TY - JOUR T1 - Siberian Arctic black carbon sources constrained by model and observation JF - Proceedings of the National Academy of Sciences Y1 - 2017 A1 - Winiger, Patrik A1 - Andersson, August A1 - Eckhardt, Sabine A1 - Stohl, Andreas A1 - Semiletov, Igor P. A1 - Dudarev, Oleg V. A1 - Charkin, Alexander A1 - Shakhova, Natalia A1 - Klimont, Zbigniew A1 - Heyes, Chris A1 - Gustafsson, Örjan KW - Arctic haze KW - atmospheric transport modeling KW - carbon isotopes KW - Climate change KW - emission inventory AB - 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–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. VL - 114 UR - 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 IS - 7 ER - TY - JOUR T1 - Preferential burial of permafrost-derived organic carbon in Siberian-Arctic shelf waters JF - JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS Y1 - 2014 A1 - Vonk, Jorien E. A1 - Semiletov, Igor P. A1 - Dudarev, Oleg V. A1 - Eglinton, Timothy I. A1 - Andersson, August A1 - Shakhova, Natalia A1 - Charkin, Alexander A1 - Heim, Birgit A1 - Gustafsson, Örjan KW - biomarkers KW - carbon KW - permafrost KW - radiocarbon AB - 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. VL - 119 ER -