Spatial Variability and Factors Influencing the Air-Sea N2O Flux in the Bering Sea, Chukchi Sea and Chukchi Abyssal Plain

Abstract

The concentrations of the ozone-depleting greenhouse gas nitrous oxide (N2O) in the upper 300 m of the Subarctic and Arctic Oceans determined during the 5th Chinese National Arctic Research Expedition were studied. The surface water samples revealed that the study area could be divided into three regions according to the distribution of dissolved N2O in the surface water, namely, the Aleutian Basin (52° N-60° N), continental shelf (60° N-73° N) and Canadian Basin (north of 73° N), with N2O in the surface water in equilibrium, oversaturated and undersaturated relative to the atmosphere, respectively. The influences of physical and chemical processes, such as eddy diffusion and sedimentary emissions, beneath the surface layer are discussed. The results of a flux evaluation show that the Aleutian Basin may be a weak N2O source of approximately 0.46 ± 0.1 μmol.m-2.d1,and the continental shelf acts as a strong N2O source of approximately 8.2 ± 1.4 μmol.m-2.d1. By contrast, the Chukchi Abyssal Plain (CAP) of the Canadian Basin is at least a temporal N2O sink with a strength of approximately -10.2 ± 1.4 μmol.m-2.d-1.