Stable carbon isotopes as tracers for benthic sources of dissolved inorganic carbon in the Eastern North Sea: The Skagerrak area

Marine sediments may act as a sink for carbon. Substrate and electron donor availabilities, sedimentology, as well as biological activity may influence the carbon cycling, impacting the release of TA and DIC. The North Sea is a highly dynamic system with shallow tidal areas and fresh water tributaries delivering nutrients and dissolved carbon. For the southern part, benthic DIC sources have been identified, with tidal areas being further hot spots, some being impacted by submarine fresh water discharge. The Skagerrak provides the unique opportunity of studying benthic DIC production under the impact of different dominant electron acceptors. Potential transformation of carbonates may impact release of TA and DIC. Here, we focused on the role of different electron acceptors in sediments from the North Sea, with a special focus on the Skagerrak. The pelagic and benthic system was investigated for the DIC source function and carbon storage capacity. The carbon (and oxygen) isotope composition of dissolved and solid phases was used to understand the specific biogeochemical processes dominating benthic mineralization and carbonate dissolution. Besides physical in-situ parameters, nutrients, and the stable isotope (H, C, O) composition were analyzed by ICP-OES, nutrient analyzer, gas irmMS, and CRDS techniques.

The present study was supported by the BMBF project COOLSTYLE as part of CARBOSTORE, and by Leibniz IOW.