Sunlight drives the abiotic formation of nitrous oxide in fresh and marine waters

2025/03/13 by Elizabeth León‐Palmero, Rafael Morales‐Baquero, Bo Thamdrup +2 · 1 voice · 5 citations
Earth and Planetary Sciences · Environmental Science · #Isotope Analysis in Ecology #Marine and coastal ecosystems #Water Quality Monitoring and Analysis

paper · doi:10.1126/science.adq0302

openalex publication_date 2025/03/13 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

Nitrous oxide (N 2 O) 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 N 2 O production pathway not previously considered in greenhouse gas budgets, which we name photochemodenitrification. Sunlight induces substantial and consistent N 2 O production under oxic abiotic conditions in fresh and marine waters. We measured photochemical N 2 O 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 N 2 O production was strongly correlated to the radiation dose. Photochemodenitrification exceeded biological N 2 O production in surface waters. Although previously overlooked, this process may contribute considerably to global N 2 O emissions through its occurrence in fresh and marine surface waters.

Citations

• A comprehensive quantification of global nitrous oxide sources and sinks
• Climate Change 2021 – The Physical Science Basis
• A Synthesis of Global Coastal Ocean Greenhouse Gas Fluxes

Cited by

• Denitrification as the dominant process in nitrous oxide production in the water column of two eutrophic reservoirs
• Mechanistic understanding of nitrate reduction as the dominant production pathway of nitrous oxide in marine oxygen minimum zones
• Biogeochemical shifts during Arctic spring: potential reduction of CH 4 and N 2 O emissions driven by surfactants in the sea-surface microlayer
• Nitrous oxide sources, mechanisms and mitigation
• A novel laser-based spectroscopic method reveals the isotopic signatures of nitrous oxide produced by eukaryotic and prokaryotic phototrophs in darkness

Discussions

• Slowly we enter surreal terrain! Direct sunlight triggers a photochemical reaction which produces N2O a highly potent GHG from freshwater systems and the oceans... Seems to be more important than f [bsky, 5 points, 0 comments]

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