Stable carbon isotopes of Dissolved Inorganic Carbon (d13CDIC) in the ocean are generally not well understood as they are governed by a complex interplay of biological processes and air-sea exchange. In the Arctic Ocean d13CDIC values are prone to change in the near future with rapidly changing climate conditions. This study provides a baseline to assess the d13CDIC of the Arctic Ocean with a focus on upper to intermediate waters (to ~500 m).Measured d13CDIC values in the Arctic Ocean range from ~ -1 to +2 per mill. In the Eurasian Basin the d13CDIC values lie between ~1 to 1.5 per mill and exhibit little variation within the upper layers. In the Canada Basin d13CDIC values reach 2 per mill in the surface layer, with lowest values of ~ 1 per mill found at ~200 m water depth. At greater depth d13CDIC values range from ~1 to 1.5 per mill within both basins. In the Canada Basin nutrient levels are higher than in the Eurasian Basin and associated variations in d13CDIC are clearly related to biological processes. However, low d13CDIC values in the Canada Basin are also strongly influenced by air-sea exchange processes. The different d13CDIC patterns between the Canada Basin and the Eurasian Basin appear to be linked to differences in transport processes within the Arctic Ocean halocline. The upper layers in the Canadian Basin have direct contributions of waters from the Laptev, East Siberian and Chukchi shelves, which contain elevated fractions of river waters and sea-ice related brines; whereas their counterparts, in the Eurasian Basin, are mostly formed by halocline waters from the Barents and Kara seas. River waters have low d13CDIC of ~ 8 per mill on average, but in the Arctic basins this signal is lost and low d13CDIC values show no correlation to river water fractions contained in the water mass. Also no relation between d13CDIC and sea-ice related brine contribution is apparent.

The dataset is a compilation of stable carbon isotopes of DIC (d13CDIC) in the Actic Ocean. The dataset also contains accompanying data (TS, nutrients, dissolved Oxygen, stable oxygen isotopes (d18O)) used within the publication.

Supplement to: Bauch, Dorothea; Polyak, Leonid; Ortiz, Joseph D (2015): A baseline for the vertical distribution of the stable carbon isotopes of dissolved inorganic carbon (d13CDIC) in the Arctic Ocean. 1(1), 1-13