Austral summer N₂O sink and source characteristics and their impact factors in Prydz Bay, Antarctica

Abstract

Abstract The ocean, particularly the Southern Ocean, is considered a significant source of atmospheric N 2 O, which is an ozone‐depleting greenhouse gas. However, there are limited data available supporting this conclusion. Thus, this study sampled and analyzed the oceanic N 2 O in Prydz Bay. The results demonstrated that the distribution of N 2 O in this embayment differed between the north and south sides of the Antarctic Slope Front (ASF), corresponding to the different hydrographic characteristics on each side. Although the air to sea N 2 O flux north of the shelf break is ∼−1.20 ± 0.44 μmol m −2 d −1 , the source sink characteristics need to be further constrained because the Circumpolar Deep Water (CDW) may occasionally outcrop over the surface layer. The water masses over the continental shelf south of the shelf break may be a temporary or even a permanent N 2 O sink when sea ice is absent. The air to sea flux south of the shelf break is ∼−3.65 ± 0.95 μmol m −2 d −1 , and the water column is undersaturated with N 2 O, which may result from the deep convection of N 2 O‐undersaturated surface water during the winter. Evidence also suggests that the formation of Antarctic Bottom Water (AABW) may provide a pathway for N 2 O removal from the upper layer at high latitudes.