Towards an improved organic carbon budget for the western Barents Sea shelf

Abstract. There is generally a lack of knowledge on how marine organic carbon accumulation is linked to vertical export and primary productivity patterns in the Arctic Ocean. Despite the fact that annual primary production in the Arctic has increased as a consequence of shrinking sea ice, its effect on flux, preservation, and accumulation of organic carbon is still not well understood. In this study, a multi-proxy geochemical and organic-sedimentological approach is coupled with organic facies modelling, focusing on regional calculations of carbon cycling and carbon burial on the western Barents Shelf between northern Scandinavia and Svalbard. OF-Mod 3-D, an organic facies modelling software tool, is used to reconstruct and quantify the marine and terrestrial organic carbon fractions and to make inferences about marine primary productivity changes across the marginal ice zone (MIZ). By calibrating the model against an extensive set of sediment surface samples, we improve the Holocene organic carbon budget for ice-free and seasonally ice-covered areas in the western Barents Sea. The results show that higher organic carbon accumulation rates in the MIZ are best explained by enhanced surface water productivity compared to ice-free regions, implying that shrinking sea ice may reveal a significant effect on the overall organic carbon storage capacity of the western Barents Sea shelf.