Past and active biogeochemical processes in the Kveithola trough (NW Barents Sea)

The Arctic Ocean plays a key role in sequestrating the carbon dioxide (the greenhouse gas mainly responsible of global climate change) from the atmosphere. However, the melting of sea ice and the release of the huge amounts of methane stored in Arctic marine sediments and permafrost have uncertain feedbacks on the Arctic marine carbon cycle. Therefore, in order to refine the future climate modelling, it is of primary importance to promote regional studies on carbon dynamics in the Arctic areas. In following this approach, studies on the interaction of carbon with chemical elements like nitrogen and sulphur in marine sediments are fundamental to the understanding of the biogeochemical cycling of these elements. This research is focused on better defining the carbon-related biogeochemical processes occurring in post-glacial sediments collected from the Kveithola trough, a glacigenic depression located at the boundary of the NW Barents Sea’s continental margin. The Kveithola trough is influenced by strong marine bottom currents, but its inner part, where active methane seepages have been recently detected, appears today as an apparently stagnant and possibly chemosynthetic environment. Thus, in order to give a contribution in clarifying what can be the local and global impact of this kind of environment in terms of carbon cycle, the aim of this PhD project was to investigate past and active dynamics of sedimentary carbon, nitrogen and sulphur in this depositional system.