Wallschuss, S., Granger, J., Bourbonnais, A., Flynn, R.F., Burger, J.M., Pillay, K., Fawcett, S.E. The role of sediments in modulating nitrous oxide production in the Southern Benguela Upwelling System: insights from isotopic tracers. Global Biogeochem Cycles 10.1029/2024GB008463 (2025).
The ocean accounts for ∼20%–30% of global nitrous oxide (N2O) emissions, with coastal upwelling systems estimated to contribute disproportionately to the sea-air flux of this potent greenhouse gas. To investigate the mechanisms of and controls on N2O production in coastal upwelling systems, we measured the concentration and nitrogen and oxygen isotopic composition of N2O (δ15N-N2O and δ18O-N2O) along a cross-shelf transect in the Southern Benguela Upwelling System (SBUS). At the shelf bottom, N2O concentrations increased from the outer shelf toward the shore (11–32 nM) inversely to dissolved oxygen (182 ± 17 to <1 μM) and in concert with the remineralization tracers, apparent oxygen utilization (108 ± 21 to 221 ± 33 μM) and nitrogen (N)-deficit (up to 20.4 μM).
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