N2O dynamics in the western Arctic Ocean during the summer of 2017

Abstract

The western Arctic Ocean (WAO) has experienced increased heat transport into the region, sea-ice reduction, and changes to the WAO nitrous oxide (N₂O) cycles from greenhouse gases. We investigated WAO N₂O dynamics through an intensive and precise N₂O survey during the open-water season of summer 2017. The effects of physical processes (i.e., solubility and advection) were dominant in both the surface (0–50 m) and deep layers (200–2200 m) of the northern Chukchi Sea with an under-saturation of N₂O. By contrast, both the surface layer (0–50 m) of the southern Chukchi Sea and the intermediate (50–200 m) layer of the northern Chukchi Sea were significantly influenced by biogeochemically derived N₂O production (i.e., through nitrification), with N₂O over-saturation. During summer 2017, the southern region acted as a source of atmospheric N₂O (mean: + 2.3 ± 2.7 μmol N₂O m⁻² day⁻¹), whereas the northern region acted as a sink (mean − 1.3 ± 1.5 μmol N₂O m⁻² day⁻¹). If Arctic environmental changes continue to accelerate and consequently drive the productivity of the Arctic Ocean, the WAO may become a N₂O “hot spot”, and therefore, a key region requiring continued observations to both understand N₂O dynamics and possibly predict their future changes.