作者：E. Leon-Palmero, R. Morales-Baquero, B. Thamdrup, C. Loscher and I. Reche

Nitrous oxide (N₂O) is a potent greenhouse gas and the main stratospheric ozone-depleting agent, yet its sources are not well resolved. In this work, we experimentally show a N₂O production pathway not previously considered in greenhouse gas budgets, which we name photochemodenitrification. Sunlight induces substantial and consistent N₂O production under oxic abiotic conditions in fresh and marine waters. We measured photochemical N₂O production rates using isotope tracers and determined that nitrite is the main substrate and that nitrate can also contribute after being photoreduced to nitrite. Additionally, this N₂O production was strongly correlated to the radiation dose. Photochemodenitrification exceeded biological N₂O production in surface waters. Although previously overlooked, this process may contribute considerably to global N₂O emissions through its occurrence in fresh and marine surface waters.

（来源：Science 2025 Vol. 387 Issue 6739 Pages 1198-1203 DOI: 10.1126/science.adq0302）