N2O Emissions from the Eastern Tropical Indian Ocean

Nitrous oxide (N₂O) is a potent greenhouse gas and the most important stratospheric ozone-depleting compound. While global efforts in the oceanographic community have been undertaken over the past decades, there are still marine areas which remain vastly undersampled, adding large uncertainties to emission estimates of N₂O. Writing in Geophysical Research Letters, Sommer and colleagues present the results of the hitherto largest high‐resolution survey of surface water N₂O concentrations and air‐sea fluxes in the region. They show significant spatial and temporal variability in N₂O concentrations driven by upwelling, riverine inputs and monsoonal influence. Furthermore, their observations indicate that the northern Bay of Bengal acts as a hotspot for N₂O emissions, while salinity‐driven stratification limited emissions in other areas of the region. The authors estimate that, overall, the Bay of Bengal contributes 0.9%–1.5% to global oceanic N₂O emissions, which is lower than comparable low-oxygen environments.

Reference: Sommer, M., Bange, H.W., Eisnecker, P., et al. (2025). N₂O emissions from the eastern tropical Indian Ocean. Geophys. Res. Lett., 52, e2025GL117627.
https://doi.org/10.1029/2025GL117627