Nitrous oxide emissions from eastern boundary ecosystems: case studies from the Peru and Benguela upwelling regions

The role of nitrous oxide (N2O) as a greenhouse gas and major ozone-depleting substance in the troposphere is well known. Since the ocean accounts for one third of the natural N2O source to the atmosphere, it’s crucial to investigate its distribution and emissions. Although oxygen minimum zones and the associated coastal upwelling bands along the eastern boundaries of Pacific and Atlantic oceans are key sites of production, consumption and exchange of N2O across the air-sea interface, still most emission estimates rely on extrapolations of open ocean values. Here we present the first comprehensive data sets of surface dissolved and atmospheric N2O measurements collected during several expeditions to the Peruvian and Benguela upwelling regions. By using high-resolution surface N2O measurements and vertical profiles of N2O and relevant biogeochemical parameters, we show that subsurface production in conjunction with vertical transport/mixing leads to enhanced supersaturations and extremely high N2O emissions to the atmosphere