire.org/content/doi/10.1073/pnas.1613401114http://www.pnas.org/syndication/doi/10.1073/pnas.1613401114},
	author = {Winiger, Patrik and Andersson, August and Eckhardt, Sabine and Stohl, Andreas and Semiletov, Igor P. and Dudarev, Oleg V. and Charkin, Alexander and Shakhova, Natalia and Klimont, Zbigniew and Heyes, Chris 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}
}
@article { ISI:000368907500001,
	title = {Multimolecular tracers of terrestrial carbon transfer across the pan-Arctic: C-14 characteristics of sedimentary carbon components and their environmental controls},
	journal = {GLOBAL BIOGEOCHEMICAL CYCLES},
	volume = {29},
	number = {{11}},
	year = {2015},
	month = {NOV},
	pages = {1855-1873},
	type = {Article},
	abstract = {Distinguishing the sources, ages, and fate of various terrestrial organic carbon (OC) pools mobilized from heterogeneous Arctic landscapes is key to assessing climatic impacts on the fluvial release of carbon from permafrost. Through molecular C-14 measurements, including novel analyses of suberin- and/or cutin-derived diacids (DAs) and hydroxy fatty acids (FAs), we compared the radiocarbon characteristics of a comprehensive suite of terrestrial markers (including plant wax lipids, cutin, suberin, lignin, and hydroxy phenols) in the sedimentary particles from nine major arctic and subarctic rivers in order to establish a benchmark assessment of the mobilization patterns of terrestrial OC pools across the pan-Arctic. Terrestrial lipids, including suberin-derived longer-chain DAs (C-24,C-26,C-28), plant wax FAs (C(24,26,2)8), and n-alkanes (C-27,C-29,C-31), incorporated significant inputs of aged carbon, presumably from deeper soil horizons. Mobilization and translocation of these {\textquoteleft}{\textquoteleft}old{{\textquoteright}{\textquoteright}} terrestrial carbon components was dependent on nonlinear processes associated with permafrost distributions. By contrast, shorter-chain (C-16,C-18) DAs and lignin phenols (as well as hydroxy phenols in rivers outside eastern Eurasian Arctic) were much more enriched in C-14, suggesting incorporation of relatively young carbon supplied by runoff processes from recent vegetation debris and surface layers. Furthermore, the radiocarbon content of terrestrial markers is heavily influenced by specific OC sources and degradation status. Overall, multitracer molecular C-14 analysis sheds new light on the mobilization of terrestrial OC from arctic watersheds. Our findings of distinct ages for various terrestrial carbon components may aid in elucidating fate of different terrestrial OC pools in the face of increasing arctic permafrost thaw.},
	issn = {0886-6236},
	doi = {10.1002/2015GB005204},
	author = {Feng, Xiaojuan and Gustafsson, {\"O}rjan and Holmes, R. Max and Vonk, Jorien E. and van Dongen, Bart E. and Semiletov, Igor P. and Dudarev, Oleg V. and Yunker, Mark B. and Macdonald, Robie W. and Wacker, Lukas and Montlu{\c c}on, Daniel B. and Eglinton, Timothy I.}
}
@article { ISI:000348452800012,
	title = {Preferential burial of permafrost-derived organic carbon in Siberian-Arctic shelf waters},
	journal = {JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS},
	volume = {119},
	number = {{12}},
	year = {2014},
	month = {DEC},
	pages = {8410-8421},
	type = {Article},
	abstract = {The rapidly changing East Siberian Arctic Shelf (ESAS) receives large amounts of terrestrial organic carbon (OC) from coastal erosion and Russian-Arctic rivers. Climate warming increases thawing of coastal Ice Complex Deposits (ICD) and can change both the amount of released OC, as well as its propensity to be converted to greenhouse gases (fueling further global warming) or to be buried in coastal sediments. This study aimed to unravel the susceptibility to degradation, and transport and dispersal patterns of OC delivered to the ESAS. Bulk and molecular radiocarbon analyses on surface particulate matter (PM), sinking PM and underlying surface sediments illustrate the active release of old OC from coastal permafrost. Molecular tracers for recalcitrant soil OC showed ages of 3.4-13 C-14-ky in surface PM and 5.5-18 C-14-ky in surface sediments. The age difference of these markers between surface PM and surface sediments is larger (i) in regions with low OC accumulation rates, suggesting a weaker exchange between water column and sediments, and (ii) with increasing distance from the Lena River, suggesting preferential settling of fluvially derived old OC nearshore. A dual-carbon end-member mixing model showed that (i) contemporary terrestrial OC is dispersed mainly by horizontal transport while being subject to active degradation, (ii) marine OC is most affected by vertical transport and also actively degraded in the water column, and (iii) OC from ICD settles rapidly and dominates surface sediments. Preferential burial of ICD-OC released into ESAS coastal waters might therefore lower the suggested carbon cycle climate feedback from thawing ICD permafrost.},
	keywords = {biomarkers, carbon, permafrost, radiocarbon},
	issn = {2169-9275},
	doi = {10.1002/2014JC010261},
	author = {Vonk, Jorien E. and Semiletov, Igor P. and Dudarev, Oleg V. and Eglinton, Timothy I. and Andersson, August and Shakhova, Natalia and Charkin, Alexander and Heim, Birgit and Gustafsson, {\"O}rjan}
}
